Abstract: A rotary borer has a body (10) mountable on a drill steel and one or more cutting tips (30) at a front of the body (10). Each tip (30) is tapered and is frictionally received in a corresponding tapered slot (22) in the body (10). The slot (22) has a trailing, rigid anvil surface (16), which extends almost to the extremity of the tip (30) to support the tip (30) and to locate it laterally, and a leading, resilient retaining surface (20) well shy of the extremity of the tip (30) to expose a portion of the tip. The tip (30) is readily replaceable. Release of the tip can be effected by heat or by means of taper drift (38) for which a transverse hole (37) is provided proximate a bottom of the slot (22).

Abstract: A rotary or rotary/percussion drill bit 10 has a taper socket 14 in one end. A wall 18 bounds the socket 14. A plurality of recesses 20 is provided in the wall. In one embodiment, each recess 20 extends longitudially and resembles a flute. It has a valley 22 flanked by peaks 24. In another embodiment, the recesses may be circumferential, e.g. helical.