Abstract: A twist drill is disclosed. The twist drill comprises a substantially cylindrical tool body having a rotational axis therethrough, a front portion, a rear portion, a plurality of web thickness, a front flank face, a plurality of flutes formed on an outer peripheral surface thereof and extending to the front flank face, and a land disposed between a pair of the flutes. The flute has a wall portion facing toward the rotational direction of the tool body. A cutting edge is formed at an intersection between the wall portion of the flute and the front flank face. The web thickness at the rear portion of the tool body is smaller than the web thickness at the front portion of the tool body.

Abstract: An insert rotary cutter for processing a metal workpiece includes a cutter body having an axis of rotation therethrough. The cutter includes at least one cutter insert releasably mounted on an outer periphery of the body. The insert is of a generally polygonal shape having a curved front face. The front face has a pair of opposed marginal ridges serving as respective main cutting edges. The front face has marginal portions disposed adjacent and extending along the main cutting edges, and the marginal portions serve as respective rake surfaces for the main cutting edges. Each of the rake surface is convexly curved as viewed from a respective one of the main cutting edges and is concavely curved as viewed along a respective one of the main cutting edges.

Abstract: A drill bit comprises a body having a shank portion and an end face at its forward end. The drill bit body has at the forward end a cutting means having at least one cutting edge provided on the end face. The cutting edge is spaced from the axis of rotation of the body. The body has a rake surface which terminates in the cutting edge and extends along the axis of rotation.

Abstract: A drill bit comprises a body having a shank portion and an end face at its forward end. The drill bit body has at the forward end a cutting means having at least one cutting edge provided on the end face. The cutting edge is spaced from the axis of rotation of the body. The body has a rake surface which terminates in the cutting edge and extends along the axis of rotation.