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About Google Book Search Google’s mission is to organize the world’s information and to make it universally accessible and useful. Google Book Search helps readers discover the world’s books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web ai[http: //books . google. com/| igug ‘4 my -_ aise wees ER rr OWT TE Ye a' us * if i : PUBLIC LIE? | . AETOR, LETS TILT v : . we foe Abrasives & Abrasive Wheels Their Nature, Manufacture and Use A COMPLETE TREATISE ON THE MANUFACTURE AND PRACTICAL USE. OF ABRASIVES, ABRASIVE WHEELS AND GRINDING OPERATIONS INCLUDING NATURAL AND ARTIFICIAL ABRASIVES, PRODUCTION AND PREP- ARATION OF ABRASIVES, GRITS, GRADE& AND BONDS, SHARPEN- ING AND GRINDING STONES AND WHEELS, TESTING WHEELS FOR EFFICIENCY, TRUING, REBUSHING AND INSTALLING WHEELS, SAFETY DEVICES, AND DUST-COLLECTING SYSTEMS, COMPLETE EXPOSITION ON SURFACE, EXTERNAL AND INTERNAL GRINDING AND COMPREHENSIVE DATA COVERING THE PHYS- ICAL AND CHEMICAL NATURE OF ABRASIVES IN GENERAL BY FRED B. JACOBS A PRACTICAL HANDBOOK FOR ENGINEERS, FACTORY SUPERINTEN- DENTS, FOUNDRYMEN, SHOP FOREMEN AND MECHANICS IN GENERAL FULLY ILLUSTRATED New York The Norman W. Henley Publishing Company . 2 West 45th Street 1919 — ewer THE NEW YORK PUBLIC LIBRARY “yar Pay § 0 a4 ix ny ASTOR, LENOX AND TILDEN FOUNDATIONS R 1919 L Copyrighted, 1919, by The Norman W. Henley Publishing Company wis Printed in U. S. A. Printing—Presswork and Binding by Harper & Brothers, New York PREFACE THE art of finishing metals by abrasion is one of the oldest mechanical practices in existence, dating from the time prehistoric man discovered that he could fashion his wood and bone implements by rubbing them on rocks of a gritty nature. The grindstone is, without doubt, the oldest form of grinding wheel known. With the early development of the mechanical arts, it was discovered that a sandstone cut in circular shape and mounted upon a revolving shaft, showed higher efficiency than the side of a rock for sharpen- ing and shaping various implements. It is definitely known that grindstones, rotated by power, were used in the manu- facture of armor as early as the year 1570. It is also known that the emery deposits of the Grecian Archipelago were known to the ancients and the value of this abrasive recognized, as many writers of early days referred to emery under various names. In considering some of the mechan- _ ical achievements of the handicraftsmen who worked with metals centuries before the Christian era, it is hard to conceive how they attained so high a degree of perfection without the use of an alumina abrasive for tool- -sharpening purposes. While the practice of fashioning tools and implements by abrasion is in all probability as old as civilization itself, — modern grinding, as we accept this term, is a compara- tively recent development. About half a century ago, the individual workman made his own grinding wheels of glue and emery. The first attempt at precision grinding consisted of finish- ing the chilled iron calender rolls used in the paper-making 5 PREFACE industry. Owing to the hard nature of the material in question, it was a long and tedious process to turn these rolls accurately. The development of the sewing-machine industry in the New England States gave impetus to the development of the grinding-wheel business. As a matter of fact, the first attempts at cylindrical grinding, aside from roll grinding, consisted of finishing parts of the Wilcox & Gibbs sewing machine. The work was done by the Brown & Sharpe Mfg. Co. With the advent of the automobile industry, over twenty years ago, the grinding-wheel business received a fresh impetus as a rapid means was in demand for the accurate finishing of parts. Today, the modern grinding wheel is among the most useful of modern shop accessories. Without it, it would be impossible to maintain the present-day standard of rapid production. In practically every line of metal working, the grinding wheel plays an important part, its usefulness ranging all the way from the rough grinding of castings and forgings to the finishing of accurate surfaces, both plane and cylindrical. In presenting this work, the writer has taken great precaution to make sure that every statement is authentic. Aside from knowledge gained through many years as a journeyman machinist, later supplemented with several years’ experience as a grinding-wheel salesman, many months were spent in collecting data, verifying statements and consulting reliable authorities, both in this country and abroad. . The writer is indebted to the following manufacturers and individuals who cheerfully answered numerous letters and supplied valuable data and photographs: Abrasive Co. The Carborundum Co. American Emery Wheel Works | Chicago Wheel & Mfg. Co. The Blanchard Machine Co. The Cincinnati Milling Machine Brown & Sharpe Mfg. Co. Co. | 6 ~ . PREFACE The Cleveland Stone Co. Norton Grinding Co. Cortland Grinding Wheel Corp. Penton Publishing Co. Detroit Grinding Wheel Co. Pittsburgh Crushed Steel Co. Diamond Machine Co. Pratt & Whitney Co. Farrel Foundry & Machine Co. Metal & Thermit Corp. H. G. Hammett. Hampden Corundum Wheel Co. The Heald Machine Co. Frederick S. Jacobs, data on axe- grinding. Landis Tool Co. Manufacturers Corundum Co., Ltd. Minnesota Mining & Mfg. Co. _’ Newton Machine Tool Works. Norton Co. Fred E. Rogers, editor emeritus of Machinery. Safety Emery Wheel Works. Springfield Grinding Co. Springfield Mfg. Co. Sterling Grinding Wheel Co. B. F. Sturtevant Co. Superior Corundum Wheel Co. United States Geological Survey. Vitrified Wheel Co. Waltham Grinding Wheel Co. Wardwell Mfg. Co. Permission to reprint material by the writer which had been previously published. was granted by the following publishers: Penton Publishing Co., M arine Review. McGraw Hill Co., American Machinist. S. S. Smith Co., The Woodworker. W. R.C Smith Publishing Co., Iron Tradesman. Iron Age Co., The Iron Age. The MacLean Publishing Co., Ltd., Canadian Machinery. The Mines Publishing Co., Ltd., publishers of The Canadian Mining Journal, gave permission to reprint material concerning corundum. June, 1919. FRED B. JACOBS. IT. IIf. IV. CONTENTS PREFACE PAGE 1X NATURAL ABRASIVE SUBSTANCES .. . Loe Pages 13 to 36 Nature of natural abrasives—Where found—History of natural abrasives—Commercial application—Sandstone—Emery—Corun- dum—Garnet — Diamond— Bort diamond — Flint — Quartz—Nat- ural sharpening stones—Arkansas—Washita—Hindustan—Tripoli —Pumice. ARTIFICIAL ABRASIVES . . . . . . . Pages 37 to 64 Various artificial abrasives—Their physical and chemical properties —Their Commercial application—Methods and processes employed in the production of artificial abrasives—Carborundum—Alundum —Aloxite—Boro-Carbone—Oxalumina—Adamite—Crystolon, etc. Relative hardness and abrasive efficiency of various materials— Artificial production of precious stones—Their abrasive properties —Other artificial abrasives and their production—Experimental work—Electro-thermic processes—Production of rouge and crocus —Diamonds and crushed steel—Angular grit. THE MANUFACTURE OF GRINDING WHEELS . . . . Pages 65 to 82 Composition of grinding wheels—Desirable and undesirable proper- ties—Bonds—Shellac—Rubber—Fusible clays—Silicate of soda— Vitrified wheels—Method of producing vitrified wheels—Puddled process—Pressed process—Silicate wheels—Shellac wheels—Rubber wheels—Clay bond used in vitrified wheels—Choice of bonding ma- terial— Wheel-turning—Kiln used—Heating of kiln and work— Cooling of kiln—Dressing wheels—Bushing wheels—Speed tests for wheels—Elastic process—Rubber process. ARTIFICIAL SHARPENING STONES . , . . . . . Pages 83 to 87 Properties of artificial stones—Carborundum stones—Method of manufacture — Bond — Grit — Grade — Finishing — Combination stones—Carborundum rubs. GRITS AND GRADES. . . . . . . Pages 88 to 96 Designation of grits and grades—Mixed grits—Grits of abrasive papers—Standard grades—Wheels—Relation of speed to grade and grit—Wheel speeds for various operations. _ 9 CONTENTS C4AP. . VI. TrEstING WHEELS FoR EFFICIENCY. ... . . . Pages 97 to 114 Selection of wheels—Improper methods of testing—Practical testing methods—lItems to be noted in a wheel test—How to figure result— Formula for finding volume of abrasive material in a wheel—General considerations— Wheel tests. VII. Lasoratory TESTS. ........ . ~~. « Pages 115 to 122 Apparatus and appliances used—Limitations of laboratory tests— Factors to be considered—Laboratory testing machine—Data for test—Work used in testing. VIII. GRINDING WHEEL VS. GRINDSTONES . .. . . Pages 123 to 128 Advantages of natural and artificial abrasive used in wheels—Early use of grindstones—Special work where grindstones are still em- ployed—Action of grinding wheel. IX. THE EcONoMic ADVANTAGE OF USING LARGE WHEELS . Pages 129 to 132 Factors to be considered in choosing a wheel—Comparative price of wheels of various sizes—Advantage of large wheels in certain work —Why large wheels are more efficient. X. TRUING DEVICES FOR GRINDING WHEELS. . . . . Pages 133 to 138 Abrasive action—Tools used in truing wheels—Use of bort and carbonado diamonds in tools—Getting stones in tool—Procedure in truing wheels. XI. RE-BUSHING GRINDING WHEELS. . ... . ._ . Pages 139 to 141 Methods used in bushing wheels—Tools employed—Metals used. XII. SUGGESTIONS TO FOLLOW IN ORDERING GRINDING WHEELS . Pages 142 to 144 Information to be given with grinding-wheel order—Factor govern- ing selection of wheels—How to determine what kind of a wheel should be used—Ordering special wheels. XIII. DesicN or Dust-coLLecTING SysTEMS . .. . Pages 145 to 150 State law requirments—Design of wheel hood—General design— Size of exhaust pipe for different size wheels—Elbows—Collars— Method of erection—Clean-out—Fan—Dust-collector—Exhaust systems. XIV. SAFEGUARDING GRINDING WHEELS. . .. . . Pages 151 to 165 Why wheels break—Cause of accidents—How wheels are packed and tested before leaving factory—Wheel speeds—Mounting wheels properly—What causes wheels to burst—Safety flanges—Work rest —Wheel guards—Grinding on small wheels—Precautions for the workman. 1) CONTENTS CHAP. XV. ABRASIVE PAPERS AND CLOTHS. ... . . ._ . Pages 166 to 175 Abrasive substances used in making abrasive paper—History of abrasive paper—How abrasive paper and cloth is manufactured— Grades of abrasive paper and cloth—Finding percentage of iron in garnet—Testing garnet paper—Paper and cloth abrasive discs— Testing discs for efficiency. XVI. SuRFAcE GRINDING. . . . . . « « .« Pages 176 to 215 Finishing work by surface grinding Development of the surface grinding machine—Finishing locomotive guide bars—Rotary grinding fixture—Wheel speeds—Cuts—Die grinding—How dies are held—Grinding punches—Care of wheels—Magnetic chucks— Demagnetizers—Proper wheel selection for surface grinding—Types of surface-grinding machines—Standard wheel list. “XVII. CyzrnpricaL GRINDING. . . . . . . © . Pages 216 to 242 Cylindrical grinders—Operation of grinders—Driving devices for work—Proper wheel speeds for various metals and work—Traverse feed—Depth of cut—Roughing and finishing cuts—Sparking— Backrest and steadyrests—Lubrication of work—Lubricating com pounds and mixtures—Dressing and truing wheels while on the grinder—Chatter marks and their remedy—Selection of proper wheels for use on cylindrical grinders—Universal grinders—Grinding tapers—Various operations on universal grinder. XVIII. INTERNAL GRINDING . .... . . . « Pages 243 to 262 Internal grinding machines—Internal grinding on universal grinder —Setting up universal grinder for internal work—Grinding double tapers—Automatic grinders—Grinding holes in spur and bevel gears —Chucks—Wet and dry grinding—Proper speeds—Selection of wheels—Operating of cylinder grinders—Cylinder grinding. XIX. SPECIAL GRINDING OPERATIONS. . . . . . . Pages 263 to 289 _ Grinding calender rolls—Special grinding machines—Roll grinders and roll grinding—Corrugating flour-mill rolls—Grinding crank- shafts—Grinding cam shafts—Locomotive valve gears. XX. CUTTER SHARPENING. . . . . « « Pages 290 to 307 Machines employed for cutter grinding Adjustments and attach- ments on cutter grinders—Grinding spiral cutters—General opera- tion of cutter grinders—Selection of wheels—Speeds—Depth of cut. XXI. Saw SHARPENING. ... » 2 « « « « « Pages 308 to 321 Band saws and circular saws—Operation of band-saw sharpening machine—Sharpening band saws—Grinding in new teeth—Care of machine—Selection of wheels for saw gumming—Machines for sharpening cold saws—Sharpening hack-saw blades. II CHAPTER ONE NATURAL ABRASIVE SUBSTANCES Nature of natural abrasives—Where found—History of natural abrasives —Commercial application—Sandstone— Emery —Corundum—Garnet— Diamond—Bort diamond—Flint—Quartz—Natural sharpening stones— Arkansas—Washita—Hindustan—Tripoli—Pumice. ATURAL abrasives are being found in many parts of the world. In a broad sense, the list includes all minerals capable of abrasive action, but from a commercial point of view, the principal natural abrasives are sandstone, emery, corundum and garnet. The diamond is, of course, a natural abrasive; indeed it is the hardest of all, but it is needless to state that its rarity excludes it from the list of commercial abrasive materials. - SANDSTONE The first abrasive to be used in the form of a wheel was in all probability sandstone. The use of a revolving stone for sharpening purposes is so old that the beginning is lost in antiquity. It seems reasonable to believe, however, that the artificers of early civilization borrowed the idea of a revolving sharpening stone from the crude mills used many centuries ago for the grinding of grain. Sandstone is a very curious mineral, indeed, as it consists of uniform grains of sand (generally quartz with a small percentage of feldspar and mica) firmly cemented together with silica. Some varieties of sandstone, the Craigleith stones used in the cut-glass industry for instance, are prac- tically pure silica, this material often running as high as 98 per cent. Sandstone is found in many parts of the 13 ABRASIVES AND ABRASIVE WHEELS world and in this country the most extensive deposits that _ are worked for the production of grindstones are in Ohio and Michigan. The Gray Canyon quarry at Amherst, Ohio, is classed as the Jargest quarry in the world. Sand- . stones are of various colors, these being derived from impurities that penetrated the mass during the formative stage. Pure siliceous stones are white, or pale yellow in cases where small quantities of iron oxide are present. A red tinge is generally due to hematite, yellow to limonite, green to glauconite, gray to clay and shale, and black, as observed in black Graileith stones for example, to manganese dioxide. The average layman is of the opinion that all grindstones are alike, but this supposition is erroneous for, in forming the sandstone of which the grindstones of commerce are made, it would appear that Nature anticipated the wants of man by providing not only several grits to choose from, but several grades as well. To insure an ample supply of grits and grades, grindstone manufacturers generally control holdings in various localities. Before the advent of the grinding wheel, sandstone was the only abrasive to be. used in the form of a wheel. Its use was, of course, limited, as practically the only grinding done in the early manufacturing days consisted of tool sharpening. Grindstones are used at present in Jarge quan- tities for sharpening edge tools, cutlery, etc., often in preference to modern abrasive wheels. Many reasons for this practice are explained later, under the heading, Grind- stones Vs. Grinding Wheels. EMERY Emery, which in reality is an impure form of corundum, has been known as an abrasive from very remote times. Its value as an abrasive was known to the ancient Greeks. Dioscorides referred to it as a stone used in gem engraving. ‘Emery was also known to the Romans, Pliny and othe ) 14 \ EMERY writers referring to it as naxium. There is also scme authority for the statement that in the ‘‘adamant”’ of the Old Testament, translated from the Hebrew, shamir referred to emery ore. The principal emery deposits that furnish the emery of commerce are located in Asia Minor, in the basins of the Sarabat and Mender rivers. In the Grecian Archipelago, the best known of these deposits are located on the Island of Naxos, and in this country near Chester, Mass., and Peekskill, N. Y. Emery looks like iron ore, being of a dense, granular con- struction. Its luster is metallic, while its color runs from blue-black to black. It can truly be called a unique mineral, as it is a mixture of alumina oxide and iron as magnetite and hematite. At one time, all of the world’s supply of emery came from the Grecian Isles, principally Naxos, but during the year 1847 Dr. J. Lawrence Smith located im- portant emery deposits in Asia Minor. Dr. Smith’s dis- coveries proved to be of great benefit to the emery-consum- ing trade owing to the fact that the price of emery was materially reduced. Asia Minor or Turkish emery, as the new material was called, at once became popular, as it proved to be an efficient abrasive for many purposes. Turkish emery always occurs in limestone or marble, the deposits resting on gneiss, schist and mica slates, while Naxos emery is generally found in limestone beds, being associated with crystalline schists. One noticeable dif- ference between the emery of the Grecian Archipelago and that of Asia Minor is that in the former are numerous small particles of mica which are seldom observed in the latter. The mining of both Turkish and Naxos emery is generally carried on in a very primitive manner. Being near the sur- face, the ore is easily removed as it is often present in loose boulders. Masses that are too large for transportation to the sea coast, are generally broken into fragments through the process of heating them for a number of hours followed by a sudden cooling with water. This causes the ore to fracture in many places, and, by means of hammer blows, 15 ABRASIVES AND ABRASIVE WHEELS it is an-easy matter to reduce the ore to pieces suitable for transportation. The low cost of mining, together, with moderate transportation costs, accounts for the fact that Turkish emery finds a ready sale in this country in competi- tion with American emery. For the purpose of grinding- wheel manufacture, however, Naxos emery is considered superior to all other kinds as it is the hardest, toughest and most uniform. The foregoing sounds like a broad statement, to be sure, but it is the consensus of opinion expressed by leading grinding-wheel manufacturers who make wheels of emery. The discovery of emery in this country dates back to about the year 1830, at which time a railroad was being built from Boston to the Hudson River. In making a cut near Chester, Mass., a deposit of emery ore was uncovered, which, at the time, was taken for iron ore. As previously stated, emery and iron ore resemble each other closely. Blast furnaces were erected and provision made for working the ore on a moderately large scale. At the first attempt to smelt the ore, however, great difficulties were encountered in separating the iron from the alumina and the deposits were ultimately condemned as too refractory for practical purposes. | . The mine remained idle and almost forgotten for a num- ‘ber of years. In 1864 or thereabout, Dr. H. S. Lucas, realizing the possibilities of working the deposits as a source of abrasive supply to compete with the foreign product, bought the property and began to successfully operate it as an emery mine. Operations have been continued in this district until the present day. The emery in question is associated with amphibolite and serpentine, and, as the veins of ore reach several hundred feet underground, it is necessary to work them by extensive tunneling. Mention should also be made of the emery deposits in New York state in the vicinity of Peekskill. This emery, which is called a spinel emery, does not occur in a continu- ous vein, but in segregated masses, being associated with 16 EMERY morite rocks. In this ore spinel, which is magnesium aluminate, MgAl,o,, furnishes the abrasive agent, since spinel has a relative hardness of 8, as against 9, the hardness of alumina, it is seen that spine] emery is somewhat softer than other varieties of true emery. The value of spinel emery should not be overlooked, however, as it furnishes an efficient polishing material in cases where a very hard and tough abrasive is not desired. The specific gravity of emery varies in different speci- mens from 3.7 to 4.3 and the percentage of alumina oxide from 30 to 70. The abrasive power, sometimes called the effective hardness, is not proportional to the amount of alumina contained, being influenced to a great extent by the proportions of other component parts in the form of impurities such ‘as silica, lime magnesia, etc., and the structure of the grain itself. For the purpose of, grinding- wheel manufacture, the value of emery as an abrasive agent. is determined by the amount of alumina oxide present and the toughness of the grain itself. In common with other natural products, emery ore varies in a: number of characteristics. This is true not only of specimens from different mines, but of the product of one mine as well. To market a high-grade emery, it is necessary to pay especial attention to the selection and grading of the crude ore, to which end the use of the micro- scope cannot be recommended too strongly, as by this means more can be learned of the quality of the emery than by resorting to any other method, aside from the actual working test of the finished product. As emery may have a high percentage of alumina and at the same time the ore may be so constituted that, after crushing, the grains will seem to possess no cutting points. Such an emery does not make a very efficient grinding — wheel. Some specimens of emery crush up into the proper kind of grains, as far as cutting points are concerned, but at the same time nothing but fine grains are produced. Again -_- -_ ABRASIVES AND ABRASIVE WHEELS it is sometimes noticed that small flakes of mica are scattered through the ore, which is sure to cause trouble in the vitrifying process if the emery is used in the manufacture of vitrified grinding wheels. It is readily seen that an efficient abrasive cannot be made of an emery ore selected at random. It is of the utmost im- portance to know the nature of the grain to adapt the same for a given abrasive purpose. At one time, all grinding wheels were made of emery. Of late years, however, corundum and the different artificial abrasives are used. At the same time, notwithstanding the efficiency of modern abrasives, the more ancient emery wheel still has its field of usefulness, and, strange as it may seem, on some classes of grinding, steel castings and heavy malleables, for instance, emery wheels continue to show the highest efficiency. This statement is not made thought- lessly, but is the result of several years of observation spent in representing grinding-wheel manufacturers. From a theoretical point of view, it would seem that abrasives containing a higher percentage of alumina than is present in emery, would prove more efficient, regardless of the nature of the work. Actual tests, however, have proven beyond a doubt that for certain purposes the emery wheel is still in a position to successfully compete with artificial abrasives. This is explained in a subsequent chapter. | Again, emery wheels are comparatively low in price, and they find a ready market among consumers whose grinding- wheel wants are few. A manufacturer who uses grinding - wheels intermittently, a few minutes at a-time, is not con- cerned whether or not the wheel shows the highest efficiency. As Jong as it gives satisfaction, within certain limits, no good reason is seen why a higher price should be paid for , a more improved abrasive. Another factor, that should be mentioned while consid- ering the emery wheel, is that owing to the high percentage of oxide of iron contained, this abrasive, grit for grit, leaves 18 we ae ie EMERY a finer finish than any other abrasive material used in grinding-wheel manufacture. Even on precision work, such as gauge grinding and other similar operations, the emery wheel still plays an important part and it is often the choice of many engineers who know abrasives for their actual worth. Emery wheels, or emery stones, as they are termed in this case, are also largely used for hulling oats and rice, taking the place of the bed and runner natural stones as used in the’ ordinary buhr mi!Jl. To whom the credit belongs for intro- ducing the above stones, is not known for a certainty, but. experience has proven that the emery stone compares favorably with the natural stones heretofore used for this purpose. Coarse emery is used in the form of bricks for rubbing stone and various metals while the finer grades of emery are made into sharpening stones, scythe stones, etc. Of Jate years, however, artificial sharpening stones made of _ electro-thermic abrasives (Carborundum, for example) have largely replaced those made of emery. For a few specific purposes, emery stones are still in use owing to the high finish they produce. In the form of grains and powders, emery