Abstract: A rock excavating device includes a shaft and a cutting element. The shaft includes a first portion and a second portion connected to an end of the first portion. The first portion is rotatable about a first axis. The second portion extends along a second axis that is oblique with respect to the first axis. The cutting element includes a cutting edge. The cutting element is supported on the second portion and rotatable about the second axis. Rotation of the first portion of the shaft about the first axis changes the orientation of the second axis and the cutting element.

Abstract: Earth-boring tools may include a body, blades extending outward from the body, and cutting elements secured to the blades. An entirety of a first blade may exhibit a first, constant or continuously variable radius of curvature different from a second, constant or continuously variable radius of curvature of at least another portion of a second blade. Methods of making earth-boring tools may involve forming at least a portion of a first blade extending outward from a body to exhibit a first radius of curvature. An entirety of a second blade extending outward from the body may be formed to exhibit a second, different, constant or continuously variable radius of curvature. Cutting elements may be secured to the first and second blades.

Abstract: According to the invention, a method for designing a rotary drill bit for drilling a cavity in a medium is disclosed. The method may include determining a characteristic of a drillstring with which the rotary drill bit is coupled. The method may also include determining an initial number of groups of cutters for the rotary drill bit, where each group of cutters includes a plurality of cutters substantially aligned along a different radius of the drilling face. The method may moreover include determining a characteristic of the medium relative to a characteristic of the cutters. The method may additionally include determining a characteristic of a rotational motion source used to rotate the rotary drill bit. The method may further include determining the angles of pitch between each of the groups of cutters to minimize an amount of sticking or slipping of the bit in the medium during a drilling operation.

Abstract: A drill bit for drilling a borehole in earthen formations comprising a bit body having a bit axis and a bit face. In addition, the drill bit comprises a primary blade extending radially along the bit face, the primary blade including a cutter-supporting surface that defines a blade profile in rotated profile view extending from the bit axis to an outer radius of the bit body. The blade profile is continuously contoured and includes a plurality of concave regions. Further, the drill bit comprises a plurality of cutter elements mounted to the cutter-supporting surface of the primary blade. Each cutter element on the primary blade has a forward-facing cutting face with a cutting edge adapted to penetrate and shear the earthen formation.

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 PDC bit includes a plurality of blades. A blade includes a primary cutter row and a secondary cutter row. Primary PDC cutters on the primary cutter row are set in accordance with a single set methodology. Backup PDC cutters on the secondary cutter row are set in accordance with a methodology wherein a radial position of each backup PDC cutter in the secondary cutter row is offset from a radial position of each primary PDC cutter in the primary cutter row. The blade further includes a tertiary cutter row. Additional backup PDC cutters on the tertiary cutter row are set in accordance with a methodology wherein a radial position of each additional backup PDC cutter in the tertiary cutter row is offset from a radial position of each primary PDC cutter in the primary cutter row. The backup cutter setting methodology is effectively radially positions the included backup PDC cutters (in the secondary cutter row and/or tertiary cutter row) between primary PDC cutters in the primary cutter row.

Abstract: A rolling cone drill bit for drilling a borehole in earthen formations. In an embodiment, the bit comprises a bit body. In addition, the bit comprises a cone cutter mounted on the bit body and adapted for rotation about a cone axis in a cutting direction. Further, the bit comprises at least one transition insert mounted to the cone cutter. Still further, the bit comprises a first asymmetric insert mounted to the cone cutter. Moreover, the bit comprises a second asymmetric insert mounted to the cone cutter. Each insert includes a cutting surface with a leading side relative to the cutting direction. The leading side of the first asymmetric insert has a leading geometry and the leading side of the second asymmetric insert has a leading geometry that is different than the leading geometry of the first asymmetric insert.

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 downhole drill bit includes, a body, a plurality of cutters attached to the body, and at least one prefabricated splitter having a proximal portion and at least one distal portion. The proximal portion is encased within the body and the at least one distal portion extends outwardly of the body. Further the at least one distal portion is in operable communication with at least one of the plurality of cutters such that the at least one distal portion bifurcates cuttings cut by the at least one cutter.

Abstract: The harmful effects of tracking are reduced for a drill bit having roller cones with at least one of the outermost rows of active teeth containing one or more teeth having a height that does not extend to the height of at least one of the outermost rows on another roller cone on the bit. The crest on this tooth may have a length in a circumferential direction that is wider than an overall width of the tooth in the outer to inner direction. The invention may be used on any cutter row, not just the outermost row. The design may be used on a different roller cone or row, or more than one cutter row. The anti-tracking feature may be located between the leading and trailing edges of the tooth on one or more roller cones.

