Abstract: A method and apparatus for creating a reamed hole below the surface are disclosed. The reaming apparatus is arranged to be connected to one or more boring stems and has an interior section and an exterior section. The interior section is rotatable independently of the exterior section. Reamed holes of various cross-sections can be produced by appropriate selection of the cross-section of the exterior section.

Abstract: A system, apparatuses and methods for anchoring are provided. The system includes two-stage drill bit and a method of anchoring into a two-stage hole drilled by the drill bit. The apparatus of the instant invention includes a two-stage drill bit for drilling a pilot hole for a common nail into a material such as concrete, stone, masonry or cementuous or other materials. The method of the instant invention includes the steps of drilling a first hole within a material to which an object is to be anchored, drilling a second hole concentric with the first hole, and placing an anchor within the holes.

Abstract: In one aspect of the invention a drill bit assembly has a body portion intermediate a shank portion and a working portion, the working portion having at least one cutting element. A shaft is supported by the body portion and extends beyond the working portion. The shaft also has a distal end that is rotationally isolated from the body portion. In another aspect of the invention, a method for steering a downhole tool string has the following steps: providing a drill bit assembly attached to an end of the tool string disposed within a bore hole; providing a shaft extending beyond a working portion of the assembly; engaging a subterranean formation with a distal end of the shaft; and angling the drill bit assembly with the shaft along a desired drilling trajectory.

Abstract: A borehole reamer which may be deployed to a desired depth in an existing uncased borehole or below existing casing and used to substantially expand the diameter of the borehole. The diameter may be expanded by an amount that ranges from a fraction to a multiple of the original diameter of the borehole. In this fashion, geological formations containing oil, gas or groundwater which were previously uneconomical to produce may be worked into a condition of economical production. In a preferred embodiment, the borehole reamer is formed as an elongated assembly having an outside diameter which is sized to fit within a diameter of a conventional borehole. The assembly is preferably attached to drill pipe and lowered into a borehole to an appropriate depth corresponding to a pay zone of interest. A lower portion of the assembly, which is located at the deeper depth in the borehole, is constructed in the form of a bellows which functions as a pilot/anchor for the assembly.

Abstract: A bit assembly for a drilling apparatus working by impact and rotation or merely by rotation, and comprising a pilot bit (1) drilling the hole centre and in connection with the pilot bit a ring bit (2) is arranged to drill the outer circle of the hole and, further, between pilot bit and ring bit surfaces are arranged to transmit impacts and/or rotary motion from the pilot bit to the ring bit, and the bit assembly also including an arrangement for pulling protection tube into the hole on drilling. In the bit assembly between ring bit (2) and pilot bit (1) at least an arrangement transmitting rotation is jointly fitted in the ring bit shirt portion (5) by forming the rear edge of the shirt portion seen in the drilling direction to comprise surfaces with different directions, which with one of their portion (4) can transmit rotary motion force to the ring bit (2) and with their adjacent part (3) force to pull said ring bit off the hole.

Abstract: In one aspect of the invention, a drill bit assembly has a body portion intermediate a shank portion and a working portion, the working portion having at least one cutting element. The working portion also has an opening to an axial chamber disposed in the body portion of the assembly. The drill bit assembly also has an axial shaft rotationally isolated from the body portion, the shaft being at least partially disposed within the chamber, and partially protruding form the working portion. The shaft is also in communication with an energy adapter disposed within the drill but assembly and is adapted to use relative motion between the body portion and the shaft to provide power to at least one downhole device.

Abstract: In one aspect of the present invention a drill bit assembly has a body portion intermediate a shank portion and a working portion. The working portion has at least one cutting element and the body portion has at least a portion of a jackleg apparatus. The jackleg apparatus has at least a portion of a shaft disposed within a chamber; the shaft has a distal end. The jackleg apparatus has a hydraulic compartment adapted to displace the distal end of the shaft relative to the working portion. The chamber also has an opening proximate the working portion of the assembly. The hydraulic compartment may be part of a hydraulic circuit which has a pump. The pump may have a first section with is rotationally fixed to the body portion and a second section rotationally isolated from the body portion.