is used for a number of purposes such as finishing bevels on plate glass, lapping hardened steel, polishing precious stones, etc., or, ‘in fact, for any purpose where a tough, durable abrasive in grain form is desired. Emery grain is also used to a great extent on polishing, or set-up wheels, as they are termed, for finishing an end- less variety of metal parts such as edge tools, cutlery, parts of firearms, etc. Various kinds of ‘emery act differently on a polishing wheel and suitable grades for specific pur- poses are generally chosen after careful experiment. One “reason why emery gives such good results on polishing ‘ wheels is that its comparatively rough fracture presents a good holding surface for the glue, which factor is not true of many of the manufactured abrasives. Caxhorun- 19 ABRASIVES AND ABRASIVE WHEELS dum, on account of its smooth, glassy surface, aoes not form a very efficient abrasive to use on a polishing wheel. Emery paper and cloth are used to a large extent in the mechanical arts for smoothing and polishing small, intricate parts of small machinery and instruments. In the study of the occurrence of emery, we are con- fronted with two very curious facts. First, emery is a mixture of iron oxides and alumina and, second, this com-. position occurs in but few places in the world—pin points on the earth’s surface, as it were. In American emery, Prof. J. H. Pratt regards the alumina and iron oxides as basic segregations from an igneous magma. This, of course, ‘is within reason since it is an accepted fact that the earth was at one time a molten mass of elements, and as this mass slowly cooled, the various elements combined and sometimes segregated. What force of nature caused the elements of iron and alumina to segregate together, in practically the same manner, is beyond the knowledge of the writer. CORUNDUM The name corundum was originally applied to the ruby and sapphire of India, the word being derived from the Sanskrit (Ruruiinda) and literally meansruby. The variety of corundum we are dealing with is called, by the older mineralogists, impure corundum and comprises the numerous varieties that are not transparent or perfect enough to be used as gem stones. Some thirty years ago, corundum was regarded as a comparatively rare mineral, but at the present time it is known to occur abundantly in several localities in this country and in Ontario, Canada. In this country, it occurs in igneous rocks, principally syenites, and in several gneisses and schists. It also occurs in alluvium deposits in sands and gravels. Canadian corundum occurs in nepheline syenite associated with Laurentian gneiss. Of the origin of corundum but little is known for a cer- 20 CORUNDUM | tainty, as a study of his mineral calls for exhaustive research ? work on the part of the geologist, who is sometimes reticent -when it comes to establishing hard and fast rules. Prof. J. H. Pratt, who has made a deep study of the occurrence of corundum, in this country and elsewhere, considers that the corundum of North Carolina segregated from a molten magma, the separation taking place at an early period of consolidation. Canadian corundum has of recent years been regarded as an essential rock constituent. Regarding the corundum of Ontario, H. E. T. Haultain states that the corundum- bearing rocks are not dykes, that they are not eruptive, and that there is no sign of separation from magma. The principal Canadian deposit of corundum occurs at Craig Mountain, which is situated in Raglan Township, Renfrew County, Ontario. In this country, corundum is found in the following states: Maine, Massachusetts, Connecticut, New York, Pennsylvania, Delaware, Virginia, North Carolina, South Carolina, Tennessee, Georgia, Col- orado, Montana, California and Idaho. Corundum is found in three different ways; block corun- dum, crystal corundum and sand corundum. Under the heading of block corundum, is included corundum found in masses whether large or small. This is the most difficult form of corundum to mine. Owing to its extreme hardness, it is impossible to drill it for the purpose of blasting. Thus it is not easily broken up. When block corundum is mixed - with foreign substances, such as feldspar, hornblende, etc., it is often difficult to clean, whereas a block corundum free from superfluous foreign matter makes an ideal ore, provided the parting planes are not too well developed. The disadvantage of numerous parting planes is explained later. Corundum crystallizes in the rhombohedral division of the hexagonal system and under the head of crystal corun- , dum is included all the crystal varieties of corundum which occur in block corundum or in sand or gravel. 21 | ABRASIVES AND ABRASIVE WHEELS Some of these crystals take the form of a hexagon with a prism at each end, in which case the crystal is termed ‘barrel corundum."’ Many of these crystals are of no defi- nite form, being enclosed in compact masses of surrounding material. Very small crystals and small grains are termed sand corundum and often occur between a corundum-bearing peridotite rock and the surrounding gneiss or schist. Corundum possesses no true cleavage, but parting planes are usually present along which the crystal fractures. How- ever, if these planes are so numerous as to be present in the small grains of abrasive materia] that constitute a grinding wheel, a low abrasive efficiency will be the result because the grains will readily fracture, thus breaking away before becoming dull and useless. An ideal corundum for an abrasive wheel is one wherein the grains are free from parting lines, thus they will, on becoming dulJ, break with the irregular to conchoidal frac- ture, which is a characteristic of corundum. As a matter of fact, all varieties of corundum have comparatively the same degree of hardness, that is, from 8.8 to g., but some varieties are much higher in abrasive efficiency than others. This is due to the fact that the parting planes are sometimes too numerous as previously stated. This accounts for the fact that some makes of corundum wheels are superior to others. The only practical test for the abrasive efficiency of a doubtful corundum is to make some sample wheels of it and have them tested on actual work under every-day working conditions. | From a theoretical point of -view, corundum contains but two elements, alumina and oxygen, its chemical formula being Al,O;. Commercial corundum, as well as the gem varieties, generally contains a trace of silica, ferric oxide and combined water. The following table, which is taken from Bulletin No. 269 of the United States Geological Survey, gives the chemical analyses of several well-known corundums. 22 CORUNDUM ANALYSES OF CORUNDUM Locality Hastings County, Ontario......... 96.92|.....]..... Corundum Hill Mine, N. Carolina. ...../98.79} . . 078 Jo ceces . Laurel Creek Mine, Since corundum occurs more abundantly than emery, the consumer of grinding wheels often asks why corundum wheels command a higher price than wheels made of emery. It is true that corundum deposits are numerous, but not all of these corundums are of the correct structure for grinding-wheel use, as above explained, and, again, co- rundum goes through a comparatively expensive process before it is fit for the grinding-wheel manufacturers. It must be borne in mind that corundum, as it comes from the mine, is not in a pure state, being mixed with other minerals, such as feldspar, hornblende, margartite, mus- covite, etc. Corundum is sometimes found in huge masses weighing many tons and in cases of this kind, the elimi- nation of the foreign matter is often a difficult problem. Again, a corundum that is to be used in the manufacture of vitrified wheels should be free from such substances as mica, garnet and feldspar. Otherwise difficulties are sure to be encountered in the vitrifying process. In describing the methods used in mining and cleaning corundum for the market, it may be well to first consider the mines at Craigmont, Canada, as the methods and facili- ' ties used there are generally acknowledged to be the most up-to-date and practicable. The above mine is worked by the Manufacturers Co- 23 ABRASIVES AND ABRASIVE WHEELS rundum Company, Limited, and the following account of the cleaning methods, etc., is taken from an article: ‘‘Co- rundum at Craigmont,’’ which appeared in the Canadian Mining Journal under the date of August rst, 1907. As this article was written by Mr. H. E. T..Haultain, who was general manager of the company at the time, it is interest- ing as well as authentic. ‘‘The first discovery of corundum in Ontario was made nearly thirty years ago on this Craig Mountain, then known as Robillard’s Hill, by Henry Robillard’s daughter. As a small child, she picked up and carried home a crystal that ‘looked like a cruet stopper.’ For years it remained as an unnamed curiosity, but at the time of the phosphate excitement, it was declared to be phosphate, and Robillard and Fitzgerald located the ground as a phosphate mine. __ ' “Tn 18096, Ferrier, of the Geological Survey, described the presence of corundum in the neighboring township. Muning operations were commenced in May, 1900, the ore being transported in wagons half a mile to a small mill driven by water power. In March, 1904, the present mill commenced crushing. This mill is by far the largest corundum mill ever built, and is the largest concentrating plant in Canada. It has three divisions, the main mill, the grader, and the finishing department. The latter is a comparatively recent development. | ‘In the main mill, the rock is crushed on till 90 per cent. of it will pass through a 2.5 millimeter hole, by means of four rock breakers and five sets of rolls. It is concentrated on 20 Overstrom tables; the concentrates, which contain from 50 to 60 per cent. corundum, passing into bins for drainage. ‘In the grader, these concentrates are dried, passed over magnetic separators, separated into 20 sizes, from 8 mesh to 200 mesh, and still further subjected to concentration on Wilfley tables and Hooper pneumatic jigs. The result- ing product is again dried and again sized and passed into bins, from which it is drawn off into ro0o-pound bags. The 24 CORUNDUM run of bags each day is sampled by hand, every size by itself, and these samples are carefully assayed, and accord- ing to the assay results, the bags are stocked in the finishing department. ‘The finishing department performs three functions. It thoroughly mixes the product so as to give a uniform ma- terial complying closely with fixed standards. It re-screens - each size so as to eliminate the results of carelessness in the grader. It automatically samples every lot of thirty bags. “The finishing foreman, knowing the assays of the con- tents of his bags, mixes thirty hundredweight at a time in a hopper. From this hopper, the corundum passes in a thin, flat stream past a draft of air, which blows away the mica. It then passes over a set of shaking screens, which screen out both undersize and oversize particles and from this it passes to a bin whence it is drawn off past an auto- matic sampler direct into canvas bags, which are filled to contain 1oo pounds of corundum. ‘The bags are then sewn up by machinery and marked for size and lot number. The samples are tested by hand screens for accuracy of sizing, by the eye for pyrites and hornblende contents, by the magnet for magnetite contents, and in the assay office for both corundum and iron content. ‘On receipt of the assay results, the bags are marked G or G1, G grade being for silicate wheels and the polishing trade, and G1 for the vitrified wheel trade. A sample weighing about half a pound, representing each lot of thirty bags, is stored for reference.” As before stated, corundum is found in many parts of this country; one of the well-known mines is called the Corundum Hill Mine. It is located in Macon County, North Carolina. Corundum was discovered here in 1870 and mining operations were commenced a year later. This corundum is found in a peridotite rock. The above mine yields block, crystal and sand corundum having a hish abrasive efficiency in both silicate and vitrfied wis 25 _— ed ABRASIVES AND ABRASIVE WHEELS The corundum of this mine enjoys a wide reputation, in- deed, one well-known manufacturer of grinding wheels ad- vertises the fact that this brand of corundum is used. Another famous mine, the Laurel Creek mine, is located in Rabun County, Georgia. This corundum is also found in peridotite and often in massive blocks, many of them weigh- ing several hundred pounds. One mass of corundum taken from this mine is reported to have weighed over 5,000 pounds. It is said that this mine has furnished the largest masses of corundum ever mined in any locality. An excellent grade of corundum is also found in Gallatin County, Montana, where it occurs in a syenite rock. The crystals are of all sizes up to eight inches long and some have been found that weighed two pounds. Montana corundum is being worked by modern methods. The mills are equipped with up-to-date machinery. Several grinding-wheel manufacturers have used this corundum, reporting it as making an excellent grinding-wheel grade. The above corundum deposits are mentioned because they are well known to the corundum-consuming trade. It must not be inferred from this, however, that excellent grades of corundum are not found elsewhere in this country. As a matter of fact, there are over 160 corundum deposits that have been listed by geologists, many of them yielding an excellent grade of material. Abrasive engineers admit that corundum of the right kind makes a very efficient grinding wheel for all purposes, with the exception of materials of low tensile strength such as cast iron, etc., and since corundum occurs so plentifully, the question is often asked: why is it not used more ex- tensively? This is at best a difficult question to answer, but we may throw some light on the subject by considering some facts that exist concerning the corundum industry. To begin with, the older methods of preparing the abrasive for the market were unsatisfactory; this resulting in an | imperfectly cleaned grain not wholly free from impurities, | for it is only within the last few years, comparatively speak- 26 CORUNDUM ing, that modern appliances, such as used at the Canadian mines, have been installed in this country. In the old process of cleaning, the ore was crushed in rock | crushers and then re-crushed by passing it between a series of rolls. The resulting grain was then washed in running water, the corundum, being the heaviest, settled while the: lighter impurities were-carried away. This, of course, applied only to such substances as were not attached to the grains of corundum themselves. The material was then ‘‘scoured’’ by passing it through a machine not unlike a screw conveyor and afterward re-washed. The grain then received a further cleaning in a wet pan muller, which consists of a revolving pan -having a shaft over it carrying two wooden rollers. The action of the muller caused the grains to rub against each other, thus gradually wearing away the impurities which were carried away by a stream of running water. The material was then thoroughly dried and sieved to the various commercial sizes. ~The old process was expensive and uncertain as to. re- sults. Again, severe competition with artificial abrasives began to creep in. The Carborundum Company was spend-. ing large sums of money int-oducing their product to the manufacturing world and the Norton Company was not far behind in extolling the merits of their artificial corundum called Alundum. That it pays to advertise is an old and true saying and artificial abrasives certainly have had the advantage of wide publicity. Again, the artificial abrasives were uniform, whereas corundum, when taken as a whole, - was not, since it was the product of many deposits, which naturally varied to some extent. It is the writer’s opinion, given for what it is worth, that corundum as an abrasive has been handled wrong from the start. It has always been sold as a raw material, in com- petition with emery at first and later in competition with the artificial abrasives. The miners of corundum, even of the very best qualities, were more than willing to sell their product to all who wished to purchase, regardless ai Une 27 ABRASIVES AND ABRASIVE WHEELS fact that not all manufacturers, a few years ago, knew how to make the best quality of grinding wheels. The writer fully realizes that it is a simple matter to say, ‘“‘I told you so,” but, nevertheless he ventures the opinion that if, upon the discovery of an exceedingly good quality of corundum, the mine owners had gone into the wheel- making business, absolutely controlling the sale of their product and keeping the same up to a high standard, the story of corundum could have been written differently at the present time. As a means of verifying the above statement, let us con- sider The Carborundum Company for a moment. Suppose they. had been willing to sell their product to all wheel manufacturers who cared to purchase. Would the carbo- rundum grinding wheel hold the high position that it does at the present day? Decidedly not. Carborundum wheels of all kinds, good and bad, would have been on the market and the result would have been that carborundum would have lost favor in a great many cases. Now it is a far easier matter to make a poor grinding wheel than it is to produce a good one and here we have the answer regarding corundum, an abrasive occurring abundantly and possessing the highest abrasive qualities, which now occupies an inferior position simply because “‘too many cooks spoiled the broth.’ Everybody had corundum wheels for sale—wheels made of pure corundum —certainly. At the same time, however, some of this ‘‘pure’’ corundum was unfit for wheel manufacture, while in other eases corundum of the highest grade was given a bad name because the actual value of the abrasive was hidden in a poorly made grinding wheel. How, then, should corundum have been handled? some one is sure to ask. The answer is simple. As before stated, the owners of a good corundum deposit should have en- gaged in the wheel-making end of the business, given their brand of corundum a good name, spent a hundred thousand dollars in equipment, and several hundred thousand more 28 DIAMOND in advertising their product, and the business would have developed itself. The sole ownership of a widely advertised product is a gold mine m itself provided, of course, the business is properly handled, and this is one factor that has made manufactured abrasives qth distinctive names sO universally used. Corundum is used for a number of purposes, and, in comparing it with emery, it is a faster cutting abrasive owing to its pure state. Corundum wheels are used prin- cipally for stee] grinding on both rough and precision work, while corundum in grain and powder form is used for vari- ous grinding and polishing operations. Sharpening stones made of corundum are very efficient, while corundum- _coated paper and cloth are also put to a number of uses, principally in the form of discs used on the disc-type of grinder for finishing steel parts, both hard and soft. Taken as a whole, corundum covers a wide field and by many it is considered to be the best all-round abrasive known. Diamonds are divided into three groups, the transparent and practically flawless varieties used as gem stones and im- perfect stones called bort diamonds. There is also a black diamond often called carbonado. The diamond has a specific gravity of 3.50 and is the hardest substance known, being placed at 10 on the mineralogist’s scale. The diamond crystallizes in the cubic system, generally taking the form of an octahedron. The fracture of the diamond is conchoidal and the crystals invariably cleave along planes parallel to the octahedral faces. Diamond cutters avail themselves of this character- istic when reducing the stone to the best shape for cutting. Of late years, however, a sawing process has been developed which is said to be superior to the older method of cleaving by means of a sharp blow. The diamond is found in India, South America, Sa 29 ABRASIVES AND ABRASIVE WHEELS Africa, New South Wales, Borneo, and British Guiana. At the present time, most of the diamond industry centers in South Africa, the mines in this locality having been worked since 1870. Previous to this time, diamonds were found in alluvial deposits and in conglomerates, but in the South African mines, the most famous of which are the Kimberley and the De Beers mines, the diamonds are found imbedded in a kind of blue clay in what are termed ‘‘pipes.’? These are supposed to be filled-up craters of long-extinct volcanoes. Ot the origin of the diamond but. little is known, although many eminent geologists have advanced well-grounded theories concerning its formation, but, as the original con- dition of the carbon, of which the diamond is composed, remains a question, the genesis of the diamond is still un- solved. The De Beers Company mine “many hundred thousand dollars’ worth of diamonds weekly and it is needless to state that operations are conducted on a large scaJe, under the supervision of the most able mining engineers available. To get at the diamond-bearing blue clay, a shaft is sunk several hundred feet into the earth just outside the pipe, tunnels from this shaft running into the diamond-bearing deposits. This material is hoisted to the ground above, where it is spread out in large fields to alow the sun and rain to crumble it to the extent of being easily washed. This weathering process is materially aided by going over the deposits occasionally with steam-plows. The disintegrated soil is next washed in shallow cylin- drical troughs wherein the diamonds are swept to the rim by means of revolving toothed arms, the lighter material escaping at the center. The findings are now concentrated to separate the diamonds from hard foreign substances and then a further separation is effected by passing the concentrates over a greased surface. For some unaccount- able reason, the greased surface holds the diamonds while the other worthless materials escape. 39 DIAMOND It takes, on an average, four tons of blue ground to yield one carat weight of diamond, and as the De Beers mines often yield from three to four pounds of diamonds a day, it is seen that an immense amount of blue ground has to be worked. The next step, and a very interesting one, is to sort out the diamonds both for color and purity. The color runs from clear white to black, a pale yellow being the most common color. The only difference between a gem stone and a bort diamond is that the former is practically flaw- less and of good color, while the latter contains black specks and other flaws, has no brilliancy and possesses an irregular fracture. It is needless to state that the diamond sorters are expert at their work and they never let a gem stone pass for a bort. As a matter of fact, dealers in bort stones look in vain for a gem stone that might have missed the eye of the inspector, but there is no record of their efforts being rewarded. Aside from truing grinding wheels, bort diamonds are used for many other purposes. In powdered form, they are used for diamond cutting, this process being introduced by L. von Berquen in the year 1476, for cutting and drilling very hard substances, for certain kinds of delicate lapping and grinding in watch factories and occasionally for very minute turning operations in the watch or jeweler’s lathe. The process of converting bort diamonds into diamond powder is sumple, being carried out as follows: Several bort stones are first crushed in a little mortar made especially for this purpose and the material thus obtained is placed in a quantity of the very best olive oil. The mixture is thoroughly stirred and allowed to stand for five minutes. The oil is then poured off and the diamond powder that remains in the vessel is called No. 0. The oil is now allowed to stand for ten minutes and again poured off, the remain- ing powder being known as No. 1. To get the various grades, the time limits used are shown in the accompanying table. . 3 I ABRASIVES AND ABRASIVE WHEELS yA o 9 © on ) nrmwwnea oO The oil is now allowed to stand untiJ it shows clear, the particles settling at che bottom being known as No. 6. Carbonado, often called black diamond, is a form of diamond found in Brazil, South America. It is of irregular form and of a black, gray or brown color. It possesses no cleavage and breaks with a granular fracture. Its specific gravity is less than that of the true diamond. It is found almost exclusively in the state of Bahia in what is called cascalho, or diamond-bearing gravel. It is generally found in small pieces, although occasionally a large piece is dis- covered, the largest on record having a weight of 3,150 carats. For truing grinding wheels, carbonado is superior to bort diamond owing to the fact that absence of cleavage makes the stone less liable to fracture. Thus carbonado is the ideal form of diamond to use in rock drills and diamond saws where the stone must withstand the impact of re- peated shocks that would speedily ruin a bort stone. GARNET The name garnet is applied to a group of very closely related minerals, some of which, in the pure varieties, are used as gem stones. There are six kinds of garnet known as follows: Lime alumina garnet.........ce0. Lime iron garnet... ......cececees Lime chrome garnet.........eee0s Magnesia alumina garnet.......... Iron alumina garnet...........00. Manganese alumina garnet........ Garnet crystallizes in the cubic system, generally in It possesses an imperfect cleavage, rhombic dodecahedra. 3 2 CazAl.Si,012 CasFe:S1;0)2 Ca;Cr.SisOr2 Mg;Al,SisOi2 Fe:Al2Si3012 Mn;AlS13;042 f GARNET the parting lines running parallel to the dodecahedron. Its hardness varies from 6.5 to 7.5 while its specific gravity also varies to quite an extent, in different specimens running from 3.4 to 4.3. Garnet has been found in crystalline schists, gneiss, gran- ite, metamorphic limestone, serpentine and volcanic rocks. In this country, deposits are located in New York, New Hampshire, Connecticut, Pennsylvania and North Caro- lina. Large quantities of garnet are mined in New York state, the deposits being located in the vicinity of the Adirondack Mountains. This garnet, which occurs in limestone and gneiss, is of the iron-alumina variety. It is often called Almandine. The garnet of New Hampshire is also of the above variety while North Carolina garnet occurs in two forms, the iron-alumina and a subdivision called rhodolite, which consists of two parts magnesia alumina and one of iron-alumina garnet. An excellent garnet, known to the trade as Spanish mineral, is mined in Spain. This material is extensively used in this country; in fact, one large manufacturer of garnet paper uses it exclusively. There are no analyses on ° record to establish the composition of this material, although The United States Geological Survey informed the writer that it 1s probably an iron-alumina garnet, or almandine. Garnet is prepared for abrasive uses by crushing, concen- trating and magnetic separation to remove the superfluous ‘iron oxide, after which it is graded into various commercial sizes. As an abrasive for smoothing wood, garnet paper and cloth enjoys great popularity, showing high efficiency over ordinary sandpaper, especially on comparatively hard woods, such as oak, cherry, maple, etc. It is not a suitable _ abrasive for grinding-wheel manufacture, owing to its soft nature, although it is sometimes mixed with corundum ~ in the manufacture of silicate wheels for such operations as knife grinding. The pure varieties of garnet are often cut as gem stones of which there are many colors from deep red to light rose. 33 ABRASIVES AND ABRASIVE WHEELS Some of the finest garnet gem stones are found in loose gravel in Macon County, N. C. QUARTZ Quartz is one of the most common of minerals and has a wide distribution throughout the world. It is composed of silicon dioxide, or silica Si0,.. Aside from being an -essential constituent of some igneous rocks, as granite, it occurs as sand and in crystals. Its specific gravity is 2.65 while its hardness is placed at 7 on Moh’s scale. It crystallizes in the trapezohedral-hemihedral class of the rhombohedral division of the hexagonal system. Inits pure state, it forms many semi-precious stones such as the amethyst, bloodstone, sardonyx and others. It has no true cleavage and breaks with a conchoidal fracture. As an abrasive, quartz has many uses. In grain form, large quantities of it are used for plate-glass grinding and in other forms of glass work. Glued on belts, it is used for sanding implement and tool handles. Owing to its hardness and sharpness, it is often used for sand blasting. - For sawing stone of the softer varieties, such as marble and limestone, quartz forms a cheap and efficient medium. It is not adapted to grinding-wheel manufacture although it is sometimes mixed with other abrasives in making knife- grinding wheels. FLINT Flint is a very hard, brown-colored stone being composed principally of silica and having a specific gravity of 2.6. Its fracture is conchoidal. It is one of the oldest known minerals, being used by prehistoric man in the manufacture of implements and weapons. It was once widely used for striking fire and until the invention of the percussion cap the flint-lock musket was used the world over. Thus it is | seen that this now little used material once played an f important part in shaping the destinies of nations. A 34 NATURAL SHARPENING STONES form of flint called flint-quartz is used in making the flint paper of commerce which is more commonly spoken of as sand-paper. In this country, the material in question is mined in several places, the more important deposits being in Maine,-Maryland and Wisconsin. NATURAL SHARPENING STONES Under this heading are included all the natural stones used, as hand stones, hones, etc., for various sharpening operations. Sharpening stones are of very ancient origin, specimens having been unearthed in Egypt dating back to 1500 B.c. Pliny, writing early in the Christian era, tells of a stone from Crete used with oil and one from Naxos used with water. The latter, in all probability, was noth- ing more or less than a fragment of emery ore. The oldest natural stone of modern civilization is the Turkey stone mined in Asia Minor. This stone became popular over one hundred years ago and to some extent is used at the present day. Other famous sharpening stones of a century ago were the Belgian razor hone, which owes its abrasive qualities to minute particles of garnet, and the German water hone. Both of these stones are sold at the present time. a The well-known Arkansas and Ouachita (Washita) stones were discovered in Arkansas in the year 1815. These are found in the foot-hills of the Ozark Mountains. There are two varieties of Arkansas stones; hard Arkansas and soft Arkansas. The former consists of 9914 per cent. pure silica, being composed of very small particles of hexagonal- shaped crystals to which it owes its cutting qualities. This stone is widely used by watchmakers, engravers, tool- makers, etc., for putting a very fine edge on cutting tools. © Soft Arkansas stones, although not as hard as the former variety, are freer cutting, therefore they are the choice of he carpenter, cabinet maker and pattern maker for putting ‘the correct cutting edge on chisels, plane irons, etc. | 35 reedadeds a scoerh Veo Cbee. cuacegstghane Citre of mctal polishes — ——e a= « - aoe « _——— _ Oe — - - = —— - —- -— ™.~- = eee ——_ ——_ a ——— -_ ~~ - —_- 37 _ — — - = ~— 7. =. - . ~ eee = ee —_ —— —uutiein ~ - 7 —_— lL —— se OO —— cw ow == —=-=2 = = — ——— —_ == —_ = —_—s= = see ——_«- + = —— — ay —_ cn = or - —_ a ~— = we 3 —_ —_——_ - - = —= mee « _- = = - - =a -— —_ - =< —— 2 oe _— = 8 oe wt anda, pal — - —_ - -— = ~~ -_ ee co". ~ - i — SR, . = — - - -_— —=— — —e_~ = -- -—_ ~ eememel —. —— = = as om _—em ~~ - - - ~ — Set E — -_ _ - =. — ——— —— _ me = & a -. —— - —_- —— ee Lee ee —_—_ «a. - —_ a ee ee ee, ee. _—= — - —~ — ad —" *— -__ "=~ oi - = ——_ = — ———— —_——_——S en oe oe — diet - _—— =-—- === — ——- - - - _———— —— ae amen, - i = . - —i7 ——_ . _o—_——_- ° — —_ wee ee @tu= - - - ~-+ = a ~_—_ . _— - - = - — _——te. =e Ley = - = -_ _— «- - . - : se = - fos 70 20S Te ll SNe ze a, = - = Ld - e 27] 550 UTS TSS eet f¢ vee "7 acer ot 2S eC SS « o t ? We id-f neal —_ --*< ae @ == = or , — 9 7. ove o_o 6 Saw ee = = hot e a =. . . ow ** fur L254, 7" & ° — Ete « @? oe 4? ‘ ‘af eeea a we Oo mee eee tes es am wewk hes po teethe tee att) SynSural qvamice is found m ranyts rT ae Selssties, “snitn Dakota and stecrte yg Whale nese h of the imported article sertet i danels ao the Mediterranean Sea. 4 yameiee i neal principally for very fine abs CHAPTER TWO ARTIFICIAL ABRASIVES Various artificial abrasives—Their physical and chemical properties—Their commercial application—Methods and processes employed in the pro- duction of artificial abrasives—Carborundum—Alundum—Aloxite—Boro- Carbone—Oxalumina—Adamite—Crystolon, etc.—Relative hardness and abrasive efficiency of various materials—Artificial production of precious stones—Their abrasive properties—Other artificial abrasives and their production—Experimental work—Electro-thermic processes—Production of rouge and crocus—Diamonds and crushed steel—Angular grit. NDER this heading can be included all grinding and polishing materials produced by the arts of man; the most commonly used being divided into two classes, carbide of silicon abrasives, the origina! of which is Carborundum, and artificial corundum, which material, in the form of>- precious stones, has been made for more than seventy years. In reality, the artificial corundum of today, sold under va- rious trade names, such as Aloxite, Alundum, Boro-Carbone, Oxalumina, etc., is an indirect outgrowth of the experiments of other days, wherein scientific investigators had to con- tent themselves with making artificial rubies and sapphires, while vainly striving to produce the artificial diamond. To class rouge and crecus as abrasives may seem rather far fetched on first thought, but it must be borne in mind that while these materials are used for polishing purposes only, their mission is accomplished through abrasion, since the finest mechanically finished surface possible to produce, when viewed under a powerful microscope, is seen to consist of a multitude of fine scratches. ) Crushed steel and chilled iron are abrasives in the true | sense of the word. The former is used for grinding and the / 37 ABRASIVES AND ABRASIVE WHEELS latter for sand blasting, which is a process of removing superfluous material by abrasive action. Carborundum is undeniably the best known and, for many purposes, the most useful of all the artificial abrasives; indeed, it is often called the father of them all, since its introduction into the mechanical world gave electro chemical engineers an impetus to produce competitive material. For the sake of clearness, the various well-known artificial abrasives will be considered in chronological order, Car- borundum being at the head of the list as it was the first artificial abrasive to be recognized commercially. CARBORUNDUM Carborundum is a trade name given to carbide of silicon, a substance discovered during the year 1891 by Edward G. Acheson. It can truly be called the most unique of all abrasives as it has never been found in nature, therefore it is not an imitation of nature’s work, but a distinct creation in a class by itself. It is a chemical combination of the two elements carbon and silicon, its chemical formula being SiC. The raw materials entering into the manufacture of Carborundum are coke, sand, salt and sawdust. Coke supplies the element carbon, while the element silicon 4s derived from the sand. The object of the sawdust is simply to make the mass porous, thereby permitting the gases generated during the burning operation a free passage to the open air. The object of the salt is to eliminate im- purities such as iron, etc. As the salt volatilizes, it im; pregnates the whole mass, taking up impurities in the form of chlorides. The Carborundum furnaces used at the present time aré fifty feet long, ten feet wide, and five feet high. The original furnaces, however, were somewhat smaller. Both types are of open construction, the sides and ends being 38 CARBORUNDUM built of brick. The end walls are approximately two feet thick, through which run the terminals for the electric cur- rent. These terminals are made of carbon rods three feet long and three inches in diameter, arranged parallel in bundles of sixty, the spaces between the rods being packed tightly with graphite. At the outer ends of the rods, copper terminals are let in, which, in turn, are connected to a large copper cap. Current is supplied by means of cables from overhead bus bars. In charging the Carborundum furnaces preparatory to burning, a mixture of thirty-four parts coke, fifty-four Fig. 1.—Carborundum furnace charged with raw material, ready for burning. parts sand, ten parts sawdust and two parts Pate is used. The materials are thoroughly mixed and brought to the furnaces by means of mechanical conveyors. Enough of this mixture i is placed in the furnace to bring the upper layer level with the ends of the electrodes. A trench is now made between the terminals, wherein a core of granulated ‘coke is laid. The object of the coke is to allow a free pas- ‘sage for the electric current. More of the material is now introduced and built up in the form of a mound as shown in Fig 1, 39 ABRASIVES AND ABRASIVE WHEELS An alternating current of 190 volts and 6,000 amperes is now turned on. As the mass heats, the resistance to the current gradually diminishes, and after about four hours’ operation, it remains constant at 125 volts and 6,000 amperes. The sawdust, of course, burns away first, after which carbon monoxide is given off. This burns freely at the sides and top of the furnace with a yellow flame. As the process of burning progresses, the mass shrinks somewhat, which necessitates adding more raw material. Occasionally the phenomenon of ‘blowing’ occurs, which makes the furnace look not unlike a miniature volcano. This is caused by an over-charge of gas suddenly igniting and bursting through the top crust of the charge. After a period of abaut thirty-six hours, the burning operation is completed. Several furnaces are in the process of burning at the same time, being started at intervals of a few hours apart. The object of this is to insure constant production as well as the economical use of current. The current is carefully watched at'all times by an electrical engineer especially trained on electric-furnace work. This is quite essential, otherwise a uniform product would be an impossibility. After the burning is completed, the furnace is allowed to cool for twenty-four hours, after which it is broken open. The top crust, which is in a comparatively unaltered state, is removed, exposing a layer of amorphous carbide of sili- con under which lies the pure crystallized Carborundum. — Next comes a mixture of Carborundum and graphite and, last of all, the core. The intense heat, estimated at ap- proximately 7,500° Fahrenheit, transforms the core into practically pure graphite. The amorphous carbide of sili- con previously mentioned was at first considered of no value and consequently thrown away. Later scientific in- vestigation, however, showed that it possessed a high refractory value. At the present time it finds a ready market as a refractory material for lining furnaces subjected to high heats of long duration. | The Carborundum crystals, while well developed, are 40 CARBORUNDUM not regular in appearance, some being hexagonal and others rhombohedral. The crystals have no lines of cleavage, breaking with a distinct crystalline fracture, invariably leaving sharp cutting edges. - Carborundum crystals are of various colors, being truly beautiful from an artistic point of view; coal black, deep brown, light green, pale blue, deep blue and purple are all intermingled in a gorgeous riot of colors seldom equaled in nature. In the early days of the industry, green Carbo- rundum predominated and at present many are of the opin- ion that green Carborundum is superior in cutting qualities to specimens of other colors. Actual tests, however, con- ducted by abrasive engineers, have proven beyond all reason- able doubt that the-above theory is absolutely groundless, the color being the result of oxidation. On Moh’s scale of hardness, Carborundum is placed be- tween nine and ten. It is probably nearer ten than nine as Carborundum has been known to scratch rubies, sapphires, and diamonds. Compared with other abrasives, Carbo- rundum is comparatively light, its specific gravity being approximately 3.18. This factor should not be under- estimated since the centrifugal force of a revolving body is proportional to the square of the velocity. Thus, wheels running at the high speeds recommended in present-day grinding practice are under a severe centrifugal strain, and it is apparent that the lightest abrasive makes the safest wheel. Fig. 2 gives a good idea of the appearance of Carborundum as it comes from the furnace, the photograph being taken after the outer layers and core had been removed. As this material looks like the products of the mine and quarry, the question is sometimes asked, ‘‘Why is carbide of silicon not found in nature?” The only reasonable answer the writer can give is that the degree of heat at which both carbide of silicon and graphite are formed is so near the same temper- ture that nature seemed content to produce graphite alone. An interesting feature of the production of Carborunduse At = _- ABRASIVES AND ABRASIVE WHEELS from the electrical engineer’s point of view, at least, is the form of circuit breaker used in making and breaking the heavy current. As this amounts to 750 kilowatts it is seen that the ordinary form of contact switch would be destroyed in short order. To overcome this difficulty, a special circuit Fig. 2.—How Carborundum looks as it comes from the furnace. — breaker of the water-regulator type is used. This collie of a number of iron plates working in a salt-water solution. Thelarge masses of crystals produced in the Carborundum furnace are reduced in crushing machines of the dry-pan muller type, illustrated in Fig. 3. Under the weight of the rolls (two tons each) and the rotary motion of the (thirty revolutions per minute), the Carborundum m: are rapidly crushed to small crystals. These range all way from very coarse to an impalpable powder. Alth: the crushing rolls are made of manganese steel, they do n last long, owing to the abrasive action of the Carborund: grains, a pair lasting but six months at the longest. Carborundum as it comes from the furnace is impreg- nated with a small amount of iron oxide taken from the sand and other minor impurities derived from the coke. To eliminate these the crystals are transferred to wooden, vats, lined with lead, where they are lixiviated with strong 42 eT 1% CARBORUNDUM sulphuric acid. The crystals are next washed in long wooden troughs, the washing being passed through settling tanks which help to separate the grains from the fine powder. The crystals are now thoroughly dried by coke fires, after Fig, 3.—Muller type of crusher used in preparing Carborundum, which they are ready for “‘grading,” or “screening,” as this operation is sometimes termed. The screening machine, as shown in Fig. 4, consists of a series of screens set on a slight incline with their ends meet- ing. -The fine screens are made of a superior quality of milling silk, while the coarser type are made of brass wire. The Carborundum grains are fed on the screen at the high end, and a vibratory motion, imparted to the screen frame, causes them to journey downward. In passing over the screens, they find an outlet suitable for their size. After passing through the screens, the grain flows into receptacles * placed under the delivery openings as the illustration shows. ‘The screens vary from six meshes to the inch to two hundred ‘and twenty meshes to the inch. Owing to the abrasive action of the grain the screens wear readily. Thus care has to be exercised to insure uni- form grading. This is accomplished by frequently testir 43, 1 ABRASIVES AND. rete WHEELS samples that have passed through the several screens in testing machines carrying master screens. When the grains are out of grade, it is a sign that the screen through which it passed has worn to the extent of warranting renewal. Fig, 4~-Screening machines used in grading Carborundum. This is promptly attended to and all over-size material regraded, It is not practicable to grade Carborundum finer than two hundred and twenty by the screening method. There- fore another method is used for grading the powders as they are termed, In this system the fine powder is carried by a stream of water through a series of settling tanks. In pass- ing through the tanks, one after another, the heavier grains sink. Thus, the last tank contains nothing but the very finest powder. At the works of The Carborundum Company, the following grains and powders are carried in stock: 6, 8, 10, 12, 14, 16, 20; 24, 30, 36, 40, 50, 60, 70, 80,_] 90, 100, 120, 150, 180, 220 and powders F, FF, FFF. ! 44 CARBORUNDUM Carborundum is very hard, exceedingly sharp, and when made into grinding wheels, it furnishes a highly efficient abrasive for the grinding of materials of comparatively low tensile strength, such as gray iron, chilled iron, brass, bronze, marble, pearl, bone, horn, etc. In grain and pow- der form, Carborundum is extensively used for lapidary work, valve grinding, plate-glass beveling, stone finishing, etc. It 1s sometimes used on ‘‘set up’’ wheels for polishing cast iron, but owing to the fact that considerable skill is required, both in preparing the glue and in covering the wheels, the above practice has not become universal. Carborundum coated paper and cloth enjoy an immense sale in the boot-and-shoe industry, where they are used for such operations as fore-part buffing, heel breasting, heel scouring, etc. In the wood-working industries, how- ever, Carborundum paper does not show efficiency over flint and garnet paper as its sharp nature causes the coated: paper to fill up very readily. In the leather-manufacturing industries, Carborundum is used in a barrel-shaped wheel form, for the ‘‘wet wheeling’”’ of leather, as this operation on skins is termed. In grain form, it is used on a special shaped cylinder for ‘‘buck- tailing,” while in the form of paper and cloth, it is used for ‘various finishing operations. It is often stated that Carborundum will not grind steel economically, but this statement is erroneous. At one time The Carborundum Company sold a large number of wheels to the lumber industry for saw gumming. As a matter of fact, this is an operation calling for a very cool and rapid-cutting wheel. The writer has used Carborundum wheels for the cylindrical grinding of cold rolled and ma- chine steel with excellent results. Not only did the wheels produce an excellent finish, but they were very uniform in grade, a feature not at all common some ten years ago. The writer has seen Carborundum wheels used for auto- mobile crank-shaft grinding by one of the largest man" ' facturers in the Middle West. The results were satis 45 ABRASIVES AND ABRASIVE WHEELS tory, Carborundum being preferred to all other makes of wheels. It must be considered that the above instances happened — some years ago, before the high development and accurate grading of manufactured alumina abrasives, which at the present time show higher efficiency on steel grinding than . is possible to attain with Carborundum. The above state- ments are made simply to show that at one time in the his- tory of grinding, Carborundum held its own on steel. Why, then, does not Carborundum, which is acknowledged to be the hardest and sharpest of all abrasives, both natural and artificial, show high efficiency on steel grinding? This is, at best, a hard question to answer and one upon which | opinions are at great variance. The writer’s opinion, based — upon many years of observation, close study, and prac- tical application, is that if Carborundum was not quite so hard, and broke with a conchoidal instead of a crystalline fracture, it would eventually drive the alumina abrasives out of the market. . The above opinion can be called pure speculation without a suitable hypothesis, therefore it is open to question. However this may be, it is set down for what it is worth, for opinions, no matter how theoretical they may appear, possess some merit, at least until they have been dis- proved by actual demonstration, and as it is an impossi- bility to produce the type of Carborundum described, the above theory may be as rational as any other. The name Carborundum is registered as a trade mark, thus it is the sole property of The Carborundum Company. It, however, grinding wheels are made of Carborundum, no matter by whom, they can lawfully be sold as genuine Carborundum wheels. OTHER CARBIDE OF SILICON ABRASIVES A carbide of silicon abrasive called ‘‘Carbosolite’’ is made in Germany. It has been sold in this country to a Jimited 46 ARTIFICIAL CORUNDUM extent, chiefly in the granite-finishing business. It is mostly of a dark-gray color and it is not considered as pure as Carborundum. Aside from the granite trade, a limited amount of this material is made into grinding wheels. Crystolon is a trade name given to a carbide of silicon abrasive made by Norton Company at their electric- ‘furnace plant in Chippawa, Canada. It is made by practi- cally the same method used in producing Carborundum; the same raw material forming the ingredients. It was first puc on the market about seven years ago, and at the present time it enjoys a large sale, both in the form of wheels and grain. The Abrasive Company of Philadelphia market grinding wheels made of carbide of silicon, calling the same ‘‘Elec- trolon.”” This material is an electric-furnace product, being made of selected materials, the grain being specially treated before being incorporated into grinding wheels. This ma- terial was first put on the market during the year 1914 and it is considered by many large consumers of grinding wheels to be a very efficient abrasive. ARTIFICIAL CORUNDUM As stated at the beginning of this chapter, artificial corundum bas been produced for more than seventy years and in considering the