Abstract: A nail care system and method using a rubber or soft plastic coated mandrel bit connected to a rotary device, the mandrel bit reducing vibration during operation of the nail care system allowing for smoother polishing and filing as well as a more comfortable experience for the client and nail care practitioner.

Abstract: A combination drill bit for use in both hand held drills and stationary drill presses has a shanking end, a working end and a helical flute portion between the shanking and working ends. The helical portion has a helix length (L) of L = ( D × ? tan ? ? ? ) . The drill bit has a core that is tapered from the working end to the shanking end. A web thickness length at the working end is 10% to 35% of the diameter and the thickness length at the junction of the shanking end is 70% to 90% of the diameter. The drill bit is manufactured from a high speed steel including at least 5% by weight of cobalt.

Abstract: Fibers for diamond-impregnated cutting tools and their associated methods for manufacture and use are described. A matrix is formed that contains fibers made from carbon, glass, ceramic, polymer, and the like. The matrix is then sintered to form a cutting portion of a drill bit. The type and concentration of the fibers can be modified to control the tensile strength and the erosion rate of the matrix to optimize the cutting performance of the tools. Additionally, the fibers may be added to the cutting section to weaken the structure and allow higher modulus binders to be used for the cutting tools at a lower cost, allowing the amount of fibers to be tailored to retain the diamonds in the cutting portion for the desired amount. As the cutting portion erodes, the fibers may also increase the lubricity at the face of the cutting portion.

Abstract: The invention provides a drill head for deep hole machining capable of raising circularity and straightness of a hole and improving precision of hole machining. In the drill head for deep hole machining constituted by fixing a cutting blade to a tip surface of a head body and fixing guide pads to a periphery of a tip of the head body, the length Lm of a margin, which is formed at a tip side of a periphery of the cutting blade in a drill rotating direction, in an axis direction is made substantially the same as the length Lp of the guide pads in the axis direction, and a top end and rear end of the margin are substantially aligned with a top end and rear end of the guide pads, respectively, in a circumference direction.

Abstract: The invention relates to a rolling bearing (1) comprising at least a first ring with an undulating rolling surface (21) and a second ring (2, 4), the rings being coaxial and given a relative rotational and reciprocating axial movement, and at least one row of rolling bodies (7) mounted in rolling contact between the respective rolling surfaces provided on the said rings.

Abstract: A method for film-coating drill bits comprises the steps of: providing a core drill bit; cleaning and further heating the core drill bit; forming an adherent film on the core drill bit; forming a mixing film on the adherent film; and forming a non-crystalline diamond-like film on the mixing film. The finish film-coated drill bit comprises an inner adherence film, a middle mixing film and an outer non-crystalline diamond-like carbon (DLC) film. The mixing film is composed of a non-crystalline diamond-like material and compositions of the adherence film. In the mixing film, the composition of the non-crystalline diamond-like material is higher in a position close to the DLC film.

Abstract: A drill bit including a shaft which has a pyramidal shaped end defining a drill tip with a plurality of edges defining the pyramidal shape. One or more recesses are provided for directing away debris produced whilst drilling, the at least one recess having a first portion extending along the shaft and a second portion having a first portion extending along the shaft and a second portion which extends along the drill tip; wherein the. The second portion which extends along the drill tip. The second portion of the at least one recess extends along an edge of the drill tip.

Abstract: A tool for metal-cutting machining of a surface of an opening particularly of a valve seat in a cylinder head of an internal combustion engines. The tool has a cutter tip with at least one geometrically defined cutting edge. The cutter tip rests on two supporting regions in the tool which are arranged at an angle ?, and an angle-bisecting line runs essentially perpendicularly with respect to the active cutting edge which then is removing chips from the valve seat. A claw holds the cutting tip to the tool end. Coolant and lubricant are supplied through an outlet from the claw.

Abstract: A resurfacing tool and method of operation for a weld gun lug having a lug face is disclosed. The resurfacing tool may comprise a hollow chip retention housing having a lug entrance, a bushing opening, and a chip retention area. A rotary attachment shaft extends through the lug entrance and rotates relative to the retention housing, driven by a rotary power tool. A cutting head assembly is mounted to the rotary attachment shaft in the retention housing for rotation with the rotary attachment shaft, with the cutting head assembly having a cutting head facing toward the lug entrance. A member defines an alignment bore oriented coaxially relative to the rotary attachment shaft. A guide pin has a lug attachment portion configured to attach to the weld gun lug normal to the cable bolt attachment hole, and a pilot shaft telescopically received in the alignment bore.