Abstract: A bottom hole assembly has a drill bit and an under-reamer on the up-hole side of the drill bit. In one aspect, the assembly further has a compliant element linking the drill bit to the under-reamer, the compliant element allowing displacement of the drill bit relative to the under-reamer in the axial direction of the assembly. In another aspect, the assembly further has a sensor element which is arranged to measure the weight-on-bit and/or the applied torque of the drill bit, and a transmitter for transmitting the weight-on-bit and/or applied torque measurements to the surface.

Abstract: A wellstring assembly comprising a tubular first wellstring part with a passageway; a second wellstring part co-operating with the first wellstring part; and a releasable wellstring-interconnecting means for selectively interconnecting the first and second wellstring parts; an auxiliary tool for manipulating the second wellstring part, which auxiliary tool can pass along the passageway in the first wellstring part to the second wellstring part, comprising a tool-connecting means for selectively connecting the auxiliary tool to the second wellstring part, and an operating means for operating the wellstring-interconnecting means.

Abstract: In one aspect of the present invention a drill bit assembly comprises a working portion opposite a shank of the bit. The working portion has a plurality of cutting elements. The drill bit assembly also has a central axis eccentric to its axis of rotation. A jack element protrudes from an opening formed in the working portion and has a distal end that is adapted to contact a formation at the axis of rotation.

Abstract: In one aspect of the present invention a drill bit assembly comprises a body portion intermediate a shank portion and a working portion. The working portion has at least one cutting element. The body portion has at least a portion of a reactive jackleg apparatus which has a chamber at least partially disposed within the body portion and a shaft movably disposed within the chamber, the shaft having at least a proximal end and a distal end. The chamber also has an opening proximate the working portion of the assembly.

Abstract: In one aspect of the invention a drill bit assembly has a body portion intermediate a shank portion and a working portion. The working portion has a recess with a side wall which is substantially coaxial with the shank portion. At least one cutting element is attached to the side wall and an indenting member is disposed within the closed end. In another aspect of the invention a method includes providing a drill bit assembly with a recess formed in a working portion of the assembly. The working portion has a plurality of cutting elements and the recess has at least one cutting element. The method further has steps of cutting a formation with the plurality of cutting elements and also of penetrating a conical profile of the formation which is formed by the recess.

Abstract: A down-hole tool guide is disclosed for deflecting various down-hole tools having a tendency to hang or bind in uncased bore holes. The down-hole tool guide or ball guide assembly, being adaptive to the down-hole tools, extends forwardly there from and includes an eccentric rotatable ball and high-pressure jets. In cases where the guide is used to guide casing, the ball guide assembly is constructed from a drillable material thereby allowing the hole bore to be extended beyond the last set casing depth without side deviation from the original bore.

Abstract: The present disclosure relates to back reamers having bases including leading ends that can be connected to a drill string and trailing ends that can be connected to product desired to be pulled through a bore being backreamed. The back reamers also include reaming components that are detachably secured to the bases.

Abstract: In one aspect of the invention a drill bit assembly has a body portion intermediate a shank portion and a working portion. The working portion has a recess with a side wall which is substantially coaxial with the shank portion. At least one cutting element is attached to the side wall and an indenting member is disposed within the closed end. In another aspect of the invention a method includes providing a drill bit assembly with a recess formed in a working portion of the assembly. The working portion has a plurality of cutting elements and the recess has at least one cutting element. The method further has steps of cutting a formation with the plurality of cutting elements and also of penetrating a conical profile of the formation which is formed by the recess.

Abstract: A rotary drill bit assembly suitable for directionally drilling a borehole into an underground formation, the drill bit assembly having a bit body extending along a central longitudinal bit-body axis, and having a bit-body face at its front end, wherein an annular portion of the bit-body face is provided with one or more chip-making elements; a pilot bit extending along a central longitudinal pilot-bit axis, the pilot bit being partly arranged within the bit body and projecting out of the central portion of the bit-body face, the pilot bit having a pilot-bit face provided with one or more chip-making elements at its front end; a joint means arranged to pivotably connect the pilot bit to the bit body so that the bit-body axis and the pilot-bit axis can form a variable diversion angle; and a steering means arranged to pivot the pilot bit in order to steer the direction of drilling.

