Abstract: A hard formation drill bit that includes a bit body, and at least one roller cone attached to the bit body, and able to rotate with respect to the bit body. Furthermore, the drill bit includes a plurality of gage cutting elements disposed on the at least one roller cone, wherein at least one of the plurality of gage cutting elements includes a cutting portion. The cutting portion includes a partially spherical leading edge and an obtuse relieved trailing edge, wherein a volume of the partially spherical leading edge is greater than a volume of the obtuse relieved trailing edge. Also, a method of drilling a formation that includes contacting a drill bit with the formation, wherein the drill bit includes a bit body. The drill bit further includes a plurality of gage cutting elements disposed on the bit body, wherein at least one of the plurality of gage cutting elements includes a cutting portion.

Abstract: A rotary drag bit includes a bit body having a face and an axis, a plurality of blades extending radially and longitudinally outward from the face, and at least one split cutter set. The split cutter set includes a plurality of cutters, where at least two of the cutters are primary and/or kerfing cutters located on different blades of the plurality of blades. The pair of primary and/or kerfing cutters of the split cutter set may be located substantially the same radial distance from a center line, or axis of rotation, of the bit and located at substantially the same longitude, or elevation, on the bit as one another, or follow substantially the same rotational or helical cutting path as each other.

Abstract: A rotary drag bit includes a primary cutter row comprising at least one primary cutter, and at least two additional cutters configured relative to one another. In one embodiment, the cutters are backup cutters of a cutter group located in respective first and second trailing cutter rows, oriented relative to one another, and positioned to substantially follow the at least one primary cutter. The rotary drag bit life is extended by the backup cutter group, making the bit more durable and extending the life of the cutters. In other of the embodiments, the cutters are configured to selectively engage a subterranean formation material being drilled, providing improved bit life and reduced stress upon the cutters. Still other embodiments of rotary drag bits include backup cutter configurations having different backrake angles and siderake angles, including methods therefor.

Abstract: A rotary drag bit includes a primary cutter row comprising at least one primary cutter and a multiple backup cutter group. The multiple backup cutter group comprises a first and second trailing cutter row, each comprising at least one cutter positioned to follow the at least one primary cutter. The rotary drag bit life is extended by the multiple backup cutter groups making the bit more durable and extending the life of the cutters. Further, the cutters of the multiple backup cutter group are configured to selectively engage a subterranean formation material being drilled, providing improved bit life and reduced stress upon the cutters. Other embodiments of rotary drag bits are provided.

Abstract: A cutting element for use in drilling subterranean formations. The cutting element includes a superabrasive table mounted to a supporting substrate. The superabrasive table includes a two-dimensional cutting face having a cutting edge along at least a portion of its periphery, and a surface comprising a chamfer extending forwardly and inwardly from proximate a peripheral cutting edge at a first acute angle of orientation of greater than about 45° with respect to the longitudinal axis of the cutting element, and to no greater than a selected depth. The chamfer may be arcuate or planar, and of a dimension sufficient to ensure that a wear flat generated during use of the cutting element remains outside the inner boundary of the chamfer within the chamfer envelope, and small enough to maintain aggressive cutting characteristics for the cutter. Drill bits and drilling tools bearing the cutting elements are also disclosed.

Abstract: The present invention provides a cutting element having a cylindrical body having a canted end face on which is formed an ultra hard material layer and to a bit incorporating such cutting element. One or a plurality of transition layers may be provided between the ultra hard material layer and the cutting element body.

Abstract: A cutter element is provided for use on a rotary drill bit of a drilling string to cut earthen formation and the like. The cutter element includes a cutting portion formed from cutting material adapted to cut into the earthen formation, and a substrate positioned adjacent the cutting portion. The cutting portion and the substrate form a body having a substantially planar front face, a longitudinal axis extending centrally through the front face and the substrate, and a circumferential surface extending inwardly form the front face and spaced outwardly from the longitudinal axis. The cutting portion includes a cutting face that provides at least a portion of the front face. The cutting portion extends longitudinally inward from the front face to a back surface engaging or inter-facing the substrate.

Abstract: A solid hard material head for a percussion drilling tool rotatable about a rotational axis (A) in a rotational direction (?), includes at least one main bit and at least one auxiliary bit (5), circumferentially offset relative to the at least one main bit (3) and having an auxiliary cutting edge (6) formed, at least piecewise, as a circular arc section (7) spaced from the rotational axis (A) radially inwardly and inclined in a radial direction, and a straight outer section (8) extending radially outwardly with respect to the circular arc section (7) and inclined in the radial direction.