Abstract: A rotary cutting system for releasable connection to a power tool, the power tool including a housing, a motor supported in the housing and a drive mechanism driven by the motor, the rotary cutting system comprising a universal shaft having a first shaft end and a second shaft end positioned opposite the first shaft end, the first shaft end being removably securable to the power tool, and a cutting tool having a first tool end, and a second tool end spaced a distance of at least 3.5 inches from the first tool end and operable to cut a workpiece, the first tool end being removably securable to the second shaft end of the universal shaft.

Abstract: A drilling head for a tubular shank having an inside diameter and threads may comprise an axial body comprising a duct exiting through a first end; threads adjacent the first end corresponding to the threads on the shank and aligning the duct with the shank inside diameter; a bore from an outer surface of the body to the duct; and two axially extending approximately parallel and offset surfaces adjacent a second end; and an insert affixed between the offset surfaces, the insert comprising: a first face at least partially contacting one offset surface and a second face at least partially contacting the other offset surface; one or more cutting edges adjacent the first face, the second face, or both; and a cutting lip adjacent one or more cutting edges.

Abstract: A rotary motion cutting tool having an axis of rotation for cutting at least a portion of the spherical surface on an internal surface of a workpiece includes a rotary slide, a rotary actuator, and an actuating plate with a rotary surface machined therein. The rotary slide is rotatably supported with respect to a rotary axis extending generally perpendicular to the axis of rotation of the rotary motion cutting tool. The rotary actuator is rotatably supported with respect to the rotary slide for rotation about a rotary actuator support axis spaced radially from, and generally parallel with, the rotary axis of the rotary slide. The actuating plate is driven in reciprocal movement along the axis of rotation for interaction with the rotary actuator. Reciprocal movement of the actuating plate translates through the rotary surface and rotary actuator into rotary movement of the rotary slide through an arc about the rotary axis.

Abstract: The invention relates to a reaming tool which has on its enveloping surface substantially helical flutes. High hardness cutting materials are brazed or soldered to the base material of the reaming tool. Thus, a cost-favourable manufacture of a reaming tool is provided. The invention makes it possible for the shaft and the head of the reaming tool to be made of solid carbide metal, the shaft and the head preferably constituting the one and same integrate body. A considerable improvement is obtained as regards the processing quality, the speed, and also the durability of the tool. This is based on the fact that the chip removal elements are sintered or brazed into the base body of the head initially shaped with the helical flutes, so that a material joint of high quality is provided compared to other joints.

Abstract: A deep hole drill comprising a cutter carrier, a replaceable cutting insert and at least one replaceable guide strip. The cutter carrier is embodied in such a way that it can be used for a predetermined nominal diameter range. In order to adjust the deep hole drill to the various desired nominal diameters in a quicker and more precise manner, a separate kit consisting of a cutting insert and at least one guide strip is associated with each nominal diameter. Fixed stops are provided on the cutter carrier for said kit.

Abstract: A plate mounting cylinder includes a magnet cylinder and not less than four reference pins. A plate is to be mounted magnetically on the outer surface of the magnet cylinder. The reference pins are provided to the outer surface of the magnet cylinder and engage with a pair of reference engaging portions formed in the plate.

Abstract: A plate guide device includes a magnet cylinder and guide plate. A plate is to be mounted magnetically on the outer surface of the magnet cylinder. The guide plate guides the plate removed from the magnet cylinder.

Abstract: The first cutting edge can advantageously remove a large burr from the edge of a drilled hole with high effectiveness, because of the particularly aggressive cutting action of the first cutting edge. The following inclined second cutting edge advantageously allows precise chamfers to be cut, i.e., the surface and the angle of the counter bore can be precisely maintained, independent of the wear on the cutting edges. A control surface located adjacent to the cutting edge in the forward region enables a precise control of the cutter.

