Patent ID: 8043555

Claim:
A method of manufacturing a cone for an earth boring bit, comprising: (a) placing a powder of hard particles and a metal binder in a mold; then (b) applying pressure to the powder to form a billet; (c) machining the billet to create a cone-shaped product out of the billet that has at least some dimensions selectively oversized from desired final dimensions of the cone; then (d) sintering the cone-shaped product to a desired density, the sintering causing the cone-shaped product to shrink to substantially to the desired final dimensions of the cone; wherein the method further comprises: inserting cylindrical displacement members into the holes after step (c) and before step (d), the displacement members having the desired finished diameters for the holes and being of a material that does not shrink during the sintering in step (d); and step (d) further comprises leaving the displacement members in the holes while sintering, which causes the holes formed in the billet to shrink in diameter around the displacement members to the desired finished diameter; and after step (d), removing the displacement members, then installing the cutting elements in the holes.