Appleton's dictionary of machines, mechanics, engine-work, and engineering : illustrated with four thousand engravings on wood ; in two volumes (1873)
D. Appleton and Company · New York : D. Appleton and Co. · leaf 176
rength in the shafts of the drills,otherwise they tremble and chatter when at work, or they occasionally twist off in the neck; the pointshould be also ground exactly central, so that both edges may be cut. As a guide for the proportionalthickness of the point, it may measure at b, Fig. 531, the… … In all the drills previously described, except Fig. 526, the size of the point is lessened each time ofharpening; but to avoid tliis loss of size, a small part is often made parallel, as shown in Fig. 531 InFig. 532, this mode is extended by making the drill with a cylindrical lump, so as to fill…
Mechanical engineering · Mechanics · Engineering
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