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). A pocket (54) in the drill bit (20) is sized to receive the support arm (70). The pocket (54) includes a wedge-shaped recess (121) sized to receive the wedge (125) of the support arm (70). A triangular weld groove (126) is provided in the convex surface of the bit body (40). A length of weld (128) is applied in the weld groove (126) for firmly securing the support arm (70) to the bit body (40).