Abstract: In one aspect of the present invention a drill bit assembly has a body portion intermediate a shank portion and a working portion. The working portion has at least one cutting element and the body portion has at least a portion of a jackleg apparatus. The jackleg apparatus has at least a portion of a shaft disposed within a chamber; the shaft has a distal end. The jackleg apparatus has a hydraulic compartment adapted to displace the distal end of the shaft relative to the working portion. The chamber also has an opening proximate the working portion of the assembly. The hydraulic compartment may be part of a hydraulic circuit which has a pump. The pump may have a first section with is rotationally fixed to the body portion and a second section rotationally isolated from the body portion.

Abstract: The present invention provides a global drilling system comprising a crown bit, a driver drill bit and a square drill bit. The crown bit has a tubular body with an inner surface and an outer surface, wherein the inner surface circumscribes a hollow passageway, and a pair of projections extending into said hollow passageway. The pair of projections are positioned substantially opposite one another on said inner surface. The driver drill bit has a drilling head with a pair of cut-away portions positioned substantially opposite one another and a pair of locking surfaces adapted for engaging the projections on the crown bit. The square drill bit has a drilling head with two tapered cut-away portions positioned substantially opposite one another. Each cut-away portion corresponds to one of the pair of projections such that the drilling head is able to pass through the hollow passageway of the crown bit.

Abstract: A back reaming tool is disclosed which includes a tool body adapted to be coupled to a drill string, and at least cutting structure mounted to a leg and having cutting elements disposed thereon. The leg is removably coupled to the tool body.

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 relates to a drilling tool (36), in particular for working concrete, rock, masonry and suchlike materials, having a single- or multi-edge tool head with at least one cutting body (1) which comprises a central region (12) which is designed in a roof shape, has rake faces and flanks and is defined laterally by two outer regions (13, 14) set back in the effective direction of the drill. In this case, the ground surfaces of the central region (12) form a pyramidal point (15) while avoiding the formation of a chisel edge.

Abstract: An auger has an outer blade and a center bit. The outer blade includes an outer ring and an inner hub, and the center bit inserts into the inner hub. The outer ring has an array of circumferentially-spaced teeth, and the inner hub is inwardly spaced from the outer ring by an array of inner spokes. Each spoke in the array of inner spokes also has a bladed portion for removing material. The center bit has a drill bit-shaped tip, a toothed cone, and a shaft all concentrically aligned with the outer ring and with the inner hub. The toothed cone includes at least one blade outwardly protruding from the toothed cone, and the shaft inserts into the inner hub to center the center bit with the outer ring and with the inner hub. The drill bit-shaped tip centers the auger bit, and the array of circumferentially-spaced teeth moves soil and cuts roots. The at least one blade outwardly protruding from the toothed cone also moves soil and cuts roots.

Abstract: A drilling head (1) is disclosed, in particular for introduction into pipelines, with a rear connector piece (2) and a forward cutting body (3) of the size of the diameter, comprising cutting ribs (4), extending in the advancing direction (V), which have a convex arch and have a cutting edge (5) on both sides of the radial end thereof in the direction of the circumference. Conventional drilling heads can be applied only with difficulty in curved pipelines and have a tendency to damage the inner wall of the pipeline. The disclosed drilling head (1) has a cutting body (3) with a conical cutting head tip (7), surrounded by the back-cut tips (6) of the cutting ribs (4) which lie set back along a longitudinal axis (Y).

Abstract: A drill out bi-center bit and a method for using the same are provided that offer the ability to drill out cement and casing shoes, and increased stability. The bi-center bit includes a bit body having a first end operable to be coupled with a drill string, a second end including a pilot section, and an eccentric reamer section intermediate the first and second ends. A first plurality of cutter assemblies is disposed upon the exterior surface of the pilot section, while a second plurality of cutter assemblies is disposed upon the reamer section. A plurality of recessed cutter assemblies is also disposed upon the pilot section, such that the recessed cutter assemblies are located within a radius beginning at a central axis of the pilot section and terminating at a central axis of the reamer section and are recessed with respect to a lower surface of the pilot.

Abstract: An improved bi-center with improved directional stability and wear resistance is disclosed, said bit optimally utilizing a plurality of shaped PDC cutting elements selectively situated about the cutting surfaces of the pilot and the reamer to produce a minimal force imbalance, where further said pilot bit and the reamer are force balanced to further reduce imbalance in the operation of the tool.

