Patent ID: 8376669

Claim:
A drill comprising: a tool body comprising a fluted portion and a shank portion, said fluted portion having a first end adjacent said shank portion and a second end opposite said first end; a tool head portion comprising a cutting tip and at least one cutting edge, said tool head portion being removably connected to said second end of said fluted portion; said fluted portion comprising a receiving pocket disposed in said second end and defined by a peripheral side wall extending about the periphery of the receiving pocket, at least a portion of said peripheral side wall having a stepped, angled, or conical profile forming an undercut portion; said second end of said fluted portion comprising a contact face disposed to completely surround said receiving pocket; said tool head portion comprising a driving projection being configured to be inserted into said receiving pocket and a contact face disposed to completely surround said driving projection and contact said contact face of said second end of said fluted portion; said driving projection having an elongated, curvilinear, dog-bone shape; said driving projection comprising a peripheral side wall, at least a portion of which having a stepped, angled, or conical profile forming a projecting portion; said receiving pocket having an elongated, curvilinear, dog-bone shape corresponding to the shape of said driving projection; said driving projection comprising a first end portion, a second end portion, and a central portion disposed between and to connect said first end portion and said second end portion; said first end portion and said second end portion each having a width that is substantially greater than a width of said central portion; and said projecting portion of said driving projection being inserted into said receiving pocket under said undercut portion to engage said undercut portion and retain said driving projection in said receiving pocket.