Patent ID: 7309196

Claim:
A cutting tool assembly for conducting rotary cutting operations on a work piece, comprising a tool shank and a replaceable cutting head which is installed on and engages the tool shank, the tool shank and the cutting head having a common rotational axis and mating peripheral surfaces when assembled together, the cutting tool assembly having a leading end which engages the work piece and a trailing end located oppositely from the leading end, relative to the rotational axis; the shank having a pocket for coupling to the cutting head, an interlocking member arranged to retain the cutting head when the cutting head is installed within the pocket, at least one abutment surface abutting the cutting head when the cutting head is installed within the pocket, and at least one driving surface arranged to rotate the cutting head when the shank is rotated with the cutting head installed within the pocket; the cutting head having a cutting portion at the leading end of the cutting tool assembly, an interlocking member engaging the interlocking member of the shank, and a driven surface oriented to abut the driving surface of the shank when the cutting head is installed within the pocket; wherein the interlocking member of the cutting head comprises a lateral surface oriented at an obtuse angle to the rotational axis and facing the cutting portion of the cutting head, and an extension adjacent to the lateral surface and projecting away from the cutting portion of the cutting head, whereby the extension reinforces the interlocking member at the lateral surface oriented at an obtuse angle to the rotational axis such that stresses are minimized due to a smoother transition between the dovetail and the pocket floor.