Abstract: A downhole tool includes a cone with an outer surface, a cone axis, and a set on the outer surface thereof. The set includes first and second cutting elements. The first and second cutting elements have respective first and second grips that are different. Another downhole tool includes a body and a cone is connected to, and rotatable relative to, the body. Cutting elements on the cone are arranged in a set to vary in radial position relative to a cone axis, with a first position nearest to, and a last position farthest from, the cone axis. A first cutting element in the first position has a different cutting element geometry type than a second cutting element in the last position. First and second cutting elements may have the same cutting element geometry type and one or more cutting elements therebetween may have different cutting element geometry types.

Abstract: A drill bit configured for boring holes or wells into the earth, the drill bit having a face and a plurality of zones, the drill bit having geometrically sharp inserts located in an inner zone and non-geometrically sharp inserts located in an outer zone.

Abstract: A drill bit having a bit body, at least one blade extending radially from the bit body, a plurality of blade cutting elements disposed on each blade, at least one journal extending downwardly and radially outward from a longitudinal axis of the drill bit, a roller cone or roller disc mounted rotatably to each journal, and a plurality of cutting elements disposed on each roller cone or roller disc, and methods for making the drill bit are disclosed.

Abstract: A drill bit includes a bit body, a plurality of blades extending radially from the bit body, a plurality of cutter pockets disposed on the plurality of blades, at least one rolling cutter disposed in one of the cutter pockets, wherein each rolling cutter has a substrate, a cutting face, a cutting edge, and a side surface, and at least one blocker positioned adjacent to each of the at least one rolling cutters on a leading face of the blade, wherein each blocker has a retention end and an attachment end. The retention end of each blocker is positioned adjacent to a portion of the cutting face of each rolling cutter to retain the rolling cutter in the cutter pocket and the attachment end is attached to a portion of the blade.

Abstract: A rolling cone drill bit for cutting a borehole comprises a rolling cone cutter mounted on a bit body and adapted for rotation about a cone axis. Further, the bit comprises a tooth extending from the cone cutter. The tooth includes a base at the cone cutter and an elongate chisel crest distal the cone cutter. The crest extends along a crest median line between a first crest end and a second crest end and includes an elongate crest apex. The tooth also includes a first flanking surface extending from the base to the crest, and a second flanking surface extending from the base to the crest. The first flanking surface and the second flanking surface taper towards one another to form the chisel crest. Moreover, the tooth includes a first raised rib extending continuously along the first flanking surfaces and across the chisel crest to the second flanking surface.

Abstract: A method includes the steps of assembling cone-leg assemblies, rotating the cones on their respective cone-leg assemblies to predetermined orientations such that cutting structures of one of the cone-leg assemblies are clear from the cutting structures of neighboring cone-leg assemblies, and installing the cone-leg assemblies in a predetermined sequence such that the plurality of cone-leg assemblies to intermesh with each other. Another method includes the steps of thermally fitting a plurality of one piece extended mud nozzles into the bit body to form a plurality of substantially straight direct unobstructed mud laminar flow paths, inserting a plurality of guide pins in preformed locator recesses in the body, and orienting a pre-assembled cone-leg assembly to align a groove on an inner surface of the leg with one of the plurality of guide pins, while thermally fitting the cone-leg assembly into a preformed bore in the body.

Abstract: Methods and systems may be provided simulating forming a wide variety of directional wellbores including wellbores with variable tilt rates and/or relatively constant tilt rates. The methods and systems may also be used to simulate forming a wellbore in subterranean formations having a combination of soft, medium and hard formation materials, multiple layers of formation materials and relatively hard stringers disposed throughout one or more layers of formation material. Values of bit walk rate from such simulations may be used to design and/or select drilling equipment for use in forming a directional wellbore.