subject in the abstract, a little light thrown on the experimentalists of other days may not be out of place at the present time. It is a well-known fact among those conversant with the values of precious stones that a true Oriental ruby, of fine color and flawless, is worth more, carat for carat, than the finest diamonds of Brazil or South Africa. The term -tuby is often misconstrued to embrace the spinel or balas tuby. Indeed, the famous ‘‘ruby”’ set in the Maltese cross in front of the imperial state crown of England is in reality -a spine]. It 1s, of course, possible for experts to readily {distinguish the difference between true and spinel rubies, but 47 ABRASIVES AND ABRASIVE WHEELS since the ruby is nothing more or less than pure crystallized alumina, colored with a small quantity of chromium, it is evident that a laboratory product of the above materials is a true synthesis of the ruby. It is as much entitled to the name as the choicest specimens of nature from the Mandalay district of Upper Burma, where the finest rubies have been found. In the year 1837, M. A. A. Gaudin successfully made true rubies by fusing alum in a carbon crucible at a very high temperature, a little chromium being added to impart the desired color. The rubies, while of a very small size, hardly visible to the naked eye, proved that it was within the means of science tc produce corundum artificially. J. J. Ebelmen’s experiments during the year 1847 resulted in the artificial production of the white sapphire and rose- colored spinel. The process consisted of fusing the desired constituents at high temperature in boracic acid. He also produced the ruby by using borax as a solvent. Not until the year 1877, however, was it proved possible to produce crystallized artificial alumina of a size suitable for cutting into small stones, the process being the result of experiments on the part of E. Frémy and C. Feil. The process used was as follows: By the fusion of lead oxide and alumina in a fire-clay crucible, lead aluminate was formed. Silica enters into the composition of fire clay, and under the influence of high temperature, the silica of the crucible gradually decomposes the lead aluminate, forming lead silicate, which remains in a liquid state while the aluming crystallizes as white sapphire. By mixing in a small amount of chromium, rubies were formed. The experiments df Sainte-Claire Deville, Caron, Elsner, Debray, and De Senarmont, too lengthy to be described fully here, did much toward reducing the art of producing artificial corun- dum to an exact science. , So much for the experimentalists of other days. The did not attempt to produce artificial corundum for abrasive purposes, to be sure, such a possibility being undreamed ot 48 ARTIFICIAL CORUNDUM _ in theirday. The fact remains, however, that their investi- gations were of value as by their means it was shown con- clusively that it was possible to produce artificial corundum. One of the first inventors to achieve success in the manu- facture of an artificial abrasive of the alumina type was Franz Hasslacher of Frankfurt-on-Main, Germany. As stated elsewhere, emery contains a high percentage of iron oxide, which possesses no abrasive value, and aside from this fact most specimens of emery are hydrous, often containing as high as 5 per cent. of combined water, which causes trouble in the kilns where wheels, in which this emery is incor- porated, are made by the vitrified process. The above- named inventor was granted a patent for changing natural emery into iron-and-water-free corundum (German patent No. 85,021, issued Nov. 20, 1894), the method of procedure being as follows: Crushed emery ore and charcoal or coke are first mixed together, the percentage of the latter being equal to the proportion of iron oxide contained in the emery ore. This mixture is then placed in an electric furnace, an illustration of which is shown in Fig. 5. The furnace consists of fire- brick walls (A), supported by the uprights (H), the electric current being transmitted by the carbons (C). In charging the furnace the opening at the bottom (D) is closed by means of a glass plate (P) and the furnace filled with the emery-and-coke mixture until the top of the mass is level with the center of the carbons. The carbons are placed about 1-% inches apart, the space between them being packed with a few lumps of coke. The furnace is now completely filled and heaped up as shown at (S). An alternating current of 300 amperes at a pressure of 110 volts is now turned on, under the influence of which the pieces of coke between the carbons-are brought up to incandescence, which causes the surrounding emery to , assume a molten state. The pieces of coke are soon ab- \ sorbed and an electric arc established between the terminals; gt the presence of which is proven by a loud buzzing sound. a ° ABRASIVES AND ABRASIVE WHEELS Carbon monoxide gas escapes through the mass, burning with a blue flame. The presence of this gas indicates that. the iron oxides are in the process of reduction. A large mass of molten emery soon forms about the electrodes; Ss ” Fig. 5.—Hasslecher’s furnace for making artificial corundum. the furnace walls being protected by the surrounding, un- melted material as the illustration shows. When a suf- ficient amount of emery has been melted, the glass plate fuses, causing the emery to run through to the floor in a dazzling, white-hot stream. At this point, the top crust is broken in, whereat the descending crust of emery cools the molten emery around the opening, causing the same to close. The furnace is then charged again and the process continued. In about fifteen minutes, the molten emery again breaks through Thus the process can be continued as long as convenient. The resulting product is fairly well crystallized alumina, running from white to blue in color, possessing a luster not unlike that of quartz. This material, being free fror iron, possesses a higher abrasive efficiency than emer and for some purposes it gives excellent results. It has bee 5° ARTIFICIAL CORUINDUM used in this country to quite an extent, but at the present time, and in fact for the last fifteen years, it has not been able - to successfully compete with American-made products. Another process for making artificial alumina was patented by Dr. G. Dollner of Rixdorf, Germany (German patent No. 97,408, issued Feb. 28th, 1897). The method is quite | simple and easily carried out, consisting of mixing crushed aluminum with oxides, peroxides and other metallic com- pounds with oxygen. This mixture, when ignited, owing to the high combustion temperature of aluminum, reacts in an endothermic manner causing the formation of oxide of alumina. This phenomenon is accompanied by the separation of the metals, the oxides and peroxides of which were used. In the reaction, the oxide of alumina is brought to a state of fusion, and, on cooling, it is characterized by extreme hardness. In his patent specifications, the inventor claims that this material is of a degree of sufficient hardness to replace diamonds for technical purposes, and further states that it 1s superior to other artificial abrasives as by this process grinding wheels can be prepared in solid blocks— that is a grinding wheel produced without a bonding material. Whether or not this has been carried out suc- cessfully the writer cannot state. Even if it were possible, however, such a wheel would be of one grade only, thus its field of usefulness would be limited. It may be well at this time to consider an abrasive called Corubin, which is a by-product resulting from the manu- facture of chromium by the Goldschmidt Thermit alumino- thermic process. The above process is one for making metallic chromium through endothermic action, the slag or by-product of which forms an excellent abrasive material as the following analysis shows. Chromium...............-4-- 13.2 per cent. S| 0 3.08 “ 7 ©) 71.65 “ Fe... cece nee 2.00 “ OF © pn Trace MgO... 1.35 * ABRASIVES AND ABRASIVE WHEELS From the above, it is seen that this material is composed chiefly of alumina and chromium, the percentage of alu- mina being high enough to form an efficient abrasive, while the amount of chromium contained renders the abrasive very hard and tough. ‘In the manufacture of other metals by the Goldschmidt Thermit process, other slags are obtained being only slightly inferior in abrasive efficiency to Corubin. The writer is informed on good authority that these abrasives are giving satisfaction, owing to the fact that several thousand tons of them are sold annually to responsible abrasive-whee] — manufacturers in this country. Large quantities of Corubin are used abroad in the manufacture of lenses, wherein the abrasive is used to grind the glass, and in other abrasive work. That the experimentalists made great strides in perfect- ing methods for the manufacture of artificial abrasives | (after Acheson and The Carborundum Company proved to the world-that there was a ready market for an artificial abrasive) no one will deny. The artificial corundum made previous to the year 1900, however, was incomplete in | that it lacked what we term at the present day abrasive temper. We all know that high-carbon steel, or tool steel as it is called, possesses a valuable characteristic inasmuch as it can be made exceedingly hard by heating it red hot and suddenly cooling it by immersion in water, or a brine solution. Further, by tempering it, or drawing the color as the smith says, we get various degrees of temper for in- numerable purposes; a very hard steel for razors, a some- what softer material for machine reamers, softer still for - lathe tools, and yet softer for cold chisels and axes. A piece of too] steel that has been hardened but not drawn, is very brittle, thus its field is limited. For an illustration, a lathe tool, a pair of scissors, or an axe thus treated would be useless—the lathe tool would crumble away as soon a it was brought in contact with the piece of work to be turne the scissors would break the first time they were dropp 52 BAUXITE . on the floor, while the axe would fly to pieces at the first stroke of the woodsman. Thus, it is seen, that the character- istic of temper is what gives tool steel its immense value in the arts and sciences. To complete the parallel we will now consider artificial] corundum, which, as originally made, was very hard and useful in a limited field only. It is evident that if means could be found whereby the temper of the material in question could be controlled, its usefulness would be in- creased a thousandfold. This has been successfully accomplished and the credit is due to an American, Charles B. Jacobs (no relation to the writer), who in the year 1900 obtained a process patent for manufacturing an abrasive from bauxite and tempering the same to a degree of hardness suitable for abrasive purposes. Briefly stated, Mr. Jacobs’ process con- sists of fusing bauxite in an electric furnace of the arc type and cooling the resultant alumina oxide in a manner to impart the desired degree of temper. Before considering Mr. Jacobs’ process, it will be of ad- vantage ai this point to touch briefly on the material bauxite as we will have occasion to refer to it several times later. BAUXITE Bauxite is a clay-like mineral, or rather a combination of minerals, containing among other constituents alumina oxide, iron oxide, silica and titanic acid. It is taken to be a decomposition product of igneous rock. It. was first dis- covered in France as long ago as the year 1821 by P. Berthier, who called it alumina hydratée de Beaux.. The present name of bauxite was given to the material in ques- tion by E. H. Sainte-Claire Deville in 1861. The name was derived from the village of Les Beaux in Southern France where the material was first observed. Bauxite is never found in a crystallized state, but always as a clay-like earth. Its color varies from light yellow to 53 ABRASIVES AND ABRASIVE WHEELS deep red. The material, while always impure, contains a high percentage of alumina oxide. Hence its value as a. raw material for the manufacture of an alumina abrasive — claimed the attention of abrasive manufacturers some years ago, when a substitute for natural alumina abrasives, that is to say emery and corundum, was seriously given consideration. In this country, bauxite is found in Georgia, Alaoama and Arkansas. In these localities, the material in question is generally associated with limestone and its origin is at- _ tributed to the action of solutions of aluminum sulphate on limestone. : CHARLES B. JACOBS’ PROCESS Mr. Jacobs’ electric furnace for carrying out his process of converting bauxite into artificial corundum is shown in Fig. 6. It consists of a rectangular casing (1) with a slop- ing top, at the apex of which is an opening (2) which serves the double purpose of chargine the furnace and carrying. off the volatile matter of the charge. The furnace casing is constructed with a sheet-tron shell (3) which is lined with _fire brick (4), which serves as a non-conducting material in regard to electricity as well as heat. Next to this, are’ laid carbon bricks (s). The hearth of the furnace consists of a cast-iron plate (6) lined first with ground lime (7) and then carbon bricks (8) laid in the lime. The hearth is mounted on a screw (9) by means of which it can be lowered or raised at will. By lowering the hearth during the furnace run, in a gradual manner, a thick body of the fused material is obtained. Over the earth are mounted four pairs of carbon electrodes (10)-tetween which the electric arc is produced. The fur- _ nace is supported by cast-iron legs (11). These are of suffi- cient height to allow the hearth to be lowered clear of the . bottom of the furnace. It is seen that the two outside pairs of electrodes are away from the furnace walls; the object being to keep the walls clear of fused material. The heart} 54 CHARLES B. JACOBS’ PROCESS ESOS HHH Hy SU ae YSSSSGYG purrs SEEKERS 55 ' artificial corundum furnace. Fig. 6.—Jacobs’ ABRASIVES AND ABRASIVE WHEELS is left free to move up and down in the furnace. An Opening is made in one side of the furnace to permit of inspection should occasion require and also to provide means of introducing a stirring rod. The opening is closed by the plug (12). | Mr. Jacobs’ process of converting bauxite into artificial corundum is as follows: The first step is to calcine the raw material, the object of which is to drive away as much moisture as possible. This saves undue expenditure of cur- rent and wear on the electrodes. The hearth is now raised until it occupies a position one inch below the electrodes, each pair of which is placed in contact, and the furnace filled with the calcined bauxite. Current is now turned on and the electrodes pulled apart, causing electric arcs to be set up between them. The bauxite fuses under the intense heat and the alumina contained therein runs down on the | hearth, which is lowered about two inches per hour. ~This results in a quiet pool of melted alumina oxide which cools‘ and solidifies in crystalline forrn while the furnace hearth © descends. During the process of fusion, the impurities in the raw material are volatilized, in which condition they escape thrcugh the opening at the top of the furnace. Regarding the temper of the material, Mr. Jacobs has | the following to say: ‘“‘The nature of the product may be varied by the slow or rapid cooling of the fused mass, so as to obtain a product of the same degree of absolute hardness, but of varying toughness, and consequently varying abrasive power, by the slow or rapid lowering of the hearth. The more slowly the product cools, the better defined will be its crystallization and the greater its tough- ness and abrasive power. The nature of the product may also be varied by agitating the mass while cooling, as by a poker or stirring rod inserted through the hole normally closed by plug 12, and thus disturbing its natural tendency of crystallization, producing thereby a finer grain of crys talline structure than when the material cools withou disturbance.” 56 ALUNDUM ALUNDUM Alundum is a trade name originated by Norton Company and is applied to an alumina abrasive manufac- tured under the above-described patent. However, the process has been modified somewhat as shown by the fol- lowing account of the same by Richard G. Williams, Me- chanical Engineer and Special Investigator of Norton Company; in a paper presented at the thirty-first general meeting of the American Electrochemical Society held in Detroit, Mich., May 2—s, 1917. ‘‘The raw material must necessarily be a substance high in aluminum oxide. The most satisfactory material is a high-grade bauxite, although satisfactory .abrasives are _ being made from other materials, such as Jow-grade bauxite and emery. Aluminous abrasives are made in the arc type of furnace. These furnaces often consist of a wrought-iron shell, or some form of pot, lined with carbon. The electrodes are suspended in the pot and then lowered to the bottom of the furnace, a train of graphite or fine coke placed be- tween the electrodes, the current turned on and an arc suitable for fusing is available as soon as the train of graphite or coke has volatilized. | ‘Before fusion in the electric furnace, the bauxite receives a calcining treatment to drive off 30 per cent. of combined water. Suitable chemicals are mixed with the calcined ore in order to facilitate the removal of such materials as iron and silicon. Furnaces of three-ton capacity consume between 650 and 700 horse power and it takes approximately 24 hours for a furnace run. After the run is completed, the shell is stripped off or the furnace sides removed and the pigs allowed to cool. When the pigs have cooled to a sufficient ‘temperature, they are broken up by sledge hammers into pieces convenient for putting through a large jaw crusher. ‘This operation reduces the material to pieces about the size of a man’s fist, and in this condition the abrasive is sent to the grinding-wheel factory for further treatment ”’ 57 ABRASIVES AND ABRASIVE WHEELS Alundum, as put on the market, consists of two kinds; ordinary Alundum and white Alundum. White Alundum makes an almost white wheel when bonded by the silicate process and a deep red-colored wheel when the vitrified process is employed. White Alundum is designated by the prefix 38. oie LSS WI Ney = SSG a c Fig. 118.—Three types of chucks used in grinding the holes in gears on a Heald internal grinding machine. 249 wherein the gear is clamped in p of three rolls evenly spaced around tion shows. If the teeth are evenly unhardened, this method is generally be borne in mind, however, that distort: place when gears are hardened and this h the spacing of the gear as well as on its « It is readily understood that any va spacing is bound to alter the even spacing example, let it be assumed that one roll narrow tooth while the next roll happens to 1 tooth. The location of the gear is bound to | The chucks shown in Fig. 118 are all ception of the locating points shown at 4. B: the chuck consists of a body (2) which screws to the nose of the spindle and a collet (3) which is split in case gs and drawn into the chuck by means of a drawing rod 250 — os 4 INTERNAL GRINDING which works through the hole in the grinding-machine head spindle. The gear is shown at 5, while 6 is the grinding . wheel and 7 the grinding-wheel spindle. The body of the chuck is generally made of cast iron, while the collet is steel and insured against reasonable wear by case hardening. For various work, aside from the grinding of gears, these collet chucks are to be preferred to ordinary three-jaw chucks because the latter soon fill up with particles of metal ground from the work which calls for frequent cleaning. For grinding gears where accuracy and quiet running are paramount factors, the Heald Company have developed the chuck shown in Fig. 119. This chuck works on the /Finish for Indicator Horaened Split Ring 6 Retainer Ring, Loose on Rolls, ot Fig. 119.—Heald multiple-roll chuck for holding gears for internal grinding. multiple-roll system and has a single split ring which col- lapses as it is forced into the chuck. In this method of locating gears, a number of rolls are used. The number depends on the number of teeth in the gear. In the gear shown in the chuck in Fig. 119, nine rolls are used. The minimum number of rolls to use, however, should not be less than five. The rolls are hardened and are carried loosely in a retainer ring which keeps them in the proper position and in shape to be readily handled by the operator. In Fig. 119, the gear (7) and the rolls (6) are inserted in @ 251 ABRASIVES AND ABRASIVE WHEELS split ring (4) made straight inside and tapering on the out- side with a short thread to enable it to be screwed in and out of the body of the chuck. The body (3) is mounted on a face plate (2) which is screwed on the chuck spindle (r). The object of making the chuck body in two pieces, 2 and 3, is to afford ready means for keeping the chuck running absolutely true. By referring to Fig. 119, it is seen that part of the outside of the piece (3) is ground cylindrical to make a path for the indicator to register on while truing up the chuck. This feature allows the operator to check up the running of the chuck as frequently as de- sired. The split ring (4) is hardened to insure it against wear. Otherwise the pressure of the rolls would soon im- pair its accuracy as they would imbed themselves slightly at the points of contact every time the chuck was tightened. In Fig. 120, is shown a Heald chuck for locating large bevel gears as used in automobile rear axles. An unhardened Fig. 120,—Heald chuck for locating large bevel gears for internal grinding. gear (2) is mounted on the face plate, which is recessed slightly to center the locating gear so that it will run true at all times. The gear to be ground (3) is located with its face to the locating gear and is held in place by three clamps 252 INTERNAL GRINDING shown at 4. As the illustration shows, a portion of the teeth . of the locating gear are cut back as at 5 leaving full-length teeth (6) at three points of the circumference. This three- point contact insures the gear against rocking on its seat. Another novel gear chuck is shown in Fig. 121. This chuck was originated by the Heald Company and is used for grinding bevel pinions. In reality it is a modification Fig. 121.—Heald chuck for locating bevel pinions for internal grinding. of the principle used in the chuck shown in Fig. 119. Taper rolls are used which are spaced around the circumference to locate the gear in proper position according to the pitch line. The taper rolls should be three, five or seven in num- ber, according to the number of teeth in the gear. The method of holding the rolls allows for a certain amount of play for the purpose of taking care of slight variations in the gears, due to hardening. Referring to Fig. 121,1 is the spindle, 2 the chuck body, 3 the clamp arms that hold the gear in position, 4 the locating rolls and 5 the retaining ring in which the rolls are mounted. While the present-day internal grinder is a production machine in every sense of the word, it is not a tool for “hogging” off stock. It is a machine especially designed for finishing operations. For this reason, attention should be paid to the amount of stock left for grinding, especially in hardened work. 253 scedicaal icy truss ko:s0n ogee no hard and fast rule to refer to, but the ator judges the correct combination of wheel speed by the quality and quantity of the of the wheel. Tees In selecting wheels for internal grinding, carbide INTERNAL GRINDING is used for cast iron and bronze while alumina abrasives should be used on steel, both hard and soft. For the aver- age run of work, grits from 36 to 50 are used in grades 4 to 6 on the writer’s grade scale. For grinding cast iron, the grades are somewhat softer, from 2 to 5. Asa general rule, soft wheels give the best results. The reason for this lies in the fact that there are comparatively few cutting points on these small wheels, and if they do not wear away readily, bringing new cutting points into action, the wheel glazes quickly. Careful attention should be given to keeping wheels on internal grinding machines true. They should never, under any circumstances, be dressed with a star-wheel dresser although a carbide of silicon brick is a good medium to use, provided it is held securely in a holder that is fastened to the platen on the machine. The operator should never attempt to true the wheel by holding the brick in his hand as this gives poor results. The diamond is an ideal tool for truing these wheels, but the present cost of bort stones makes their use prohibitive in cases where another medium will serve the purpose equally well. Because of their high rotative speed, internal grinding machine wheel spindles should be properly lubricated with a grade of oil that is especially adapted for the purpose. There is a great difference between ordinary slow-running bearings and those of a high-speed grinding spindle. The former takes a heavy oil which forms a thick film on which the journal rests. With the latter, the bearings are adjusted very closely and for this reason a light-bodied, high-grade oil should be used. A special internal grinding machine that is widely used in the automobile and airplane engine industry is shown in Fig. 122. This is a cylinder grinder made by the Heald Machine Co. With the development of the automobile industry, considerable difficulty was experienced in finish- ing cylinders by ordinary methods, that is, boring or ream- ing. ‘This was due to several factors, chief among them 255 ate] ABRASIVES AND ABRASIVE WHEELS being the fact that cylinder walls are comparatively thin, thus they sprang away from the finishing tools which left the cylinder considerably out of true, Again, internal- combustion engine cylinders should be made of a compara- tively hard, close-grained iron which is always difficult to Fig. 122.