Patent ID: 8348575

Claim:
A self-countersinking screw comprising: a threaded shank having a longitudinal axis, a screw head including driver engageable means on a top surface; and an underside having a frustoconical shoulder tapering to the threaded shank; the frustoconical shoulder having a plurality of generally triangular recesses therein, whereby the recesses have a generally vertical wall substantially in a plane parallel to the axis of the screw, the underside of the head having a plurality of pairs of cutters arranged peripherally around the circumference and abutting each triangular recess; the cutters comprising a succession of two cutter shapes, a first cutter having a first generally scalene triangular shape adjoining the vertical wall of the triangular recess and a second cutter having a second generally scalene triangular shape different from the first generally scalene triangular shape and being incorporated into the triangular recess.