Abstract: An earth-boring bit has a bit body that includes head sections, each having depending bit legs with a circumferentially extending outer surface, a leading side, and a trailing side. A bearing shaft depends inwardly from each of the bit legs for mounting a cutter. The bit includes a beveled surface formed at a junction of the leading side and the outer surface of each bit leg. The beveled surface is angled relative to a radial plane emenating from the axis of the bit. The angle of the beveled surface is at least 20 degrees, and extends to an inner surface of the bit leg. The bit can also have a layer of hardfacing on the leading, trailing and shirttail surfaces of the bit leg. A diversion finger of hardfacing extends circumferentially to direct cuttings.

Abstract: An earth-boring bit has a bit body that includes head sections, each having depending bit legs with a circumferentially extending outer surface, a leading side, and a trailing side. A bearing shaft depends inwardly from each of the bit legs for mounting a cutter. The bit includes a beveled surface formed at a junction of the leading side and the outer surface of each bit leg. The beveled surface is angled relative to a radial plane emenating from the axis of the bit. The angle of the beveled surface is at least 20 degrees, and extends to an inner surface of the bit leg. The bit can also have a layer of hardfacing on the leading, trailing and shirttail surfaces of the bit leg. A diversion finger of hardfacing extends circumferentially to direct cuttings.

Abstract: An earth-boring bit has a bit body, at least one cantilevered bearing shaft depending inwardly and downwardly from the bit body, and a cutter mounted for rotation on the bearing shaft. The cutter includes a plurality of teeth that are covered with a hardfacing layer. At least some of the teeth have a leading side that has a streamlined contour. The streamlined contour is generally conical in some of the embodiments. In others, the streamlined contour is defined by a corner between diverging inner and outer sections of the leading side.

Abstract: An earth-boring bit has a bit body, at least one cantilevered bearing shaft depending inwardly and downwardly from the bit body, and a cutter mounted for rotation on the bearing shaft. The cutter includes a plurality of teeth that are covered with a hardfacing layer. At least some of the teeth have a leading side that has a streamlined contour. The streamlined contour is generally conical in some of the embodiments. In others, the streamlined contour is defined by a corner between diverging inner and outer sections of the leading side.

Abstract: A three cone roller bit with rolling cone cutters that are provided with both primary and secondary cutting elements. The primary cutting elements extend outwardly from lands on the outer surface of the cutter body. The secondary cutting elements are disposed within grooves on the cutter body so as to either protrude with its cutting surface from the bottom of the groove or be flush or slightly recessed within it. During normal operation, the primary cutter elements of the rolling cone cutters engage the borehole formation. The secondary cutters do not engage the formation. After substantial wear has occurred to the primary cutter elements, and wear begins to occur to the body of the cone cutters, the secondary cutter elements serve as a secondary cutting structure that engages and cuts into the formation.

Abstract: A three cone roller bit with rolling cone cutters that are provided with both primary and secondary cutting elements. The primary cutting elements extend outwardly from lands on the outer surface of the cutter body. The secondary cutting elements are disposed within grooves on the cutter body so as to either protrude with its cutting surface from the bottom of the groove or be flush or slightly recessed within it. During normal operation, the primary cutter elements of the rolling cone cutters engage the borehole formation. The secondary cutters do not engage the formation. After substantial wear has occurred to the primary cutter elements, and wear begins to occur to the body of the cone cutters, the secondary cutter elements serve as a secondary cutting structure that engages and cuts into the formation.

Abstract: An earth-boring bit for attachment to a drill string has rotatable cones with rows of cutting elements. The cutting elements are arranged in generally circumferential rows on each of the cones and interference fit into apertures in the shell surface. The rows include a heel row of cutting elements on the heel surface of each of the cones, and an adjacent row of adjacent row cutting elements next to the heel row cutting elements. Each heel row cutting element has at least one counterpart adjacent row cutting element that is spaced no farther from it than any other adjacent row cutting element, defining a proximal pair. Each of the cutting elements in each of the proximal pairs has a grip ratio, which is the barrel length divided by the diameter. Some of the proximal pairs having cutting elements with higher grip ratios than other cutting elements. None of the proximal pairs has both cutting elements with higher grip ratios.

Abstract: An earth-boring bit has a bit body and at least one cutter rotatably secured to the bit body. The cutter has a cutter shell surface including a gage surface and a heel surface. A plurality of cutting elements inserts are arranged in generally circumferential rows on the cutter. At least one scraper cutting element is secured at least partially to the heel surface of the cutter. The scraper cutting element includes an outermost surface, generally aligned with the gage surface of the cutter, that defines a plow edge or point for shearing engagement with the sidewall of the borehole while redirecting cuttings up the borehole.

Abstract: An earth boring bit having a cone rotatably secured to a cantilevered bearing shaft and a nozzle that discharges a jet stream of fluid having a high velocity core and a lower velocity skirt. The high velocity core is fully contained in a space bounded by the backside of the cone, bit leg, borehole wall and a radial plane tangent to the tips of the heel teeth and intermittently strikes the exposed ends of the erosion and wear resistant teeth when the cone rotates the teeth on the trailing side in and out of the jet stream. Less than half of the fluid in the lower velocity skirt strikes the surface of the cone, while the remainder continues on a path toward the wall and the borehole bottom. The centerline of the high velocity core is aimed no lower than the corner of the borehole.