Abstract: Disclosed herein is a lawn perforating tool and method of using same to prepare new lawn or garden areas or distressed regions of existing lawns or gardens for the planting of seed, example of which include, but are not limited to, grass seed, clover seed, wildflower seed, and the like. The lawn perforating tool of the present invention is particularly configured to provide in the soil and dead grass holes or indentations of a size, shape, and depth that is optimal for receiving and germinating new grass seed and of a density and distribution suitable to provide the resulting grass with a visually desirable pattern, rendering new growth indistinguishable from old growth.

Abstract: Embodiments of a system, method, and apparatus for predicting and reducing tracking by roller cone bits by adjusting compact spacing are disclosed. Different pitches between adjacent compacts or teeth provide a cone row that is substantially less likely to track. A given row on a cone may include compacts that are arrayed at a single pitch in a contiguous group for approximately half of the row. The remaining approximately half of the row includes alternating pitches. This configuration enables anti-tracking behavior without very wide spaces and consequent breakage and wear seen in prior art anti-tracking pitch schemes.

Abstract: An earth boring drill bit comprising a milled cutter having rows of hardfacing guides on the cutter. Hardfacing is applied between adjacent hardfacing guides to form a hardfacing web that serves as a cutting element. The hardfacing web defines an interface between the hardfacing web and the hardfacing guide. The hardfacing web may extend past the crest of the hardfacing guides or end along the hardfacing guides flanks. Projecting hardfacing is provided on the interface to form trimmers.

Abstract: A rolling cone drill bit includes a cutter element having a cutting portion with a chisel crest and a pilot portion extending beyond the chisel crest. The pilot portion includes a cutting surface that may be generally conical, or form a second chisel crest. The cutting tip of the pilot portion is supported by buttress portions which emerge from and extend beyond the flanks of the chisel crest to provide additional strength and support for the material of the pilot portion that extends beyond the height of the chisel crest.

Abstract: In one aspect of the present invention a force balanced drill bit may comprise a bit body comprising a plurality of fixed blades, each blade comprising cutters defining a cutter profile. Junk slots may be disposed between the blades and define the blade boundaries. The blade boundaries may be spaced apart sufficiently to achieve force balance. In another aspect of the present invention a method of designing a downhole fixed bladed bit comprises the steps of modeling a fixed bladed bit by inputting blade and cutter parameters into a computer program, performing a force balance on the modeled fixed bladed bit, and modifying at least one blade parameter to adjust the force balance. The parameters for modeling a fixed bladed bit include cutter placement on a plurality of blades integrally formed in a bit body and a position for each blade.

Abstract: An earth boring drill bit comprising a milled cutter having rows of teeth hardfacing guides on the cutter. Hardfacing is applied between adjacent teeth hardfacing guides to form a cutting element. The hardfacing may extend past the crest of the teeth hardfacing guides or end along the teeth hardfacing guides flanks.

Abstract: A roller cone drill bit for drilling earth formation includes rows arranged on each of the cones such that, when viewed in routed profile, cutting element profiles partially overlap other cutting element profiles. The roller cone drill bit having at least a first three interior rows adjacent a gage row, each have a cutting element count selected from the group of 16, 18, 21 and 26 cutting elements.

Abstract: A drill bit for drilling a borehole includes a cutter element comprising a base portion. In addition, the cutter element comprises a cutting portion extending from the base portion and terminating in an elongate crest extending between a first crest end and a second crest end, and having an intermediate portion therebetween. The first crest end has a width W1 and the second end has a width W2 that is greater than the width W1. Still further, the intermediate portion of the crest has a width W3 that is less than the width W2 and less than or equal to the width W1.

Abstract: A method of optimizing drill bit design and an optimized drill bit for drilling a well into an earth formation comprising a bit body; a number of blades spaced around the bit body, each blade having a curved outer edge and a forward face; a first row of cutter pockets recessed into the face along the outer edge of each blade; a second group of cutter pockets recessed into the face of each blade offset from the first row; and a plurality of cutting elements, each cutting element being brazed into a different one of the cutter pockets.

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: A rolling cone drill bit includes a cutter element having a cutting portion with a chisel crest and a pilot portion extending beyond the chisel crest. The pilot portion includes a cutting surface that may be generally conical, or form a second chisel crest. The cutting tip of the pilot portion is supported by buttress portions which emerge from and extend beyond the flanks of the chisel crest to provide additional strength and support for the material of the pilot portion that extends beyond the height of the chisel crest.