Abstract: Described herein are roller cone drill bits and modified roller cones for use in drilling subterranean earth formations, and more specifically roller cone drill bits and roller cones having optimized spear point designs and blade orientations on at least one of the roller cones for reduced tracking and/or increased drilling performance during bit use. The roller cone drill bits include a bit body with a longitudinal axis, one or more bit legs depending from the body, and at least one roller cone attached to each of the bit legs and able to rotate with respect to the bit body, wherein at least one of the roller cones includes a spear point at the cone apex having two or more cutting blades, the cutting blades being oriented at a variety of non-equal, asymmetric angles about a central cone axis with respect to each other, such that tracking during drilling using the drill bit is minimized or eliminated.

Abstract: A method of forming an earth-boring tool includes introducing metal into a die, rotating the die to generate centrifugal forces on the metal, and cooling the metal in the rotating die. A rotary drill bit may include a unitary, centrifugally cast bit body including an integral shank, at least one blade, and at least one cutting element on the blade. A rotary drill bit or a roller cone may include a first centrifugally cast material and a second centrifugally cast material. Another rotary drill bit includes a bit body comprising a maraging steel alloy. A method of forming a rotary drill bit may include disposing cutting elements on a rotary drill bit comprising maraging steel and aging the rotary drill bit to form at least one intermetallic precipitate phase. Methods of repairing a rotary drill bit include annealing and aging at least a portion of a rotary drill bit.

Abstract: A drill bit may include a bit body rotatable about a longitudinal axis and having, at one end, a connection for securing the drill bit to a drill string and having a face opposite the connection end; and a plurality of cutting structures having at least one fixed cutting structure disposed on the bit body face and at least one cutting body rotatably attached to the face of the bit body; wherein, in a rotated view of the plurality of cutting structures into a single plane, there is substantially no radial overlap between at least one fixed cutting structure and the at least one cutting body.

Abstract: A rotating cone drill bit includes a plurality of mud nozzles extending from the bit body, which are thermally fitted by controlling the temperature differential depending on the corresponding materials, the amount of fit desired, and the diameters of the elements to be fitted and which provide substantially obstruction-free mud paths toward the wellbore bottom. The bit has a plurality of reduced diameter cutter assemblies, each having a journal projecting from a corresponding leg. The journal has at least two cylindrical bearing surfaces and an annular groove formed therebetween and a spindle. An annular retention segment is rotatably mounted in the groove. The retention segment has an outer radial surface engaging a portion of one of the bearing surfaces of the cone, and an energy beam welding area fusing substantially the entire engaging surfaces of the retention segment and the cone.

Abstract: A rolling cone drill bit comprises a bit body and a plurality of rolling cone cutters mounted on the bit body. Each cone cutter includes a plurality of gage cutting elements. Each gage cutting element has a cutting portion extending from a base portion to an extension height. Further, each gage cutting element contacts a gage curve at a gage curve contact point in a composite rotated profile view. Each gage cutting element has a cross-sectional area A1 in a first offset reference plane parallel to a base reference plane and offset from the base reference plane by an offset distance d1 equal to 10% of the extension height. The ratio of A1 to a cross-sectional area Ab of the base portion of each gage cutting element is less than 11%.

Abstract: Methods and systems may be provided simulating forming a wide variety of directional wellbores including wellbores with variable tilt rates and/or relatively constant tilt rates. The methods and systems may also be used to simulate forming a wellbore in subterranean formations having a combination of soft, medium and hard formation materials, multiple layers of formation materials and relatively hard stringers disposed throughout one or more layers of formation material. Values of bit walk rate from such simulations may be used to design and/or select drilling equipment for use in forming a directional wellbore.

Abstract: New cutting structures for roller cone drill bits are disclosed. In one aspect, a drill bit includes a bit body, roller cones attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on each of the roller cones, such that axial force on the bit during drilling is substantially balanced between the cones. In another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that the amount of work performed by each cone during drilling is substantially the same as the amount of work performed by each of the other cones. In yet another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that distribution of axial force on the bit is optimized. Additional aspects of the invention are also disclosed.

Abstract: A drill bit according to one embodiment includes a center member configured to rotate at a first speed and an outer member disposed outside the center member, wherein the outer member is configured to rotate at a second speed. The drill bit also includes a first cutter disposed on the center member and a second cutter disposed on the outer member, wherein the first speed and second speeds are configured to control a resultant side force of the drill bit.

