Indexable cutting insert

Claim 1

An indexable cutting insert comprising a generally rectangular block of cutting material having a pair of flat, parallel and comparatively wide side surfaces, a hole extending through said block from one side surface to the other side surface and adapted to receive a fastener for crowding the block edgewise against an abutment projecting from the plane of a flat platform of a cutter body, said block also having a pair of narrower edge surfaces located at opposite edges of said side sUrfaces and extending transversely of the side surfaces, narrow grooves undercut along the length of each opposite edge portion of each said edge surface and terminating short of the midportion of such edge surface to leave an intervening flat and planar land extending along said midportion for locating the block in a precise position when the block is crowded edgewise , all four of said grooves extending parallel to one another to leave said lands with edges extending parallel to one another and to said side surfaces, the bottom of each of said grooves constituting the cutting face of a cutting edge defined by the intersection of such face and a clearance face formed by the adjacent side surface of the block, each cutting face sloping inwardly and away from said cutting edge to provide between the clearance and cutting faces of each cutting edge an included angle which is less than a right angle thus permitting each cutting edge to act on a workpiece with conventional clearance across the clearance face and with positive axial rake across the cutting face, and each cutting face curving arcuately and convexly along its length on a radius several times the width between said edge surfaces.