—Heald cylinder grinding machine. machine accurately. With these factors in mind, engineers turned to the grinding machine for a solution of the difficulty. The ordinary single cylinder of other days was a difficult piece to grind inasmuch as it could not be rotated readily —a special grinding fixture was necessary which had pro- vision for running and balancing each individual cylinder. Again, it would be impossible to rotate a cylinder of the type illustrated in Fig. 123, which is cast en bloc. There- fore the machine shown in Fig. 122 was developed. The base and upright of this machine are cast in one piece. The wheel spindle is mounted at the top of the upright and is of the planetary type. The main spindle revolves to carry 256 1 automobile engine as finished by ture is made use of in grinding cylinders Fig. 123. The platen is fed longi- 1s an automatic feed, the movement rolled by adjustable dogs that actuate the re- versal at each end of the stroke. The operation of grinding the cylinder shown in Fig. 123 is shown in Fig. 124. The cylinder is mounted on a special angle-iron fixture that is clamped to the platen of the machine. One bore of the cylinder is ground at a time and completely finished before moving the platen to grind the next hole. The amount to leave for grinding depends upon the size of the cylinder and the condition in which the holes are left by the rough boring operation. Usually cylinders are rough bored with a coarse feed which leaves j deep tool marks. This is advantageous as the tool marks 257 — ; ABRASIVES AND ABRASIVE WHEELS exert a shearing motion of the wheel which helps to keep it true. If the holes are accurately spaced in the boring operation from 0.10 to 0.15 inches below the bottom of the boring tool marks are sufficient for finishing. This is not a hard and fast rule by any means as local conditions must be taken into consideration, thus experimentation is the Fig, 124.—Grinding a four-cylinder unit for an automobile engin feald cylinder grinding machine. only accurate guide. If the operator finds that h large amount of stock to remove after the holes show up true, the amount left for finishing should be reduced and, on the other hand, if the holes fail to ‘grind out” the allow- ance must be increased. It is best when first installing a grinder for this work to start with a liberal allowance which can be reduced if too much stock has been left. Cylinder grinding is a precision operation in every sense of the word, especially when finishing cylinders for aireraft engines. For this reason, the wheel must be kept true and in cutting condition at all times. By again referring t0 Fig. 124, it is seen that there is a bracket set at an angle under each cylinder location. These are for holding a dia- 258 INTERNAL GRINDING mond tool used for truing the wheel. In this illustration, the diamond tool is fastened in the bracket at the right of the cylinder being ground. For grinding cast-iron cylinders, carbide of silicon wheels should be used. The grits commonly furnished run from 30 to 36 and the grades from 2 to 4 on the writer’s proposed grade scale. For grinding steel cylinders, alumina abrasives Fig. 125.—Grinding Hall-Scott airplane engine cylinders on a Heald cylinder grinding machine. should be used. The grits in this case run from 30 to 4o and the grades from 1 to 4. Two important factors involved in cylinder grinding are: keeping the work cool and carrying away the dust. It is needless to say that the work must be kept cool if accurate sizes are to be maintained while the dust must be disposed of to conform with the laws relative to grinding-room prac- tice in force in the majority of states. Excellent means to attain both these ends are illustrated 259 ABRASIVES AND ABRASIVE WHEELS in Fig. 125 which shows the operation of grinding cylinders for the well-known Hall-Scott airplane engines. The cylinder to be ground is held on a special angle-iron fixture which is clamped to the platen of the machine. Water supplied from the city mains is circulated through the water jacket Fig. 126.—Grinding a special internal combustion engine cylinder on a Heald cylinder grinding machine. by means of the connections seen at the top near the upright of the angle iron and at the end of the cylinder. The dust is exhausted by means of an air suction connected to the exhaust opening of the cylinder. Cylinders are often ground, however, with no provision made for water cooling, and, if the depth of cut taken is not too heavy, good results are obtained. Such a grinding operation is shown in Fig. 126. The work consists of grinding a special cylinder of the air-cooled type. The dust can be readily disposed of by placing a hood connected to the exhaust system over the end of the hole being ground. The cylinder grinder has, without a doubt, gone a long way toward perfecting the present-day automobile and air plane engine. Ground holes are more accurate than it is pos- 260 anal INTERNAL GRINDING sible to produce by boring and reaming and every hole can be made exactly the same size with very little trouble. Far less accuracy is required in boring, in fact, the boring Fig. 127,—Grinding the hole in a coil spring on a Heald cylinder : grinding machine. operation is for roughing out only and the time spent in reaming is eliminated. Multiple cylinders are handled as easily as are single ones and interchangeability of cylinders, pistons and rings is assured. No time has to be spent in Fig. 128.—Grinding a hole in a piece of tile pipe on a Heald cylinder grinding machine. lapping a ground cylinder and a maximum amount of com- pression is always possible. Aside from cylinder grinding, the cylinder grinder lends 261 ABRASIVES AND ABRASIVE WHEELS itself readily to a number of operations that would be diffi- cult to handle by ordinary methods. A novel grinding operation of this kind is shown in Fig. 127. This showsa flat, coiled spring 14 inches in diameter and 10 inches in length. It was ground to a plus-and-minus dimension of o.oo1 inches. Another unusual job is shown in Fig. 128. Fig. 129.—Grinding a hole in a large worm gear on a Heald cylinder grinding machine. This is a piece of tile pipe 16 inches long and 8 inches inside diameter and was ground to within a limit of 0.001 inches, plus-or-minus. Fig. 129 shows a large worm gear mounted for internal grinding. The manner in which the work is held in each case is easily understood by referring to the illustrations and it is seen that these pieces did not require elaborate special fixtures for holding them in position. CHAPTER NINETEEN SPECIAL GRINDING OPERATIONS _ Grinding calender rolls—Special grinding machines—Roll grinders and roll grinding—Corrugating flour-mill rolls—Grinding crankshafts—Grinding cam shafts—Locomotive valve gears. [* this category can be included a number of grinding operations that are interesting because of the ingenuity shown in adapting the grinding wheel to unusual problems. They are also very important operations. One unusual grinding operation consists of finishing the calender rolls of Fourdrinier paper-making machines. The machine takes its name from Henry Fourdrinier who introduced the first paper-making machine into England. After the paper has been formed and partially dried, it passes through a series of calender rolls which impart a smooth finish. If paper were not calendered, it would have the appearance of a sheet of newspaper that had been wet and afterward dried. The largest stack of calender rolls in use at the present time in the United States or Canada is shown in Fig. 130. The relative size of the stack can be judged by the man standing at the left. When it is taken into consideration that these rolls are made of hard chilled iron and that they must have a mirror-like finish, to say nothing of fitting together so per- fectly that light will not show between them, it is seen that roll grinding is indeed an exacting operation. These rolls are in use at the Ontario Paper Co., Thorold, Canada, and are designated as follows: Bottom, next to bottom, intermediates and top. All these rolls are 196 inches long. The bottom roll is 30 inches in diameter and weighs 44,000 pounds. The next to bottom roll is 20 inches 263 | ABRASIVES AND ABRASIVE WHEELS in diameter and weighs 18,000 pounds. The intermediate rolls are seven in number, 14 inches in diameter and weigh 9,000 pounds each, while the top roll is the same diameter and weight as the next to bottom roll. As the work of calender rolls is nothing more or less than to press paper, it would appear that they should stay in Fig. 130.—The largest stack of calender rolls on the American continent. shape indefinitely, but this is not the case. The constant rolling action gradually affects the mirror-like finish and, again, the ‘‘doctors,” which are thin plates of specially tempered steel used for seraping them, sometimes leave scratches. What is termed a ‘“‘plug” in paper-mill parlance often occurs. As the Paper maker says: ‘'A plug plays the mischief ,with the rolls.” It occurs usually when the web of paper breaks and banks up and a large wad is pulled be tween the rolls. When this happens, one roll may stop 264 SPECIAL GRINDING OPERATIONS revolving while the next roll to it continues to revolve. Under these conditions, a flat spot is sometimes worn on the roll. It will be seen that a special grinding machine is necessary to keep the calenders in condition. The majority of paper mills keep a few spare rolls in stock which are substituted for worn’ ones. Most paper mills also have a completely equipped grinding department which saves the time and expense involved in cases where rolls are sent to a distant point for grinding. As stated in the introduction, roll finishing was one of the first attempts at cylindrical grinding. The rolls in use at that time, some 50 years ago, were, of course, much smaller than the ones shown in Fig. 130. as the turning operation in the lathe is eliminated, there” may be truth in the claim that this method is the most 277 with other exacting operations, through long practice. As crankshafts are always made of are used for grinding them. i who cater to this class of trade ha wheels for the work. These wheels bination grits and great care has been bonds that will insure the corners h out danger of burning the work. grinding crankshafts from the rough paratively hard—from 16 to 24 grit in rr to 14. For finishing, finer and s Perhaps the greatest difficulty exp grinding is keeping the work true. It free-cutting wheels are used, but they n otherwise more wheel is wasted in keeping proper radii than is used in actual grinding. are too hard, in the finishing operation, they 278 SPECIAL GRINDING OPERATIONS unduly which causes sprung work and burned spots in the fillets. Especial care must be exercised in taking the finish- ing cuts on the main bearings as these must test true, or at least within close limits, in the finished shaft. An expert can, of course, bend a sprung shaft until it runs true, but it is much better to have the work true as it comes from the grinder. The finish left on the journals and pins is another im- portant factor and the high degree of finish required by the government on crankshafts for airplane motors has caused more than one manufacturer much anxiety. There was a time when manufacturers of crankshafts used a final lapping with emery cloth and oil to impart a high degree of finish, but the government frowns on this practice. The amount to be left for finishing should be determined by experimentation as it is impossible to set any definite rule. The accuracy with which the shafts are roughed out, both as regards dimensions and the spacing of the off- sets are important factors bearing on this point. Again, the size of the shaft, whether long or short must be con- sidered. On an average, however, 0.020 inch should suffice in the majority of cases where the operator who roughs out the work uses reasonable care. Never under any conditions should it be attempted to grind a crankshaft without backresting it. Crank grinding machines are equipped with a special form of back rest that bears directly on the surface being ground and there is no excuse for not using these. Another special grinding operation that has been de- veloped by the automobile industry is that of grinding cam shafts. In the early development of the internal- combustion motor, in the days of single cylinder and two cylinder double-opposed type engines, individual cams were used. These were cut by methods used in cutting ordinary face cams after which they. were hardened to eliminate wear. These early cams were not ground; for at that time rule-of- thumb methods were the general ones employed, thus after 279 ment made by the Norton dividual cams is shown in Fig. r4¢ consists of a spindle which carries and the master cam which, running the desired contour of the cam face. headstock of the machine and a master cam in contact with its roller to the wheel by means of the cross An attachment designed for grindin; in Fig. 141, while Fig. 142 is a close- ment taken from the back of the m are removed in this view to show the A is the driving arm, B the master ca C the roll which is set in position before by slipping along the shaft D, This is locking device to hold it in place as E is the case that covers a stiff spring whicl cam in contact with the roll. F is the d steady-rests and H the tailstock. As the n revolved their bearing against the roll } 280 SPECIAL GRINDING OPERATIONS Fig. 141.—Norton grinding attachment for finishing cams made integral with their shafts, 281 | ABRASIVES AND ABRASIVE WHEELS ment to oscillate which, of course, produces a duplicate motion of the cams in position before the grinding wheel. In cam grinding, no traverse feed is used. The wheel is fed directly into the work by means of the cross feed until the required depth is reached. The handle J is for the pur- Fig. 142,—Rear view of Norton cam-grinding attachment. pose of lifting the work away from the wheel for inspection and removal and to move the guide roll from one position to another. In cam-grinding, it is very necessary to use steady-rests to support the work. These should be located reasonably close to the cam being ground and should bear on the round part of the shaft which is finished by grinding for this pur- pose. The Norton Grinding Co. provide two types of steady-rests, as illustrated in Figs. 143 and 144. Fig. 143 is an open type rest and Fig. 144 a closed type rest. It is obvious that the open type has the advantage of being readily handled in locating and removing the work. The closed rest is used in cases where great accuracy is demanded, for instance, on cams for high-class automobile engines and on aircraft engine work. 282 SPECIAL GRINDING OPERATIONS As the cams in question are made of steel, alumina abra- sives are used in grinding them. The degree of accuracy demanded and the finish sought are important factors governing the selection of wheels for cam grinding. For =t{ O S \ fo) Ly Ly Yy Y ig. 143. —Open- Norton Fig. 144.— Closed -type Norton Big. 8 for Pamsbate grinding. steady-rest for camshatt grinding. roughing out the cams before they are hardened, which is common practice, wheels in 16 to 24 grit and 12 to 17 grades will be found satisfactory. It is seen here that the wheels used for this purpose are comparatively hard. For roughing out hardened cams 24 to 40 grit in grades 4 to 7 will give good results. For finishing hardened cams, grits 36 to'50 in grades 3 to 5 will be found satisfactory. The grades are according to the writer’s grade scale. One of the most interesting factors pertaining to cam grinding is the method followed in producing the leaders or master cams. It is necessary that these be accurate as regards contour if accurate results in the ground cams are sought. In grinding a cam, we use a leader of the desired form to produce the outline on the cam that oscillates be- fore the grinding wheel. In making these leaders, we re- verse the practice. This will be clearly understood by the following description. The operation is shown in Fig. 145. This is the same attachment used for cam grinding but set up differently. In place of the grinding wheel the disk (2) is used. This is made of cast iron and occupies the position 283, ABRASIVES AND ABRASIVE WHEELS taken by the grinding wheel in grinding operations. The | model cam (4) bears against the disk and from it is produced the leader, several of which are shown at'5. This is ground | by the grinding wheel (1). The spindle (6) carries the master Fig. 145.—Grinding the leaders for a Norton cam-grinding attachment. cams. The master cams, which are hardened, were roughed approximately to the desired shape before hardening. The bearings of the master-cam spindle and the centers of the attachment must be exactly in line. As the grinding wheel and the master cam revolve, the model runs over the disk which produced the desired contour on the master. It looks simple, which in truth it is, but to assure satisfactory results two important factors must be borne in mind. The disk (2) must be the size of the grinding wheel that is to be used in grinding the cam on regular production work and the grinding wheel (1) must be exactly the same size as the roll that is to follow over the master cams when they are in use as producers for the finished cams. As previously stated the master cams are roughed out before they are hardened and a few words concerning a 284 SPECIAL GRINDING OPERATIONS simple method to follow in marking the outline will not be out of place here. The blanks, while soft, are mounted on the roughing master-cam spindle, it being understood that in cam grinding two sets of masters are necessary, one for roughing and the other for finishing master cams. The machine is started up and the model produces the desired motion to the master cam shaft. The wheel (1) is brought to bear slightly against the side of the master where it marks the outline from which the toolmaker roughs out the cam. As stated previously, the disk over which the model cam runs in making a master cam must be the same size as the Roll 4"Oiam, — == wen -~-~-—— — — we oe — Bee eee = -— = em ee -_—-2— «= — <= on —_— on eee oe oe oe Tramme!l-9 Rad represent; Grinding Wheel 9 wy Generated with Generated with Generated wi Under Size Wheel Correct, Size Wheel Over Srewrer (18"Diam) Fig. 146.—Effect of varying wheel diameters in cam grinding. grinding wheel to be used in grinding the cams later in pro- duction work. As all grinding wheels wear in use, it is evident that after the wheel is worn away somewhat it will not grind the same shape as it did when it was up to size. This is graphically illustrated in Fig. 146 which was pre- pared for explanatory purposes by Howard W. Dunbar, and illustrates clearly just what takes place in cam grinding. The model cam is in position bearing against the guide roll. 285 Another interesting grinding ope ing the radii on links used in va motives. Three types of links are is a built-up link in which the m fine the block D, are held together with bolts, t spaces being filled with the filler pieces type are generally made of wrought against excessive wear by case ha is shown at B, Links of this type are g steel castings. Sometimes they are case | other instances they are left in their soft st shown at C is the type used in the Walschaert Considering the link shown at A, it is hardening will distort it to a certain extent. If working surfaces are desired, the errors must be Bbeiecked by grinding. Son Re ey, Jinks of this type wets gonna SPECIAL GRINDING OPERATIONS by hand on the face of a wide wheel. This practice, of course, called for the services of an expert workman and even under these conditions the results were not always satis- factory. The machine shown in Fig. 148 was designed especially for grinding links and link blocks and is called a radial Fig. 147.—Three types of locomotive valve-gear links. grinder. However, as these machines are used principally in railroad shops they are generally called link grinders. The machine is designed and built by H. G. Hammett, Troy, N. Y. The fulcrum of the bar seen in the foreground is adjust- able to accommodate links of different radii and causes the upper section of the platen to describe a curve as it traverses back and forth. The grinding wheel is carried on a vertical spindle and is fed downward as the grinding pro- gresses. The link is lined up to the desired radius and securely strapped to the platen of the machine, although in some cases special fixtures are provided for locating the work. 287 re ABRASIVES AND ABRASIVE WHEELS ~ | In fitting up links of any kind, the first step is generally to grind the block which is then used as a gauge in grinding the link to the correct width. This is a much easier pro- cedure than to attempt to grind the link first and then Fig. 148—Hammett link-grinding machine, : fit the block. In fitting up new links of the type shown at A, the built-up link, excellent results can be obtained by grind- ing the block and fillers at one operation and the other members next. In assembling, the clearance to allow the block to slide is obtained by means of paper shims or liners placed between the fillers and the members 1 and 2. Links wear quite rapidly, especially those used in con- nection with Stephenson link motions. This is due prin- cipally to the slip of the block caused, among other things, by offsetting the saddle pin to secure the desired cut-off motion. Built-up links can be readily re-ground and new blocks fitted, but with solid links the only thing to do is to | grind them until the radii are trued up and then fit new blocks. The operation of link grinding is simple after the link 288 SPECIAL GRINDING OPERATIONS ; been correctly located on the platen of the machine. e depth of cut should be comparatively light as this rk is done dry and the wheel should be fed down by means the automatic feed. The wheels generally used are from to 40 grits in the writer’s 12 grade. As the work is el, an alumina abrasive should be used. CHAPTER TWENTY CUTTER SHARPENING Machines employed for cutter grinding—Adjustments and attachments on cutter grinders—Grinding spiral cutters—General operation of cutter grinders—Selection of wheels—Speeds—Depth of cut. O insure maximum production on the milling machine, it is necessary to use properly sharpened cutters. Dull cutters throw an extra load on the machine, produce un- satisfactory surfaces and leave heavy burrs. Cutter sharpen- ing is a comparatively simple operation that can be done by any mechanic of ordinary ability, provided reasonable care is exercised to see that the depth of cut is not deep enough to cause the wheel to burn the teeth. There are two kinds of machines used for cutter grinding, small universal grinders arranged for dry grinding and special cutter sharpening machines. A machine of the former type is illustrated in Fig. 149. This is a product of the Cin- cinnati Milling Machine Co. and is the result of many years’ study and experimentation to produce an economical machine that could be adapted to cutter grinding and small tool-room cylindrical grinding. On this machine the base, platen and head are all equipped with swivel adjustments while a vertical adjustment is also provided to enable the machine to take care of such work as grinding formed cutters without having to resort to the use of drop centers. Owing to its wide range of adjust- ments, this machine can be readily adapted to any kind of cutter grinding. The machine shown in Fig. 150 is a Brown & Sharpe 290 CUTTER SHARPENING cutter grinder. It embodies a number of adjustments and, with the necessary attachments, can be set up to do any kind of cutter grinding. The operation shown in Fig. 150 Fig. 149.—Cincinnati universal grinding machine adapted for tool-room and cutter grinding. is that of grinding the peripheral teeth on an ordinary milling cutter. For grinding end mills, the work is located A 7 ABRASIVES AND ABRASIVE WHEELS in a sleeve that fits the swivel head seen under the oper- ator’s hand. The attachment shown in Fig. 155, is for grinding the end teeth of cutters and similar pieces while the attachment illustrated in Fig. 163 is for grinding formed cutters. . While the primary object in sharpening a milling cutter is to put its teeth in cutting condition, care must be exer- Fig. 150,—Grinding the peripheral teeth of a milling cutter on a Brown & Sharpe cutter grinding machine. cised to see that the cutter is kept round and that the teeth are ground straight with the axis of the cutter. If the cutter is not round, comparatively few of its teeth cut and if it is tapered accurate work cannot be obtained. One of the most rapid and simple methods of sharpening a cutter properly, with the above factors in mind, is shown 292 CUTTER SHARPENING in Fig. 150. The cutter is mounted on a hollow work arbor as shown in Fig. 151 where it is held between two collars, A and B. These collars have several steps on them to ac- commodate cutters with different-sized arbor holes. This hollow arbor carrying the cutter is slid back and forth by Fig. 151.