Abstract: The invention relates to a cutting tool for rotating and drilling into solid blocks, comprising a drill shank (1) and a cutting head (2) on one end. The cutting head (2) has a straight, front-face cutting edge (4) extending approximately crosswise in relation to the drill axis (3). The cutting head (2) also comprises a section (8) protruding from the shank of the drill (1) at a height (h) ranging from at least 5% to a maximum of 40% of the diameter (d) of the drill and at a width (b) ranging from at least 5% to a maximum of 40% of the diameter (d) of the drill. The section (8) comprises a straight, lateral cutting edge (5) which merges into a straight, rear-sided cutting edge (7) extending in an approximately parallel manner in relation to the front-faced cutting edge (4).

Abstract: A method of forming deep holes and a gundrill therefore is disclosed. The gundrill has an elongate tubular shank and a cutting tip, each provided with a tubular central region supplying pressurized drilling fluid and a non-circular fluid cross-section defining a drilling fluid return path in conjunction with the hole being formed. The cutting tip flute defines a primary rake surface terminating in an offset point, and a secondary flank surface for forming an outlet with the hole being drilled, sized to maintain fluid pressure in the bottom end space to cool the cutting surfaces and to effectively remove chips as they are formed. The drilling fluid exiting an orifice of the cutting tip, forms a maximum angle ? relative to the hole axis when viewed radially, which is greater than sixty-six degrees in order to minimize drilling fluid stagnation in an elongate fluid return path.

Abstract: A small drill includes one chip-discharging flute which is helically formed in the exterior surface of a cutting portion of the small drill. The small drill also includes a flute-shaped portion which is formed in the front region of the chip-discharging flute in the rotating direction, which is connected to the chip-discharging flute, and which is open at the exterior surface of the cutting portion. The core diameter ratio d/D, in percent, of the small drill is set to 60% or more, and a margin angle ? thereof is set to 120° or more.

Abstract: A cylindrical cutting tool for a tire detreading or machining machine, the circular blade of which has a beveled cutting edge, wherein the cutting edge is interrupted by at least one notch, that is to say a portion having a lower axial height than the cutting edge.

Abstract: Boring bits and methods for manufacturing boring bits. The method includes the acts of forming a shank including one end connectable to a power tool and an opposite end, molding a cutting head separate from the shank, the cutting head including a base wall and a side wall extending from the base wall, the base wall having an interior base surface and an exterior base surface, and bonding the shank and the cutting head as a unit including bonding the opposite end of the shank to the exterior base surface.

Abstract: A longer life, low cost tool and tool holder enabling change of posture with respect to a spindle, having a high machining accuracy of a workpiece, and resistant to generation of vibration or heat, provided with a working tool for processing a workpiece, a motor having an output shaft to which the working tool is connected and rotating the working tool, a first holder for holding the working tool and the motor, a mount attached to the spindle, a generator to which rotational force is transmitted from the spindle through the mount and generating electric power for driving the motor, a second holder for holding the mount rotatably, holding the generator, and engaged with a nonrotating portion of the machine tool, and a posture adjustment mechanism which connects the first holder and the second holder and is able to change the posture of the working tool with respect to the spindle.

Abstract: A drywall routing bit for cutting laterally in a drywall or sheetrock panel includes an elongated body terminating at one end in a tip for penetrating the panel. The bit includes a single helical flute which defines a cutting edge at a helix angle relative to said longitudinal axis of the bit of 36°-38°. The cutting edge of the flute is defined at a rake angle of 20°-26°. The fluted portion of the bit has a web thickness that is 60%-63% of the bit outer diameter, for a ⅛″ diameter bit. The tip of the bit includes angled chisel edges subtending an angle of 113°-123° and following a shallow S-shaped curvature relative to a plane including the subtended angle.

Abstract: A torque control system for electrically driven rotating tools capable of always properly and efficiently effecting constant-torque tightening of screws or the like and capable of easily achieving the miniaturization of the whole device and the improvement in torque control accuracy, the torque control system comprising a clutch mechanism that, when a load torque of predetermined value or above acts on a driven shaft joined to the output shaft of an electric motor, operates to cut off the engagement between the output shaft and the driven shaft, a torque setting mechanism that adjusts the engagement point for the clutch mechanism, and a torque detecting mechanism (42) for detecting the clutch operation of the clutch mechanism to effect drive stop control of the electric motor, wherein the torque detecting mechanism (42) is set so that it effects drive stop control of the electric motor simultaneously with the detecting operation thereof in a state in which the clutch operation has been completed as the cam en

Abstract: A portable tool includes a motive power section, a mechanical section driven by the motive power section, and an outer frame covering the motive power section and the mechanical section. A label or a sticker is affixed to an outer peripheral surface of the outer frame. The label contains specific pattern or specific color or specific character representing a specific user of the portable tool. The cover is made from a transparent resin and is removably disposed to the outer frame for protectingly covering the label. A sheet containing a plurality of labels having colors or pattern different from each other is provided. A user can select one of the labels.