Abstract: A rotary drill bit is disclosed, including at least one cutting element affixed thereto and configured to form a distinct borehole surface in response to drilling a subterranean formation. At least one substantially helically extending feature associated with the at least one cutting element may be formed upon the leading end of the rotary drill bit. Alternatively, a rotary drill bit may include a plurality of substantially helically extending features. Methods of operating a rotary drill bit are also disclosed. Specifically, a subterranean formation may be drilled with a rotary drill bit to form an on-center bottomhole pattern, which may be at least partially contacted by at least one substantially helically extending feature of the rotary drill bit. Alternatively, a subterranean formation may be contacted with at least one substantially helically extending feature of the rotary drill bit. A method of designing a rotary drill bit is disclosed.

Abstract: A method for designing a roller cone bit that includes steps of selecting design parameters for the roller cone bit, drilling parameters, and parameters of an earth formation, simulating drilling of the earth formation by the roller cone bit using the selected drilling parameters, calculating drilling performance parameters from the simulated drilling, and analyzing at least one of a tensile stress or a compressive stress parameters for a cutting element of the roller cone bit from the calculated drilling performance parameters is disclosed.

Abstract: A two-cone drill bit that exhibits improved stability. In one embodiment, the two-cone drill bit has a first and a second roller cone arranged to have a cone separation angle between about 145 degrees and about 166 degrees. In some embodiments, the two-cone drill bit has a plurality of cutting elements arranged on the roller cones such that a bottom hole coverage greater than about 17 percent is achieved per revolution of the two-cone drill bit.

Abstract: In one aspect of the present invention, a drill bit has an axis of rotation and a working face with a plurality of blades extending outwardly from a bit body. The blades form in part an inverted conical region and a plurality of cutters with a cutting surface are arrayed along the blades. A jack element is coaxial with the axis of rotation and extend within the conical region within a range defined by the cutting surface of at least one cutter.

Abstract: A cutting element for a rotary drill bit that has a superabrasive member joined to a substrate at a three-dimensional interface is disclosed. The interface of the cutting element preferably incorporates a first ring pattern comprising a plurality of circumferentially arranged raised sections which are separated by a plurality of radially extending grooves. Also, the interface configuration may include at least a second ring pattern comprising a plurality of circumferentially arranged raised sections which are separated by a plurality of radially extending grooves. Radially adjacent ring patterns may substantially circumferentially overlap with one another. An interface of a cutting element including at least one ring pattern having an odd number of sections is also disclosed. Further, rotary drill bits including at least one such cutting element are disclosed.

Abstract: The present invention is directed to a drill bit with non-cutting erosion resistant inserts. In one illustrative embodiment, the apparatus comprises a matrix drill bit body comprising a plurality of blades, a plurality of cutting elements positioned on each of the blades, the cutting elements defining a plurality of web regions, and a plurality of spaced apart, non-cutting erosion resistant inserts positioned along a face of at least one of the blades, at least a portion of each of the non-cutting erosion resistant inserts being positioned in front of one of the web regions.

Abstract: A superabrasive cutting element including a diamond or other superabrasive material table having a peripheral cutting edge defined by at least two adjacent chamfers having an arcuate surface substantially tangent to each of the at least two chamfers interposed therebetween. Methods of producing such superabrasive cutting elements and drill bits equipped with such superabrasive cutting elements are also disclosed.

Abstract: The present invention provides a cutting element having a cylindrical body having a canted end face on which is formed an ultra hard material layer and a method of forming the same. One or a plurality of transition layers may be provided between the ultra hard material layer and the cutting element body.

Abstract: Compacts are oriented in certain places on roller cones of an earth boring bit to increase the number of compacts in certain rows. The compacts that are pressed into holes in rows on the cones. The compacts are of tungsten carbide and have a cutting end axis and a barrel axis. The barrel axis intersects the cutting end axis at an obtuse angle. In one of the cones, the barrel axis of at least some of the compacts is rotated to have less inclination than the barrel axis of the compact nearest to it. The nearest compact may be in the same row or an adjacent row. Also, at least some of the compacts may be asymmetrical, with a cutting end axis that diverges from a barrel axis.

