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THE MARINE REVIEW DEVICE FOR CUTTING ACCURATE THREADS ON THE ENGINE LATHE arbor runs in a steel bushing that is fitted to the base. The base is fitted with a micrometer stop which engages a locking pawl on the operating lever. It is graduated to read by % thousandths of an inch on a dial that gives 5/32 of an inch between the graduations. The front of the base is fitted with a square- head set screw which supports the operating tooth of the cutter and per- mits of adjustment as the cutter is worn away through sharpening. The operating lever is fitted direct- ly to the cutter arbor through the 'medium of a square hole and is held in place by a lock nut. This lever is equipped with a locking pawl which is controlled by means of a compres- sion spring, push rod and thumb pad. The clamping plate has a groove milled in it to coincide with the rib in the sub-base, the upper portion of which bears against the side of the base. It is held in place by means of a substantial bolt. This method of mounting, it is said, permits of angu- lar adjustment and rigid construction. The cutters are made of high-speed or carbon steel, at the option of the user. They are furnished for any pitch and style of thread such as V, United States standard, Whitworth, British association, Acme and Inter- national standard. Surface Grinder _ Present-day practice has resulted in many flat surfaces, heretofore machined by planing or milling, being finished ad- vantageously by grinding. This is due 'to the rapid des lopment made in abrasive engineering and grinding ma- chine construction during the decade which has given good results. past -- The machine shown in the accompany- ing illustration is an oscillating surface grinder, designed for heavy duty by the Springfield Mfg. Co., Bridgeport, Conn. To insure rapid and adequate location of the work, it is equipped with a magnetic chuck. The machine is de- signed to accommodate grinding wheels 30 inches in diameter in any width up to 10 inches. The bed is of the box type on which the platen travels. The housings that carry the wheel-spindle bearings are bolted directly to the base, somewhat after the design followed in an ordinary iron planer. The platen is driven by means of bevel gears and a screw re- versing device. The wheel and wheel spindle are carried in heavy and sub- June, 1919 _ These are fitted to the saddles on the face of the up- rights. As the work passes under the wheel, the wheel oscillates from Side » to side. This movement is accomplished through the medium of the crank and connection shown at the right hand side of the tool. The lever shown just above the oscillating connecting rod operates a clutch that engages with the bevel gear which actuates the oscillating arrange- ment. f A The oscillating motion is particularly valuable when taking heavy roughing euts, due * to the fact that as the wheel moves sidewise while the work passes under it, a shearing motion is imparted which tends to keep the wheel sharp and free cutting. In taking finish- ing cuts, the oscillating motion is gen- erally dispensed with. During the grind- ing operation, the work is kept cool by a liberal stream of water which flows over the wheel. To prevent the water "lashing as it is thrown from the wheel, stantial slides. -sheet-metal guards are provided. The machine will grind work 60 inches long and 26 inches wide. ,For grinding nonferrous metals, such as brass and aluminum, the magnetic chuck is removed and the work strapped directly to the platen as in ordinary planer prac- tice, While grinding steel and iron, how- ever, better results are obtained through the use of the magnetic chuck as this device holds the work securely without distorting it. Electric Rivet Heater An electric rivet heater for use in shipyards and shops has been de- veloped by the American Car & Foundry Co., Berwick, Pa. Power HEAVY-DUTY OSCILLATING SURFACE GRINDER EQUIPPED WITH A MAGNETIC. CHUCK FOR HOLDING THE WORK