Abstract: Two-piece drill bits and methods of manufacturing same provide a preferably hexagonal shank, and a drill portion having a proximal end inserted into an axial hole in a distal end of the shank. In a preferred embodiment, at least part of the area adjacent the proximal end of the drill portion is knurled. Alternative embodiments have wings, polygons, tapers or other irregular shapes, or combinations of same. A variety of means may be employed to mechanically capture the drill portion in the shank.

Abstract: The invention is a tool bit for use in a socket or chuck mechanism. The tool bit includes an elongated shank having an operative tip end and an opposite tail end. A polymer jacket is molded about the tail end of the shank, and the jacket in the lateral cross-section, has a hex-shaped outer surface.

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 drill used for dry drilling, characterized by the asymmetry of those cutting edge parts only whose faces are in the drill core area, in particular its entire chisel edge. This asymmetry can result from the fact that the individual chisel edges have different lengths.

Abstract: A cutting insert for a during includes a broken main cutting edge, the ends of which join respective additional edges of the insert by curved nose portions. Each curved nose portion forms a curved cutting edge defined by at least three sequentially arranged curved cutting edge segments defined by respective radii of different sizes. A first of the segments joins one end of the main cutting edge and has a first radius. The next segment has a radius of different length than the first radius and projects farther laterally than the first segment to perform a wiping function.

Abstract: A drill bit for use in association with a power or hand drill comprising a drill bit head and shaft. The drill bit head includes a drill bit cutting head and a guide point. The drill bit cutting head includes a first and a second cutting vane. Each cutting vane includes a first cutting edge which extends perpendicular to the axis of rotation and is provided for removing workpiece material, a second cutting edge which extends parallel to the axis of rotation and is provided for forming a substantially smooth workpiece bore, and a channel for facilitating the expulsion of removed workpiece material away from the first cutting surface as the drill bit passes through the workpiece.

Abstract: A drill bit for boring non-linear holes in a workpiece, the drill bit having a generally elongate post, for mounting the drill bit to a tool; a generally elongate shank; and a head. The head has a front portion, a rear portion and there between a main body portion. A plurality of flutes are arranged in a generally helical shape along the main body portion, arched with respect to a longitudinal direction of the drill bit, each flute having an outer cutting edge arranged on an outside edge of the flute, to provide cutting capability in a direction substantially sideways compared to the longitudinal direction of the drill bit. A central point, arranged on the front portion of the head, is connected to at least one flute via a tapered first cutting portion, the first cutting portion being provided with a first cutting edge, to provide cutting capability in a direction substantially forwards.

Abstract: The invention relates to an indexable drill for drilling a hole in a metal workpiece. The drill includes an elongated generally cylindrical body having a central longitudinal axis and a pair of cutting inserts. The body includes a tip end portion having first and second recessed pockets on generally diametrically opposite sides of the longitudinal axis. Each cutting insert is removably secured within a pocket and includes at least one cutting edge having an outer peripheral corner and an inner corner. The at least one cutting edge extends linearly from the outer peripheral corner to a curve extending convexly toward an inner region proximate the central longitudinal axis and then to a linear relief edge extending linearly from the inner region in a direction away from the longitudinal axis to the inner corner.

Abstract: The present invention relates to a throwaway tip of single tip type having an inner cutting edge for cutting a center area of a hole being drilled and an outer cutting edge for cutting a circumference area of the hole, and to a drill holder for holding the throwaway tip. The tip is characterized in that a step gap between a first rake face and a second bearing face on the side of the inner cutting edge are spanned by a first curved surface, and the drill holder is characterized in that a connection surface thereof adjacent to the first rake face is inclined in the same direction as an inclination of the helix of a flute, whereby chip ejection is facilitated.

Abstract: A throwaway tip comprises a base which is to be held between a pair of holder pieces of a holder. A cutting edge is provided on a front edge of the base. A pair of holder bearing faces to be respectively brought into abutment against the holder pieces are respectively provided on sides of the base. A rear bearing face to be brought into abutment against a bottom of a pocket of the holder is provided on a rear side of the base. The rear bearing face is substantially orthogonal to the holder bearing faces. Most of a thrust load exerted on the tip during a drilling operation is stably received by the bottom of the pocket.

Abstract: This bit has an axis and a tip end with an obtuse angle. There are multiple scraping surfaces, each facing counter-clockwise into a longitudinal recess in the tip end. Each scraping surface has a scraping edge at an angle of about 55° to 70° to the axis. Behind each scraping surface the outer surface of the tip end curves down to a rearward edge adjacent another of the longitudinal recesses, the rearward edges each being disposed at a sharper angle to the axis than the scraping edge so that there is some relief, allowing the scraping edge to be more pronounced and enhance its ability to dig into the metal of a deformed screw at points removed from the axis to get a good purchase on the screw.

Abstract: The present invention provides a method and apparatus for forming a plurality of parts, such as spade-type boring bits, from a continuous stock material. Thus, the various steps of the forming method of the present invention can be performed to predetermined portions of the continuous stock material prior to separating the continuous stock material into discrete parts, thereby enhancing the efficiency of the forming process. The present invention also provides an improved forge for forming portions of the continuous stock material into parts having a predetermined shape. The forge can be designed to provide a clearance region proximate the forward end of the ram to permit slight flexing of the forward end of the ram in a radially outward direction during forging operations. The forge can also include a lubrication system for lubricating its various components. In addition, the forge can incrementally rotate the ram after one or more parts have been forged.

