Abstract: A combination of a pullback adaptor and a drill bit includes a pullback adaptor having a first end, a second end, a body extending between the first end and the second end, and a protrusion extending from the body adjacent the second end. The protrusion has a threaded aperture defining an adaptor mounting axis, and the protrusion defines an annular planar mount surface generally perpendicular to the adapter mounting axis. A drill bit has a body with a steering surface, an aperture extending through the body at the steering surface, and an adaptor mount surface adjacent the aperture. The pullback adaptor is mounted to the drill bit with a fastener that extends through the aperture in the drill bit and into the threaded aperture of the pullback adaptor such that the annular planar mount surface of the protrusion engages the mount surface of the drill bit.

Abstract: In one aspect, a bit for removing a plug from a branch conduit extending from a main pipe has a boring head at a distal end portion of a shaft configured to bore a pilot hole in the plug. A catch on the shaft is configured to pass through the pilot hole and then engage the plug after the pilot hole is bored for pushing the plug proximally. A burr proximal of the boring head is configured to remove a portion of the plug to separate a removable section from a durable section of the plug. In a method of restoring fluid communication between a main pipe and a branch conduit, the bit bores a pilot hole with the boring head, separates the removable section from the durable section with the burr, and then with the catch, withdraws the removable section only.

Abstract: The present concept is a method of slot recovery for the oil industry. The method involves running an internal cutter down the production casing to cut through a preselected number of existing casings at predetermined depths before drilling around the outermost preselected casing with a hollow drill bit. The hollow drill bit drills through the preslected outermost casing cement to the predetermined depth before a removal tool attached to the inside of the production casing is used to remove the existing casings to the predetermined depth. These steps are repeated using appropriately sized hollow drill bits and casings to drill around the next preselected outermost casings to the next predetermined depth, continuously removing the existing casings until all desired existing casings are removed.

Abstract: A PDC drill bit for use in downhole air drilling includes a body with a face for engaging a bottom of a hole being drilled and a gauge for engaging a side of the hole being drilled. The face includes a cone, a nose outward of the cone, a shoulder outward of the nose. The bit further includes channels formed in the face of the bit that extend from within the cone to the gauge. The channels define a plurality of blades separated by the channels. Each of the plurality of blades has a leading edge with PDC cutters mounted thereon. One or more of the channels are defined by two side walls and a bottom wall and has a length, width and depth. The width or depth remains substantially constant from a first point on its length within the cone to a second point within the shoulder.

Abstract: A sonde housing for horizontal directional drilling includes a cylindrical housing body with walls defining a longitudinal cavity. A lid is provided for covering the cavity in the housing body. A series of tabs on the lid longitudinal side surfaces are engaged in mating grooves provided in the housing body to secure the lid on the housing body. A further independent locking member also engages the lid and housing body.

Abstract: A sonde housing for a fluid-actuated percussive impact tool includes a sonde compartment formed in the sonde housing and defining an open side along an exterior side surface of the sonde housing. A sonde is removably secured in the sonde compartment, and a cover is removably mounted upon the open side of the sonde compartment to close the open side thereof.

Abstract: A drive point for a substantially tubular driven pile, wherein the drive point can be fitted onto a pile end of the driven pile, wherein at least one first support limb with a first support surface configured to abut an end face of the pile end of the driven pile is arranged at an inside wall of the drive point, wherein at least one support device with a ground surface is arranged at an outer surface of the drive point, and wherein the ground surface of the at least one support device supports the drive point when on a ground into which the drive point is to be driven in a driving-in direction.

Abstract: A stacked-plate system for a backreamer. The backreamer has a set of plates disposed about a central shaft for providing fluid for use in reaming operations. A distributor plate forms a cavity within a plate assembly for receiving fluid from the central shaft through radial fluid ports. Fluid from the cavity is then expelled through nozzles that overlay the cavity in a separate plate. The direction of fluid flow at the nozzles is axial, rather than toward the sidewall of the enlarged bore.

Abstract: A horizontal directional drilling sonde housing has a cavity for receiving a sonde. Signal channels extend from the cavity to an exterior of the housing. A polymer lines at least part of the cavity and fills the signal channels. The drilling tool has a bit body and a drilling body. The two bodies have respective lateral surfaces which engage each other to prevent the transverse movement of the drilling body relative to the bit body during operations. The drill bit has a forward extending drill tooth, which drill tooth is removable from a bore. A spacer is located in the bore between the bottom end of the bore and the tooth. The drilling bit has buttons located on the side in a spiral configuration about a longitudinal axis of the bit.