—Hollow work arbor for locating milling cutters for grinding. hand along the bar C, which is also seen in Fig. 150. This bar is clamped in the swivel head. If the bar is straight, it naturally follows that the teeth of the cutter will be ground parallel, regardless of the setting of the swivel head, and if the work arbor is true, a round cutter will result. This m2thod of cutter grinding is not new by any means, but it produces accurate results. The first step in setting up the cutter grinder is to clamp the cutter on the work arbor, set the bar in place and then set the guiding finger under the cutter tooth nearest the wheel to impart the correct angle for clearance. This is generally from five to seven degrees. Too little clearance will cause the cutter to cut slowly, while too great a clear- ance makes the teeth dull quickly. In setting the guide finger to impart the desired clearance, the expert operator is generally guided by experience alone. In grinding, the cutter should be fed past the wheel with a fairly quick motion and the depth of cut should be com- paratively light as this work is generally done dry and thus it is obvious that a deep cut will burn the tooth. It is a good plan to mark the first tooth with chalk and grind the teeth evenly and carefully until all have been sharpened. It is generally found that the wheel wears a little in going around the cutter once and for this reason a very light finishing cut should be taken to insure the cutter not being 293 ABRASIVES AND ABRASIVE WHEELS out of round from excessive wheel wear. In connection with this point it may be well to mention the fact that com- paratively wide-faced wheels give better results in cases where they can be used than do narrow ones, owing to the fact that the wide-faced wheel wears longer. A spiral cutter is ground in the same manner as a straight one with the exception that the guide finger is set to con- form to the pitch of the spiral. It is a more difficult matter Fig. 152.—Grinding a milling cutter with the guide-finger over the tooth. to grind spiral cutters than straight ones as an inexperienced operator sometimes has difficulty in setting the guide finger properly and in keeping the cutter in correct contact. There are two ways to locate the guide finger in grinding milling cutters and both have their good and bad features. By again referring to Fig. 150, it is seen that the guide finger is under the tooth being ground. The wheel is run- ning toward the operator. Thus the action of the wheel 294 CUTTER SHARPENING keeps the cutter tooth in contact with the guide finger. This is the safest way to grind a milling cutter, but it is more liable to burn the teeth than the method illustrated - in Fig. 152 In the latter method, it is seen that the guide finger is placed just opposite to what it is in the former case and also that the cutter has been reversed. The operator must exercise great care to keep the cutter in contact with the wheel, the action of which has a tendency to pull the work away from the guide finger. Should the operator relax his diligence, the wheel might force the tooth away from the guide finger which would result in an injured tooth or perhaps a broken wheel. In grinding cutters by this method, the wheel is not as liable to burn the work, thus a deeper cut can be taken. For this reason, this method is used by many mechanics. In considering the best method to use, it is best for a green operator to use the first-described one while the latter should be left for more experienced operators. In grinding the teeth of a straight or spiral milling cutter, the clearance is obtained by raising or lowering the guide finger. In grinding angular cutters, however, another = 8 A Fig. 153.—Correct and incorrect methods of locating angular cutters for grinding. method must be used. Correct and incorrect set-up posi- tions for angular cutters are shown in Fig. 153. A illus- trates the correct position in which the tooth makes a straight line toward the center. This is necessary in pre- serving the correct angle as given by the swivel head when 295 ABRASIVES AND ABRASIVE WHEELS the machine is set up for the grinding operation. If the guide fingers were dropped to give the clearance angle, ~ the result as shown in B would be had. Here it is seen that the tooth does not bear evenly on the guide finger. In setting up the cutter grinder for grinding teeth on angular cutters, the clearance is obtained by raising the Fig. 154.—Grinding an angular milling cutter on a Cincinnati grinder. wheel center above that of the cutter in the machine shown in Fig. 154, which is a Cincinnati grinder set up for grind- ing the peripheral teeth of an angular cutter, The cutter is held on the end of the swivel head spindle and the angle for clearance obtained by raising the wheel head, while the swivel head is set over to the desired angle. As a general thing, the side teeth of milling cutters require grinding but seldom, owing to the fact that most of the cut- 296 i | CUTTER SHARPENING ting is done by the peripheral teeth. In some cases, however, the side teeth require sharpening, it being obvious that this is imperative with new cutters that have never been backed off. Side teeth are sharpened in two ways, that is to say, with the face or the periphery of the wheel. For some milling operations, the periphery of the wheel is to be preferred asit gives a better cutting clearance. Grinding under these conditions is illustrated in Fig. 155 which shows an attach- Fig. 155.—Grinding the side teeth of a milling cutter on the periphery of the wheel on a Brown & Sharpe cutter grinding attachment. ment for this purpose on the Brown & Sharpe cutter grinder depicted in Figs. 150 and 152. The cutter is held on the end of an arbor that fits in the head and is fed back and forth by the lever seen in the lower part of the illustration. The guide finger at the right locates the teeth. 207 ABRASIVES AND ABRASIVE WHEELS The operation of sharpening side teeth with the side of the wheel is illustrated in Fig. 156. The work is held on the end of an arbor which fits the swivel head and fed back and forth past the face of the wheel. The machine is a Cincinnati grinder and its makers give the following direc- tions for setting up for this operation. “After the cutter is placed in position as above described, the head should be set to zero and the cutter set central by means of the centering gauge. The tooth-rest is next Fig, 156.—Grinding the side teeth of a milling cutter using the side of the wheel on a Cincinnati grinder. adjusted and the head depressed to give the proper angle of clearance. The knee of the machine is next set to 90-1/2 degrees so that the grinding is done with the down side of the wheel, the upper side clearing. Should the tooth next 298 : CUTTER SHARPENING to the one being ground strike the wheel, the table should be raised to make the clearance desired. The above applies to the grinding of right side teeth. In grinding the left side teeth, the operation is reversed and the knee set to 89-1/2 degrees so that the grinding is done with the up side of the _ wheel instead of the down side.’” Another device often made use of in grinding the side teeth of milling cutters is shown in Fig. 157 and is called a universal head. These heads are very handy for a diversity Fig. 157.—Universal head for grinding milling cutters, etc. of grinding operations. The machine shown is a Walker grinder and the operator is grinding the end teeth of a butt mill. This is held on a short arbor which is located in the vee block of the universal head. The head is tilted to impart the desired angle and the teeth are located by means of the guide finger which is strapped to the platen of the machine. On first thought, it might seem that a large machine would be necessary to sharpen large inserted-tooth milling 299 _ ABRASIVES AND ABRASIVE WHEELS cutters. This is not the case, however, as they are readily } sharpened on ordinary cutter grinding machines. Fig. 158 illustrates the operation of sharpening the face teeth of a | large mill on a Cincinnati grinder. The cutter is mounted on a shank held in the swivel head spindle and the swivel Fig. 158.—Grinding a large inserted-tooth milling cutter Oa. Cincinnati grinder. head is depressed to impart the desired clearance. The face of the tooth should be brought to a horizontal position and the tooth-rest adjusted to bear on it. It is a well-known fact that the corners of the teeth of any face mill wear readily and experience has proven that excellent results are obtained by rounding these corners. A corner relieved in this manner is illustrated in Pig. 159 and the operation of grinding it on a Cincinnati grinder is 300 CUTTER SHARPENING illustrated in Fig. 160. The cut is obtained by swiveling the head 45 degrees, 22~1/2 degrees and 67-1/2 degrees. While grinding large cutters, it is often necessary to swivel Fig. 159.—Relieved corners on face-mill tooth both the table and the head to allow for clearance. In this method the angle is obtained by a combination of both dials. Fig. 160,—Cincinnati grinder set up to relieve corners of cutter teeth. 301 EEE | ABRASIVES AND ABRASIVE WHEELS The operation of sharpening the per:pheral teeth of large end mills is shown in Fig. 161.. By referring to the | illustration, it is seen that the tooth-rest is fastened to the top of the swivel head which avoids interference with Fig. 161-—Grinding the peripheral teeth ofa Ln cinnati grinder. the grinding-wheel head. The angle for clearance is ob- tained from the graduations on the swivel e As the illustrations show, cup wheels are used | grinding these large cutters. As the grinding is done with the face of the wheel, it is obvious that a straight surface is obtained. This is considered a decided advantage in these large cut- ters as it insures the maximum amount of wear. An important branch of cutter grinding consists of sharp- ening the so-called formed cutters as used for milling irregu- Jar outlines. While an ordinary milling cutter is ground by 302 CUTTER SHARPENING cutting away its periphery, a different method must be followed with formed cutters as the outline is often of such a complicated shape that it would be impossible to grind it. The relief of these cutters is in the form of regular curves, and they can readily be sharpened by grinding away the dulled part of the tooth face. The principle is illustrated in Fig. 162, wherein A is the cutter and B the grinding wheel. In grinding formed cutters the dotted Fig. 162.—Principle involved in grinding formed cutters. line C, which is a continuation of the wheel face, must pass through the center of the cutter. Otherwise the cutter will not mill exactly the form for which it was designed. 393 Fig. 163.—Grinding a formed cutter on a Brown & Sharpe formed-cutter grinding attachment. cutter-grinding attachment that is fitted to the company’s regular cutter grinder as shown in Fig. 150. The work is held on an arbor between two centers and the cutter is 304 CUTTER SHARPENING indexed around by means of the worm wheel seen in the illustration. - The first step in setting up the machine for grinding cutters of this type is to see that the face of the wheel is perfectly true. As a matter of fact, it is a good plan to true the face of the wheel every time it is placed on the spindle. Next, the center must be brought in line with the face of the wheel. After the cutter is in position on its arbor, the wheel is adjusted to the correct depth and one tooth fed around radially until it strikes the wheel. Then the index pin is located. The cut taken should be com- paratively light as it is an easy matter to burn the teeth of the cutters in question, even with the best wheels ob- tainable. One tooth should be ground at a time with a fairly rapid reciprocating motion until the wheel ceases to spark heavily. After all the teeth have been ground enough to insure their being sharp, the cutter should be gone around once or twice with a slight cut to make sure that the grinding has left the teeth evenly spaced. Otherwise, only a few of the teeth will cut after the cutter is put in operation. While the operation of sharpening milling cutters of any kind is comparatively simple, care should be exercised in the selection of the wheels used which should be free cutting and made of an alumina abrasive, since the work is steel grinding. It should also be borne in mind that wheels for sharpening high-speed-steel cutters should be somewhat coarser than those used for sharpening carbon-steel cutters. Again, the cup-and-saucer wheels used for sharpening both plain and formed cutters should be somewhat softer than the disk wheels so commonly used for sharpening peripheral teeth. The following wheels have been found to give good results in cutter grinding. The gradings are according to the writer’s grade scale. For high-speed-steel cutters, 36 to 46 grit, 4 to 7 grade. For carbon-steel cutters, 50 to 60 grit, 4 to 7 grade. After the peripheral teeth of an ordinary milling cutter have been sharpened several times, the tooth land becomes 3°95 | ABRASIVES AND ABRASIVE WHEELS so wide that the clearance for chips is practically ground away, in which case the cutter is consigned to the scrap heap or annealed and re-cut on the milling machine. This process generally destroys the size of the hole, and, again, many cutters are lost in this manner through fire cracking. Milling cutters can be successfully re-cut, without an- nealing them, on the attachment illustrated in Fig. 163 or on the surface grinder, in which case it is understood that ‘EL -Grinaing Wheel Fig. 164.—Method followed in re-cutting milling cutters without annealing them. they are held on an arbor between centers. The method followed in re-cutting cutters without annealing them is illustrated in Fig. 164. After the cutter is placed on an arbor and the arbor located between centers, the first step is to grind grooves as shown at A. The illustration is self- explanatory. The wheel used for this work should be of medium grade in shellac bond about 4o to 50 grit. After the cutter has been gone around and all the teeth cut out, 3,06 Pe asigd ening she wapestions sist as shown at B. This work is done with a wheel in 46 grit on the writer's 6 grade. The face of the wheel is trued to produce the desired angle to the teeth. The operation is simple and after a little practice, the average operator can secure excellent results through the exercise of a little care. In gashing out the teeth, one tooth should be operated on at a time and several cuts taken to bring the gash to the required depth. In the re-cutting pdt Fee the beveled wheel, the Hepth tied should Fig. 165.—Steps taken in re-cutting a milling cutter without annealing. not be deep enough to cause the wheel to burn the work. In the latter operation also, one tooth should be worked on at a time until it is ground to the required depth as this practice will give better results than can be obtained by taking a small cut from each tooth, one after another. Upon first trial, the operator will, no doubt, burn and ruin a few cutters, but a little practice will make him pro- ficient. In Fig. 165, two cutters are shown. Cutter A has been gashed only while B shows the finished cutter ready to be put to use again. The side teeth can be cut if neces- sity demands, but since these teeth are seldom ground, they are rarely worn to the extent of needing re-cutting. 307 it probably will endure for years to « Saws are of two kinds, that is circular saws, and there are vario For cutting up logs, circular saws as band saws owing to the fact that of a comparatively thicker gauge to stiffness and strength. The added makes extra sawdust which is an eco days, circular saws are used in compa Still, there are a few circular mills left as large as 6 feet in diameter. Many circular as cut-off saws for various purposes such 308 SS _. “En SAW SHARPENING logs into the desired lengths before they are sawed into boards and for edging and trimming lumber, etc. The majority of mills today are band mills and the saws used are often 50 feet long, being driven by two large pulleys. in width, they run from ro to 14 inches. A smaller type of band saw, called a re-saw, is generally about 25 feet long and from 6 to ro inches wide. Many filers make their re- saws from old hand saws. Two machines used for saw gumming are shown in Figs, 166 and 167. The machine shown in Fig. 166 is for sharp- ening band saws, while the 6ne shown in Fig. 167 is for Fig. 166.—Type of machine used for gumming band saws. circular saws, the saw shown being a cut-off saw which is readily seen from the shape of the teeth. Both types of machines operate on practically the same principle, that is to say, means are provided for feeding the saw under the wheel, tooth by tooth, and for lowering 309 The operation of ro the filer comes, for logs, as composed wholly of wood by felling, a small stone becomes Again perhaps, the log grew on farmer might have hung a ho or other bit of discarded metal in t limbs, which in time grew over and cover Logs are often bound together in ra the river by wooden cross-pieces, held nails. The holes for the treenails are bo augers and sometimes an auger is broken ‘off and teft in the log. The rafts are often chained together and the chains are spiked to the logs. From this it is seen that many factors are present to keep the filer continually on the job for when a saw, traveling at a high speed, strikes one gio _ Ey = > SAW SHARPENING of these obstructions it sometimes happens that every tooth is literally stripped off nearly down to the bottom of the gullets. When accidents of this kind happen, the operation of roughing out the saw isin order. This requires much grind- Fig. 167—Type of machine used for gumming circular saws. ing as every tooth has to be ground in again, to the desired depth, which takes many hours of heavy grinding. When the filer makes a new saw from a blank, which is common practice in some parts of the country, the roughing out gir correspondingly faster than uneven wheel speed interferes w this reason the mills, where ca are equipped with small indepen power to the filing room. Saw-grinding machines are very means for carrying away the dust cat for this reason they should receive careful wheel spindle boxes should be examined fr wear taken up when necessary, for a loose” cannot be depended upon for the best rest and their rolls should be examined and oiled The cams wear out of shape in time: thus they 3i2 SAW SHARPENING duce the proper kind of tooth. A worn cam lets the wheel down into the gullet of the tooth too abruptly, which not only spoils the shape of the tooth, but wears away the wheel too rapidly. Great care should be used in the selection of wheels for saw gumming because inferior abrasives often burn and case harden the saws, causing them to crack. If a crack shows up at the bottom of a tooth, the only thing to do is to cut the tooth out and braze in a new one which is an expensive operation. These wheels should be of an alumina abrasive and soft enough to cut freely, but not soft enough to wear out too fast. The grade depends principally on the condition the machine is in and other local factors such as undue vibration. Too much vibration wears out the wheels QA LIZZ. A LLL. VEZ ; Cc Fig. 168.—Three types of wheels used for saw gumming. readily and a harder wheel must be used than could be employed under more favorable conditions. The wheels used for this work run from 30 to 46 grit and 7 to 10 grade according to the writer’s grade scale. Combination grit wheels with a base of 30 or 36 are excellent for this purpose. There are three shapes of wheels used for saw gumming, as illustrated in Fig. 168. r clearance, how obtained, 295. system, 147. 2r grinder, Brown & Sharpe, Design of elbows for dust collecting 3. system, 147. 2r grinder, Cincinnati, 290. Designation of alundum varieties, 58. ar grinder, Walker, 299. Designation of wheel grades, 91. 2r grinding attachment, Brown Determining grit and grade, 143. Sharpe, 297. Development of artificial corundum, 2r grinding, cup wheels for, 302. 48. 2r grinding, locating work, 291. Deville, E. H., Sainte-Claire, 53. 2r grinding, machines used for, Diamond, 13, 29. : ). Diamond, bort, 31. 2r grinding sleeve, 293. Diamond, classes of, 29. 2r grinding wheels, fixture for Diamond, color of, 31. ing, 136. Diamond cutting, introduction of, 31. 3r grinding, wheels for, 305. Diamond, fracture of, 29. 2 grinding, wide faced wheels Diamond, hardness of, 29. , 294. Diamond, how found, 30. xr teeth corners, rounding, 300. Diamond, how mined, 30. 2rs, angular, grinding, 295. Diamond, how to use for truing grind-. srs, formed, -grinding, 302, 305. ing wheel, 135. ider grinder, adaptability of, 261. | Diamond mines, De Beers, 30. ider grinder, Heald, 255. Diamond powder, how prepared, 31.. ider grinding, 257. Diamond powder, uses of, 31. ider grinding, wheels for, 259. Diamond, preparing for market, 30.. idrical grinding, applications of, | Diamond, resetting of, 135, 3, Diamond, specific gravity of, 29. idrical grinding, how to order Diamond steel emery, 64. | eels for, 144. Diamond, wheel truing, setting of, drical grinding, machine for test- 134. ' wheels for, I19. ‘Diamond, where found, 29. drical grinding machines, 216. Diamonds, sorting, 31. drical grinding, speed for wheel, Diamonds, wheel truing, kinds of, 5. 133. drical grinding, testing wheels Die grinding, 187. , 121. Die grinding, abrasives used, 192- drical grinding, wheels for, 235. Die grinding, cross feed for, 192. drical grinding wheels, star Die, grinding, depth of cut, 192. eel dresser for truing, 137. Die grinding fixture, 190. Die grinding, wheels for, 188, 192, D 199. Die grinding wheels, truing, 193. for wheel test, IOI. Die, sheared, 190. eers diamond mines, 30. Dies, locating for grinding, 188. ‘ades, QI. Dioscorides, 14. ugnetizer, Heald, 197. Discovery of American emery, 16. agnetizing switch, 196. Discovery of bauxite, 52. sits of Canadian corundum, 21. Discovery of Carborundum, 38. sits of garnet, 33. Discovery of Craigmont corundum, h of cut, 224. 24. h of cut for die grinding, 192. Discs, abrasive, manufacture of, 169. 327 Early calender rolls, how finished, ~ 20% Early manufacture of abrasive paper and cloth, 167. Early production of artificial corun- dum, 47, 48. Early uses of emery, 14. Eaming power of grinding wheels, 102, Ebelmen, J. J., 48. Economical use of wheels, 1, 53. Economical value of soft wheels, 104. Effect of change in grade, 105. Effect of fine grit wheels on surface grinding, 200. Effect of vibration, 131. Effect of wheel speed on grade, 95. Efficiency of grindstones, 125. Efficiency of large grinding wheels, 131. Efficiency test, ideal casting for, ror. 328 Ferro silicon, 59. _ Filing room, 312. Fine grit wheels, effect of on surface grinding, 200. Finish allowance in cylinder grinding, 257. Finishing Carborundum ‘sharpening stones, 86. Finishing chip, allowance for, 223. Finishing crank cases, 185. Finishing cut, depth of for surface grinding, 199. Firing a grinding wheel kiin, 71. Fixture for holding punches, 192. Fixture for truing cutter grinding wheels, 136. Fixture for die grinding, 190. Fixture for truing surface grinding wheels, 136. Fixture, grinding, rotary, 183. Flanges, safety, 154. Flanges, wheel, plain, danger of, 153. ' Flanges, wheel, proportion of, 153. Flint, composition of, 34. Flint, fracture of, 34. Flint quartz, uses of, 35. Flint quartz, where found, 35. Flint, specific gravity of, 34. . Formation of Tripoli, 36. Formed cutter grinding attachment, Brown & Sharpe, 304. Formed cutters, grinding, 302, 305. Fourgrinder, Henry, 263. Fracture of carbonado, 32. Fracture of Carborundum, 41. Fracture of diamond, 29. Fracture of flint, 34. Fracture of quartz, 34. Frémy, E., 48. Full heat of kiln, 73. Furnace, Aloxite, 58. Furnace, Carborundum, 38. Furnace, Carborundum, by-product of, 40. Furnace, Carborundum, contents of, 40. Furnace, Carborundum, heat of, 40. G Garnet, 32. Garnet, hardness of, 33. Garnet, how crystallized, 32. Garnet, how found, 33. . Garnet, how prepared, 33. Garnet, impurities of, 171. Garnet, kinds of, 32. Garnet paper belts, testing, 172. Garnet paper, kinds of, 168. Garnet paper, testing, 170. Garnet, specific gravity of, 33. Garnet, testing, 171. Garnet, uses of, 33. Garnet, where found, 33. Gaudin, M. A. A., 48. Gear case covers, facing, 184, 185. Gear chucks, 248, 251, 252, 253. Gears, grinding holes in, 248. German artificial corundum, made, 49. German carbide of silicon, 46. Grade blocks, master, 91. Grade, change in, effect of, 105. Grade list, reliable, how compiled, 92. Grade lists, comparative, inaccuracy of, gI. Grade, running, 96. Grade scale, reliability of, 94. Grade scale, universal, 93, 94. Grades of grinding wheels, 91. Grades, wheel, how designated, 91. Grading Carborundum, 43. . Grading Carborundum powder, 44. Grinder, cylindrical, preparing work for, 220. Grinder, plain cylindrical, 217. how . Grinder, roll, Farrel, 266. Grinder, setting straight, 222. Grinder, surface, Brown & Sharpe, 188. Grinder, 203. Grinder, universal, 217. Grinding allowance for cylinders, 257. Grinding allowances, 220. Grinding a taper, 238, 240. Grinding axes, 125. Grinding calender rolls, 269. Grinding centers, 240. Grinding chain links, 112. Grinding chilled car wheels, 106. surface, Pratt & Whitney, Grinding crankshafts, 277. Grinding cylinders, 257. Grinding, cylindrical, applications of, 238. Grinding, cylindrical, wheels for, 235. 