Abstract: In one aspect of the present invention, a high impact resistant tool comprises a sintered polycrystalline diamond body bonded to a cemented metal carbide substrate at an interface, the body comprising a substantially pointed geometry with an apex, the apex comprising a curved surface that joins a leading side and a trailing side of the body at a first and second transitions respectively, an apex width between the first and second transitions is less than a third of a width of the substrate, and the body also comprises a body thickness from the apex to the interface greater than a third of the width of the substrate.

Abstract: A rotating cone drill bit includes a plurality of mud nozzles extending from the bit body, which are thermally fitted by controlling the temperature differential of 300° F.-900° F. depending on the corresponding materials of the elements to be fitted, the amount of fit desired, and the diameters of the elements to be fitted and which provide substantially obstruction-free mud paths toward the wellbore bottom. The bit has a plurality of reduced diameter cutter assemblies, each having a journal projecting from a corresponding leg. The journal has at least two cylindrical bearing surfaces and an annular groove formed therebetween and a spindle. An annular retention segment is rotatably mounted in the groove. The retention segment has an outer radial surface engaging a portion of one of the bearing surfaces of the cone, and an energy beam welding area fusing substantially the entire engaging surfaces of the retention segment and the cone.

Abstract: A drill bit for drilling through an earthen formation to form a borehole with a radius R. In an embodiment, the drill bit comprises a bit body having a central bit axis and including a pin end, an internal plenum, and a dome side. The dome side includes a central dome region extending from the bit axis to about 10% of the radius R and an intermediate dome region extending from the central region to about 50% of the radius R. In addition, the drill bit comprises an intermediate receptacle having a central axis and extending through the intermediate dome region. Further, the drill bit comprises a first and a second rolling cone, each including an intermediate cone region. A projection of the central axis of the intermediate receptacle passes between the intermediate regions of the first cone and the second cone.

Abstract: Described herein are roller cone drill bits and modified roller cones for use in drilling subterranean earth formations, and more specifically roller cone drill bits and roller cones having optimized spear point designs and blade orientations on at least one of the roller cones for reduced tracking and/or increased drilling performance during bit use. The roller cone drill bits include a bit body with a longitudinal axis, one or more bit legs depending from the body, and at least one roller cone attached to each of the bit legs and able to rotate with respect to the bit body, wherein at least one of the roller cones includes a spear point at the cone apex having two or more cutting blades, the cutting blades being oriented at a variety of non-equal, asymmetric angles about a central cone axis with respect to each other, such that tracking during drilling using the drill bit is minimized or eliminated.

Abstract: Methods and systems may be provided simulating forming a wide variety of directional wellbores including wellbores with variable tilt rates and/or relatively constant tilt rates. The methods and systems may also be used to simulate forming a wellbore in subterranean formations having a combination of soft, medium and hard formation materials, multiple layers of formation materials and relatively hard stringers disposed throughout one or more layers of formation material. Values of bit walk rate from such simulations may be used to design and/or select drilling equipment for use in forming a directional wellbore.

Abstract: A drill bit, insert and method useful for subterranean drilling, or forming boreholes in subterranean formations is provided. More particularly, a more efficient cutting structure and method is provided in the central portion of a PDC drill bit. The present invention provides a drill bit, insert and method having a central cutting portion with a more normalized angle of attack. The drill bit of the present invention provides for various attack angles much closer to the optimum side rake.

Abstract: A rolling cone drill bit comprises a bit body and a plurality of rolling cone cutters mounted on the bit body. Each cone cutter includes a plurality of gage cutting elements. Each gage cutting element has a cutting portion extending from a base portion to an extension height. Further, each gage cutting element contacts a gage curve at a gage curve contact point in a composite rotated profile view. Each gage cutting element has a cross-sectional area A1 in a first offset reference plane parallel to a base reference plane and offset from the base reference plane by an offset distance d1 equal to 10% of the extension height. The ratio of A1 to a cross-sectional area Ab of the base portion of each gage cutting element is less than 11%.

