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. American Emery Wheel Works The Carborundum Co. Chicago Wheel & Mfg. Co. The Cincinnati Milling Machine The Cleveland Stone Co. H. G. Hammett. Hampden Corundum Wheel Co. Frederick S. Jacobs, data on axegrinding. Landis Tool Co. Manufacturers Corundum Co., Ltd. Minnesota Mining & Mfg. Co. Newton Machine Tool Works. Norton Co. Norton Grinding Co. Fred E. Rogers, editor emeritus of Safety Emery Wheel Works. Sterling Grinding Wheel Co. Waltham Grinding Wheel Co. Permission to reprint material by the writer which had been previously published, was granted by the following publishers: Penton Publishing Co., Marine Review. 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. FRED B. JACOBS. June, 1919. CONTENTS CHAP. PREFACE PAGE I. NATURAL ABRASIVE SUBSTANCES Nature of natural abrasives-Where found-History of natural abrasives-Commercial application-Sandstone-Emery-Corun- dum-Garnet-Diamond-Bort diamond-Flint-Quartz-Nat- 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 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 Selection of wheels-Improper methods of testing-Practical testing methods-Items to be noted in a wheel test-How to figure result— Formula for finding volume of abrasive material in a wheel-General Apparatus and appliances used-Limitations of laboratory tests- Factors to be considered-Laboratory testing machine-Data for Advantages of natural and artificial abrasive used in wheels-Early use of grindstones-Special work where grindstones are still em- 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 Abrasive action-Tools used in truing wheels-Use of bort and carbonado diamonds in tools-Getting stones in tool-Procedure in Information to be given with grinding-wheel order-Factor govern- State law requirments-Design of wheel hood-General design— Size of exhaust pipe for different size wheels-Elbows-Collars- |