329 IN! Grinding dies, 187. Grinding dog, 221. Grinding, face, 240. Grinding fixture, rotary, 183. Grinding holes in gears, 248. Grinding, internal, 243. Grinding internal tapers, 245. Grinding links, 288. Grinding locomotive guide bars, ~ marks, 181. Grinding lubricant, 210, 231. Grinding machine, face, 180. Grinding machine, surface, wet, 193. Grinding machines, cylindrical, 216. Grinding machines, internal, types of, 245. Grinding machines, modern, 218. Grinding machines, saw, 309. Grinding metal cutting saws, 315, 319. Grinding milling cutters, 292. - Grinding pearl buttons, 114. Grinding plow points, 105. Grinding punches, 191. Grinding saws, 310. Grinding sides of milling cutters, 243. Grinding size blocks, 176. Grinding, spot, 176. Grinding steel with Carborundum, 45. Grinding wheel bond, 66. Grinding wheel bonds, how standard- ized, 67. Grinding wheel bonds, varieties of, 67. Grinding wheel, dressing, 232. Grinding wheel, early development of, 123. Grinding wheel, efficiency value of, 106. Grinding wheel, future of, in axe in- dustry, 127. Grinding wheel grades, 91. Grinding whéel grits, 88. Grinding wheel, how to true with dia- mond, 135. Grinding wheel kiln, firing, 71. Grinding whcel materials, methods used in mixing, 68. Grinding wheel press, 68. Grinding wheel, rebushing, 141. Grinding wheel sagers, 71. Grinding wheel speeds, 96. Grinding wheel, surface, guards for, 159. DEX Grinding wheel, surface, sizing power of, 199. * Grinding wheel, truing, 232. Grinding wheel volume, how to find, 107. Grinding wheels, advantages of, in axe grinding, 126. Grinding wheels, balancing, 76. Grinding wheels, causes of breakage, ISI. Grinding wheels, comparative val- ues of, 129. Grinding wheels, composition of, 65. Grinding wheels, cutter, fixture for truing, 136. Grinding wheels, earning power, 102. Grinding wheels, economical use of, 153. Grinding wheels, facing and edging, 14 Grinding wheels, factors to consider in selecting, 129. . Grinding wheels and grindstones, comparative costs of, 126. Grinding wheels, hardness, how con- trolled, 67. . Grinding wheels, how bushed, 75. Grinding wheels, inspecting for grade, 4 Grinding wheels, large, advantages of using, 130. Grinding wheels, large, efficiency of, 131. Grinding wheels, mounting, 153. Grinding wheels, operating speed, how designated, 152. Grinding wheels, ordering, informa- tion to give, 142. Grinding wheels, reasons for over: speeding 152. Grinding wheels, re-bushing, advan- tages of, 139. Grinding wheels, re-bushing tools used for, 139. Grinding wheels, selection of, 97. Grinding wheels, shaving, 69. Grinding wheels, small, why used, 132. Grinding wheels, sorting, 73. Grinding wheels, special how to order, 144. Grinding wheels, speed testing, 76. Grinding wheels, surface, fixture for truing, 136. 330 INDEX Grinding wheels, tamping, 79. Grinding wheels, ‘testing for sound- ness, 74. Grinding wheels,: tests, laboratory, 115. Grinding wheels, three methods of testing, 114. Grinding wheels, tools used for dress- ing, 133. Grinding wheels, wire web, 124. Grinding wheels, wire web, 80. Grinding with face of wheel, 238. Grindstone action, 124. Grindstone, efficiency of, 125. Grindstone, life of, 125. Grindstone, uses of, 125. Grindstones and grinding wheels, cost comparisons, 126. Grindstones, characteristics of, 127. Grindstones, uses of, 14. Grit and grade, how determined, 143. Grit and grade of wheels for spot grinding, 178. Grit, angular, 64. Grits, combination, 89. Grits of abrasive paper and cloth, 89. Grits of Carborundum sharpening stones, 85. Grits, grinding wheel, 88. Grits, mixed, 88. Grits, straight, 88. Guard, pulley, 162. Guard, spindle, 161. Guard, wheel, 247. Guarded surface grinding wheels, 159. Guards, wheel, 156. Guards, wheel, unsafe, 164. Guide bar, locomotive, grinding, 181. Guide bars, locomotive, lapping, 170. Guide bars, locomotive, wear on, I81. Guide finger, locating, 294. H Hack saw blade grinder, Wardwell, 319. Hack saw blades, grinding, 321. Hammett link grinder, 287. Hard and soft spots, how caused, 72. Hard or soft wheels, how to rectify, 95. Hard or soft wheels, how to remedy, 144. Hardness of Carborundumfn, 41. Hardness of corundum, 22. Hardness of diamonds, 29. Hardness of garnet, 33. Hardness of grinding wheels, how controlled, 7. Hardness of quartz, 34. Hardness of spinel emery, 16. Hasslacher’s electric furnace, 49. Hasslacher, Franz, 49. Haultain, H. E. T., 21, 24. Head, universal, 299. Heald bushing chuck, 248. Heald cylinder grinder, 255. Heald demagnetizer, 197. Heald internal grinder, 246. Heald magnetic chuck, 194. Heald ring grinder, 200. Heald rotary surface grinder, 202. Heat of Carborundum furnace, 40. ~ Holes in gears, grinding, 248. Hollinger, J. H., 108. Hone, razor, Belgian, 35. Hood, dust collecting, 145. Horsepower required to operate Alun- dum furnace, 57. I Ideal casting for efficiency test, ror. Ideal corundum, 22. Impurities of Carborundum, 42. Impurities of emery, 17. Impurities of garnet, 171. Impurities of pumice, 36. Impurities of sandstone, 14. Inaccuracy, causes of, in roll winding, 272. Inaccuracy of comparative grade lists, gl. Information to give in ordering grind- ing wheels, 142. Ingot, Aloxite, 59. Inspecting grinding wheels for grade, 74- a Internal grinder, Heald, 246. Internal grinding, 243. Internal grinding, allowance for, 253. Internal grinding, chucking work for, 247. Internal grinding machines, types of, 245. Internal grinding, setting up univer- sal grinder for, 243. 331 Lapping locomotive guide bars, 170, Large cutters, sharpening, 299. Large grinding wheels, advantages of using, 130, Large grinding wheels, efficiency of, 131. Leaders for cam grinder, 283. Leaders for cam grinding, how made, 284. Life of grindstone, 125. Limits in using soft wheels, 104. Link grinder, Hammett, 287. Link grinding, 288. a Link grinding, wheels for, 289. , Master grade blocks, ot. Links, valve gear, types of, 286. * Materials, bonding, 66. grinding wheel sagers, 71. Locating cutters for grinding, 291. INDEX Matteson saw grinder, 315. Medium grade, fallacy of, 92. Metal cutting saws, 315. Metal cutting saws, grinding, 31 5, 319. Methods of mixing grinding wheel materials, 68. Mill roll grinder, Landis, 270. Mill roll grinder, Norton, 271. Mill rolls, locating fcr grinding, 272. Milling cutters, dull, results of using, 290. Milling cutters, grinding, 292. Milling cutters, grinding sides of, 242. Milling cutters, re-cutting, 306. Mills, end, grinding, 302. Mineral, Spanish, 33. Mining of diamonds, 30. Mining of emery, 15. Mixed grits, 88. Mixing grinding wheel materials, methods used, 68. Modern grinding machines, 218. Molding Carborundum sharpening stones, 84. Mounting grinding wheels, 153. N Natural abrasives, 13. Natural sharpening stones, 35. Naxos emery, 16. Newton saw grinder, 316. Norton backrest, setting, 226. Norton cam grinding attachment, 280. Norton mill roll grinder, 271. Norton plain grinder, 219. Norton solid backrest, 226. Numbers of Carborundum grain, 44. O Operating speed of grinding wheels, how designated, 152. Operation of Blanchard grinder, 212. Ordering grinding wheels, informa- tion to give, 142. Ordering special grinding wheels, 144. Ordering wheels for cylindrical grind- ing, 144. Oriental ruby, 47. Origin of name of bauxite, 53. Origin of pumice, 36. 333 Overspeeding of grinding wheels, rea- sons for, 152. Oxalumina, 63. Oxalumina, composition of, 63. Oxalumina, how made, 63. Oxalumina, uses of, 63. Pp Paper and cloth, abrasive, early man- ufacture of, 167. Paper and cloth, abrasive, uses of, 166. Paper, Carborundum, 168. Paper, emery, 168. Paper, garnet, kinds of, 168. Paper, garnet, testing, 170. Paper, sand, 169. Pearl button grinding, 114. Peripheral speed, effect on surface grinding, 199. Pigs, Alundum, 57. Plain cylindrical grinder, 217. Plain grinder, Landis, 217. Plain grinder, Norton, 219. Plain grinding wheel flanges, danger of, 153. Pliny, 14. Plow points, grinding, 105. Pointing up saws, 310. Power required to operate Aloxite furnace, 58. Pratt & Whitney surface grinder, 203. Pratt & Whitney surface grinder, samples of work done on, 206. Pratt, Prof. J. H., 20, 21. Preparation of Aloxite grain, 59. Preparation of corundum, 24. Preparation of diamond powder, 31. Preparation of garnet, 33. Preparation of work for cylindrical grinder, 220. Preparing diamonds for market, 30. Press, grinding wheel, 68. Pressed process, 68. Pressed wheels, characteristics of, 68. Process for making Jacobs’ artificial corundum, 56. Process of making Aloxite, 58. Process of making Alundum, 57. Process of making Carborundum, 39. Process of making crushed steel, 63. Process of making Oxalumina, 63. Radius truing device for crankshaft grinder, 277. Raw materials, Carborundum, 38. Razor hone, Belgian, 35. Razor hones, Carborundum, 85. Re-bushing grinding wheels, 141. Re-bushing grinding wheels, advan- tages of, 139. Re-bushing grinding wheels, tools used for, 139. Records of tests, how to keep, 119. Rectifying hard or soft wheels, 95. Re-cutting milling cutters, 306. Red heat of kiln, 72. Reliability of grade scale, 94. Reliable grade list, how compiled, 92. Remedying hard or soft wheels, 144. Re-saws, band, 309. Re-saws, band, grinding, 314. INDEX Ss ) Safety flanges, 154. Sagers, grinding wheel, 71. Sagers, how loaded, 71. Samples of work done on Blanchard . surface grinder, 210. Samples of work done on Pratt & Whitney surface grinder, 206. Sand-paper, 169. Sandstone, 13. Sandstone, colors of, 14. Sandstone, impurities of, 14. Sandstone, where found, 14. Saw grinder, Matteson, 315. Saw grinder, Newton, 316. Saw grinding, effect of speed in, 312. Saw grinding machines, 309. Saw grinding machines, care of, 312. Saw grinding wheels, shapes of, 313. Saw grinding, wheels used for, 313. Saws, band, 308. Saws, case hardening, causes of, 313. Saws, circular, 308. Saws, grinding, 310. Saws, hack, grinding, 321. Saws, metal cutting, 315. Saws, metal cutting, grinding, 315, 319. Saws, pointing up, 310. Saws, roughing out, 310. Saws, wood-working, types of, 308. Scythe stones, 36. Selecting grinding wheels, factors to consider, 129. Selection of abrasive discs, 173. Selection of grinding wheels, 97. Selection of wheels for surfacing, 187. Semi-automatic grinding operations, testing wheels for, 111. Setting grinders straight, 222. Setting wheel truing diamond, 134. - Shafting, testing wheels for grinding, 109. Shape of Carborundum crystals, 41. Shapes of saw grinding wheels, 313. Sharpening large cutters, 299. Sharpening stones, Arkansas, 35. Sharpening stones, artificial, 83. Sharpening stones, Carborundum, 83. Sharpening stones, Carborundum, how finished, 86. Sharpening stones, natural, 35. Sharpening stones, Turkey, 35. Shaving machine, 69. Sheared die, 190. Side surfacer, 180. Side surfacer, varieties of work ground on, 182. Side teeth, grinding, 297, 298. Silicate bonded wheels, purposes used for, 79. Silicate process, 79. Silicon carbide, 38. Silicon, ferro, 59. Size blocks, grinding, 176. Size of branch pipes for dust collect- ing system, 146. Sizes and numbers of abrasiye paper and cloth, 168. Sizes of angular grit, 64. Sizes of crushed steel, 64. Sizing power of surface grinding wheel, 199. Sleeve for cutter grinding, 293. Small grinding wheels, why used, 132. Smith, Dr. J. Lawrence, 15. soft wheels, economical value of, 104. Soft wheels, limits in using, 104. Solid backrest, Norton, 226. Sorting diamonds, 31. Sorting grinding wheels, 73. Spanish mineral, 33. Sparking, uneven, 225. Special wheels, how to order, 144. Specific gravity of carbonado, 29 Specific gravity of Carborundum, 41. Specific gravity of diamond, 29. Specific gravity of emery, 17. Specific gravity of flint, 34. Specific gravity of garnet, 33. Specific gravity of quartz, 34. Speed, effect of, in saw grinding, 312. - Speed of wheel for cylindrical grind- ing, 223. Speed of wheel, rule for finding, 224. Speed, table for surfacing, 187. Speed testing grinding wheels, 76. Speed, work, 223. Speed, work, for roll grinding, 269. Speeds for surface grinding, 185. Speeds of grinding wheels, 96. Spindle guard, 161. Spindles, loose, 156. Spinel, emery, 16. Spinel, emery, component parts of, 16. 335 Surface grinding machine, wet, 193. Surface grinding, speeds for, 185. Surface grinding wheel guards, 159. nme grinding wheel, sizing power of, 199. Surface grinding wheels, fixture for truing, 136. Surfacer, side, 180. Hurfacer, side, varieties of work, wround on, 182, wultacing, selection of wheels for, 187. Burlacing, table speed for, 187. Sie AT ER Ede denty vn MEN it JING CO. S.A. f , oO receipt of price ae —— a INDEX : ee ety Td fe, Qs. bd =e ue . : ; : ; ye Blanchard rine ef, a eed fer eyvlindrical grinding, 4 . tee “i “a al . r iti. need for rll grinding, 269, \ » wo ™ s oe oeed rule for finding, 224. “ . ve “; Feeds for internal grinding, naa eect data, Fol. ; Whee , truing diam md, setting of, 134. Wheel truing diamonds, kinds of, 133. Wheel wear, effect of, in cam grinding, 285. ; Wheel wear, rapid, 104. Wheels, elastic, purposes used for, 80. Wheels fur Blanchard grinder, 212. Wheels for cam grinding, 283. Wheels for crankshaft grinding, 278. Wheels for cutter grinding, 305. Wheels for cylinder grinding, 259. Wheels for cylindrical grinding, 235. Wheels for die grindiny, 188, 192, 199. Wheels for flour mill roll grinding,274. Wheels for link grinding, 289. Wheels for roll grinding, 263. Wheels, pressed, characteristic: Wheels, selection of, for sur 187. « Wheels, silicate, purposes ust Wheels, soft, limits in using, Ic Wheels, unguarded, 157. Wheels used for rough operatioi chine for testing, 116. Wheels used for saw grinding, Wheels, wide faced for cutter ing, 294. Why Carborundum is not fo nature, JI. Why corundum is not used m tensively, 26. Willams, Richard G., 57. Wire web grinding wheels, 80, Wood working saws, types of, Work carrying fixtures for crar grinding, 275. Work rest, 154. Work rests as cause of acciden’ Work speed, 223. Work speed for roll grinding, 2¢ THE END 1919 CATALOGUE of the Latest and Best Practical and Mechanical Books Including Automobile and Aviation Books | PRACTICAL BOOKS FOR PRACTICAL MEN Each Book in this Catalogue is written by an Expert and is written so you can understand it ] { PUBLISHED BY THE NORMAN W. HENLEY PUBLISHING Co. 2 West 45th Street, New York, U.S. A. Established 1890 QF Any Book in this Catalogue sent prepaid on receipt of price INDEX —“s- we t~iee = Sfrnmete - =— wt S-vemrrle Ueswe toa 7 B. seme rte © gt nrerret rs Becomes ~ Agee 4 S +4 mer he Gare an oreterne & BB oermrernie itn” s Ber vnet ie “gerne idl «rane & hesrrcde ste Tonga ng t BP rere og ing *7-.terhe 4 Assen ene “wre wm ~ Ang" of A-tirnerve U tding 3 L-‘gtinn ~ 2 at a “nn ges Mt fe Agnyp “p99 a Lael ? aA thd PAV Ad SPatpwmmet, » ta aad oe ; A Ure eae “Wn F490 pps “A fA” MO AGA tm Ties ae hd 6 OS AO f ive 72 4 WS fonwey ee fran bern Vrenny LAattds 4 ite te wath Keele $199, SWE Sets erege Fey Aavingy er eyee WG tre ed a Lf Aw fenve a EL a had | AL ALE A al ew ‘ AN AGEL CN Airgbsapgyt Vi he Viel FE pertile 0 pyagt imeptilne trl Flas ig pee t4é- Cpe Bangin 0 copetperetien, Cine Frwite-e Cyrene ‘Prue ten Cheschiy need C' mem Mfenting fiwts Ppecgueney Ageperiatins crore Plernee © hint Oh Warten Menthe enenes Wirth. Jyelentelde-e te ee a ee] a a ee oe ooo ee qrve-pud tertas Crogin ‘ thee rk Noth ANfeothenm. oo... ee euenes ' ee ee cs @ re he a Ve evel da ~~! Wok ae yt w A weer Wily Laltiest Accutenra eurest “liars . - ee ew wee #8 6 Mee ell le ee ee ee ey Shitering |. Sphices and Kope Work... ; Steam Pneineering............ 34. 35... Stearn Heating................-.. .. Stoel re ee ee ee a a Switeth Boards...................- 15, ee ee) Tractor, Gas... . ce ce ee tt ec wee Train Rules...............0c cece Turbines. .......... 0. cc ee ee cence Vacuum Heating..............006 Valve Setting. ......... ccc ewe cee Ventilation, . 0.0.0.0... cee eee eee Any of theae books promptly sent prepaid to any addre in the world on receipt of price. How to remit.-. By Postal Money Order, Express Money Orde Bunk Draft or Registered Letter. CATALOGUE OF GOOD, PRACTICAL BOOKS AUTOMOBILES AND MOTORCYCLES THE MODERN GASOLINE AUTOMOBILE—ITS DESIGN, CONSTRUC- TION, MAINTENANCE AND REPAIR. By Vicror W. Paaé, M.E. . E that anyone av e intelligence may gain a comprehensive Ow e of the air ; sleeve valve, rotary valve and other types of silent motors; in tendency to favor worm-gear power-transmission; versal application of magneto ignition: development of automobile electric-lighting systems: block motors; under- ung chassis; application of practical self-starters; long stroke and offset cylinder what to do, how and when to do it. Nothing has been omitted, no detail has been slighted. Every part of the automobile, its equipment, accessories, tools, supplies, spare parts necessary, etc., have been discussed comprehensively. If you are or intend to become a motorist, or are in any way interested in the modern Gasoline Automobile, this is a book you cannot afford to be without. Over 1,000 pages— and more than 1,000 new and speciaily made detail illustrations, as well as many full- page and double-page plates, showing all parts of the automobile. Including 12 large Iding plates. Price .......... i.e. . 6 « « «© $8.80 WHAT IS SAID OF THIS BOOK: “It is the best book on the Automobile seen up to date.’’—J. H. Pile, Associate Editor Automobile Trade Journal. **Every Automobile Owner has use for a book of this character.’’—-The Tradesman. **This book is superior to any treatise heretofore published on the subject.’’—The Inventive Age. “We know of no other volume that is so complete in all its departments, and in which the wide fleld of automobile construction with its mechanical intricacies is so plainly handled, both in the text and in the matter of illustrations.’’—The Motorist. “The book is very thorough, a careful examination failing to disclose any point in connection with the automobile, its care and repair, to have been overlooked.’’— ron Age. *“*Mr. Pagé has done a great work, and benefit to the Automobile Field.’"-—W. O. Hasford, Mer. Y. M. C. A. Automobile School, Boston, Mass. “Tt is just the kind of a book a motorist needs if he wants to understand his car.’’— American Thresherman. THE MODEL T FORD CAR, ITS CONSTRUCTION, OPERATION AND REPAIR, RNCLUDING THE FORD FARM TRACTOR. By Vicror W. ack, M.E. This is a complete instruction book. All parts of the Ford Model T Car are described and illustrated; the construction is fully described and operat principles made clear to everyone. Every Ford owner needs this practical book. ou don't have to guess about the construction or where the trouble is, as it shows how to take all parts apart and how to locate and fix all faults. The writer, Mr. Pagé, has operated a Ford car for four years and writes from actual knowledge. Among the contents are: 1. The Ford Car. Its Parts and Their Functions. 2. The Engine and Auxiliary Groups. How the Engine Works—The Fuel Supply System-——-The Carburetor— Ma the Ignition Spark—Cooling and _ Lubrication. 3. Details of Chassis. Change Speed Gear—Power Transmission—Differential Gear Action—Steering Gear —Front Axle—Frame and Springs —_ Brakes. 4. How to Drive and Care for the Ford. The Control System _Explained—Starting the Motor—Driving the Car—Locating Roadside Troubles—Tire Repairs—Oiling the Chassis—Winter Care of Car. 5. Sys- tematic Location of Troubles and Remedies. Faults in Engine—Faults in Carburetor —Ignition Troubles—Cooling and Lubrication System Defects—Adjustment of Transmission Gear—General Chassis Repairs. The Ford Tractor and Tractor con- version sets and Genuine Ford Tractor. 106 illustrations. 310 pages. Two large folding plates. Price. . . a oe eh lel 00 AUTOMOBILE REPAIRING MADE EASY. By Victor W. Paat, M.E. A comprehensive, practical exposition of every phase of modern automobile repairing practice. Outlines every process incidental to motor car restoration. Gives plans for 3 apt lige est bec! 8.9 Goa QUESTIONS AND ANSWERS RELATING CONSTRUCTION, DRIVING AND REPAIR. matter to all branches of Bees ak otinhasa ie language. WHAT IS SAID OF THIS BOOK: “If you own a car—get this book."—The Glassworker, -. Pagé has the faculty of making difficult subjects plain BHsiol Press sf . “We can name no writer better qualified to. ‘book W. Page." —Sclentigc American, ae STARTING, LIGHTING AND IGNITION S + Paas, ‘This practical volume has been written with special eC reader desiring easily understood, types of automobile ignition, starting and anyone, even without electrical knowledge, considered before any attempt CATALOGUE OF GOOD, PRACTICAL BOOKS shown in both technical and non-technical forms. All symbols are fully explained. It is a comprehensive review of modern starting and ignition system practice, and includes a complete exposition of storage battery construction, care and repair. All types of starting motors, generators, magnetos, and all ignition or lighting system units are fully exp . The systems of cars already in use as well as those that are to come in 1919 are considered. E ersonin the automobile business needs this volume. 5x74. Cloth. 530 pages, 297 illustrations, 3 folding plates. Price . . $2.00 GASOLINE AND KEROSENE CARBURETORS, CONSTRUCTION, IN- STALLATION AND ADJUSTMENT. By Masor Victor W. Paag&. New Up-to-date Book on Modern Carburetion Practice. This is a simple, comprehensive, and authoritative treatise for practical men ex- plaining all basic principles pertaining to carburetion, showing how liquid fuels are vaporized and turned into gas for o ting all types of internal combustion engines in- tended to operate on vapors of gasoline, kerosene, benzol, and alcohol. All leading types of carburetors are described in detail, special attention being given to the forms devised to-use the cheaper fuels such as kerosene. Carburetion troubles, fuel system troubles, carburetor repairs and installation, electric primers and economizers, hot spot mani- folds and all modern carburetor developments are considered in a thoro manner. Methods of adjusting all types of carburetors are full discussed as well as sugges- ons for securing maximum fuel economy and o taining g engine power. This book is invaluable to re en, students, and motorists, as it_includes the most complete exposition on kerosene carburetors ever published. The drawings sho carburetor construction are made from accurate e eering designs and show parts of late types of carburetors. 250 pages. 89 illustrations. . $1.50 HOW TO RUN AN AUTOMOBILE. By Victor W. Pacts. This treatise gives concise instructions for starting and running all makes of gasoline automobiles, how to care for them, and gives tinctive features of control. De- scribes every step for shifting gears, controlling engine, etc. Among the chapters contained are: [. Automobile Parts and Their Functions. II. General Starting and Dri Instructions. III. Typical 1919 Control Systems—Care of Auto- mobiles. Thoroughly illustrated. 178 pages. 72 illustrations. Price . . $1.00 THE AUTOMOBILIST’S POCKET COMPANION AND EXPENSE RECORD. By Victor W. Pac&. This book is not only valuable as a convenient cost record, but contains much in- formation of value to motorists. Includes a condensed digest of auto laws of all ' States, a lubrication schedule, hints for care of storage battery, and care of tires, location of road _ troubles, anti-freezing solutions, horse-power table, driving hints and many useful tables and recipes of interest to all motorists. Not a technical book in any sense of the word, just a collection of practical facts in simple language for the every-day motorist. Convenient pocket size. Price... . . $1.00 AUTOMOBILE WELDING WITH THE OXY-ACETYLENE FLAME.) By M. Keita DunHaAM. Explains in a simple manner apparatus to be used, its care, and how to construct necessary shop equipment. Proceeds then to the actual welding of all automobile ,in a@ manner understandable by every one. Gives principles never to be for- gotten. This book is of utmost value, since the perplexing problems arising when metal is heated to a melting point are fully explained_and the proper methods to overcome them shown. 