Grinding angle gauge for high speed twist drill - has reference surfaces aligned and angled to detect discrepancy between lengths of cutting edges

摘要

The two parts (11,13) of the gauge are held together by pins (21,23) projecting from one part (11) through elongated slots (15,17) in the other part (13). The drill (27) is placed against the edges (25,25') of both parts (11,13) so that its cutting edges (35,35') abut against the reference surfaces (31,31') which meet at the standard angle of 118 deg. If the lengths of the cutting edges (35,35') which meet at the standard angle of 118 deg. If the lengths of the cutting edges (35,35') are not equal, the discrepancy is brought to light by the appearance of a gap between the longer cutting edge and one reference surface of the gauge when the drill is turned through half a revolution. ADVANTAGE - Possible to verify not only that cutting edges are at correct angle to each other, but also that their lengths are equal.