Abstract: An earth-boring bit of the rolling cutter variety is provided with hard gage inserts that protrude from the gage surface of the cutter to engage the side of the borehole for holding gage. The gage insert has a substantially flat face with sharp cutting edges formed thereon and has cutting surfaces that define a negative rake angle with respect to the sidewall of the borehole that is being sheared by the gage insert. The cutting surfaces are comprised of multiple chamfers. The face, cutting edge, and cutting surfaces of the gage insert are formed of a super-hard and abrasion-resistant material such as polycrystalline diamond or cubic boron nitride. The body of the insert is formed of a hard, fracture-tough material such as cemented tungsten carbide. The improved gage inserts provide an actively cutting gage surface that engages the sidewall of the borehole to promote shearing removal of the sidewall material.

Abstract: An earth-boring bit has a bit body and at least one cutter rotatably secured to the bit body. The cutter has a cutter shell surface including a gage surface and a heel surface. A plurality of cutting elements inserts are arranged in generally circumferential rows on the cutter. At least one scraper cutting element is secured at least partially to the heel surface of the cutter. The scraper cutting element includes an outermost surface, generally aligned with the gage surface of the cutter, that defines a plow edge or point for shearing engagement with the sidewall of the borehole while redirecting cuttings up the borehole.

Abstract: An earth-boring bit has a bit body and at least one cantilevered bearing shaft depending inwardly and downwardly from the bit body. A cutter is mounted for rotation on the bearing shaft and includes a plurality of cutting elements. At least one of the cutting elements has a generally cylindrical body formed of hard metal with a convex cutting end. A plurality of substantially linear, parallel lands are formed on the cutting end of the body. The lands have arcuate top surfaces and define grooves between the land having arcuate bottom surfaces. A layer of super-hard material is formed on the cutting end of the body and engages the lands and grooves formed thereon.

Abstract: An earth-boring bit has a bit body. At least one cantilevered bearing shaft depends inwardly and downwardly from the bit body and a cutter is mounted for rotation on the bearing shaft. The cutter includes a plurality of cutting elements, at least one of which has a generally cylindrical element body of hard metal. A pair of flanks extend from the body and converge to define a crest. The crest defines at least one sharp cutting edge at its intersection with one of the flanks.

Abstract: An earth-boring bit has a bit body and at least one cantilevered bearing shaft depending inwardly and downwardly from the bit body. A cutter is mounted for rotation on the bearing shaft and includes a plurality of cutting elements arranged in generally circumferential rows, including inner heel rows, of cutting elements. At least one of the cutting elements in one of the inner rows has a crest at least partially formed of super-hard material that defines a cutting edge and cutting surface for shearing engagement with the bottom of the borehole during drilling operations, the remainder of the cutting end of the element is formed of hard, fracture-tough material for crushing engagement with the bottom of the borehole.

Abstract: A bit body has at least one cantilevered bearing shaft depending inwardly and downwardly from the bit body. A cutter is mounted for rotation on the bearing shaft and includes a plurality of cutting elements arranged in generally circumferential rows on the cutter, the rows including a heel row. The cutting elements in the heel row include at least one chisel-shaped cutting element having a crest oriented transversely to the axis of rotation of the cutter. The remainder of the cutting elements in the heel row have a configuration different from the chisel-shaped elements. All of the cutting elements have approximately the same projection from the surface of the cutter.

Abstract: An earth-boring bit has a bit body and at least one cantilevered bearing shaft depending inwardly and downwardly from the bit body. A cutter is mounted for rotation on the bearing shaft and includes a gage surface and an adjacent cutter backface. The cutter has negative offset with respect to the axis and direction of rotation of the bit. A plurality of cutting elements are arranged on the cutter including a plurality of gage cutting elements on the gage surface of the cutter. At least one of the gage cutting elements projects beyond the gage surface and defines a cutting surface facing the backface of the cutter for engaging the sidewall of the borehole being drilled as the gage cutting element moves up the sidewall.

Abstract: An earth-boring bit is provided with hard gage inserts that protrude from the gage surface of the cutter to engage the side of the borehole for holding gage. The cutting end of the gage insert has a cutting end defining at least one sharp cutting edge and at least one cutting surface that define a negative rake angle with respect to the sidewall of the borehole that is being sheared by the gage insert. The cutting end, cutting edge, and cutting surface of the gage insert are formed of a super-hard and abrasion-resistant material such as polycrystalline diamond or cubic boron nitride. The body of the insert is formed of a hard, fracture-tough material such as cemented tungsten carbide. The improved gage inserts provide an actively cutting gage surface that engages the sidewall of the borehole to promote shearing removal of the sidewall material. Such an improved gage insert provides an earth-boring bit with improved gage-holding ability, and improved steerability in directional drilling operations.

Abstract: A large hole earth boring bit with a clevis-type coupling for mounting the rolling cutters to the bit. The mounting apparatus includes a first member having two ends with aligned holes and a second member having its end inserted between the two ends. The end of the second member has an aperture that is spaced slightly out of alignment with the apertures in the first member, providing a generally elliptical passage. Bearing surfaces prevent them from coming into alignment. A pair of wedges are inserted into the elliptical passage and drawn together to exert a force in the direction toward alignment of the apertures. The force exerted is transmitted into the base, positively locking the two members together.