Abstract: An earth boring drill bit comprising cones, each cone having a land on its mid portion with at least two rows of compacts that are staggered with respect to adjacent compacts on another row. The compacts of these two rows may also have the same size. The compacts of these two inner rows are closer to each other than to any other compacts on the cone.

Abstract: Methods and systems may be provided simulating forming a wide variety of directional wellbores including wellbores with variable tilt rates and/or relatively constant tilt rates. The methods and systems may also be used to simulate forming a wellbore in subterranean formations having a combination of soft, medium and hard formation materials, multiple layers of formation materials and relatively hard stringers disposed throughout one or more layers of formation material. Values of bit walk rate from such simulations may be used to design and/or select drilling equipment for use in forming a directional wellbore.

Abstract: Drill bits are provided. The drill bits are of the fixed-cutter, rotary-type. The drill bits have a plurality of blades having cutting elements disposed therealong. Junk slots are formed between the respective blades. A knife opening is formed in at least two of the junk slots. Preferably, the knife openings are disposed substantially transverse to a longitudinal axis of the drill bit. The drill bit also has one or more ribbon cutters. The ribbon cutters cyclically protrude through knife openings in the junk slots in order to facilitate the fragmentation of cuttings ribbons moving through the junk slots during a drilling operation.

Abstract: A drill bit for drilling through earthen formations and forming a borehole. In an embodiment, the bit comprises a bit body having a bit axis. In addition, the bit comprises a plurality of cone cutters, each of the cone cutters being mounted on the bit body and adapted for rotation about a different cone axis. Further, at least one cone cutter on the bit comprises an array of cutter elements mounted in a band. Still further, the cutter elements in the array are mounted in a plurality of differing radial positions relative to the bit axis.

Abstract: An earth boring drill bit comprising: a bit body; a plurality of fixed blades extending downwardly from the bit body, each blade having a leading edge; a plurality of fixed-blade cutting elements arranged on the leading edge of the fixed blades; at least one rolling cutter mounted for rotation on the bit body; and wherein the rolling cutter is configured to act as a depth-of-cut limiter, thereby reducing the risk of damage to the fixed-blade cutting elements. The fixed-blade cutting elements may include thermally stable polycrystalline diamond wafers mounted on tungsten carbide substrates and/or a mosaic of geometrically-shaped thermally stable diamond elements cooperatively arranged and bonded to form a unitary cutting surface. The rolling cutter may be positioned, relative to the fixed blades, to also limit rate of penetration and/or exposure of the fixed-blade cutting elements.

Abstract: An earth boring bit has cutting elements arranged to avoid tracking. The bit has a bit body having a bit axis of rotation. First, second and third cones are rotatably mounted to the bit body, each of the cones having a plurality of rows of cutting elements including a heel row and an adjacent row. The heel row of the first cone has at least equal the number of cutting elements as the heel rows of the other cones. The adjacent row of the second cone has at least 90 percent as many cutting elements as the heel row of the first cone. The heel row of the third cone has a pitch that is in the range from 20-50% greater than the heel rows of the first cone.

Abstract: An earth boring bit has three cones, each cone being mounted for rotation about a cone axis while the bit rotates about a bit axis. An outer row and an adjacent row of cutting elements are integrally formed on each of the cones. Each of the cutting elements of the adjacent row on each of the cones has a crest extending perpendicular to a direction of rotation of the cone. Annular spaces are located between the outer row and the adjacent row on each of the cones. The annular space on one cone has a width that is less than the annular spaces on the other cones. The width of the narrowest annular space is greater than the width of the crests of the adjacent row.

Abstract: An earth-boring bit has a high density row on one of its cones. Each cone has a nose area and a gage area with a heel row of teeth at the gage area. One of the cones has a farther intermediate row of teeth and another one of the cones has a closer intermediate row of teeth. The remaining cone has a high density row of teeth, which is located closer to the axis of rotation of the bit than the farther intermediate row and farther from the axis of rotation of the bit than the closer intermediate row. The high density row has a smaller pitch between crests of the teeth than the closer and farther intermediate rows. The smaller pitch provides more teeth in the high density row than in the closer intermediate row and the farther intermediate row.

