Abstract: A method is disclosed for CVD wear coating of carbide rotary cutting tools without jeopardizing the sharpness and utility of the cutting edges. Initially, the tool is finish ground on all surfaces but for the cutting edges and the trailing relief surfaces adjacent thereto, which are left rough ground and "high". Then the entire tool is CVD coated with a suitable material at a very high temperature. This provides a tough coating, but embrittles or decarburizes the cutting edges. Next, the relief surfaces are finish ground, which brings all surfaces to final specification, sharpens the cutting edges, and removes the brittle layers. While the CVD coating is removed just behind the cutting edge, the relief surfaces behind the cutting edges are not as needful of a wear coating as the rake surfaces ahead of the cutting edges.

Abstract: A metal turning chip breaking apparatus includes an impulse actuator in the form of a piezoelectric element that rapidly expands and contracts in response to a rapidly applied and removed voltage. This, in turn, is used to impulsively move a cutter support in a matching fashion, causing a cutter to rapidly withdraw from and return to the cut in a chopping action. This breaks up the chip, which would otherwise form continuously. There is no need to synchronize the incremental motion of the cutter with the rotation of the workpiece.

Abstract: A hole reamer takes a rough, undersized hole to final size while providing better correction of any initial axial mislocation of the hole. A pair of cutting sections, a smaller diameter lead cutting section and a larger diameter trailing cutting section, are axially separated by a relieved section of smaller diameter. The relieved section is small enough in diameter that it does not make contact with the hole, and is longer axially than the hole is thick. When the lead section enters the hole, it is bent off axis slightly, but the reamer shifts back on axis when the relieved section enters the hole. Thus, the trailing, final hole sizing section is back on axis as it works to finish the hole, bringing it closer to the desired axial location.

Abstract: A method is provided for tipping the leading edge of teeth on a thread cutting tool with wear resistant material, without altering the basic size and shape of the tool, and without having to alter the way in which the teeth are cut. A plurality of veins of wear resistant material are hardened in slots in the tool body before axial flutes are cut into the tool body. When the flutes are cut, one side of the veins is exposed, and when the teeth are cut, they are thereby armored by the remainder of the exposed veins.

Abstract: The brazing seams that attach cutting edge wear inserts on a drill are protected against wear and erosion. The inserts are deliberately differentially sized so that the points where the brazing seams that attach them intersect the cutting edges are differentially spaced from the drill center line. Then, a notch is cut into each cutting edge just wide and deep enough to prevent the brazing seam from contacting the cut. Cutting is still complete, despite the notches, since they do not overlap.

Abstract: The inserts and pockets in an inserted drill are provided with differing curvatures on their arcuate back edges. Consequently, when the insert is aligned in the pocket, a crescent shaped, instead of annular, gap is created, with minimal or no thickness at the outboard ends. Very little braze seam is thus exposed to erosion at the cutting edge, but the braze seam is as strong or stronger than conventionally. It is also easier to maintain the desired thickness of the braze seam during manufacture.