Abstract: A drill bit includes a body defining an axis and first and second cylindrical portions, a coupling adapted for connection with a rotary driver, and a depth stop adjustably secured to a first portion by a plurality of adjusting fasteners in a manner to limit penetration of the bit into a target surface. A method of drilling a hole into the surface includes locating a drilling machine fitted with a drill bit over a target location, compensating for wear on the bit by setting a depth stop to limit travel of the bit at the predetermined depth, drilling at the target location until the depth stop contacts a surface, where the primary cutting surface forms a portion of the hole defined by a first diameter and the secondary cutting surface forms a portion of the hole defined by a second diameter in a single step, and removing the drill bit from the hole.

Abstract: The invention concerns a method and a device for coring and/or drilling through a wall of a bore hole, to deflect transversely from a longitudinal direction of the hole, further comprising selecting a core barrel (1) equipped with a core bit (3) having an inner gauge bore (5), an arrangement, in the core barrel (1), of an abrasion resistant internal guide (7), which is internal at least with respect to the bore (5) so that the bit (3) can move along guide (7), and is designed to deflect the bit (3) along a desired deflected path, start-up of the coring process with bit (3) and guiding the bit (3) through co-operation between its bore (5) and the guide (7).

Abstract: A sponge core barrel for use in performing sponge coring and methods of assembling the sponge core barrel, as well as methods of performing sponge coring. The sponge core barrel includes an outer barrel assembly, a core bit secured to a lower end thereof, and an inner barrel assembly disposed therein. The inner barrel assembly may comprise multiple, sponge-lined inner tube sections and may also include a near-bit swivel assembly. The sponge core barrel may include a piston assembly configured to be released by contact with a core sample without imparting high compressive forces to the core. The sponge core barrel may also include a pressure compensation mechanism and, optionally, a thermal compensation mechanism cooperatively configured to maintain the pressure of presaturation fluid. The sponge core barrel may also include a valve assembly enabling the make-up and presaturation of multiple, sections of inner tube to form a single, continuous chamber.

Abstract: The present invention relates to an abrasive that decreases the heat generation by a core bit due to boring and allows the boring of a deep hole while maintaining the boring speed even when a deep hole is cut using a dry method. This abrasive contains abrasive grains, particles of anhydrous silica having a particle diameter from 5 nm to 50 nm and silanol groups in the surface thereof, and hydrous resin which discharges water when the hydrous resin is pressed by a core bit or the temperature of the hydrous resin rises. The abrasive 51 is supplied between the distal end of a rotating core bit 11 and a working material 20.

Abstract: A core bit for abrasive cutting including a cylindrical tube (3) provided at its end surface with cutting or abrasive bodies (2) and a cover (4) provided at an opposite end surface of the cylindrical tube (3) and secured thereto and having, along its central axis (A), a shank (5) to be received in a rotary power tool, with the cover (4) being dimensioned, with respect to a set excitation frequency, for forming a whole number of maximum amplitude oscillations of a concentric flexural oscillation, and the cylindrical tube (3) being dimensioned, with respect to a set excitation frequency, for forming a whole number of maximum amplitude oscillations of axial longitudinal oscillations.

Abstract: A plurality of chip evacuating grooves (16, 26, 36, 46a, 46b) in a vertical direction in parallel with a rotational axis of a core main body (14) are formed at an outer peripheral face of the core main body (14) in a circumferential direction from a lower end portion to an upper end portion of the core main body (14) in a cylindrical shape provided with a drilling blade (15) at a lower end edge thereof. Further, a sectional area of the chip evacuating groove (16) is formed to gradually increase from a lower end to an upper end of the core main body (14). Further, a number of projections (52, 62, 70, 72) are formed at the outer peripheral face of the core main body (14) between the chip evacuating grooves.