Abstract: A rolling cone drill bit for drilling in earthen formations. In an embodiment, the drill bit comprises a plurality of rolling cone cutters. Each cone cutter includes a plurality of gage cutting elements, a first plurality of bottomhole cutting elements, and a second plurality of bottomhole cutter elements. Each of the first plurality of bottomhole cutting elements is staggered relative to the gage cutting elements on each cone cutter, and the profiles of the gage cutting elements and the first plurality of bottomhole cutting elements on each cone cutter overlap in rotated profile view. Each of the second plurality of bottomhole cutting elements is staggered relative to the first plurality of bottomhole cutting elements on at least one cone cutter, and the profiles of the first plurality of bottomhole cutting elements and the second plurality of bottomhole cutting elements on at least one cone cutter overlap in rotated profile view.

Abstract: A drill bit for drilling through an earthen formation to form a borehole. In an embodiment, the drill bit comprises a bit body having a central axis, an internal plenum, and an underside. The underside includes an annular outer region. The bit body includes an outer receptacle extending from the plenum to the outer region. In addition, the drill bit comprises a first and a second cone cutter. Each cone cutter comprises an outer region distal the bit axis. Further the drill bit comprises an outer sleeve having an upstream end received by the outer sleeve receptacle and a through passage. The through passage includes an upstream section having an upstream axis and a downstream section having a downstream axis that is skewed at an angle ? relative to the upstream axis. A projection of the downstream axis passes between the outer regions of the first and second cone cutters.

Abstract: An earth boring drill bit comprising cones, each cone having rows of inserts, where the inserts are in the form of a pyramid with four sides. The insert includes ridges at the juncture of each adjacent side. The ridges extend to the top of the insert and meet at a crest. Oppositely disposed ridges on the insert lie substantially in the same plane, thereby forming two planes intersecting on the crest. The two planes are substantially perpendicular. The inserts are arranged on the cone such that one plane is substantially parallel with the insert row, and the other is substantially parallel with the cone axis.

Abstract: A hybrid drill bit having both roller cones and fixed blades is disclosed. The cutting elements on the fixed blades form a continuous cutting profile from the perimeter of the bit body to the axial center. The roller cone cutting elements overlap with the fixed cutting elements in the nose and shoulder sections of the cutting profile between the axial center and the perimeter. The roller cone cutting elements crush and pre-fracture formation in the weak and highly stressed nose and shoulder sections.

Abstract: Roller cone drill bits may be formed with cutting elements and cutting structures having cutting element profile angles selected to minimize cone wobble and improve life of associated bearings and seals. Normal force axes of the cutting elements may intersect with each other as a force center. Crest points of the cutting elements may be disposed on one or more circles extending from the associated force center.

Abstract: A drill bit for cutting a borehole comprises a bit body including a bit axis. In addition, the drill bit comprises a rolling cone cutter mounted on the bit body. Further, the drill bit comprises a cutter element having a base portion with a diameter and a cutting portion extending therefrom. The cutting portion comprising a first pair of flanking surfaces that taper towards one another to form a first elongate chisel crest, and a second pair of flanking surfaces that taper towards one another to form a second elongate chisel crest that intersects the first elongate chisel crest in top view. The first crest tangent angle at 10% of the diameter measured radially from the central axis on the first elongate chisel crest in profile view is greater than 75° and less than or equal to 90°.

Abstract: A rolling cone drill bit including multiple cones with regions of intermeshing and non-intermeshing cutter elements. In the non-intermeshed regions, an array of cutter elements is disposed about the cone surface in a non-circumferential arrangement with the cutter elements being mounted at differing radial distances from the bit axis. This non-circumferential arrangement, which may be a spiral, multiple spirals, other patterns of offset cutter elements, or a random arrangement, provides a composite cutting profile having substantial width and bottomhole coverage and is free of ridge-producing voids. In certain embodiments, the composite cutting profiles of the arrays at least partially overlap, and may be arranged to cover a portion of or the entire non-intermeshed region on the cones.

