Abstract: A rotary cutting tool includes three complexly-configured, equally-spaced cutting edges. In a first embodiment, which may generally be characterized as an angle milling cutter or countersink, the cutting edges are defined by the intersection of right circular cylinders, offset from the axis of the countersink, with the frustum of a cone. The axes of the cylinders are displaced from the cone axis a distance greater than their radii. The second embodiment, which may generally be characterized as an end mill, also includes three flutes and three cutting edges. Rather than a frustum of a cone, however, the end mill includes a circumferentially radiused edge defining a quarter section of a torus disposed coaxially about the cutter axis. The cutting edges are thus defined by the inter-section of the flutes defined by offset right circular cylinders and the circumferentially radiused edge. A third embodiment is similar to the first embodiment but comprehends a conical milling cutter which converges to a vertex.