Drills and their manufacture

摘要

A method of producing a fluted drill in which the flutes are formed by grinding a generally cylindrical blank using a grinding wheel having a profiled circumferential face for generating the cross-sectional form of the flutes is characterized in that the radial cross-section of the profiled circumferential face of the grinding wheel includes a main cutting portion having a convexly curved profile, and a secondary cutting portion forming a continuation of the main cutting portion, there being a change in profile shape at the junction between the main and secondary cutting portions with the secondary cutting portion extending outwardly, away from the extended curve of the main cutting portion profile, to a radially outermost peak of the circumferential face.