Abstract: A hard rock drill barrel has a barrel portion with a downhole hammer drill disposed therein at the barrel's periphery. A pilot portion, in substantial axial alignment with the barrel but having a smaller diameter, extends distally from the barrel for inserting into a pilot shaft of slightly larger diameter than the pilot portion. In operation, the hammer drill excavates a collar around the pilot shaft when the drill barrel is rotated and supplied with pressurized air, thereby excavating a relative large diameter shaft. The drill barrel is hollow and open at its proximal end to receive and collect cuttings flushed into the shaft above the drill barrel. The piloted drill barrel is adjustable to excavate variable diameter shaft portions, enabling the placement of casing within a larger diameter shaft portion. After adjustment of the drill barrel, smaller-diameter shaft excavation proceeds beyond the casing.

Abstract: An apparatus for the directional drilling of bore hole through a solid substrate includes a main bore head mounted for rotation on a flexible drive shaft and a pilot bore head for weakening a region of substrate in advance of the main bore head, the weakened region being eccentrically located relative to the main bore head. The apparatus further includes structure for enabling the drilling access of the main bore head, during subsequent drilling of the bore hole, to become substantially aligned with the weakened region of substrate.

Abstract: The present invention provides a global drilling system comprising a crown bit, a driver drill bit and a square drill bit. The crown bit has a tubular body with an inner surface and an outer surface, wherein the inner surface circumscribes a hollow passageway, and a pair of projections extending into said hollow passageway. The pair of projections are positioned substantially opposite one another on said inner surface. The driver drill bit has a drilling head with a pair of cut-away portions positioned substantially opposite one another and a pair of locking surfaces adapted for engaging the projections on the crown bit. The square drill bit has a drilling head with two tapered cut-away portions positioned substantially opposite one another. Each cut-away portion corresponds to one of the pair of projections such that the drilling head is able to pass through the hollow passageway of the crown bit.

Abstract: A reaming tool is disclosed which includes a body having reaming blades affixed thereto at azimuthally spaced apart locations around a circumference of the body. The reaming blades each have at least one cutter attached thereto at selected positions and orientations on each of the blades to minimize a net lateral force developed by the reaming tool. The tool includes a pilot hole conditioning section comprising a plurality of azimuthally spaced apart pilot blades affixed to the body longitudinally ahead of the reaming blades.

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 hole opener including a tool body having upper and lower ends. The upper and lower ends may be coupled to adjacent drilling tools. At least two blades are formed on the tool body and are arranged so that the hole opener is positioned concentric with a wellbore, and cuffing elements are located on the blades. The at least two blades and the cutting elements are arranged to increase a diameter of a previously drilled wellbore.

Abstract: An improved bi-center with improved directional stability and wear resistance is disclosed, said bit optimally utilizing a plurality of shaped PDC cutting elements selectively situated about the cutting surfaces of the pilot and the reamer to produce a minimal force imbalance, where further said pilot bit and the reamer are force balanced to further reduce imbalance in the operation of the tool.

Abstract: Enhanced stabilization is provided for an eccentric reaming tool when a pilot borehole is undersized with respect to a following pilot stabilization pad (PSP). Alternatively, offset of a rotational axis of at least a portion of the assembly including the reaming tool is employed to accomplish stabilization of the reaming tool. In either case, a reamed diameter larger than a physical diameter of the reaming tool may be drilled. More specifically, an enlarged PSP relative to pilot bit diameter or PSP offset or even pilot bit offset is employed in order to engage a PSP with the wall of a pilot borehole of greater diameter than a physical diameter of the pilot bit. The PSP or pilot drill bit, or both, may be laterally offset, angularly offset, or a combination thereof in order to effect substantially continuous PSP contact with the pilot borehole wall.

Abstract: A novel drill bit includes a cutting reamer portion that cuts to gage diameter, and a pilot portion that cuts to a radius about 50%-80% of the reamer portion. The pilot portion extends downward from the reamer portion to create a distinct cutting area including pilot. The torque and weight on bit is evenly distributed between said pilot portion and said reamer portion of said drill bit by iterative adjustment of criteria such as backrake, siderake, cutter height, cutter size, and blade spacing.