Abstract: A quick-change core drill includes an adapter and a generally tubular drill barrel. The adapter comprises a first end adapted to be removably connected to a drill spindle and a second end adapted to be removably connected to the drill barrel. The drill barrel includes an inside diameter D1, a first end, and a second end having a crown with an inside diameter D3. The first end of the drill barrel is adapted to be removably connected to the second end of the adapter such that the inside diameter D1 is at least as large as the inside diameter D3. Upon detection of a jammed core inside the drill barrel, the user can quickly and easily remove the jammed core from the drill barrel by disconnecting the drill barrel from the adapter. Since there are no obstructions present, the user can simply remove the jammed core from the first end of the drill barrel.

Abstract: A boring device for producing a bore with a casing tube has a linkage, a boring tool, which can be fixed to the lower end of the linkage, a mounting frame for mounting on the casing tube, a drive and a connecting device, which is used for producing a rotary connection between the casing tube and the mounting frame. The linkage is hollow and has a first and a second flushing line. In the vicinity of the upper end of the link-age are provided a first connection for the supply of a fluid to the first flushing line and a second connection for removing the borings via the second flushing line. A boring method introduced the casing tube into the soil prior to an excavation.

Abstract: A tool holder (1) and a shank (8) for quick mounting and dismounting an annular core bit (2) and both having cooperating respective guide members (4, 4′) provided at their bit-side ends, flanges (3, 9) arranged coaxially with the guide members (4, 4′) for axially locking same and having, respectively, outer and inner threads, outer and inner cone surfaces (6, 10) located inwardly of the guide members (4, 4′) and axially spaced therefrom with the outer and inner cone surface (6, 10) tapering toward their bit-side ends, and torque transmitting means (5, 5′) arranged between the respective inner guide members (4, 4′) and the outer cone surfaces (6, 10).

Abstract: A tool holder (1) for an annular core bit has a bit-side axial stop surface (4) and an end-side splined profile (3) extending in a bit direction and having an outer thread (5) forming radial spline projections of the splined profile (3).

Abstract: A device for preserving the orientation of a core is described. A core barrel is attached to a rotatable orienting rod. A plurality of projections are located on an inner surface of the core barrel. Three projections are grouped together and opposite from a fourth projection. A ratchet assembly is included at an end of the rotatable orienting rod opposite from the core barrel. The ratchet assembly includes a first body, to which the rotatable orienting rod is attached, a plate, a second body, and a biasing mechanism. A turning rod is mounted on the plate, which is located between the two bodies. The plate and the second body each have teeth which intermesh, but which slip if a clog in the core barrel inhibits rotation of the rotatable orienting rod.

Abstract: A sponge core barrel for use in performing sponge coring and methods of assembling the sponge core barrel, as well as methods of performing sponge coring. The sponge core barrel includes an outer barrel assembly, a core bit secured to a lower end thereof, and an inner barrel assembly disposed therein. The inner barrel assembly may comprise multiple, sponge-lined inner tube sections and may also include a near-bit swivel assembly. The sponge core barrel may include a piston assembly configured to be released by contact with a core sample without imparting high compressive forces to the core. The sponge core barrel may also include a pressure compensation mechanism and, optionally, a thermal compensation mechanism cooperatively configured to maintain the pressure of pre-saturation fluid. The sponge core barrel may also include a valve assembly enabling the make-up and pre-saturation of multiple, sections of inner tube to form a single, continuous chamber.

Abstract: A sponge core barrel for use in performing sponge coring and methods of assembling the sponge core barrel, as well as methods of performing sponge coring. The sponge core barrel includes an outer barrel assembly, a core bit secured to a lower end thereof, and an inner barrel assembly disposed therein. The inner barrel assembly may comprise multiple, sponge-lined inner tube sections and may also include a near-bit swivel assembly. The sponge core barrel may include a piston assembly configured to be released by contact with a core sample without imparting high compressive forces to the core. The sponge core barrel may also include a pressure compensation mechanism and, optionally, a thermal compensation mechanism cooperatively configured to maintain the pressure of presaturation fluid. The sponge core barrel may also include a valve assembly enabling the make-up and presaturation of multiple sections of inner tube to form a single, continuous chamber.

