A drill bit (20) for a modular arm (70) is provided. The modular arm (70) includes an inside surface (76) having first (144) and second (146) angled surfaces whose lower portions form an inwardly projecting wedge (125). A curved throat relief area (87) connects to a lower edge (152) of the wedge (125)....http://www.google.com/patents/US5641029?utm_source=gb-gplus-sharePatent US5641029 - Rotary cone drill bit modular arm
