Patent ID: 8517645

Claim:
An attachment to a milling machine head having a rotary drive, for cutting sharp interior corners in a workpiece, said attachment comprising: a rotary shaft couplable to the rotary drive of the milling machine head so as to be rotatable about a longitudinal axis of the rotary shaft; a conical cutter member comprising: a rotary axis, an apex located on said rotary axis, at least one external conical surface portion having a leading end at said apex and a trailing end spaced apart from said rotary axis and from said apex along said rotary axis; and a cutting edge constituting a part of said conical surface portion and extending between said leading and trailing ends thereof; said rotary axis of the conical cutter member being oriented transversely though not perpendicularly to said shaft longitudinal axis; and the conical cutter member being coupled to the rotary shaft so as to be rotated about said rotary axis by the shaft, upon the shaft's rotation about said longitudinal axis; wherein the attachment further comprises: a coupling sleeve with top and bottom walls, and side walls extending therebetween, and an opening at an intersection between the bottom wall and two adjacent side walls, with which opening the conical cutter member is aligned, and wherein said apex of said conical cutter member is locatable to be flush with the outer surfaces of said two adjacent side walls and bottom wall of the coupling sleeve at said intersection, such that said coupling sleeve enables the conical cutter member to cut a sharp interior corner in a workpiece.