Abstract: A double-ended drill bit having opposed cutting ends of different structural configurations is provided in combination with a sleeve or holder to be received within a drill chuck. The sleeve is provided with a cylindrical body having a top end with a pair of helically-shaped longitudinally extending members in spaced mating relation attached thereto. One cutting end of a drill bit is received within the cylindrical body and the spaced helically-shaped members.

Abstract: A carbide substrate including a binder prepared to receive a cutting material such as a diamond coating thereon. The substrate is immersed in an electrolyte solution with the substrate acting as the anode thereby providing for an electro-polished substrate surface. The electro-polished substrate surface is then etched to substantially remove the binder phase of the carbide substrate, the etching being to a depth of up to about 15 microns. The resulting surface is susceptible for receiving a coating of the diamond cutting material.

Abstract: A masonry drill and method of manufacture is disclosed. The drill has an elongated axial body with at least one discharge groove and a transverse slot located at one end with a hardened drill bit insert brazed within the slot. The hardened insert has projections extending outward from flat planar surfaces which hold the insert in proper orientation within the axial drill body so that it may be brazed into place subsequent to insertion into the drill body.

Abstract: A drill bit is provided with a pair of spiral cutting blades having opposed cutting edges which come together at an angle to form a starting tip. Each of the spiral cutting blades includes a spiral flute which extends longitudinally thereof and is provided with a cutting face thereon. Each cutting edge is provided with an inner edge segment and an outer edge segment wherein the inner edge segment extends outwardly from the starting tip a preselected distance and terminates at an inwardly extending inner wall portion of a gullet. The inner wall portion of the gullet is arcuate in structure and terminates at a preselected inward position with an outer wall of the gullet. The outer wall of the gullet extends angularly outwardly terminating at the intersection with an outer segment of the cutting edge. The outer edge segment of the cutting edge is defined by the outward terminating end of the outer wall of the gullet and the outer most extremity of the cutting edge.

Abstract: A template used in installing door locks. A side bracket is slidably received by a front bracket and the two brackets are aligned for the door width or thickness of the door to be drilled. The template permits properly related pilot holes to be drilled into the door edge using the side bracket and the door face using the front bracket.

Abstract: A circular saw blade with improved stability, the blade having a plurality of radial expansion slots, preferably having a "J"-shape. The blades may also have a plurality of arced body slots and may be coated with a "TEFLON" paint mixture.