Abstract: A drill bit for drilling a borehole in earthen formations comprises a bit body including a cone region, a shoulder region, and a gage region. In addition the bit comprises a first primary blade and a second primary blade. Further, the bit comprises a plurality of primary cutter elements mounted to the first primary blade in different radial positions. Still further, the bit comprises a plurality of primary cutter elements mounted to the second primary blade in different radial positions. Moreover, a first primary cutter element of the plurality of primary cutter elements on the first primary blade and a first primary cutter element of the plurality of primary cutter elements on the second primary blade are each positioned in the cone region and are redundant. The shoulder region has a total cutter redundancy percentage that is less than a total cutter redundancy percentage in the cone region.

Abstract: A rock drill bit having a shank fitted with a clamping end and a drilling tip located from the clamping end. The drilling tip has at least three blades and a central zone centered on a drill bit axis. The blades each include on a top side thereof a lip constituted by a leading chipping face and a trailing flank. The lips substantially converge onto each other within a the central zone of the drilling tip, wherein in the central zone, a long lip of the lips runs through the drill bit axis and has a commensurate overshoot segment extending beyond the drill bit axis.

Abstract: A drilling apparatus is adapted for connection to a drill string such that the drill string rotates the drilling apparatus in a rotational cutting motion. The drilling apparatus includes a sonde housing having a distal end and a proximal end. The sonde housing includes a top platform positioned adjacent the distal end of the sonde housing and further includes a tongue positioned on the top platform. The drilling apparatus further includes a rotary cutting tool mounted to the distal end of the sonde housing.

Abstract: A drilling unit for drilling a borehole and having an outer drill bit being rotationally driven by a primary rotary drive mechanism about a primary axis of rotation and having an outer bit cutting face disposed for drilling engagement with formation material. The outer drill bit defines an inner bit passage intersecting the outer bit cutting face. An inner drill bit is rotationally driven within the inner bit passage by a secondary rotary drive mechanism and has a secondary axis of rotation that can be the same or can be laterally offset from the primary axis of rotation. An inner bit cutting face is defined by the inner drill bit and is located within the inner bit passage. Rotation of the outer drill bit for borehole drilling causes orbital rotation of the inner drill bit about the primary axis of rotation simultaneously with rotation of the inner drill bit about the secondary axis of rotation for continuously cutting away formation material at the central region of the borehole being drilled.

Abstract: Downhole drilling tools designed and manufactured to reduce bit axial force and torque and to enhance drilling efficiency comprising laying out some cutters in one spiral direction of rotation about a bit rotational axis and other cutters in an opposite spiral direction of rotation; evaluating forces acting on cutters during simulated engagement with a downhole formation (straight and transitional drilling); and modifying cutter layout with respect to a spiral direction of rotation. Some embodiments further comprise, prior to simulation, placing cutters in cutter groups/sets at respective locations to obtain a level of force balance. Multilevel force balanced downhole drilling tools may be designed using five respective simulations: cutter group level, neighbor cutter group level, cutter set level, group of N (N=3 or N=4) consecutive cutters level and all cutters level. Cutter layout procedures and algorithms to minimize respective bit forces and in some embodiments to obtain force balance are described.

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 head is provided with three main cutting edges each having a straight direction of extension with a predominant radial direction component. The directions of extension limit two adjacent main bore dust discharge sectors, each spanning a main sector angle. Three drill head cutting legs each forming a main cutting edge where the three main cutting edges have different lengths along their directions of extension. Concentric ring shaped removal areas overlap at least partially such that a triple removal area coverage is provided in an outer ring zone and a double removal area coverage is provided in an inner ring zone.

Abstract: A sectorial force balanced drill bit, including conventional and bi-center drill bits, having the true center of rotation the same as, or about the same as, the bit mass axis. The bit mass axis is a longitudinal axis located off-center to the geometric axis of the bit and comprises the center of mass point. Additionally, a method for sectorially force balancing drill bits is provided. The method includes dividing the drill bit into one or more sections, calculating the magnitude and direction of the resultant radial imbalance force for the cutters of each section, adjusting the cutters and/or blades until the magnitude of the resultant radial imbalance force is about the same for each section and the direction of the resultant radial imbalance force for each section is about 2?/n, where n is the number of sections, from the adjacent section.

Abstract: A casing end tool has a bowl-like (or cup-like) body defined by a wall having an outer convex surface and an inner concave surface opposite of the outer convex surface. The bowl-like body has a center axis. The inner concave surface is non-axisymmetric with respect to the center axis, while the outer convex surface is axisymmetric with respect to the center axis. The non-axisymmetric configuration is provided in one implementation through the presence of a set of raised boss or land structures formed on the inner concave surface. In another implementation, the non-axisymmetric configuration is provided by channels formed in the inner concave surface.