Abstract: A rotary drag bit and method for drilling subterranean formations, including a bit body being provided with at least one cutter thereon exhibiting reduced, or limited, exposure to the formation, so as to control the depth-of-cut of the at least one cutter, so as to control the volume of formation material cut per bit rotation, as well as to control the amount of torque experienced by the bit and an optionally associated bottomhole assembly regardless of the effective weight-on-bit are all disclosed. The exterior of the bit preferably includes a plurality of blade structures carrying at least one such cutter thereon and including a sufficient amount of bearing surface area to contact the formation so as to generally distribute an additional weight applied to the bit against the bottom of the borehole without exceeding the compressive strength of the formation rock.

Abstract: Asymmetrical compacts are utilized in certain places on roller cones of an earth boring bit to increase the number of compacts in certain rows. The compacts that are pressed into holes in rows on the cones. The compacts are of tungsten carbide and have a cutting end axis and a barrel axis. The barrel axis intersects the cutting end axis at an obtuse angle. In the heel row, the barrel axis of at least some of the compacts is rotated to have less inclination than the cutting end axis. In an adjacent row to the heel row, each of the compacts has a barrel axis that is rotated to have more inclination than its cutting end axis and more inclination than the barrel axes of the heel row.

Abstract: A rotary drill bit is used both for milling a casing window and drilling a lateral borehole into subterranean earthen materials, without the prior need of having separate drill bits for milling of the casing and for drilling of the borehole. The rotary drill bit is lowered into a casing set within a borehole; and the drill bit is rotated to engage an inner surface of the casing. A first set of cutting elements on the drill bit remove casing material to mill a casing window. The drill bit is then moved through the casing window so that a second set of cutting elements on the drill bit create a lateral wellbore in subterranean earthen material.

Abstract: A cutter element for a rolling cone bit includes a cutting surface having front and back surfaces, a pair of flanking surfaces that intersect in a rounded nose that is offset from the central axis of the cutter element's base. At least one flanking surface includes a concave region. The back surface presents a generally wedge-shaped top profile.

Abstract: A superabrasive cutter-equipped rotary drag bit especially suitable for directional drilling in subterranean formations is provided. The bit may employ PDC cutters in an engineered cutter placement profile exhibiting optimal aggressiveness in relation to where the cutters are positioned along the profile of the bit extending from a cone region laterally, or radially, outward toward a gage region therefore. The engineered cutter placement profile may include cutters exhibiting differing degrees of aggressiveness positioned in order to maximize rate-of-penetration and minimize torque-on-bit while maintaining side cutting capability and steerability.

Abstract: The present invention provides a cutting element having a cylindrical body having a canted end face on which is formed an ultra hard material layer and a method of forming the same. One or a plurality of transition layers may be provided between the ultra hard material layer and the cutting element body.

Abstract: A rotary drag bit and method for drilling subterranean formations, including a bit body being provided with at least one cutter thereon exhibiting reduced, or limited, exposure to the formation, so as to control the depth-of-cut of the at least one cutter, so as to control the volume of formation material cut per bit rotation, as well as to control the amount of torque experienced by the bit and an optionally associated bottomhole assembly regardless of the effective weight-on-bit are all disclosed. The exterior of the bit preferably includes a plurality of blade structures carrying at least one such cutter thereon and including a sufficient amount of bearing surface area to contact the formation so as to generally distribute an additional weight applied to the bit against the bottom of the borehole without exceeding the compressive strength of the formation rock.

Abstract: A superabrasive cutting element including a diamond or other superabrasive material table having a peripheral cutting edge defined by at least two adjacent chamfers having an arcuate surface substantially tangent to each of the at least two chamfers interposed therebetween. Methods of producing such superabrasive cutting elements and drill bits equipped with such superabrasive cutting elements are also disclosed.

Abstract: Cutter elements for use in rolling cones rock bits are disclosed having a crown that includes multiple, spaced-apart cusps for enhancing formation removal by creating overlapping Hertzian contact zones. The cusps may be partially dome-shaped, berm shaped or otherwise. The cutter elements provide multiple cutting edges for engaging the formation and may have differing radii and extension length as suitable for particular applications.

Abstract: A rotary drill bit for penetrating earth strata wherein the drill bit includes a drill bit body that has an axial forward end. The drill bit body has a hard insert, which is preferably monolithic, that is affixed to the drill bit body at the axial forward end thereof. The hard insert presents at least three discrete leading cutting edges for cutting the earth strata. Each cutting edge is stepped.