Abstract: A hollow auger head assembly for penetrating geological formations that utilizes drill bit assemblies to which both blades and finger bits are attached. The method of securing the individual drill bit assemblies to the auger head reduces incidents of the drill bit assembly becoming detached from the auger head during drilling operations. Additionally, a rust-resistant attachment mechanism is used attach the drill bit assemblies to the auger head, which makes the drill bit assemblies easier to remove and replace. The configuration and arrangement of the bits improves cutting efficiency, increases wear life and reduces the likelihood of the bits breaking during operation.

Abstract: A flightless rock auger is used for drilling postholes through rock with the use of hydraulic pressure and at slow revolution per minute. The rock auger is used in combination with a conventional flighted auger used for drilling postholes in dirt and clay. During a posthole drilling operation, the rock auger is substituted for a conventional flighted auger as needed for drilling through and removing rock or other hard material such as concrete from the posthole. The rock auger is designed for use at very low revolutions per minute and can function utilizing only the weight of the auger; however, the rock auger is designed for use with pressure drilling units as well for cutting a circular hole through the rock and forming a plug which is to be lodged in the cavity of the rock auger cylinder to be removed from the posthole.

Abstract: A core bit for abrasive cutting including a cylindrical tube (3) provided at its end surface with cutting or abrasive bodies (2) and a cover (4) provided at an opposite end surface of the cylindrical tube (3) and secured thereto and having, along its central axis (A), a shank (5) to be received in a rotary power tool, with the cover (4) being dimensioned, with respect to a set excitation frequency, for forming a whole number of maximum amplitude oscillations of a concentric flexural oscillation, and the cylindrical tube (3) being dimensioned, with respect to a set excitation frequency, for forming a whole number of maximum amplitude oscillations of axial longitudinal oscillations.

Abstract: A core drill bit (1) for working brittle material has an axially extending tubular shaft (2) with a rotation driver (4) coaxially fitted to a trailing end portion (3a) and a plurality of had material inserts (5a, 5b) arranged on the opposite open leading end portion (3b), which are formed with a defined cutting edge, whereby each individual hard material insert (5a, 5b) is fitted on precisely one intermediate carrier members (6a, 6b) associated therewith, which is fitted on the leading open end portion (3b) of the tubular shaft (2).

Abstract: A flightless rock auger is used for drilling postholes through rock with the use of hydraulic pressure and at slow revolution per minute. The rock auger is used in combination with a conventional flighted auger used for drilling postholes in dirt and clay. During a posthole drilling operation, the rock auger is substituted for a conventional flighted auger as needed for drilling through and removing rock or other hard material such as concrete from the posthole. The rock auger is designed for use at very low revolutions per minute and can function utilizing only the weight of the auger; however, the rock auger is designed for use with pressure drilling units as well for cutting a circular hole through the rock and forming a plug which is to be lodged in the cavity of the rock auger cylinder to be removed from the posthole.

Abstract: A core drill extender apparatus comprises an extender tube that is adapted to make a screw connection to a driver, and a connector assembly releasably mounted in the front end of the tube for connecting the extender tube to a core drill. The connector assembly comprises a tapered mandrel having a threaded axial extension at its front end for making a screw connection to a core drill, and an expandable locking sleeve that surrounds and engages the outer surface of the mandrel. The sleeve is made so that moving it relative to the mandrel in the direction of increasing mandrel outer surface diameter will cause the sleeve to expand radially and into tight frictional engagement with the extender tube.

Abstract: A core drill extender apparatus comprises an extender tube that is adapted to make a screw connection to a driver, and a connector assembly releasably mounted in the front end of the tube for connecting the extender tube to a core drill. The connector assembly comprises a tapered mandrel having a threaded axial extension at its front end for making a screw connection to a core drill, and an expandable locking sleeve that surrounds and engages the outer surface of the mandrel. The sleeve is made so that moving it relative to the mandrel in the direction of increasing mandrel outer surface diameter will cause the sleeve to expand radially and into tight frictional engagement with the extender tube.

