A drill comprising a shank and an elongate body with an axial slot near one end thereof. A generally hexagonal insert of sintered tungsten carbide or high speed steel is placed in the slot and received in a V-shaped seat formed in the bottom of the slot. A cross-screw extends through a hole in the insert...http://www.google.com/patents/US4047826?utm_source=gb-gplus-sharePatent US4047826 - Drill having indexable replaceable insert tip
