Items related to Modern shop practice Volume 3; a general reference...
Synopsis
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. 1916 Excerpt: ...withdrawn, the nut loosened, and the cutter turned on the arbor to bring the next tooth in position to be backed off, this operation being repeated until all the teeth are backed off alike. The amount of backing off must be determined by the cross-feed stop or by a graduated dial on the cross-feed screw. After the roughing cut has been taken on all the teeth, the forming tool should be sharpened by grinding or by oil-stoning, and the finish cut taken on the teeth. Backing Off by Stud in Faceplate. Another method of backing off cutter teeth is shown in Fig. 228. A stud is screwed in the faceplate of a lathe near the outer edge, as shown. The cutter, which must be a fit on the stud, is clamped by means of the nut. The finger A is movable in the slot in the stationary block B, which is so located on the faceplate as to bring the tooth to be backed off into its proper location, and to keep it from turning during the operation. The forming tool is fed in gradually until the tooth is formed. The finger is then disengaged from the space in the cutter, which is revolved by means of the set screw until the next tooth is in position. Each tooth is machined separately; that is, the forming tool is fed in the required distance for each tooth when it is in position, the cutter is turned until the next tooth is in position, and the process repeated until each tooth has been backed off. In backing off cutters in this device, it is necessary to cut the notches (the spaces between the teeth) somewhat wider than the teeth. General Directions for Backing Off. When backing off the teeth for clearance by any of the means described, it is first necessary to form the blank, then to gash it or to cut the notches as described; then to back off the teeth. After backing off, it is ne...
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