Abstract: A system and method for excavating a subterranean formation is described.

Abstract: A method of fabricating the drill bit includes employing known layered-manufacturing techniques to fabricate the bit crown, positioning a bit gage mold adjacent the bit crown, and disposing a core material within an interior of the bit crown and a cavity of the bit gage mold. A mold that may be employed to fabricate the drill bit includes an initially conforming mold region, in which the prefabricated bit crown may be disposed, and a second, substantially rigid mold region including a cavity to define the gage of the drill bit. Preferably, the conforming mold region is formed of a nonwettable, granular material.

Abstract: A rotary-type earth-boring drill bit including a layer-manufactured, substantially hollow bit crown and an integral bit interior and bit gage. The bit interior and bit gage may be formed of a particulate material infiltrated with an infiltrant material. A particulate material of the bit crown may be integrally infiltrated with the particulate material of the bit interior and bit gage. Alternatively, the bit interior and bit gage may comprise a single cast material. The particulate material of the bit crown may be infiltrated with the cast material of the bit interior and bit gage. A method of fabricating the drill bit of the present invention includes employing known layered-manufacturing techniques to fabricate the bit crown, positioning a bit gage mold adjacent the bit crown, and disposing a core material within an interior of the bit crown and a cavity of the bit gage mold.

Abstract: A rotary-type earth-boring drill bit including a layer-manufactured, substantially hollow bit crown and an integral bit interior and bit gage. The bit interior and bit gage may be formed of a particulate material infiltrated with an infiltrant material. A particulate material of the bit crown may be integrally infiltrated with the particulate material of the bit interior and bit gage. Alternatively, the bit interior and bit gage may comprise a single cast material. The particulate material of the bit crown may be infiltrated with the cast material of the bit interior and bit gage. A method of fabricating the drill bit includes employing known layered-manufacturing techniques to fabricate the bit crown, positioning a bit gage mold adjacent the bit crown, and disposing a core material within an interior of the bit crown and a cavity of the bit gage mold.

Abstract: A torque limiting device that allows a drill string to rotate relative to the cutting structure of the bit when a predetermined torque is applied between the cutting structure of the drill bit and the drill string. The torque limiting device utilizes a retaining member which restricts rotational movement of a first component of the torque limiting device relative to a second component. When a sufficient torque load is placed on the cutting structure of the drill bit, the retaining member allows rotational movement of the first component relative to the second component and allows the drill string to continue to rotate relative to the cutting structure of the bit until the torque is sufficiently reduced. The torque limiting device may be an integral part of a drill bit, may be a separate device attached between the drill string and the drill bit or between the drill string and a downhole motor, or may be part of a near-bit sub or incorporated in a downhole motor.