Eccentric counterbore for diamond insert stud

摘要

Conventional drag bits for diamond insert studs generally require a two-step operation which includes a first drilled hole to accept the grip length of the diamond stud. A second counterboring operation relieves the upper portion of the bored hole to clear the bottom edge of the diamond cutting face of the insert. Counterboring also facilitates insertion of the studs within the hole. Conventional insertion methods for the studs unfortunately leave a portion of the insert vulnerable to breakage because the back side of the insert opposite the cutting face is unsupported. This invention corrects this problem by drilling the counterbore hole eccentrically with respect to the insert hole so that the counterbore surface is, for example, tangent with the insert hole at a point opposite the cutting face of the insert stud, thus providing support for the upper portion of the stud during operation of the drag bit.