Abstract: A core drill bit segment (10) comprises an elongated member (12) having an upper end (14), a lower end (16), first side (18) and opposite second side (20). Attached to the lower end (16) is matrix (22). The matrix (22), while depending from the lower end (16) also extends upwardly toward the upper end (14) along first and second sides (18, 20) of the member (12). The lower end (16) is provided with a lip (24) that is turned upwardly to extend in front of the first side (18) to define a recess (26) for seating a lower edge of a drive sub (25).

Abstract: A pilot tool assembly for a core drill comprises a pilot tool unit that fits within the core drill and expandable means engagable with the interior surface of the core drill for releasably locking the pilot tool unit to the core drill, the pilot tool assembly being removable from the core drill by application of an axial force to the pilot tool unit. The pilot tool unit comprises a pilot tool that projects from the front end of the core drill and serves as a centering aid for the core drill. The pilot tool may be inserted into a predrilled pilot hole whereby to keep the core drill centered on a desired location. The pilot tool may be a small diameter drill that is used to drill the pilot hole.

Abstract: A pavement coring machine having rotating cutting heads of various diameter, the optimum speed of rotation of the heads varying with the diameter of the cutting head and the nature of the pavement being cored has a direct reading tachometer positioned to be observed by an operator of the machine, the tachometer being operatively connected to display the speed of rotation of the cutting head. A method of operating the machine includes determining the optimum speed of rotation of a cutting head, and regulating the speed of the cutting head as displayed by the direct reading tachometer.

Abstract: A rock auger for drilling postholes through rock without the use of hydraulic pressure and at a slow rate of revolutions per minute can function utilizing only the weight of the auger, shaft, and/or boom providing a floating auger to reduce shock and vibration stress on the auger, boom, and drive unit. It does not require any additional hydraulic pressure for cutting a circular hole through the rock and forming a plug which is to be lodged in the cavity of the rock auger cylinder to be removed from the posthole. A quick connection shaft enables the conventional flighted auger to be quickly substituted for the rock auger to facilitate fast removal of soft dirt from the posthole. A center drill bit can be disposed within the cutting head for extending outwardly pass the cutting edge thereof for starting the hole, breaking up rock, and holding the auger in position guiding it during the drilling operation.

Abstract: An ice auger system for drilling a bore within ice with significantly reduced ice shavings. The ice auger system includes an elongate tube having a lower end, an upper end, an outer wall, a lumen and a connector shaft attached to the upper end for connecting to a motor. A length of flighting is attached to the outer surface of the elongate tube in a coiled manner. At least one bit is attached to the lower end of the elongate tube for engaging and cutting the ice in a circular pattern to receive the elongate tube and flighting. As the elongate tube is manipulated through the ice, a core is created that is positioned within the lumen of the elongate tube. When the user has drilled completely through the ice, the user then removes the elongate tube from the ice leaving the core within the newly created bore within the ice. The user then either may remove the core from the bore, or may push the core downwardly through the bore underneath the ice.

Abstract: A pilot tool assembly for a core drill comprises a pilot tool unit that fits within the core drill and expandable means engagable with the interior surface of the core drill for releasably locking the pilot tool unit to the core drill, the pilot tool assembly being removable from the core drill by application of an axial force to the pilot tool unit. The pilot tool unit comprises a pilot tool that projects from the front end of the core drill and serves as a centering aid for the core drill. The pilot tool may be inserted into a predrilled pilot hole whereby to keep the core drill centered on a desired location. The pilot tool may be a small diameter drill that is used to drill the pilot hole.

Abstract: The present invention relates to a core drill wherein initial drilling workability is improved through reduced frictional resistance on the segment tips, when they are seated on the surface of an article to start cutting operation, and wherein cutting scraps or sludge produced by the segment tips are smoothly discharged through the helical grooves formed on the core body so as to reduce the friction between the core body and the cutting scraps or sludge, whereby both the cooling and cutting performance of the core drill are improved. The invention proposes a core drill with a cylindrical core body with a predetermined diameter and length and with plural cutting segments provided on the lower part of a core body at a finite interval, wherein the cutting thickness surface of the cutting segment consists of inclined sharp thickness portion for decreased frictional resistance with an article to be processed.

