Abstract: The cutting insert disclosed is a block of hard metal configured on at least one of its major faces to provide peripheral cutting edges successively index able about a central fastener location to position each edge serial for cutting. The major face slopes downwardly and inwardly from the cutting edges to provide rake surfaces of positive rake behind the cutting edges, and then rises as a sloping ledge to a central boss. A series of depressions disposed along the rake surface produce a ribbed chip which breaks more readily, and into smaller chips, easier to flush or otherwise remove from the cutting site.

Abstract: A generally cylindrical drill, particularly an insert drill having multiple cutting inserts, helical chip grooves to clear the chips from the hole, and a gripping shank opposite the cutting end of the drill, wherein the drill experiences an unbalanced resultant transverse force upon the cutting tip of the drill, and that resultant is oriented perpendicularly to an axial plane containing the neutral axis of the maximum resistive moment at the grooved section of maximum bending stress adjacent to its juncture with the gripping shank.