Abstract: The present invention generally relates to positioning and/or orienting inserts on a gage row and/or a first inner row to optimize the duty among inserts on the gage row and/or insert row of cutting a sidewall and bottom hole of a bore hole such that wear and breakage of inserts are reduced and the life of the bit is enhanced.

Abstract: A drag-type drill bit for bore hole drilling in earth formation comprises a bit body having a threaded pin on one end for coupling to a drill string. A substantially dome-shaped cutter head is formed integral with the bit body opposite from the threaded pin. Formed integral with and extending from the cutter head is a plurality of circumferentially spaced fixed and/or variable pitch spiral blades having a succession of curved segments. The variable pitch pattern curves from substantially the center of and around the cutter head to the gage area. A plurality of generally cylindrical cutting elements, such as PDC elements, are fixed to each of the spiral blades and a plurality of nozzles are positioned around the cutter head to direct drilling fluid passing through the bit body against the blades to the annulus surrounding the bit body and the bore hole.

Abstract: A superabrasive cutting element for use with a drill bit for drilling subterranean formations and having a superabrasive table, or cutting face, in which a conglomerate of superabrasive particles are dispersed and bonded, or sintered, and in which at least one exposed cutting region of the superabrasive table develops a rough, asperital surface for improving the cutting efficiency of the drill bit, particularly in but not limited to relatively hard, relatively nonabrasive formations. The superabrasive table may include superabasive particles of substantially differing size, quality or a combination of differing size and quality. A rotary drill bit including cutting elements embodying the present invention is also disclosed.

Abstract: A rotary drag bit and method for drilling subterranean formations including a bit body being provided with at least one cutter thereon exhibiting reduced, or limited, exposure to the formation so as to control the depth-of-cut of the at least one cutter, so as to control the volume of formation material cut per bit rotation, as well as to control the amount of torque experienced by the bit and an optionally associated bottomhole assembly regardless of the effective weight-on-bit. The exterior of the bit preferably includes a plurality of blade structures carrying at least one such cutter thereon and including a sufficient amount of bearing surface area to contact the formation so as to generally distribute an additional weight applied to the bit against the bottom of the borehole without exceeding the compressive strength of the formation rock.

Abstract: A superabrasive cutting element including a diamond or other superabrasive material table having a peripheral cutting edge defined by at least two adjacent chamfers having an arcuate surface substantially tangent to each of the at least two chamfers interposed therebetween. Methods of producing such superabrasive cutting elements and drill bits equipped with such superabrasive cutting elements are also disclosed.

Abstract: A rotary drag bit and method for drilling subterranean formations including a bit body being provided with at least one cutter thereon exhibiting reduced, or limited, exposure to the formation so as to control the depth-of-cut of the at least one cutter, so as to control the volume of formation material cut per bit rotation, as well as to control the amount of torque experienced by the bit and an optionally associated bottomhole assembly regardless of the effective weight-on-bit. The exterior of the bit preferably includes a plurality of blade structures carrying at least one such cutter thereon and including a sufficient amount of bearing surface area to contact the formation so as to generally distribute an additional weight applied to the bit against the bottom of the borehole without exceeding the compressive strength of the formation rock.

Abstract: The present invention provides a new drilling tool useful in machining hydraulic port seals for fluid power ports. The drilling tool drills the port hole to size in a solid material for the minor thread diameter in combination with forming the port in a single operation. The drilling tool has a tool holder having a rotational axis, a first drilling insert having cutting surfaces on a first side and a mounting surface on a second side, at least one second drilling insert having a predetermined cutting surface portion and a mounting portion which is mounted on the holder at a location from the rotational axis of the holder. The at least one second drilling insert has first and second portions which engage and machine a work piece in a drilling operation to form a spot face and a seal form.

Abstract: Compacts are oriented in certain places on roller cones of an earth boring bit to increase the number of compacts in certain rows. The compacts that are pressed into holes in rows on the cones. The compacts are of tungsten carbide and have a cutting end axis and a barrel axis. The barrel axis intersects the cutting end axis at an obtuse angle. In one of the cones, the barrel axis of at least some of the compacts is rotated to have less inclination than the barrel axis of the compact nearest to it. The nearest compact may be in the same row or an adjacent row. Also, at least some of the compacts may be asymmetrical, with a cutting end axis that diverges from a barrel axis.

Abstract: A fixed-cutter drill bit is optimized so that cutter torques are evenly distributed not only during drilling of homogeneous rock, but also in transitional formations.