Abstract: The present invention provides a brush bit for cutting a core sample from an unconsolidated formation with reduced fragmentation or damage to the core sample by using a plurality of stiff bristles to cut rock from around the core sample. The present invention also provides an improved method of obtaining a core sample from an unconsolidated formation.

Abstract: Disclosed is a high speed-perforating apparatus 1 comprising a rotor 17 into and through which a cylindrical rotary shaft 11 is integrally inserted, a stator 18 disposed around the outer periphery of the rotor 17 and a core bit 13 which is directly connected to the head end portion of the rotary shaft. A bit 15 having an outer diameter of up to 40 mm and a cutting edge thickness of less than 2 mm is used for the core bit 13. Perforation is carried out by the core bit 13 which is rotated at a high speed of 4000 rpm or more by a direct motor 2 comprising the rotor 17 and the stator 18. A perforating time can be greatly shortened by rotating the core bit at high speed.

Abstract: A core sampler, particularly for oil prospecting, including a coring bit (2), an outer barrel (3) for rotating the coring bit (2), and an inner barrel (5) for receiving the core sample (7) in its internal space (8) during coring, the inner (5) and outer (3) barrels being substantially coaxial, and further comprising an intermediate barrel (15) coaxially arranged between the inner (5) and outer (3) barrels and defining a first longitudinal coring fluid channel (16) with the outer barrel (3), and a second longitudinal coring fluid channel (17) with the inner barrel (5), as well as said longitudinal channels (16, 17) and valving for at least temporarily selectively causing and/or cutting off coring fluid communication between the rear end (17B) of the second longitudinal channel (17) and/or the rear end (16B) of the first longitudinal channel (16) and/or the rear end (8B) of the internal space (8).

Abstract: A flightless rock auger For drilling postholes through rock without the use of hydraulic pressure. The rock auger has a plurality of teeth extending downwardly at a selected angle from the edge of a cylinder connected to a quick connect shaft. The rock auger is utilized for drilling through rock and used in combination with a conventional flighted auger used for drilling postholes in dirt and clay. During a posthole drilling operation, the rock auger is substituted for the flighted auger as needed for drilling through and remove rock or other hard material such as concrete fron the posthole. The rock auger is designed for use at very low revolutions per minute and utilizes only the weight of the auger and shaft and does not require any additional hydraulic pressure for cutting a circular hole through the rock and forming a plug which is to be lodged in the cavity of the rock auger cylinder to be removed from the posthole.

Abstract: A wellbore mill has been invented that has a body having a top and a bottom and a first fluid flow channel extending longitudinally therethrough from top to bottom, the first fluid flow channel having an upper end and a lower end, the lower end of the first fluid flow channel having an opening sized for receiving a core of material from a tubular member milled by the mill, and at least a portion of the first fluid flow channel offset from the remainder thereof to facilitate separation of the core from the tubular member.

Abstract: A crown drill including a hollow cylindrical carrier body, which is formed of two coaxially arranged tubes connected with each other, and a cutting member attached to the carrier body and projecting axially beyond the leading end of the carrier body.

Abstract: An apparatus for forcing a member or device, such as a sample tube or seismic or geological instrument, through a material such as soil along a selected line of action. The apparatus includes a derrick with first and second plates mounted thereto, the second plate having a locking dog extending through a hole therein for engaging the material, and the first plate being provided with a hydraulic cylinder or other device for forcing the member through the material. The first plate is also provided with an extruder head for releasably mounting the sample-containing sample tube thereto, and the hydraulic cylinder is provided with a plunger releasably mounted to the ram thereof for extruding the sample from the sample tube. The locking dog positively engages the material to provide an apparatus for transmitting the reactive forces resulting from forcing the member through the material to the material.

