Abstract: A tool assembly includes a plurality of tool bit inserts, each having a cutting edge formed on at least one end of the insert, the insert being securely clamped to the head portion of a shank which is mountable to a machine tool, with the cutting edges of the inserts projecting outwardly from an edge of the shank in an ascending staggered configuration starting with the first cutting edge to contact the workpiece. As preferably embodied, the shank has a cut-out in its front end, providing a seating surface to support the inserts and a bearing surface segment for each insert to abut the back edge of its corresponding inserts, the segments being formed in an ascending step-like configuration to provide the stagger for the cutting edges of the inserts.