Abstract: An offset rock bit (12) has a steering face (28) and a shoe (30) provided by a recess formed into the steering face (28). A slot (66) formed into the shoe (30) for receiving a pull back adapter (50) in a centrally located position in the forward end of the offset rock bit (12). The pull back 5 adapter (50) has a pull back eye (52) with a central axis (62) which is aligned with a centrally disposed longitudinal axis (20) of the offset rock bit (12) and the tool string (10). This aligns the pull back eye (52) of the pull back adapter (50) with a borehole formed using the offset rock bit (12). The pull back adapter (50) also includes side edges (54, 56) which are configured for centering the pull back adapter (50) and pull back conduit within the borehole.

Abstract: Drilling a sidetrack wellbore out of the side of an existing wellbore utilizing a drillable billet having a path formed in the billet to lead a bi-centered drillbit to kick-out from the wellbore and form a sidetrack wellbore. The bi-centered bit is arranged for the lands of the pilot section to follow the path of the billet while the wings of the ream out a portion of the billet and also ream out the earth to form the full dimension sidetrack wellbore. The bi-centered bit is used to drill the sidetrack wellbore to the target zone so that the entire drilling process extends from the existing wellbore to the target zone without a mandatory withdrawal of the drillstring from the wellbore.

Abstract: A drill bit includes a plurality of continuous segments impregnated with diamond that are each mounted to form a corresponding blade. The regions between the blades define a plurality of fluid passages on the bit face. The blades extend radially outwardly to the gage. The continuous segments may be either straight or spiral in design. Furthermore, the design of the segments supports varying one or more of: diamond content, width, back rake angle and/or relief angle along a length of the segment.

Abstract: An offset rock bit (12) has a steering face (28) and a shoe (30) provided by a recess formed into the steering face (28). A slot (66) formed into the shoe (30) for receiving a pull back adapter (50) in a centrally located position in the forward end of the offset rock bit (12). The pull back 5 adapter (50) has a pull back eye (52) with a central axis (62) which is aligned with a centrally disposed longitudinal axis (20) of the offset rock bit (12) and the tool string (10). This aligns the pull back eye (52) of the pull back adapter (50) with a borehole formed using the offset rock bit (12). The pull back adapter (50) also includes side edges (54, 56) which are configured for centering the pull back adapter (50) and pull back conduit within the borehole.

Abstract: A drill bit includes a plurality of continuous segments impregnated with diamond that are each mounted to form a corresponding blade. The regions between the blades define a plurality of fluid passages on the bit face. The blades extend radially outwardly to the gage. The continuous segments may be either straight or spiral in design. Furthermore, the design of the segments supports varying one or more of: diamond content, width, back rake angle and/or relief angle along a length of the segment.

Abstract: An offset rock bit (12) has a steering face (28) and a shoe (30) provided by a recess formed into the steering face (28). A slot (66) formed into the shoe (30) for receiving a pull back adapter (50) in a centrally located position in the forward end of the offset rock bit (12). The pull back adapter (50) has a pull back eye (52) with a central axis (62) which is aligned with a centrally disposed longitudinal axis (20) of the offset rock bit (12) and the tool string (10). This aligns the pull back eye (52) of the pull back adapter (50) with a borehole formed using the offset rock bit (12). The pull back adapter (50) also includes side edges (54, 56) which are configured for centering the pull back adapter (50) and pull back conduit within the borehole.

Abstract: Cutting elements for downhole cutting tools comprise a top surface having a cutting surface portion and a cutting profile disposed across the top surface. The cutting elements comprise first and second longitudinal side surfaces and first and second lateral side surfaces, each having a respective cross-section. The cutting profile can be disposed on the cutting surface either asymmetrically or symmetrically. Asymmetrical disposition permits two cutting elements to be arranged facing each other to cover a center point of a cutting tool. The cutting edge of asymmetrical or symmetrically disposed cutting profiles can have a shape that facilitates self-sharpening during cutting.

Abstract: Cutting elements for downhole cutting tools comprise a top surface having a cutting surface portion and a cutting profile asymmetrically disposed across the top surface. The cutting elements comprise first and second longitudinal side surfaces and first and second lateral side surfaces, each having a respective cross-section. The cross-section of one of the longitudinal side surfaces can have one beveled portion and the cross-sections of the other longitudinal side surface and the first and second lateral side surfaces can have two beveled portions. A cutting end of a downhole cutting tool comprises two cutting elements disposed facing each another with a portion of the cutting surface portion of a first cutting element being disposed opposite the cutting profile of the second cutting element and the cutting surface portion of the second cutting element being disposed opposite the cutting profile of the first cutting element.