Abstract: A sampling device includes a barrel having a downhole end, an exterior surface, an interior surface defining a hollow interior, and an open end at the downhole end of the hollow interior. A fluid entrance penetrates the exterior surface. A fluid path having an outlet port is fluidly coupled to the fluid entrance. The device is driven into a subsurface so that a soil sample is forced into the hollow interior. While the device is still in the subsurface a fluid sample is collected through the least one fluid entrance and fluid path.

Abstract: A high-speed drill for rock stake engineering includes an outer tube and an inner tube fixed in the outer tube, and an annular space is formed by the outer and the inner tube for pressured air and water to flow down from a power shaft connected with an upper portion of the outer tube. An annular cushion block is connected with a bottom of the outer and the inner tube, having many through holes. Further, cutters are fixed under a bottom surface of the cushion block, rotating together with the outer tube rotated by the power shaft, cutting into rock and cooled and washed synchronously by the pressured air and water coming through the annular space down from the power shaft.

Abstract: A center drill used for machining a hole in a work piece which is adapted to be partially enclosed in a cup shape drill member in a side view thereof, includes a drill portion provided on a leading end of the center drill, and a dust extractor radially outwardly extending from a portion of the center drill which is enclosed in the cup shape drill member.

Abstract: A drill bit is formed of an insertion end part (1) and carrier part (2) containing drilling cutter members (8). The insertion end part (1) and the carrier part (2) are joined together by a threaded connection. The two parts are secured by a radially flexible spring washer (7) for preventing an unintended detachment of the two parts.

Abstract: A drilling bit includes a carrier member (3) shaped, for instance, as a hollow annular crown. In such a crown several cutter members (4) are distributed angularly apart around the circumferentially extending leading end of the carrier member. The cutter members (4) project both radially outwardly and inwardly from the wall thickness of the carrier member. A step (S) is formed in the cutter members spaced from the leading end thereof opposite of the drilling direction. The step (S) is located at the trailing end of a region (K) with a continuous reduction in the radial dimension (R) of the cutter member and the radial dimension is further reduced at the step. Due to the further reduction in the radial dimension at the step (S), the length of the cutter member (4) in the drilling direction, causing friction with the wall surface of the borehole to be drilled, is limited after extended use of the drilling bit, so that the drilling bit retains a higher drilling efficiency even after such extended use.

Abstract: A hollow annular drill bit is formed of an axially extending hollow cylindrical carrier member (1) and cutter members (2). The cutter members (2) are secured in recesses (1c) in the carrier member, so that they project axially from and radially inwardly and radially outwardly from the leading end region of the carrier member. The carrier member (1) has increased wall thickness sections enclosing the recesses, whereby sufficiently large connecting surfaces are available for securing the cutter members (2).

Abstract: In a hollow earth auger head assembly a plurality of bit-holding pockets are provided, spaced circumferentially from one another around an open mouth of an auger head, and bits taken selectively from a multiplicity of types of cutting teeth, have a shank portion that seats in any and all of the pockets. A retaining pin extends chordally, off set from a diameter, through holes in the pocket and into a retaining pin receiver in the bits. In those bits that are intended to rotate in the pocket, the retaining receiver takes the form of an annular channel. In those bits that are not supposed to rotate, the retaining pin extends through a linear passage in or along a flat on the bit shank. In certain embodiments of sockets a chordal plug or weldment defines a space with one flat side against which a tail of the shanks of certain bits designed not to rotate bear.

Abstract: The present invention relates to an improved roller cone core bit comprising a plurality of cone cutters facing inboard and a single cone cutter facing outboard. The single outboard facing cone cutter provides additional cutting elements for cutting a core. The single outboard facing cone cutter also creates an unbalanced loading condition on the core bit causing the bit to drill smoother than conventional reversed cone core bits.

Abstract: A roller cone drill bit is disclosed that leaves uncut a substantial formation core having a diameter from 10% to 25% of the bit gage diameter. The bit is designed to have normal size bearings, cone shell thickness and cutter protrusion to allow the use of standard drilling weights and RPM, thereby achieving a significant increase in drilling rate. When drilling abrasive formations, ultra hard cutting teeth are used in the cone apex to maintain the core diameter.

