Apparatus for machining round holes

摘要

A trepanning tool for making holes having a plurality of tool insert holders with pockets wherein replaceable carbide tool inserts are secured by retaining screws, the inserts being positioned so that alternate tool inserts cut overlapping inner and outer portions of a leading surface. Spiral chip relief grooves are provided on the exterior of the trepanning tool to receive cuttings made by each tool insert and remove cuttings from the hole. A tool insert which is positioned to cut the inner portion of the leading surface may be angled to direct cuttings outwardly, toward an adjacent chip relief groove. The flanks of the tool insert holders are cut back to allow access to the retaining screw in the adjacent tool insert holder for tool insert replacement.