Abstract: An apparatus for milling away tubular conduits encased within well bores is disclosed. The milling device consists of a cylindrical body. The body forms longitudinal slots therein for radially disposed replaceable cutter blades that are inserted through the slots from the inside of the body. A central mandrel mechanically locks the replaceable blades between the mandrel and the tubular body. A finned pilot head or guide is affixed to the downstream end of the milling apparatus, the opposite threaded upstream end is adapted to be connected to a drill string.

Abstract: This invention comprises a diamond insert grinding process to remove stress riser cracks formed in a critical area of a tungsten carbide insert body. The cracks are caused by leaching of cobalt from the carbide during the process of brazing a tungsten carbide backed polycrystalline diamond disc to the body. A grinding wheel selectively removes material from the intersection of the braze below the depth of the cracks in the tungsten carbide body thereby relieving the stress riser in the critical area of the body.

Abstract: A diamond tipped twist drill for drilling holes in a work piece consists of a body forming a pair of flutes, each flute forming a channel that essentially parallels the flutes. Each channel ends at an aperture formed in the body nearest a cutting end of the drill. Diamond material is pressed into the flutes and through the aperture. Subsequent machining at the cutting end of the drill bit body exposes the sintered diamond forming a finished diamond cutting tip for the twist drill.

Abstract: A rotary rock bit is described having a plurality of legs extending downwardly from the main bit body. Each leg includes an annular bore extending through the lower extremity thereof. A separate journal pin is provided for each leg, with each journal pin having a mounting end and a bearing end. The mounting end of each journal pin is adapted to extend into the bore of a respective leg and be secured thereto by an electron beam welding process. The bearing end of the journal pin is adapted to receive an annular thrust member extending over the bearing surface thereof. The annular thrust member is secured to the journal pin by the same electron beam welding process step which welds the journal pin to the bore of the leg. A cone type cutter is adapted to be rotatably mounted on the bearing end of each journal pin with the annular thrust member functioning to retain the cutter on the journal pin and to absorb the in and out-thrust and radial loads passing therethrough.