167 pages. Fully illustrated. Price. . . . . $1.25 MOTORCYCLES, SIDE CARS AND CYCLECARS, THEIR CONSTRUCTION, ' MANAGEMENT AND REPAIR. By Vicror W. Paaf, M.E. The only complete work published for the motorcyclist and cyclecarist. Describes fully all leading types of machines, their design, construction, maintenance, operation and repair. his treatise outlines fully the operation of two- and four-cycle power plants and all ignition, carburetion and lubrication systems in detail. Describes all representative types of free engine clutches, variable speed gears and power trans- ssion systems. Gives complete instructions for operating and repairing all types. Considers fully electric self-starting and lighting systems, all types of spring frames and springs forks and shows leading control methods. For those desiring technical information a complete series of tables and many formule to assist in designing are included. The work tells how to figure power needed to climb grades, overcome air resistance and attain high speeds. It shows how to select gear ratios for various Woighte and powers, how to figure braking efficiency required, gives sizes of belts and eh to transmit power safely, and shows how to design sprockets, belt pulleys, etc. This work also includes complete formuls for figuring horse-power, shows how dyna- 5 to se power, rt is valuable to students, owners, and drivers, wits. Of great advantage as an instructor for the ‘he more ‘4s a work of reference and heavy bond paper. Price". “« r CHART, LUBRICATION OF THE MOTOR CAR CH Vicror W. Pach, M.E. Bupa pene must be lubricated and the kind motor-car maintenance, Size 24x38 inches. Price CHART. LOCATION OF CARBURETION TROUBLES piled by Vieror W. Pacs, M. aaa eee ret Bea h CATALOGUE OF GOOD, PRACTICAL BOOKS CHART. LOCATION OF IGNITION SYSTEM TROUBLES MADE EASY. Compiled by Vicror W. Paaé£, M.E. In this diagram all parte of a ical double ignition m using battery and magneto current are shown. and suggestions are @ tenttic ae hiiee finding ignition troubles and eliminating them when found. Size 24x38 inches.: Price . . . . . 85 cents CHART. LOCATION OF COOLING AND LUBRICATION SYSTEM FAULTS. Compiled by Vicror W. Paaé, M.E. This com te diagram shows a typical automobile power plant using pump circulated water-coo ng system and the most popular lubrication method. vos cugeestions for curing all overheating and loss o power faults due to faulty action of the oiling or cooling group. Size 24x38 inches. ce. ww ltl tl tl wl elle «RS COME CHART. MOTORCYCLE TROUBLES MADE EASY. Compiled by Victor W. Paaé, M.E. A e@hart showing sectional view of a single-cylinder line engine. This chart simplifies location of all power-plant troubles. A single-cylinder motor is shown for simplicity. It outlines distinctly all parts liable to give trouble and also details the derangements apt to interfere with smooth engine operation. This chart will prove of value to all who have to do with the operation, repair or sale of motorcycles. No details omitted. Size 30x20 inches. Price ~ ew lel tl lw ll wlll w= COMICS AVIATION ABC OF AVIATION By Majsor Vicror W. Pacé&. This book describes the basic principles of aviation, tells how a balloon or dirigible is made and why it floats in the air. Describes how an airplane flies. It shows in detail the different parts of an airplane, what they are and what they do. Describes all types of airplanes and how they differ in construction: as well as detailing the advantages and disadvantages of different ty of aircraft. It includes a complete dictionary of aviation terms and clear dra of leading airplanes. The reader will find simple instructions for unpacking, setting up, and rigging airplanes. A full descri ton of airplane control principles is given and methods of flying are dis- at length. This book answers every question one can ask about modern aircraft, their con- struction and operation. A self-educator on aviation without an equal. 275 pages. 130 specialiy made illustrations with 7 plates. Price... . .. . $2'50 AVIATION ENGINES—DESIGN; CONSTRUCTION; REPAIR. By Masor Victor W. Pacé, A.S., 8.C.U.S.R. This treatise, written by a recognized authority on all of the practical aspects of internal combustion engine construction, maintenance, and re , fills the need as no other book does. he matter is logically arranged; all descriptive matter is simply expressed and copiously illustrated, so that anyone can understand airplane engine operation and repair even if without previous mechanical training. This work is invaluable for anyone desiring to become an aviator or aviation mechanic. The latest rotary types, such as the Gnome Monosoupape, and LeRhone, are fully explained, as well as the recently developed Vee and radial types. The subjects of carburetion, ignition, cooling, and lubrication also are covered in a thorough manner. The chapters on repair and maintenance are distinctive and found in no other book on this subject. Not a technical book, but a practical, easily understood work of reference, for all interested in aeronautical science. 576 pages. 253 usta OO ce, ne e e ° ° ° e e e e e e ° e e e e e e e GLOSSARY OF AVIATION TERMS—ENGLISH-FRENCH; FRENCH- ENGLISH. By Masor Victor W. Paas, AS., S.C.U.S.R., and Lieut. Paut Monrariou, of the French Flying Corps. A complete glossary of practicaliy all terms used in aviation, having lists in both French and English with equivalents in either language. Price, net. . 31.00 AVIATION CHART—LOCATION OF AIRPLANE POWER PLANT TROUBLES: MADE EASY. By Maysor Victor W. Pacé, A.S., 8.C.U.S.R. A large chart outlining all parts of a typical airplane power plant, showing the points where trouble is apt to occur and suggesting remedies for the common defects. In- tended especially for aviators and aviation mechanics on school and fel duty. ce e e e e e e e e e e e e e e e e e e e e cen 8 CATALOGUE OF GOOD, PRACTICAL BOOKS BRAZING AND SOLDERING peels) AND SOLDERING. By James F. Hopart. ‘kinks. se Te ath edition of tis Book has as “and to Set nee maton a large number of tested fluxes have been Tiusteated. ss 4 ey ee CHARTS See CHART—LOCATION OF AIRPLANE POWER PLANT TRO! E EASY. By Masor Victor W. Pacé, AS., S.C.U.S.R. iss chart outlining all Eee oe where trouble Is ert phd and Intended especially f¢ Viator and KS San nee <0 eee GASOLINE ENGINE TROUBLES MADE EASY—A CHART eee SEC- TIONAL VIEW OF GASOLINE ENGINE. Compiled by Vieror W. Pach. Sam Sti ae ta fata ses See dae iestons apt to fnterfere reith engine operat Valuable to students, motorists, sicher } repalrmen. s, earieaipal een are men, chauffeurs, motor-boat owners, motor truck and tractor drivers, aviators, motor cyclists, and all others who have to do with gasoline power plants. Naa: It simplifies location of all engine troubles, and while it will the novice, it can be used to advantage by the more Tt should be on. of every able ‘and private garage, automobile repalr shop, dub boueieg ‘the automobile or pocket “wit and will insure against loss of ‘When engine trouble manifests itself, ‘This sectional view of engine is ete review of all motor troubles. Tt pared by 8 br Dractical motorist tor ‘ail who “motor” No details omitted, i= LUBRICATION OF THE MOTOR CAR CHASSIS, chart ypical chassis of Pair eee retinas Petals nee eat Poe must be lubricated and the kind of oil to use. pp Descicry chart for E motor-car maintenance. Size 24x38 inches. Price prose working of metals; treating on the Designing, Constructing, and Use of T ures and Devices, together with the manner in which they should be used in the Power . Its 505 illustrations show dies press fixtures and sheet-metal wo devices, the descriptions of which are so clear and mechanics and are in use in large sheet-metal establishments and machine shops. 5th Edition. Price e e e e es e e e e e e e * e e e e e e es $3 560 PUNCHES, DIES AND TOOLS FOR MANUFACTURING IN PRESSES. By J. V. Woopworru. ails work is a com on volume to the author's elementary work entitled ‘‘Dies, Their , Piercing, Drawing, Compressing and Assembling Sheet- cles of other Materials in Machine Tools. 2d Edition. Price. .... . DROP FORGING, DIE-SINKING AND MACHINE-FORMING OF STEEL. By J. V. Woopwortu. This is a practical treatise on Modern Shop Practice, Processes, Methods, Machine Tools, and Details treating on the Hot and Cold Machine-Forming of Steel and Iron into Finished Shapes; together with Tools, Dies, and Machinery involved in the manufacture of Duplicate Fo s and Interchangeable Hot and Cold Pressed Parts from Bar and Sheet Metal. T book fills a demand of long standing for information regard drop-forgings, die-sinking and machine-forming of relates to the engraving or sinking of . drop-fo gs, hot and cold machine forging, swedging and the press working of metals. he process of force- In addition to the arts above mentioned the book contains explicit information re- the drop-forging and hardening plants, designs, conditions, equipment, drop mmers, fo machines, etc., machine forging, hydraulic forging. autogenous welding and shop practice. The book contains eleven chapters, and the information 13 CATALOGUE OF GOOD, PRACTICAL BOOKS Cantained Jn these chapter is jusb what will prove moat. to the forged-metal Bemmpentive, Econes and ie eae s nentee iY sbo dead ot DRAWING—SKETCHING PAPER PRACTICAL PERSPECTIVE. By Ricuarps and Cotvin. feu ete See ee ee Saketch or drawing in this way. Saves tlrme in tho dra and the ‘Contains practical examples of various classes Pree ath ition, 60 cents LINEAR PERSPECTIVE SELF-TAUGHT. By Herman T. C. Kraus. This work gives the theory and practice of linear ve, ae used In are , thems Ives will be able, by ‘the use of the instruction iven, to grasp nent of the book is good? the plate is om the dy while the ive text WS On ite page, 80 as to be readily referred to. ea rire anes eae sufficiently large scale to the work and are plainly included a self-explanatory chart which gives all. ‘necessary for the thorough podertendin ers] e. chart: worth many times over the of SELF-TAUGHT MECHANICAL DRAWING AND ELEMENTARY DESIGN. By F. L. Srivesrer, M.E., Draftsman, with additions by Onura, associate editor of “ Machinery.” ‘This {s a practical treatise on Mechanical Drawing and Machine Design. comprising first principles of geometric and mechanical ‘workshop the ‘rst of esa a ‘drawing, Cape mechianie-and young drat Sto pfeont the matory ay lene and doneise mat as manner as possible. "To meet the demands of this class of students, ‘all the important elements of machine de ve boon dealt with int saa aa formulas have been explained. and elements of trigonomé best suited to the needs of the practical man. ‘The ivided tod int 0130 oh and in arrat iterial, mechanical drawing, pure and simple, has “2 iB Be He gree ae 3 ue het : F A riee t # elements entering into machine design, such as various cams, gears, cone pulleys, bolts, screws, couplings, clutches, shafting and_ fly-wheels, treated in stich a way as to make possible the lise of the work as a a continuous course of study. It is easily comprehended and students of limited previous training. 330 pages, 215 engravings. Price. . A NEW SKETCHING PAPER. A now specially ruled paper to enable you to make skotches or drawings in. perspective mithout any Aguring or Tussi {s being used for shop details as for assembly drawings, aeitmakes one Ketch do ther wock at Gare ‘no. can help seeing just what is wai Pads of 40 sheets, 6x9 inches, 25 cents. of 40 sheets, 9x12 inches, BO ce outa 40 sheets, 12x18, Price»... « ELECTRICITY ARITHMETIC OF ELECTRICITY. By Prof. T. O’'Conor SLoane. A, Practical treatise on electrical ealeulations of all kinds reduced to a series of rues, of The simplest forms, and involving only ordinary metic; each by one or more practical problems, with detailed bution of each one j among the most useful works published on the science of lect ag it does the mathematics of electricity in a manner that will attract of those who are ae ae me igeeaics Soemaienn th Edition. — Baath fie” Mik re 5 CATALOGUE OF GOOD, PRACTICAL BOOKS COMMUTATOR CONSTRUCTION. By Wma. Baxter, Jr. The business end of any or motor of the direct current is the commutator. This book goes into the designing, building, and maintenance of commutators, shows how to locate troubles and how to remedy them; everyone who fusses with dynamos needs this. 4th Edition . . ... «=... +. 6 © © « « « « « 8S cents DYNAMO BUILDING FOR AMATEURS, OR HOW TO CONSTRUCT A FIFTY-WATT DYNAMO. By Artuour J. WEED, Member of N. Y. Electrical Society. A practical treatise sho in detail the construction of a small dynamo or motor, the entire machine work of which can be doneon a small foot lathe. Dimensioned working Grawings are given for each piece of machine work, and each operation is clearly described. This machine, when used as a dynamo, has an output of fifty watts; when used as a motor it will drive a small drill press or lathe. It can be used to drive a sewing machine on any and all o work. The book is illustrated with more than original engra showing the actual construction of the different parts. Among the contents are pters on: 1. Fifty-Watt Dynamo. 2. Side Bea Rods. 3. Field . 4 Bearings. 5. Commutator. 6. Pulley. 7. B Holders. 8. Connection Board. 9. Armature Shaft. 10. Armature. 11. Armature Winding. 12. Field Winding. 13. Connecting and Starting. Price, cloth, $1.00 ELECTRIC WIRING, DIAGRAMS AND SWITCHBOARDS. By Newron Hazgrison. 4 A thoroughly treatise cov the subject of Electric Wiring in all its branches, ‘ incl tions and diagrams which are thoroughly explicit and greatly simplify Ww es. ment of the switchboard, the connections of the various instruments, including the ligh: arrester, are also plainly set forth. Alternating current wiring is treated, with explanations of the power factor, conditions for various sizes of wire, and a simple way of obtaining the sizes for single-phase, two- and three-phase circuits. This is the only complete work issued showing you what you should know about direct and alternating current wiring. It isa reference. The work is free from advanced technicalities and mathematics, arithmetic being used throughout. It is in every respect a handy, well-written, instructive, comprehensive volume on wiring for the wireman, foreman, contractor, or electrician. 2 pages; 105 illustrations. ice . 1 ww whl wl wl wll wlC6BR00 ELECTRIC FURNACES AND THEIR INDUSTRIAL APPLICATIONS. By . RIGHT. This is a book which will prove of interest to many classes of people: the manufacturer who desires to know what product can be manufactured successfully in the electric furnace, the] chemist who wishes to post himself on electro-chemistry, and the student of science who merely looks into the subject from curiosity. New revised and enlarged edition. 320 pages. Fully illustrated. Cloth. Price . . $8.50 ELECTRIC TOY MAKING, DYNAMO BUILDING, AND ELECTRIC MOTOR CONSTRUCTION. By Prof. T. O’Conor SLOANE. This work treats of the making at home of electrical toys, electrical apparatus, motors Gynamos and instruments in general, and is designed to bring within the reach of pouns and old the manufacture of genuine and useful electrical appliances. The work especially designed for amateurs and young folks. F E f 3 : o z E 3 3 E c 3 i : Thousands of our young people are daily experimenting, and busily engaged in maki electrical toys and apparatus of various kinds. The present work is just what is want ed to give the much needed information in a plain, practical manner, with illustrations to e easy the carrying out of the work. 20th Edition. Price . .. . $1.00 PRACTICAL ELECTRICITY. By Prof. T. O’Conor Sioans. This work of 768 pages was previously known as Sloane’s Electricians’ Hand Book, and is intended for the practical electrician who has to make things go. The entire 15. STANDARD ELECTRICAL DICTIONARY. By T. O’Conor § ble work to all interested in electrical science. ce wractical of words and phi at the end of the v 16 CATALOGUE OF GOOD, PRACTICAL BOOKS are indexed in ev reasonable combination of words, reference to the proper place in the body of the kK is readily made. It is difticult to decide how far a book of this character is to keep the dictionary form, and to what extent it may assume the encyclopedia form. For some P , concise, exactly worded definitions are needed; for other purposes, more extended Nescri tions are req . This book seeks to satisfy both demands, and does it with considerable success. Complete, concise and con- venient. 682 pages. 393 illustrations. Twelfth Edition. Price... . $38.00 SWITCHBOARDS. By Wuuiam Baxter, Jr. Thig book appeals to every engineer and electrician who wants to kncw the practical side'of things. It takes up all sorts and conditions of dynamos, connections and circuits, and shows by diagram and illustration just how the switchboard should be conn Includes direct and alternating current boards, also those for arc lighting, incandescent and power circuits. Special treatment on high voltage boards for power transmission. 2d Edition. 190 pages. Iliustrated. Price... o $2.00 AND MAINTENANCE. By W. H. Ranpcuirre and H. C. Cusine. This book is intended for the amateur, the wireman, or the engineer who desires to establish a means of telephonic communication between the rooms of his home, office, or shop. It deals only with such things as may be of use to him rather than with theories. Gives the principles of construction and operation of both the Bell and Independent instruments; approved methods of installing and wiring them; the means of protecting them from lightning and abnormal currents; their connection together for operation as series or bri stations; and rules for their inspection and maintenance. Line wiring and the and operation of special telephone systems are also treated. Intricate mathematics are avoided,and all apparatus, circuits and systems are thor- oughly described. The appendix contains definitions of units and terms used in the text. Selected tables, which are very helpful, are also included. Among the subjects treated are Construction, Operation, and Installation of Telephone Instru- ments; Inspection and Maintenance of Telephone Instruments; Telephone Line Wiring Testing Telephone Line Wires and Cables; Wiring and Operation of Special Telephone Systems, etc. 2nd Edition, revised and enlarged. 223 pages. 154 B CONSTRUCTION, INSTALLATION, WIRING, OPERATION | Pelophone Systems, ete. . 8 8 oe © we ew - »« $1.25 WIRELESS TELEGRAPHY AND TELEPHONY SIMPLY EXPLAINED. By ALFRED P. Moraan. ° This is undoubtedly one of the most complete and comprehensible treatises on the subject ever published, and a close study of its pages will enable one to master all the details of the wireless transmission of messages. The author has filled a long-felt want and has succeeded in furnishing a lucid, comprehensible explanation in simple language of the theory and practice of wireless telegraphy and telephony. Among the contents are: Introductory; Wireless Transmission and Reception—The Aerial System, Earth Connections—The Transmitting Apparatus, Spark Coils and Transformers, Condensers, Helixes, Spark Gaps, Anchor Gaps, Aerial Switches—The Receiving Ap tus, Detectors, etc.—Tuning and Coupling, Tuning Coils, Loose Couplers, Variable Condensers, Directive Wave Systems —M llaneous Apparatus, Telephone Receivers, Range of Stations, Static Interference—Wireless Telephones, Sound and Sound Waves,The Vocal Cords and Ear—Wireless Telephone, How Sounds Are Changed into Electric Waves—Wireless Telephones, The Apparatus—Summary. 164 pages. 156 engravings. Price cs. Oe”, WHAT IS SAID OF THIS BOOK: **This book should be in both the home and school library.’-—The Youths’ Instructor. ‘WIRING A HOUSE. By Herserr Pratt. Shows a house already built; tells just how to start about wiring it; where to begin: what wire to use; how to run it according to Insurance Ruies; in fact, just the informa- tion you need. Directions apply equally toashop. Fourthedition . . 85 cents RADIO TIME SIGNAL RECEIVER. By Austin C. LescarBoura. This new book, ‘‘A Radio Time Signal Receiver,’’ tells you how to build a simple outfit designed expressly for the beginner: You can build the outfits ix your own workshop and install them for jewelers either on a one-payment or a rental basis. The ap tus is of such simple design that it may be made by the average amateur mec Cc possessing a few ordinary tools. 42 pages. Paper. Price . . 85 cents 17 CATALOGUE OF CONSTRUCTION OF A TRANSATLANTIC WIRELESS _By L, G. Pacenr and T, 8. Curtis, ——- HIGH FREQUENCY APPARATUS, ITS CONSTRUCTION AN APPLICA’ Corts. (ON. By Tuomas STanuey ‘The most comprehensive and thorough work on this int ‘The book is essentially practical in its treatment and it of the researches of its author over a period of sev e of coils were built and experimented with. \ A complete treatise on bat operating prineiples, The greatl, increasing application of storage vtteries in’ n mechanical work has created a demand for a book that ely and exclusively. ‘This is the most thorough 18 = rs and 7 Mustrations deals with a te Sar cus ENGINE ae aoe FARM: ITS OPERATION, REPAIR ‘Xeno W. CATALOGUE OF GOOD, PRACTICAL BOOKS ‘the ble tasks which otherwise be disagreeable small must Tate, barden and bara ith ate made contrivances for has eller eg as ieinapicae Setar a eas cee Teading the pages ook. Tt is ‘result ‘invalual Tote up farmer, student, blacksmith, fapement dal nd in fic, all who can apply practical know thonary ‘engines or gas tractors to advan- tage.” 530 pages. Nearly 180 engravings. emirarads ett UE WHAT IS SAID OF THIS BOOK: “Am [go et in ene so ra aa jeeec veer eee seen ee het eae Gistison Colleges 8. : “7 foe} that Mr, Putnam's book covers the main points which a farms chould know. R. z ‘Agronomy, University of V Ve. “Tt ‘will be a valuable addition to our library upon James A. Farra, Inst. in Agri. Engineering, Sesto Universite of En Levinetons 6 ae ENGINES: THEIR OPERATION, USEAND CARE, By A. Hyarr we a ae latest and most, work published on Gasctine tener fine the Gasoline engine ine is; bing what, the tine Eng Construction and operation; how GAS, SAS eee Ow casera = By, Garpner D, Hiscox. Just issued, cin ofa Y: oy eee eee ae ais lesigned and manufactured in the United States. ‘motors f marine and Vehicle poms are fully treated, together — illustrations of and tabulated sizes, also their care and are included. induction coil and jump spark are an? Snes a illustrated, information on the testing for for econom; power and the erection | eal rules and ee of the Boandc of Fire iy in Be a ; ent of gasoline ¥ of explosive motor power. _A list of United States Patents on gas, ofl engines and thelr adjuncts from 1876 to date is includ pages. Folding plates. “Price . Pie: GAS ENGINE CONSTRUCTION, OR HOW TO BUILD A HALF-HORSE- POWER GAS ENGINE. By Parsett and Wanp working dra\ the scientific investigator, and the amateur mechanic. ‘This book treat more from the standpoint of practice than that of theory. | TRe/prias of Gas Engines are simply described. Pa mese Dawes ag ne taken up, step by step; showing in ‘indetallt d * HOW TO RUN AND INSTALL GASOLINE ENGINES. By C. Revised and enlarged edition tjust isqued. | The object of this little @ pocket instructor for the beginner, the busy man who uses an Drbht, but who doce not have the tine or inclination for ate 20 — | CATALOGUE OF GOOD, PRACTICAL BOOKS to thoroughly understand how to properly operate, install] and care for his own engine. The index refers to each trouble, remedy, and subject alphabetically. Being a quick reference to find the cause, remedy and prevention for troubles, and to become an expert with his own engine. Pocket size. Paper binding. Price . . 88 cents MODERN GAS ENGINES AND PRODUCER GAS PLANTS. By R. E. ATHOT. A guide for the gas engine designer, user, and engineer in the construction, selection, urchase, installation, operation, and maintenance of gas engines. More than one book on gas engines has been written, but not one has thus far even encroached on the field covered by this book. Above all Mr. Mathot’s work is a practical guide. Recog- nizing the need of a volume that would assist the gas engine user in understanding thoroughly the motor upon which he depends for power, the author has discussed his subject ‘without elaborate theoretical ex- THE MODERN GAS TRACTOR. By Vicror W. Paaés. A complete treatise describing all types and sizes of gasoline, kerosene and oil tractors. Considers design and construction exhaustively, gives complete instructions for care, a) tion and repair, outlines all practical applications on the road and in the field. e best and latest work on farm tractors and tractor power plants. A work needed by farmers, students, blacksmiths, mechanics, salesmen, implement dealers, d ers and engineers. 500 pages. Nearly 300 illustrations and fol plates. Price $23.50 CHEMISTRY OF GAS MANUFACTURE. By H. M. Rov es. This book covers points likely to arise in the ordinary course of the duties of the engineer or manager of a gas works not large enough to necessitate the employment of a separate chemical staff. It treats of the testing of the raw materials employed in the manufacture of illuminating coal gas and of the gas produced. The preparation of standard solutions is given as well as the chemical and physical examination of coal. 534 x83. Cloth, 328 pages. 82 illustrations, 1 colored plate. Price $6. } GEARING AND CAMS BEVEL GEAR TABLES. By D. Aa. Enastrom. A book that will at once commend itself to mechanics and draftsmen. Does away with all the trigonometry and fancy figuring on bevel gears, and makes it easy for any- one to lay them out or make them just right. There are 36 full-page tables that show every necessary dimension for sizes or combinations you're apt to need. No puzzling, ng or guessing. Gives placing distance, all the angles (including cutting ang es), and the correct cutter to use.