Abstract: A drill for working in metallic materials includes a tool body having located in its front end at least one cutting insert, wherein the tool body is provided with one or several damping elements mounted such that during machining, a relative movement (i.e., sliding and/or deformation) of the tool body and the damping element is allowed to occur.

Abstract: A tapping tool for repairing damaged threads on PVC pipe and PVC pipe fittings (e.g. T-connectors, elbows, etc.) includes an elongate shaft with a handle member fixed to a proximal end and a head fixed to an opposite distal end. A threaded tap formed of hardened steel is positioned and disposed on the head for forced, threaded engagement with the threads of the PVC pipe or fitting. Manual rotation of the handle serves to advance and withdraw the head along the threads of the PVC pipe or fitting as the tap cuts and reshapes damaged threads, thereby restoring the threads of the PVC pipe or fitting to a uniform, functional condition.

Abstract: Boring bits and methods for manufacturing boring bits. The method includes the acts of forming a shank including one end connectable to a power tool and an opposite end, molding a cutting head separate from the shank, the cutting head including a base wall and a side wall extending from the base wall, the base wall having an interior base surface and an exterior base surface, and bonding the shank and the cutting head as a unit including bonding the opposite end of the shank to the exterior base surface.

Abstract: A drywall routing bit for cutting laterally in a drywall or sheetrock panel includes an elongated body terminating at one end in a tip for penetrating the panel. The bit includes a single helical flute which defines a cutting edge at a helix angle relative to said longitudinal axis of the bit of 36°-38°. The cutting edge of the flute is defined at a rake angle of 20°-26°. The fluted portion of the bit has a web thickness that is 60%-63% of the bit outer diameter, for a ⅛″ diameter bit. The tip of the bit includes angled chisel edges subtending an angle of 113°-123° and following a shallow S-shaped curvature relative to a plane including the subtended angle.

Abstract: An aftermarket retrofit kit is used to prepare control arm bosses of automotive suspension systems to receive new, replacement ball joints. The kit includes a special cutting tool for forming obtuse threads in the apertures of aluminum suspension system mounting bosses for replacement of spent or used steel ball joints originally pressed-fit into forged aluminum control and steering arms. Since unthreaded apertures of bosses of control and steering arm joints in which the original pressed fitted equipment ball joints may be threaded to receive the new joints, avoidance of having to replace expensive original control and steering arms is made possible by the reuse of such arm parts normally discarded. A separate alignment block is included to assure accurate piloting of the cutting tool. Threading of the control arm bosses can be done on or off of the vehicle, and separate kits are provided for upper and lower control arms.

Abstract: A tapping tool for repairing damaged threads on PVC pipe and PVC pipe fittings (e.g. T-connectors, elbows, etc.) includes an elongate shaft with a handle member fixed to a proximal end and a head fixed to an opposite distal end. A threaded tap formed of hardened steel is positioned and disposed on the head for forced, threaded engagement with the threads of the PVC pipe or fitting. Manual rotation of the handle serves to advance and withdraw the head along the threads of the PVC pipe or fitting as the tap cuts and reshapes damaged threads, thereby restoring the threads of the PVC pipe or fitting to a uniform, functional condition.

Abstract: A drill bit assembly having a housing that has an outer diameter, an inner diameter and a distal radial shoulder extending therebetween at a distal end of the housing. A first drill bit has an outer diameter and an inner diameter, wherein the first drill bit outer diameter is less than the housing inner diameter. The first drill bit includes a shank portion that is mounted within the housing inner diameter and a drill portion that extends from the shank portion and axially protrudes from the distal radial shoulder of the housing. A second drill bit has an outer diameter that is less than the first drill bit inner diameter. The second drill bit includes a shank portion that is mounted within the first drill bit inner diameter and a drill portion that extends from the shank portion and axially protrudes from a distal end of the first drill bit. The first drill bit outer diameter is larger than the second drill bit outer diameter.

