The Mechanics' Handbook; A Convenient Reference Book for All Persons Interested in Mechanical Engineering, Steam Engineering, Electrical Engineering, Railroad Engineering, Hydraulic Engineering, Bridge Engineering, Etc (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1904 Excerpt: ...clear. MACHINE TOOLS. SPEED OF EMERY WHEELS. The speed most strongly recommended by their manufacturers is a peripheral velocity of 5,500 ft. per min. for all sizes. All things being considered, it is stated that no advantage is gained by exceeding this speed. If run much slower than this, the wear on the wheels is much greater in proportion to the work accomplished, and if run much faster, the wheel is likely to burst. SPEED OF GRINDSTONES. Grindstones used for grinding machinists' tools are usually run so as to have a peripheral speed of about 900 ft. per min., and those used for grinding carpenters' tools at about 600 ft. per min. With regard to safety, it may be stated in general that with any size of grindstone having a compact and strong grain, a peripheral velocity of 2,800 ft. per min. should not be exceeded. SPEED OF POLISHING WHEELS. Polishing wheels are run at about the following peripheral speeds: Leather-covered wooden wheels.7,000 ft. per min. Walrus-hide wheels 8,000 ft. per min. Rag wheels 7,000 ft. per min. SPEED OF CUTS FOR MACHINE TOOLS. Brass: Use high speeds, about the same as for wood. Bronze: 6 to 18 ft. per min., according to alloy used. Cast or wrought iron: 20 ft. per min. is a good average for ill machines, except millers. 30 is about the maximum. Machinery steel: 15 ft. on shapers, planers, and slotters. 20 to 45 on turret lathes, according to cut. Tool steel: 8 to 10 ft. Hilling Cutters.--Gun metal, 80 ft. per min.; cast iron, 30; wrought iron, 35 to 40; machinery steel, 30. These are good speeds to adopt, with a view to economy, time required for regrinding. etc. Twist Drills.--The best results are obtained when the rates of speed of twist drills are as given in the following table: The following are recommended as the best rat...