Abstract: A core drill bit having a nozzle screen and designed for drilling into an underground formation and obtaining samples of the formation. As the bit cuts through the formation, a core of the formation material is forced upwardly through the drill bit into the attached core barrel and drilling fluid is pumped from the surface, through the core barrel and the screen mounted in the body of the bit and subsequently, through jet nozzle orifices radially arranged in the crown of the bit. The screen prevents oversized formation fragments, gravel and debris from lodging in the jet nozzles and obstructing the nozzle orifices and thus facilitates unobstructed flow of drilling fluid through the jet nozzles.

Abstract: A diamond tool for combination drilling and routing. The tool has a shaft end and a cutting end with an aperture therein. The cutting end includes abrasive grit on the outer peripheral surface for routing purposes and has abrasive grit on the terminal end and the surfaces forming the aperture for drilling purposes.

Abstract: A hollow drill (1) is made up of a tubular carrier part (2), a cutter part (3) and an intermediate part (4) extending between the carrier part (2) and cutter part (3). The intermediate part (4) is rigidly fixed to the cutter part (3). The carrier part (2) and the intermediate part (4) have axially extending extensions (11, 12) which telescope one into the other with solder (8) located between and removably connecting the extensions (11, 12) together.

Abstract: A hollow drilling tool is made up of an axially extending tubular carrier part, a cutting body at one end of the carrier part, and guide elements located in the axial direction of the carrier part between the cutting body and the carrier part. The radially outer surface of each guide element is in alignment in the axial direction of the carrier part with the radially outer surface of the cutting body. The guide elements guide the hollow drilling tool in a borehole formed by the cutting body.

Abstract: A cutting tool (10) for removing metal tubular members held in stationary position downhole from a well bore and adapted to be inserted within a well. The cutting tool (10) includes a plurality of elongate blades (32,34) on the cylindrical body (22) of the cutting tool (10) which extend below the bottom of the tool body (22). Cutting elements (42) of a predetermined size and shape are arranged in a symmetrical predetermined pattern on the lower portion of each blade (32,34) in a plurality of predetermined transversely extending rows below the tool body (22). The cutting elements (42) in adjacent transverse rows for each blade (32) are staggered horizontally and have different concentric cutting paths. Preferably, the cutting elements (42) in corresponding transverse rows on adjacent blades (32,34) are staggered and have different concentric cutting paths.

Abstract: A blade (8) for a pipe milling tool having a body (1) and a longitudinal axis (100) has a plurality of slots (12) extending both in a generally radial direction and in an intended direction of rotation of the milling tool about the longitudinal axis. Located in each slot (12) is at least one cutting element (13), the slot and the cutting element both having a greater depth in the blade in the intended direction of rotation than height in the longitudinal axis direction. The provision of such dimensions for the slot and cutting element affords the blade with improved life. The cutting elements may each have a negative axial rake angle (A) and the cutting elements are preferably brazed in each of the slots. In a preferred embodiment the slots and the cutting elements are both similarly decreasingly tapered from a forward (leading) face (221) to a rearward face (218) with respect to the intended direction of rotation of the tool by an angle in the range 1.degree. to 20.degree..

Abstract: A whirl resistant drill bit is disclosed for use in rotary drilling. The drill bit includes a generally cylindrical bit body with a plurality of cutting elements extending out from a lower end surface. The cutter elements are grouped in sets such that a first set of cutters are disposed at substantially an equal radius from a center of the bit body to create a groove in the material being drilled. A second set of cutters is connected to the lower end surface with each cutter therein in overlapping radial relationship with each other and extending a maximum distance from the lower end surface less than that of the first set of cutters. At least one cutter of the second set is in overlapping radial relationship with at least one of the cutters within the first set of cutters. This cutter arrangement causes the drill bit to cut grooves within the formation material that tends to prevent destructive bit whirl. Further, adjustments can be made to vary the back rake angle and side rake angle to prevent bit whirl.