DRILL BITS AND TOOLS FOR SUBTERRANEAN DRILLING

摘要

A drill bit includes at least one extension pad extending rotationally forward or backward of an associated blade in a gage region of the bit body. The extension pad includes a circumferential bearing surface that extends the circumferential bearing surface of the associated blade and reduces the chordal drop between any blade having an extension pad associated therewith and a circumferentially adjacent blade toward which the extension pad protrudes. A drill bit that reduces a chordal drop segment extending across a junk slot is also disclosed.