Abstract: A hole-finishing hole finishing tool includes a pilot cone within which a quarter round section is free to be displaced in an axial direction. The quarter round section is resiliently biased away from a workpiece. When the tip of the pilot cone is inserted into a hole in a workpiece and force is applied, the quarter round section having a cutting element at its tip is displaced forward into contact with the perimeter of the hole, whereby chamfering is performed. The use of a single lip quarter-round cutting edge permits the tool to be used on small holes.

Abstract: A method of producing a fluted drill in which the flutes are formed by grinding a generally cylindrical blank using a grinding wheel having a profiled circumferential face for generating the cross-sectional form of the flutes is characterized in that the radial cross-section of the profiled circumferential face of the grinding wheel includes a main cutting portion having a convexly curved profile, and a secondary cutting portion forming a continuation of the main cutting portion, there being a change in profile shape at the junction between the main and secondary cutting portions with the secondary cutting portion extending outwardly, away from the extended curve of the main cutting portion profile, to a radially outermost peak of the circumferential face.

Abstract: A method of making a drill comprising a tip (16), a shank (10) and a flute area having chip spaces (12, 14) formed therein, the drill being substantially completely coated with a hard material, and is characterized by applying an abrasive material to merely the tip (16) before coating the drill with the hard material. The drill may more particularly be a solid carbide drill.

Abstract: A fluteless pyramid point drill for spotting holes for drills having an included angle from 90-160°. The preferred tool is double ended. Another embodiment features the pyramid point on the back end of a penetrating drill. An enhanced pyramid point geometry enables construction from technical ceramics. These embodiments included a notched pyramid, a dual pyramid, a beveled pyramid, and an eccentric pyramid. Another embodiment utilizes a grooved-body hollow pyramid for reaming holes. Geometries for a single sided penetrating drill for drilling hardened materials include a limited flute with a flute depth of ⅓ the drill diameter. Point angle embodiments include a 0-20° primary cutting edge and a steeper relief angle with a negative rake along the edge, a radial edge and steep relief angle with a negative rake along this edge. Additionally a pyramid point may be superimposed on the dual point angle for superior centering guidance.

Abstract: A valve insertion method without stopping passage of fluid, wherein, first, a part of an already-installed pipe is enclosed air-tightly with a valve casing, a milling type cutting tool which has cutting edges on a free end surface and an outer circumferential surface thereof, and a gate being housed in the valve casing with the gate and the cutting tool fixed thereto. The gate and cutting tool are provided in positions spaced from each other in the axial direction of the already-installed pipe. A worker then feeds the cutting tool in the radial direction of the already-installed pipe as he has the cutting tool make cutting motions for cutting the pipe by the rotation of the cutting tool. The valve casing is then turned in the circumferential direction of the already-installed pipe as the cutting motions are kept made, whereby a cut groove cut in the direction of the range of the whole circumference of the pipe is formed.

Abstract: A reamer for the fine machining of surfaces of drilled holes in metal workpieces has a reamer body and at that body has at least one main blade and at least one auxiliary blade, a chip surface adjoining the blades at one side and a chip deflector step limiting the chip surface. That deflector step falls away in the zone of the auxiliary blade, exhibiting an increasing distance from the auxiliary blade. The chip deflector step rises in the zone of the main blade, exhibiting a decreasing distance from the main blade. The blades, chip surface and deflector step may be on a cutter plate attached to the reamer body or be part of the body itself. The invention also concerns that cutter plate.

Abstract: In a method for the manufacture of a drilling tool a conical seat is constructed by abrasion on the drilling tool (11) for the preferably positionally accurate, oriented connection of drill head and drill shank. Abrasion preferably takes place by milling or erosion.

Abstract: A cutting tool in the form of drill bit or lathe knife is formed with a cutting edge to slice off material from a work piece and with a construction providing minimal contact of the tool against the side wall of the work piece cut by the tool. The cutting tool generates heat in reduced amounts in the tool itself and the work piece.

Abstract: A tool includes a tool body and a cutting portion detachably mounted thereon, the tool being rotatable about a longitudinal center axis. The tool body includes flutes formed in an outer surface thereof, and a pair of forward projections at a front end thereof. The cutting portion includes front flutes formed in an external side thereof, and a pair of recesses extending circumferentially in communication with respective ones of the front flutes. To connect the cutting portion to the tool body, the cutting portion and tool body are converged longitudinally so that the projections enter the front flutes. Then, relative rotation is produced between the cutting portion and tool body to align the front flutes with the rear flutes while causing the projections to enter the recesses and form therewith a bayonet coupling.