Abstract: A drill bit for drilling a borehole in earthen formations. In an embodiment, the bit comprises a bit body having a bit axis and a bit face. In addition, the bit comprises a pin end extending from the bit body opposite the bit face. Further, the bit comprises a plurality of gage pads extending from the bit body, wherein each gage pad includes a radially outer gage-facing surface. The gage-facing surfaces of the plurality of gage pads define a gage pad circumference that is centered relative to a gage pad axis, the gage pad axis being substantially parallel to the bit axis and offset from the bit axis.

Abstract: A drilling tool has a body with a main drilling region and a pilot drilling region, eccentric to the main drilling region. The main drilling region has main blades and the pilot drilling region has pilot blades. The main drilling region has a main pass-through diameter, centered upon a first axis, one of the main blades extending to the main pass-through diameter, the pilot region having a pilot gauge diameter, centered upon a second axis of rotation at least one of the pilot blades extending to the pilot gauge diameter, wherein part of a circle of diameter equal to the pilot gauge diameter and centered upon the second axis of rotation extends outside of a circle of diameter equal to the main pass-through diameter and centered upon the first axis.

Abstract: A drill bit includes a plurality of continuous segments impregnated with diamond that are each mounted to form a corresponding blade. The regions between the blades define a plurality of fluid passages on the bit face. The blades extend radially outwardly to the gage. The continuous segments may be either straight or spiral in design. Furthermore, the design of the segments supports varying one or more of: diamond content, width, back rake angle and/or relief angle along a length of the segment.

Abstract: A process is provided to drill through a composite frac plug. The plug is in an oil well. The process utilizes an improved mill. The process also rotates drill pipe at one hundred to five hundred rpm and circulates drilling fluid such that the velocity of the fluid upwardly over the exterior of the drill pipe is in the range of three hundred to four hundred and seventy-five feet per minute. One thousand to three thousand pounds of slack off weight is applied during the process.

Abstract: A bi-center drilling tool comprises a main reamer region located eccentrically to an axis of rotation of the tool, and a leading cutting structure located ahead of the main reamer region, in the drilling direction. The leading cutting structure is located so as to apply a side loading to the drilling tool. The side loading is in direction to counter the loading which, in use, is due to the main reamer region being eccentric to the axis of rotation.

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: A drill bit comprises a plurality of cutting blades arranged circumferentially, the cutting blades having a cutting edge formed by a connecting ridge line between a cutting face and a flank; and a tip formed by coupling radially inner ends of the cutting edges to each other at a center portion of a bit tip end, wherein at least one of the cutting blades has a first flank and a second flank, wherein the first flank has a blade tip side flank close to the cutting edge and a base end side flank formed on the base end side of the blade tip side flank, and wherein a tilt angle ?1 of the blade tip side flank 3a is smaller than a tilt angle ?2 of the base end side flank 3b which is tilted toward the axial direction.

Abstract: Methods of forming cutting element pockets in blades of earth-boring tools include forming a first recess and a second recess intersecting at a location defining the a back of the pocket using a cutter oriented in a manner so as to avoid tool path interference with adjacent blades. A filler material is disposed in the second recess to the location of the back of the pocket. Earth-boring tools including such cutting element pockets.

Abstract: A drill bit and a single pass drilling apparatus are disclosed. The one-piece drill bit is rotatable about a drilling axis and has a connection portion, adapted to be rigidly connected to a drill steel, a pilot part and a reamer part. The reamer part has a leading and at least one trailing first rock machining means disposed on one side of the pilot part within a sector defined by sector angle ?. At least one of the trailing first rock machining means is axially spaced from the leading first rock machining means in the direction toward the trailing end of the drill bit.

Abstract: An earth boring drill bit design for alleviating balling varies the junk slot depth in junk slots subject to balling from the other junk slots. Using variable depth bit bodies enhances the hydraulic characteristics of the bit as well as assists in the placement of the nozzles for machining purposes. This flexibility optimizes the area changes along the ducts required by the bit's operation.

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: A bit having improved dropping tendencies includes a first plurality of cutters in an active region and a second plurality of cutters in a passive region. The second plurality of cutters has unique radial positions with respect to the first plurality of cutters. The first and the second pluralities of cutters also have cutting tips that extend to the primary cutting profile of the bit. A third plurality of cutters is located in the passive region with cutting tips positioned recessed from the primary cutting profile. A forth plurality of cutters is positioned as back up cutters in the active, region and includes cutters positioned in radial locations such that they overlap, when viewed in rotated profile, with cutters in the third plurality of cutters. The fourth plurality of cutters has cutting tips positioned to extend to the primary cutting profile. The cutters on the bit are arranged such that an imbalance force vector exists on the bit when used to drill though earth formation.