Abstract: A back reaming tool is disclosed which includes a tool body adapted to be coupled to a drill string, and at least one roller cone rotatably mounted to a leg and having cutting elements disposed thereon. The leg is removably coupled to the tool body. The at least one roller cone is open at only one axial end thereof.

Abstract: The present invention generally provides an apparatus and method for forming a pilot hole in a formation. In one aspect of the present invention, the apparatus may comprise a starter mill connected to a bearing mill by a body joint. The apparatus may further comprise a lead bearing connected to a starter mill by a lead joint. Preferably, an outer diameter of the bearing mill is about the same as an inner diameter of a wellbore. As the lead bearing travels along the concave, the apparatus will bend between the bearing mill and the lead bearing. The bend urges the starter mill into contact with the wellbore wall. In another aspect of the present invention, a method for forming a pilot hole in a wellbore includes running a tool into the wellbore, the tool comprising a starter mill disposed between a first bearing and a second bearing. While running the tool along a concave of a whipstock, the tool bends between the first and second bearing and urges the starter mill to form the pilot hole.

Abstract: The hole-opener is designed so that it can be disassembled in the field to replace worn cones or to enlarge the effective diameter of the tool. It comprises: a tubular drive sub, which connects at its front end with a rotating drill string which is being pulled along a pilot hole; a sleeve which slides over the rear portion of the drive sub; and a retainer sub which is connected with the rear end of the drive sub. The drive sub has external protruding bars which engage slots formed in the forward end of the sleeve, for limiting forward movement of the sleeve and locking the drive sub and sleeve together so that they rotate as a unit. The retainer sub has a radial shoulder which abuts the rear end of the sleeve to lock it in place. The retainer sub also transmits axial pull from the drive sub to the sleeve. The sleeve carries rotary cutting elements which are pulled and rotated to cut formation and enlarge the pilot hole.

Abstract: A telescopic drilling method includes the steps of drilling an outer bore through a surface, inserting a hollow outer conduit into the outer bore, and at least partially inserting a first hollow inner conduit through the outer conduit. Next, the method includes the steps of preventing the first inner conduit from moving longitudinal with respect to the outer conduit engaging a rotatable inner drill bit with a ring drill bit and further drilling the outer bore using a unitary drill bit head to a successive depth. The inner drill bit is disengaged from the ring drill bit and a second end of a successive hollow inner conduit is attached to a first end of a preceding one, and the preceding inner conduit is unclamped.

Abstract: A hole opener including a tool body having upper and lower ends. The upper and lower ends may be coupled to adjacent drilling tools. At least two blades are formed on the tool body and are arranged so that the hole opener is positioned concentric with a wellbore, and cutting elements are located on the blades. The at least two blades and the cutting elements are arranged to increase a diameter of a previously drilled wellbore.

Abstract: An earth boring bit for boring a hole having a predetermined depth into the earth. The earth boring bit includes a cylindrical drum for being mounted for rotation on the end of a boom of a mobile machine and connected to and rotated by a power supply mounted on the boom. The drum includes an exterior for defining the diameter of the hole being bored and an interior adapted for receiving upturned earth therein as the hole is being bored. A plate is carried by the drum adjacent a lower end thereof for movement between a closed position for cooperating with the interior of the drum for retaining the upturned earth therein and an open position for dispensing the upturned earth out of the interior of the drum at a predetermined location away from the hole being bored. A cutting member is carried on the plate for cutting the earth in a progressive slice and directing the earth into the drum, thereby boring the hole into the earth.

Abstract: A guide assembly (1) for a core drill bit (2), which is at least partially guided at an inner wall (3) of the core drill bit (2) and projects radially with projections (10) between the plurality of cutting inserts (5) arranged on a frontal surface of the drill tube (4) of the core drill bit (2), wherein a centering means (6) projects at least axially, in part, beyond the cutting inserts (5), whereby the centering means (6) is shorter than the axial length (L) of the drill tube (4), and is axially spring-biased inside the guide assembly (1) and has limited axial displacement.

Abstract: The invention is directed to a bi-center drilling tool adapted to fit within and drill through a casing shoe without damage to the surrounding casing. In one embodiment, the tool comprises a bit body having a proximal and a distal end where the distal end defines a pilot bit and an intermediate reamer section, where each the pilot and reamer sections define a bit face including primary and secondary cutting blades and cutting elements disposed on said blades. In this embodiment, the cutting or wear elements disposed on the one or more cutting blades which extend to or are proximate to the pass-through gauge define a selected angle between the line of contact on the cutting or wear elements and the material to be drilled.