Abstract: A drill (10) has a housing (12) with a motor (14) which includes an output pinion (104) which defines an axis (102). A power source (16) is coupled with the motor (14). An activation device (44) energizes and deenergizes the motor (14). As the motor (14) is activated, an output (18), which is coupled with the motor (14) is driven. The output (18) defines an output axis (156) which is substantially perpendicular to the motor axis (102). A transmission (20) is coupled between the motor (14) and the output (18). The transmission (20) changes speed and torque of the output (18) between at least two different settings.

Abstract: The invention intends to provide a drilling apparatus capable of forming a beautiful hole with stabilized configuration thereof without special post treatment in a sheet made of flexible thermoplastic material which is a different material from a strict one but a thick material, and ensuring a high productivity.

Abstract: A method and a device for hand-operated machine tools, particularly for hammer drills, for optimal cutting of different substrates by energy adaptation, wherein the machine tool, when turned on, is operated initially—preferably in a pre-selectable manner—in a first operating state (I) with reduced power consumption at reduced nominal voltage (e.g., 170 V). After a predetermined time period of 5 seconds, for example, a second operating state (II) with increased power consumption at full nominal voltage of, for example, 230 V, is switched to automatically. In the first operating state with reduced power consumption, the single-blow energy is reduced and/or the hammer rate and rotational speed are decreased. In particular, such a method and device ensures that cutting is carried out without damage in the case of hollow block material and a precise tap-drilling is ensured in the case of solid material.

Abstract: A drill bit for drilling a hole of a selected diameter in a wood workpiece includes a conically shaped tip having a main cutting portion and a thread series operable to threadingly draw the drill bit into the wood workpiece. The thread series has a diameter which progressively increases in a direction opposite to the drilling penetration direction of movement of the drill bit to a maximum diameter which is the same as the selected diameter of the hole to be drilled. The drill bit also includes a cylindrical portion extending from the conically shaped tip, a spiral screw shaped splinter groove for conducting splinters in the drilled hole away from the drill bit penetration area and a centering drill portion with a self cutting thread series.

Abstract: A first embodiment of a non-adjustable single cylindrical lip boring tool includes a shank, a body, a straight side lip, and a front cutting edge. The shank is formed on an end opposite the body. The straight side cutting lip is formed on the body. The straight side lip has a radially convoluted relief which blends into the body. A second embodiment of a non-adjustable single cylindrical lip boring tool includes a shank, a body, a helical side lip, and a front cutting edge. The shank is formed on an end opposite the body. The helical side lip is formed around the body. The helical side lip has a radially convoluted relief which blends into the body. Both embodiments of the non-adjustable single cylindrical lip boring tool may be sharpened on a hand grinder.

Abstract: A reamer including; a generally cylindrical cutter body having (a) a flute formed in an outer circumferential surface of the cutter body and extending from an axially distal end of the cutter body toward an axially proximal end of the cutter body, (b) a cutting blade portion positioned at a longitudinally distal end of a downstream one of widthwise opposite edges of the flute as viewed in a rotating direction of the reamer, and (c) a guide portion having a guide surface which is circumferentially adjacent to the flute and which circumferentially extends over at least 240° about an axis of the cutter body. The guide surface is a part of the outer circumferential surface of the cutter body.

Abstract: The present invention is directed to a semiconductor device having an ultra thin gate oxide and a method for making same. The method is comprised of implanting nitrogen into a region of a semiconducting substrate, and forming a gate dielectric above the region in the substrate. The method further comprises forming a gate conductor above the gate dielectric and forming at least one source/drain region. The present invention is also directed to a transistor having a gate dielectric positioned above a surface of a semiconducting substrate, the gate dielectric being comprised of a nitrogen bearing oxide having a nitrogen concentration ranging from approximately 4-8%. The transistor further comprises a gate conductor positioned above the gate dielectric and at least one source/drain region.

Abstract: A gun drill having a reversed taper approximately ten times greater than the conventional drills, or approximately 0.3 mm per 100 mm, between a tip of the cutting edge and a point some distance away therefrom is provided. The gun drills deep holes at high speed and with sufficient exactness by preventing the peripheral surface of the gun drill from coming into contact with the inner surface of the hole being drilled.