Appleton's dictionary of machines, mechanics, engine-work, and engineering (1861)
Appleton, firm, publishers, New York. (1852, D. Appleton & Co.) · New York : D. Appleton · leaf 177
-~-f u … Fig. 522 is the ordinary double-cutting drill; the two facets forming each edge meet at an angle ofabout 50 to 70 degrees, and the two edges forming the point meet at about 80 to 100 ; but the watch-makers, who constantly employ this kind of drill, sometimes make the end as obtuse as an angle…
Mechanical engineering
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