Importance

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Abstract

A steel tooth bit includes one or more rolling cone cutters having a generally conical surface, a heel surface, and preferably a transition surface therebetween. A row of gage cutter elements are secured to the cone cutter on the transition surface and have cutting surfaces that cut to full gage. A first inner row of off-gage steel teeth is positioned on the conical surface of the cone cutter so that the gage-facing cutting surfaces of the teeth are close to gage, but are preferably off-gage a distance D at a knee that is formed on the gage facing surface. Distance D is strategically selected such that the gage and off-gage cutter elements cooperatively cut the corner of the borehole. The lower most portion of the gage facing surface of these steel teeth are off gage a distance D' which is greater than D so as to bring the cutting tip of the teeth off gage to prevent undesired wear and rounding off of the tip of the cutter element. The upper most portion of the gage-facing surface is also preferably off gage a distance D' that is greater than D so as to optimize the surface area on the gage facing surface that is in contact with the borehole corner.

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First Claim