Abstract: A shear cutter drill bit for drilling a subterranean formation is provided having a bit body; a bit face on the bit body having at least a center zone, an efficiency zone, and an outer zone, the efficiency zone being located between the center zone and the outer zone; and a plurality of cutters having a backrake angle located on the bit face; wherein a majority of the cutters located in the efficiency zone of the bit face have a more aggressive backrake angle than a majority of the cutters located in the center zone of the bit face and a majority of the cutter located in the outer zone of the bit face.

Abstract: In one aspect of the present invention, a drill string has a drill bit with a body intermediate a shank and a working face. The working face has at least one cutting element. A jack element is disposed within the drill bit body and has a distal end substantially protruding from the working face. The distal end has a primary deflecting surface having an angle relative to a central axis of the jack element of 15 to 75 degrees.

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: 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: 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 is provided that employs a plurality of discrete, post-like, abrasive, particulate-impregnated cutting structures extending upwardly from the bit face. The cutting structures may be disposed on abrasive, particulate-impregnated blades that also define a plurality of fluid passages on the bit face. One or more of the cutting structures may include outermost ends that exhibit a cross-sectional geometry that is elongated in a direction along a defined axis. The cutting structures may be oriented such that the defined axis is neither coplanar with, nor parallel to, an intended rotational path of the at least one discrete cutting structure during operation of the bit. In one embodiment, the cutting structure is oriented such that the defined axis is at an acute angle relative to a tangent of the intended rotational path for the associated cutting structure. Other or different features may include, for example, additional, differently configured cutting elements.

Abstract: A drill steel includes a drill bit and a reamer bit. The drill steel rotates the drill bit to form a hole in a work surface and drives forward to insert the reamer bit into the hole. The reamer bit includes a plurality of inserts positioned on a cylindrical drilling surface to ream out the hole by carving channels in the hole interior surface. The inserts include cutting elements that have radiused or arcuate edges.

Abstract: Methods of forming cutting element pockets in blades of earth-boring tools include forming a first recess and a second recess intersecting at a location defining the a back of the pocket using a cutter oriented in a manner so as to avoid tool path interference with adjacent blades. A filler material is disposed in the second recess to the location of the back of the pocket. Earth-boring tools having such cutting element pockets are also disclosed.

Abstract: Disclosed within is a drill bit with a plural set of blades having redundant cutter elements and single sets of blades having unique cutter element arrangements. The redundant cutter elements have equivalent longitudinal and axial spacing as corresponding cutter elements. The distance from a longitudinal axis of the bit to a redundant cutter element is equivalent to the distance from the longitudinal axis to the corresponding cutter element.

Abstract: A drill bit has a pair of cutting teeth with cutting elements extending from a cutting end portion of the drill bit. Each cutting tooth extends radially, outwardly parallel to a longitudinal axis of the drill steel. The cutting teeth are juxtaposed with one another on the longitudinal axis. Each cutting tooth includes a plurality of raised cutting elements connected to a plurality of lowered edge portions. The cutting elements produce concentric circular channels in the working surface of a rock formation, as the drill bit rotates during the cutting operation. The drill bit also includes a pocket for accumulating and removing dislodged material during the cutting operation.

Abstract: A drill bit constructed to improve a tip end of the cutting pointed portion to efficiently discharge chips from a center portion of a crush face of a drill hole to thereby improve cutting efficiency, is disclosed. A plurality of cutting blades 3a, 3b, and 3c are formed to be arranged in a circumferential direction of a cutting blade chip 3 formed by a cemented carbide block body. The cutting blades 3a, 3b, and 3c are each structured to have a cutting edge 4 formed by an edge between a face 6 and a flank 7 of the associated cutting blades. In this drill bit, a groove 8 is configured to be provided in a center portion of the tip end of the cutting blade chip in contact with tip ends of the cutting blade chip, and the tip ends of the cutting edges 4 have pointed portions.

Abstract: Disclosed are cutter elements for a drill bits having particular, but not exclusive, application on the nose portion of the cone cutters of a rolling cone bit. The cutter elements include a base, a cutting portion, and a plurality of cutting lobes extending radially from the cutting portion. Each lobe includes a forward-facing cutting face and trailing portion having a trailing surface that intersects the cutting face in a nonlinear cutting edge. The trailing surface is non-planar and recedes away from the cutting edge. In certain embodiments, the trailing surface is a partial dome shaped surface. The trailing portion provides strength and buttresses the cutting edge.