Abstract: A novel drill bit includes a cutting reamer portion that cuts to gage diameter, and a pilot portion that cuts to a radius about 50%-80% of the reamer portion. The pilot portion extends downward from the reamer portion to create a distinct cutting area including pilot. The torque and weight on bit is evenly distributed between said pilot portion and said reamer portion of said drill bit by iterative adjustment of criteria such as backrake, siderake, cutter height, cutter size, and blade spacing.

Abstract: Enhanced stabilization is provided for an eccentric reaming tool when a pilot borehole is undersized with respect to a following pilot stabilization pad (PSP). Alternatively, offset of a rotational axis of at least a portion of the assembly including the reaming tool is employed to accomplish stabilization of the reaming tool. In either case, a reamed diameter larger than a physical diameter of the reaming tool may be drilled. More specifically, an enlarged PSP relative to pilot bit diameter or PSP offset or even pilot bit offset is employed in order to engage a PSP with the wall of a pilot borehole of greater diameter than a physical diameter of the pilot bit. The PSP or pilot drill bit, or both, may be laterally offset, angularly offset, or a combination thereof in order to effect substantially continuous PSP contact with the pilot borehole wall.

Abstract: A method to design a bi-center drill bit designed to drill out the cement and other material in the casing and then proceed to drill out the full gauge drilling diameter borehole with a diameter greater than the inside of the casing. The bi-center drill bit has a pilot section on the end of the bit body, an eccentric reamer section and a plurality of cutting elements on the pilot section. The design method comprises the steps of: defining a first center of rotation of the pilot section about the longitudinal axis, defining a radius of rotation R1 of the drill bit about the first center of rotation, defining a second center of rotation of the pilot section spaced apart from the first center of rotation by a distance D, defining a radius of rotation R2 of the drill bit about the second center of rotation, and setting the relationship between D, R1 and R2 such that R1 is less than the sum of R2 and D.

Abstract: An earth boring bit for boring a hole having a predetermined depth into the earth. The earth boring bit includes a cylindrical drum for being mounted for rotation on the end of a boom of a mobile machine and connected to and rotated by a power supply mounted on the boom. The drum includes an exterior for defining the diameter of the hole being bored and an interior adapted for receiving upturned earth therein as the hole is being bored. A plate is mounted in the drum adjacent a lower end thereof for movement between a closed position for cooperating with the interior of the drum for retaining the upturned earth therein and an open position for dispensing the upturned earth out of the interior of the drum at a predetermined location away from the hole being bored. At least one cutting member is carried on the plate for cutting the earth in a progressive slice and directing the earth into the drum, thereby boring the hole into the earth.

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 backreamer assembly for enlarging shallow depth boreholes in an earthen environment includes a substantially conical cutting surface. Contained within the substantially conical cutting surface is a speed reduction, torque increasing gearbox which transmits rotational power from a drive motor to the substantially conical cutting surface.

Abstract: In a fastener of a post-installation type which is embedded after a drilled hole is provided at concrete structure, a sleeve (2) and a plug (3) press-fitted to the sleeve are positioned by convexoconcave engagement between a projecting portion at an inner periphery of an expansion portion (6) and a recess groove (11) at a tip end of the plug (3) before installation, and therefore the separation therebetween is prevented. After installation, the projection portion at the inner periphery of the expansion portion (6) expanded is again engaged with the recess groove (12) of the tip end of the plug (3). By this positioning effect, the fastener performs an effect for preventing a loosening between the sleeve and the plug against the vibrations.

Abstract: A drilling tool having a pilot bit on an end of a main shaft is surrounded by outer shafts having mills on their ends. The bit and mills employ cutters with PDC. The pilot bit rotates in a direction opposite the direction of rotation of the mills. A transmission for rotating a main shaft, on which the pilot bit is mounted, and several secondary shafts, on which the mills are respectively mounted, is carried within a housing using diamond thrust and radial bearings. Power is applied to the main shaft and transmitted to the secondary shafts through diamond hardened gears. Drilling fluid is used to cool and lubricate the bearings and gears.