Abstract: A drill bit including improved gage pads is particularly adapted for side cutting a borehole wall. In a preferred embodiment, the drill bit gage pads alternate between an active gage pad with a cutting surface portion and a non-active gage pad with a wear-resistant surface. Gage pad cutting elements placed on a first active gage pad cooperate with gage pad cutting elements placed on other active gage pads. What results is a contiguous series of overlapping cutting elements suitable to cut the borehole wall. Non-active gage pads are preferably placed between the active cutting gage pads. These non-active gage pads have a wear-resistant surface (such as steel or diamond insert) that extends to the gage diameter. These non-active gage pads help to maintain borehole size and prevent undue torque being placed on the drill bit.

Abstract: Methods of drilling subterranean formations with rotary drag bits equipped with cutting elements including superabrasive, multi-aggressive cutting faces or profiles which are especially suitable for drilling formations of varying hardness and for directional drilling through formations of varying hardness are disclosed. Methods including providing and using rotary drill bits incorporating cutting elements having appropriately aggressive and appropriately positioned cutting surfaces so as to enable the cutting elements to engage the particular formation being drilled at an appropriate depth-of-cut at a given weight-on-bit to maximize rate of penetration without generating excessive, unwanted torque on bit are disclosed.

Abstract: A rotary drag bit carrying PDC cutters and elongated bearing elements associated with at least some of the PDC cutters on the bit face thereof Lateral positioning and angular positioning of the elongated bearing elements are adjusted so that all portions of an elongated bearing element travel substantially completely within a tubular clearance volume defined by the path through the formation being drilled by a PDC cutter with which that elongated bearing element is associated, the associated PDC cutter being positioned at about the same radius from the bit centerline as the elongated bearing element. A method of drilling and a method of drill bit design are also disclosed.

Abstract: A roller cone drill bit is disclosed which includes a bit body adapted to be coupled to a drill string. A bearing journal depends from the bit body. A single roller cone is rotatably attached to the bearing journal. The roller cone has a plurality of inserts disposed at selected positions about the cone. The journal defines a rotation angle with respect to an axis of rotation of the bit such that the roller cone includes a wall contact zone and a bottom contact zone. At least one of the inserts disposed in the wall contact zone has an extension portion terminating in a substantially planar upper surface.

Abstract: Hardfacing is deposited on a PDC-equipped steel body rotary drag bit and forms substantially protruding structural elements, such as wear knots or chip breakers. Hardfacing may also be applied to features such as gage pads, wherein at least two different hardfacing compositions are utilized and specifically located in order to exploit the material characteristics of each type of hardfacing composition employed. The use of multiple hardfacing compositions may further be employed as a wear-resistant coating on various elements of the drill bit. The surfaces to which hardfacing is applied may include machined slots, cavities or grooves providing increased surface area for application of the hardfacing. Additionally, such surface features may serve to effect a desired residual stress state in the resultant hardfacing layer or other structure.

Abstract: An earth-boring bit for drilling a borehole comprises a bit body having a bit axis, at least two rolling cone cutters rotatably mounted on the bit body, a plurality of inner row cutter elements positioned on at least one cone cutter in a first inner row, a plurality of gage-cutting cutter elements positioned in a first fanned-gage row on a first one of the one cutters, and a plurality of gage-cutting cutter elements positioned in a second fanned-gage row on a second one of the one cutters, wherein the gage-cutting cutter elements on the bit define a gage curve and cutter elements in the first fanned-gage row and the second fanned-gage row contact the gage curve at different points. In one embodiment, each cutter element has an extension, and the extensions of the uppermost fanned-gage row cutter element and the first inner row cutter element define a step distance such that the ratio of the step distance to the extension of the first inner row cutter element is greater than 0.5.

Abstract: The invention relates to a roller cone drill bit for drilling earth formations. The drill bit includes a bit body and a plurality of roller cones attached to the bit body and able to rotate with respect to the bit body. Each roller cone of the bit includes a truncated apex and a side surface. The drill bit further includes a plurality of cutting elements disposed on the side surface of each cone. The cutting elements on at least one cone are arranged such that at least one cutting element on that cone extends past an axis of rotation of the bit body as the bit is rotated. In one embodiment, the drill bit includes three cones and the cutting elements are arranged on the cones so that cutting elements on adjacent cones intermesh between the cones.