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 drill bit having cutting elements disposed on a roller cone surface in a non-linear pattern, wherein at least one of the cutting elements is asymmetrical to its axis of orientation. Also, a method for selecting and adjusting a cutting element orientation based on crater profile geometry which results in increased bottom hole coverage.

Abstract: Roller cone drill bits are provided with cutting elements and cutting structures optimized for efficient drilling of soft and medium formations interspersed with hard stringers. The cutting elements and cutting structures may be satisfactorily used to drill downhole formations with varying amounts of hardness. The cutting elements and cutting structures may also be optimized to reduce tracking and increase wear resistance.

Abstract: Embodiments of a system, method, and apparatus for predicting and reducing tracking by roller cone bits by adjusting compact spacing are disclosed. Different pitches between adjacent compacts or teeth provide a cone row that is substantially less likely to track. A given row on a cone may include compacts that are arrayed at a single pitch in a contiguous group for approximately half of the row. The remaining approximately half of the row includes alternating pitches. This configuration enables anti-tracking behavior without very wide spaces and consequent breakage and wear seen in prior art anti-tracking pitch schemes.

Abstract: A method for designing a roller cone drill bit having a plurality of cutting elements in a row. The method includes defining a pitch pattern for the plurality of cutting elements such that a first group of adjacent cutting elements are arranged in a first pitch and a second group of adjacent cutting elements are arranged in a second pitch in the row, wherein the first group of adjacent cutting elements have a different extension length than the second group of adjacent cutting elements, evaluating the pitch pattern of the plurality of cutting elements in the row, and modifying at least one of the plurality of cutting elements based on the evaluating of the pitch pattern of the plurality of cutting elements.

Abstract: A method for designing a roller cone drill bit having a plurality of cutting elements in a row. The method includes defining a pitch pattern for the plurality of cutting elements such that a first group of adjacent cutting elements are arranged in a first pitch and a second group of adjacent cutting elements are arranged in a second pitch in the row; evaluating the pitch pattern of the plurality of cutting elements in the row; and modifying at least one of the plurality of cutting elements, based on the evaluating the pitch pattern of the plurality of cutting elements.

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: A drill bit for drilling a borehole with a steerable drilling system, the drill bit comprising a longitudinal axis, and a cutting profile with a leading face section blended with a curved region into a tapered gauge region having a tapered gauge profile. The tapered gauge region being tapered with respect to the longitudinal axis determined by the steerable drilling system. The cutting profile and the gauge profile lie wholly within a bit profile envelope made up of a three dimensional surface of two complimentary conical sections set at the tilt angle and separated by and blended with a rounded section which forms an outermost diameter of the bit profile envelope. The rounded section has a diameter substantially equal to a maximum allowable API diameter for the drill bit, and further has a radius of curvature substantially equal to one-half the diameter.

Abstract: A method for evaluating a cutting arrangement for a drill bit includes selecting a cutting element arrangement for the drill bit and calculating a score for the cutting arrangement. This method may be used to evaluate the cutting efficiency of various drill bit designs. In one example, this method is used to calculate a score for an arrangement based on a comparison of an expected bottomhole pattern for the arrangement with a preferred bottomhole pattern. The use of this method has lead to roller cone drill bit designs that exhibit reduce tracking over prior art bits.

Abstract: A method for designing a roller cone drill bit having a plurality of cutting elements in a row. The method includes defining a pitch pattern for the plurality of cutting elements such that a first group of adjacent cutting elements are arranged in a first pitch and a second group of adjacent cutting elements are arranged in a second pitch in the row; evaluating the pitch pattern of the plurality of cutting elements in the row; and modifying at least one of the plurality of cutting elements, based on the evaluating the pitch pattern of the plurality of cutting elements.

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: 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: Disclosed is a rolling cone cutter and drill bit employing multiple inserts retained as a cluster in an aperture in the cone cutter. Apertures in which the insert clusters are retained are multilobed apertures formed by intersecting bores formed in the cone steel. The apertures may also be created by forming spaced apart bores and milling regions of the cone steel that extends between the bores. The inserts in a cluster may be retained within the aperture to differing depths, may extend above the cone steel to differing extension lengths, and may have cutting portions having a variety of shapes. The inserts in a cluster may be made of different materials in order to optimize cutting duty.

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 tunnel boring including a rotatable head is disclosed. The head has a cutting face transverse to a head axis of rotation. A plurality of cutters are mounted in the face each on an associated one of a plurality of hubs. The hubs mounted for rotation about a respective hub axes. Each such respective hub axis is in an imaginary plane intersecting another imaginary plane including the head axis. Each of the cutters has a cutting edge symmetrical about another imaginary plane which is skewed with respect to the respective hub axis of the associated hub.

