of first reference surface 20 and second reference surface 22 this cylindrical hole 23 assures clearance for the corner of insert 10 formed by the intersection of first peripheral surface 26 and second peripheral surface 28 and proper seating of the insert 10 in pocket 12 the cutter insert 10 has a cylindrical hole 30 perpendicular to planer surface 24 to receive a cam lock pin 32 when the insert 10 is placed over the cam lock pin 32 and the three positioning surfaces engage the corresponding surfaces on the holder the cam lock pin 32 is rotated and the cutter insert 10 is locked into precise engagement with the holder 14 two simple cutting surfaces are found on the prior cutting insert 10 the first or main cutting edge 34 is formed by the intersection of a beveled plane and the outside surface of the insert a second cutting edge 36 is formed by the intersection of a second beveled plane and the outside surface of the insert these two cutting edges define two frustoconical surfaces when the cutter insert 10 is held in the holder 14 and the holder 14 is rotated around its axis of rotation 18 when the cutter 10 is rotated and forced into a workpiece two frustrocones result the purpose of having the two frustroconical surfaces in the countersunk hole in the workpiece is so that the head to shank.