Abstract: A drill bit is disclosed which includes a bit body having a plurality of blades thereon. The blades have a plurality of cutting elements affixed thereon at selected positions. The cutting elements are disposed into at least two groups. A first one of the groups has at least 60 percent of the cutting elements therein disposed at a first mean backrake angle. A second group has at least 60 percent of the cutting elements therein disposed at a second mean backrake angle. The second backrake angle is at least about fifteen degrees more than the first backrake angle. A bottom hole coverage of the cutting elements in the second group is at least about eighty percent.

Abstract: Disclosed is a polycrystalline diamond or diamond-like element with greatly improved wear resistance without loss of impact strength. These elements are formed with a binder-catalyzing material in a high-temperature, high-pressure (HTHP) process. The PCD element has a body with a plurality of bonded diamond or diamond-like crystals forming a continuous diamond matrix that has a diamond volume density greater than 85%. Interstices among the diamond crystals form a continuous interstitial matrix containing a catalyzing material. The diamond matrix table is formed and integrally bonded with a metallic substrate containing the catalyzing material during the HTHP process. The diamond matrix body has a working surface, where a first portion of the interstitial matrix in the body adjacent to the working surface is substantially free of the catalyzing material, and a second portion of the interstitial matrix in the body adjacent to the working surface contains the catalyzing material.

Abstract: A rock drill has at least one hard material insert (2) with at least two cutting edges (3, 7) consisting of hard material and extending radially to the drill axis (A), whereby, in a radial range of 20% to 50% of their drilling radius, at least two cutting edges (3, 7) each have an axial recess (4), and the cutting edges (3, 7) rotating around the drill axis (A) extend with their cutting edges in their entirety without any gaps over the entire drilling radius.

Abstract: A fixed cutter, or rotary drag, bit exhibiting enhanced lateral stability for drilling subterranean formations and a method of drilling. The bit includes one or more gage pads longitudinally extended in the direction of the leading end of the bit and preferably forwardly of the bit face, the gage pads and preferably the adjacent shoulder regions each bearing at least one cutting element thereon exhibiting a reduced exposure in comparison to cutting elements carried on the face of the bit. The increased gage pad area may be employed as a bearing area to accommodate a large resultant lateral force vector and the extended, reduced-exposure cutting element-carrying gage pads and adjacent shoulder regions may be deployed about the entire circumference of the bit so the direction of any resultant force vector is substantially immaterial to the bit design.

Abstract: A fixed cutter drill bit particularly suited for plastic shale drilling includes rows of cutter elements arranged so that the cutting tips of the cutters in a row are disposed at leading and lagging angular positions so as to define a serrated cutting edge. The angular position of the cutting tips of cutters in a given row may be varied by mounting cutters with different degrees of positive and negative backrake along the same blade. Preferably, within a segment of a given row, the cutters alternate between having positive backrake and negative backrake while the cutters mounted with positive backrake are more exposed to the formation material than those mounted with negative backrake. Nozzles are provided with a highly lateral orientation for efficient cleaning. The positive backrake cutter elements have a dual-radiused cutting face and are mounted so as to have a relief angle relative to the formation material.

Abstract: One aspect of the invention is a roller cone drill bit including a bit body having three legs depending therefrom, each leg having a journal, a roller cone rotatably mounted on each journal, and each roller cone having a plurality of cutting elements thereon. The cutting elements are arranged in rows on each cone. The rows include at least a gage row and a first row interior of the gage row. The first interior row is staggered with respect to the gage row on each of the three cones. Another aspect of the invention is a roller cone drill bit including a bit body having three legs depending therefrom. Each leg has a journal, a roller cone rotatably mounted on each journal, and each roller cone has a plurality of cutting elements thereon. The cutting elements are arranged in rows on each cone. The rows include at least a gage row and a first row interior of the gage row. The first interior row is staggered with respect to the gage row on at least two of the three cones.

Abstract: Asymmetrical compacts are utilized in certain places on roller cones of an earth boring bit to increase the number of compacts in certain rows. The compacts that are pressed into holes in rows on the cones. The compacts are of tungsten carbide and have a cutting end axis and a barrel axis. The barrel axis intersects the cutting end axis at an obtuse angle. In the heel row, the barrel axis of at least some of the compacts is rotated to have less inclination than the cutting end axis. In an adjacent row to the heel row, each of the compacts has a barrel axis that is rotated to have more inclination than its cutting end axis and more inclination than the barrel axes of the heel row.