. American engineer and railroad journal . clamped and then swiveled across the platen,the slots can be cut with a regular axial cutter. After th<* cut-ters have been inserted into the slots, and locked, the millingmachine is geared again for the proper helix, and the cuttingface of each cutter is milled helical and radial. The number ofcutting edges for milling cutters with inserted blades may be asgiven bHnw, which is good average practice: TAI .K OF CUTTING EDG1 [ILLS WITH INSERTED CUTTERS Diameter. r. Diameter. Number. 6 12 18 35 7 II 20 38 8 22 41 e IS 21 44 in 46 12 i 2H 48 14 28 30 5
. American engineer and railroad journal . clamped and then swiveled across the platen,the slots can be cut with a regular axial cutter. After th<* cut-ters have been inserted into the slots, and locked, the millingmachine is geared again for the proper helix, and the cuttingface of each cutter is milled helical and radial. The number ofcutting edges for milling cutters with inserted blades may be asgiven bHnw, which is good average practice: TAI .K OF CUTTING EDG1 [ILLS WITH INSERTED CUTTERS Diameter. r. Diameter. Number. 6 12 18 35 7 II 20 38 8 22 41 e IS 21 44 in 46 12 i 2H 48 14 28 30 50 L6 3:; :-,4 52 The proportions of the cutters may be about as follows: tSeeFig. 3.) The thickness of the cutter may be about one-fourththe distance from one cutting edge to the next ojie. The depthK may be about .75 of the pitch of the cutting edges, and thedepth M of the slots may be about .55 of the pitch. By pitchhere is meant the distance from one cutting edge to the othermeasured along the arc of the circle circumscribed about the. FIG. 2.— MILLING CUTTER WITH NICKED TEETH. FIG. 4.—STRAIGHT BLADE SET AT AN ANGLE. •cutters, this method is not used, but the cutters are dovetailed inand the back of the cutting edge is then caulked. Inserted milling cutters may be given a helical cutting edgefor the same purpose that solid cutters are provided with it. butif a helical slot is cut in the body the cutting tool will have tobe helical in order to fit. This is very hard to make, however,and cannot successfully be made with the machinery found inthe average tool room. For this reason straight slots are cutat an angle which will vary with the length of the cutter. Iv, nocase should this angle be so small that when one blade leavesthe work, the other is not engaged in cutting. Straight cutters are universally used. Straight cutters set at anangle are open to one objection, which is that the front face ofthe cutter is not radial throughout its length, but changes fromfront rake
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