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 method for evaluating a cutting arrangement for a drill bit includes selecting a cutting element arrangement for the drill bit and calculating a score for the cutting arrangement. This method may be used to evaluate the cutting efficiency of various drill bit designs. In one example, this method is used to calculate a score for an arrangement based on a comparison of an expected bottomhole pattern for the arrangement with a preferred bottomhole pattern. The use of this method has lead to roller cone drill bit designs that exhibit reduce tracking over prior art bits.

Abstract: A method for optimizing drilling performance of a roller cone drill bit is disclosed. The method includes simulating drilling with the bit in a selected earth formation to determine at least one drilling performance parameter. The orientation of at least one non-axisymmetric cutting element on the bit is adjusted and the simulating the drilling and determining the at least one performance parameter are repeated. The adjusting and simulating the drilling are repeated until the at least one performance parameter is determined to be at an optimum value. In one embodiment, the performance parameter includes rate of penetration.

Abstract: A hardfacing material is applied to cutting elements formed on the surface of cutters of an earth-boring bit. The hardfacing material forms the outer surface of the teeth, and also substantially forms scrapers on the shell of each of the cutters. The adding of the hardfacing material to the outer surface of the teeth and the forming of the scrapers is accomplished through welding. The hardfacing material is machined from its “as-welded” state to have a smoother surface finish.

Abstract: A drill bit has a bit body and at least one roller cone rotatably mounted on the bit body. The cone has a plurality of milled teeth at selected locations on the cone. At least one of the milled teeth has a substrate having a convex crest and a layer of hardfacing applied to the convex crest. The convex crest is adapted to produce at least one of a convex axial stress distribution, a substantially even axial stress distribution, and a substantially smooth axial stress distribution.

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. 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: 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: The invention concerns a self-penetrating drilling method and a thrust-generating tool: the tool (1) comprises N blades (2a, 2b, 2c, 2d). Each blade comprised K drill bits (3a, 3b, 3c, 3d). The shapes, positions and orientations of said drill bits are determined in the following manner: the kth drill bit of the last blade drills, at the (q−1)th of the tool rotational cycle, a cut in the rock downstream of the one produced by the (k+1)th drill bit of the first blade at the qth rotational cycle of the tool; the kth drill bit of the nth blade drills, at the q?th rotational cycle of the tool, a cut in the rock downstream of the one produced by the kth drill bit of the (n+1)th blade at the qth rotational cycle of the tool; the normal to the leading edge of the drill bit has a component along the axis of rotation oriented towards upstream.

Abstract: A roller cone drill bit having selected left hand walk is disclosed. The bit includes a bit body adapted to couple to a drill string, and a plurality of legs depending from the bit body. Each leg has a roller cone rotatably mounted thereon. Each cone includes a plurality of cutting elements thereon. At least one cone has a nose point of its profile displaced radially inward with respect to a nose point of the profile of the other cones. A roller cone drill bit having selected right hand walk is also disclosed. The bit include a bit body adapted to couple to a drill string, and a plurality of legs depending from the bit body. Each leg has a roller cone rotatably mounted thereon, each cone including a plurality of cutting elements thereon defining a profile. At least one cone has a nose point of the profile displaced radially outward with respect to a nose point of the profile of the other cones.

Abstract: This invention relates to a roller bit applying for the oil, natural gas, mine and geological drilling, and more particularly relates to a kind of roller bit with the parallel inlayed compacts, it includes head and cone, the compact land and the teeth-groove are arranged on the cone, the difference is that there are 2 to 3 compacts having the cylindrical body being arranged on the top of the base teeth along the teeth direction.The cutting performance of the present invention is similar to that of the oblate compacts, and, by utilizing the conventional cylindrical compacts, it is not only easy to process and with low manufacturing cost, but the bit can effectively drill through the stringered earth formation with both hard and soft formation and thus better economic benefit from drilling the stringered formation can be obtained.

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 bearing failure indicator for sealed and lubricated rolling cutter earth boring drill bits is disclosed. A plurality of cutting inserts, arranged in a plurality of rows, are secured in the rolling cone cutters. At least two of the rolling cone cutters are intermeshing cutters, arranged such that they have intermeshing rows of cutting inserts. A groove is formed in the intermeshing cutters with a row containing a plurality of generally flat top bearing inserts. In the normal operation of the drill bit, the rows of generally flat top bearing inserts do not contribute to the drilling action of the drill bit. However, when a bearing assembly fails in operation, the generally flat top bearing inserts engage the intermeshing rows of inserts in the adjacent intermeshing cutter causing the drilling torque to increase and thereby providing a signal indicating the bearing has failed.