Abstract: An earth-boring bit has a body with three bit legs. A cone is rotatably mounted to each of the bit legs. Each of the cones has an outer row and an inner row of teeth machined on it. Each of the teeth has a rectangular root with inner, outer and lateral boundaries. A layer of hardfacing is applied to each tooth and on an exterior portion of each of the cones surrounding the inner, outer and lateral boundaries of each of the teeth. Conical surfaces between the inner and outer rows contain at least portions of the hardfacing.

Abstract: An earth bit includes an earth bit body which carries a lug. The lug is repeatably attachable to and detachable from the earth bit body. A retaining ring retains the lug to the earth bit body and restricts the movement of the lug in response to a force applied to it. The retaining ring has a height less than its diameter.

Abstract: An earth bit includes a cutting cone mounted to a lug to form a bearing cavity. A valve is in fluid communication with the bearing cavity and a bit chamber, wherein the valve includes a diaphragm with an aperture. The aperture is repeatably moveable between open and closed conditions in response to a pressure difference between the material in the bearing cavity and bit chamber.

Abstract: Roller cone drilling wherein the bit optimization process equalizes the downforce (axial force) for the cones (as nearly as possible, subject to other design constraints).

Abstract: A rotary-cutter Earth-penetrating bit in which a given track of bottom hole is attacked by inserts of two different types, e.g. chisel-shaped and pointed, wider and narrower, higher and shorter, and/or of different materials. The different types of inserts can both be included within a single row of a cone.

Abstract: A novel and improved roller cone drill bit and method of design are disclosed. A roller cone drill bit for drilling through subterranean formations having an upper connection for attachment to a drill string, and a plurality cutting structures rotatably mounted on arms extending downward from the connection. A number of teeth are located in generally concentric rows on each cutting structure. The actual trajectory by which the teeth engage the formation is mathematically determined. A straight-line trajectory is calculated based on the actual trajectory. The teeth are positioned in the cutting structures such each tooth having a designed engagement surface is oriented perpendicular to the calculated straight-line trajectory.

Abstract: Roller cone drilling wherein the bit optimization process equalizes the downforce (axial force) for the cones (as nearly as possible, subject to other design constraints). Bit performance is significantly enhanced by equalizing downforce.

Abstract: Roller cone drilling wherein the bit optimization process equalizes the downforce (axial force) for the cones (as nearly as possible, subject to other design constraints). Bit performance is significantly enhanced by equalizing downforce.

Abstract: New cutting structures for roller cone drill bits are disclosed. In one aspect, a drill bit includes a bit body, roller cones attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on each of the roller cones, such that axial force on the bit during drilling is substantially balanced between the cones. In another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that the amount of work performed by each cone during drilling is substantially the same as the amount of work performed by each of the other cones. In yet another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that distribution of axial force on the bit is optimized. Additional aspects of the invention are also disclosed.

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: New cutting structures for roller cone drill bits are disclosed. In one aspect, a drill bit includes a bit body, roller cones attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on each of the roller cones, such that axial force on the bit during drilling is substantially balanced between the cones. In another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that the amount of work performed by each cone during drilling is substantially the same as the amount of work performed by each of the other cones. In yet another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that distribution of axial force on the bit is optimized. Additional aspects of the invention are also disclosed.

Abstract: New cutting structures for roller cone drill bits. In one aspect, a drill bit includes a bit body, roller cones attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on each of the roller cones, such that axial force on the bit during drilling is substantially balanced between the cones. In another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that the amount of work performed by each cone during drilling is substantially the same as the amount of work performed by each of the other cones. In yet another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that distribution of axial force on the bit is optimized.

Abstract: An earth boring bit has cutting elements arranged to avoid tracking. The bit has a bit body having a bit axis of rotation. First, second and third cones are rotatably mounted to the bit body, each of the cones having a plurality of rows of cutting elements including a heel row and an adjacent row. The heel row of the first cone has at least equal the number of cutting elements as the heel rows of the other cones. The adjacent row of the second cone has at least 90 percent as many cutting elements as the heel row of the first cone. The heel row of the third cone has a pitch that is in the range from 20-50% greater than the heel rows of the first cone.