Abstract: A cutter assembly, for a rotary drill bit, comprises a stud to be received in a socket in the surface of the bit body, the stud being formed, adjacent one end, with a plane surface inclined to the longitudinal axis of the stud. A preform cutting element comprises a front surface, a peripheral edge surface, and a flat rear surface which is brazed to the surface on the stud, the peripheral edge surface of the cutting element being wholly exposed. The junction between the peripheral edge surface and the rear surface of the cutting element is chamfered. Any external fillet of brazing alloy is preferably removed or is not allowed to form during brazing, and the space between the chamfer and the surface of the stud may also be free of brazing alloy. Removal of the brazing fillet may also be advantageous in the case of a non-chamfered cutter.