Abstract: A drill bit, includes a shank and a cutter head connected to the shank. The cutter head has a center point, and first and second cutting edges extending radially outwards from opposite sides of the center point, wherein the first and second cutting edges are formed along their radial extension with valleys and peaks in alternating disposition such that in relation to the center point, as viewed in radial direction, the valleys of the first cutting edge are arranged at locations where the peaks of the second cutting edge are disposed, and the peaks of the first cutting edge are arranged at locations where valleys of the second cutting edge are disposed.

Abstract: The invention is directed to an improved cutting tool point. In the preferred embodiment, the cutting tool is comprised of a marginal end portion (15), adapted to selectively remove material from a work piece when the tool is moved relative to the work piece and having a leading cutting lip (16), a trailing dam (18), a recessed surface (19) extending into the marginal end portion between the cutting lip and the dam, and a coolant hole (20) communicating with the recessed surface, such that the recessed surface forms a reservoir (40) for coolant (36). The present invention also discloses a marginal end portion having an axis of rotation (42), at least one flute (21), and at least one chip-forming notch (31) extending from the flute into the marginal end portion and beyond the axis of rotation. The present invention also discloses a marginal end portion having a chip former (37) and a chip breaker (32).

Abstract: A cutting tool or drill insert with chip control geometry comprising a body including a portion securable in a holder and a forward portion. The forward portion defining at least one cutting edge extending from the central axis of the body to an edge of the body. A chip groove is defined by the surface of the body adjacent to the cutting edge. The chip groove incorporates chip control geometry as spaced apart elongate projections.

Abstract: The invention provides a flexible guide tube with prongs or other work-engaging means at one end. These prongs may be stabbed into an obstruction in a hollow wall to set the position of a throughhole and to hold the tubular guide in a fixed position against the torsional, or other, forces of a drill or other cutting tool used to cut the hole. The drill may be rotated by means of a flexible shaft running within the guide tube. After a throughhole is cut in the obstruction, a line-fishing member may be inserted through the guide tube and the obstruction and into a space on the distal side of the obstruction. The line-fishing apparatus may comprise an end portion having a collapsed state in which it can pass through the guide tube and an expanded state in which it provides a visible target that can be readily engaged by tools operated by a worker on the distal side of the obstruction who is prohibited from getting any closer than a few yards from the target.

Abstract: A wood turning tool has an elongated handle with an end and a blade mounted to that end. The blade is formed as a plow with top and bottom surfaces and a working edge extending between those surfaces and having an apex. The working edge has an undercut ground bevel forming with the blade top surface a first cutting edge on one side of the apex and an overcut ground bevel forming with the blade bottom surface a second cutting edge on the other side of said apex, each bevel having a selected bevel angle.

Abstract: A drill having a drill head with a drill shank extending between the drill head and a plug-in end lying opposite the drill head, said drill shank having a conveying helix formed by at least two helical flutes and webs located between the flutes. The flutes comprise the same clear cross section at least in the region of the end of the drill shank adjacent the drill head and are arranged at an angle a in a range of 130° through 170° relative to one another.

Abstract: A spade drill bit for use in association with a drill having a direction of rotation includes an elongate shank, a spade portion and a center spur. The elongate shank portion has a central longitudinal axis and one end adapted to engage the drill. The spade portion extends longitudinally from the other end of the elongate shank. The spade portion has opposed spaced apart planar faces and each planar face has a leading shoulder edge and a trailing shoulder edge. Each planar face has a leading face portion and a trailing face portion proximate to the respective leading shoulder edge and trailing shoulder edge that are twisted in the direction of rotation. The center spur extends outwardly from the spade portion along the central longitudinal axis. Preferably the center spur has an elongate flute that has a volume that increases toward the spade portion. Preferably a dimple is formed proximate to a corner leading edge which is between the leading shoulder edge and the leading longitudinal edge.

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: In a shaft-type cutter body of hard material including a shaft for mounting the cutter in a chuck and a head including cutting areas with cutting edges disposed around the circumference of the head, the shaft and the head are formed integrally by injection die casting of powdered raw material followed by sintering. The unfinished cutter body includes cutting edge sections with recessed areas adjacent the cutting edge front surface area for receiving wood chips and delimiting the cutting edge surface area and a surface area receding radially inwardly from the rear cutting edge surface area of the cutting edge so as to limit the rear cutting edge surface area.

Abstract: A twist drill includes a shank which defines a longitudinal center axis and has a helical, chip-transporting flute formed therein. A cutting insert is arranged at a front end of the flute. The insert includes a body forming a cutting edge and a flank surface arrangement situated behind the cutting edge. The flank surface arrangement includes first and second flank surfaces extending at respective first and second acute angles relative to a reference plane which contains the center axis. The sizes of the first and second acute angles are different from one another. In one embodiment, each of the first and second flank surfaces intersects the cutting edge. In a second embodiment, only the second flank surface intersects the cutting edge, with the first flank surface extending from a rear end of the second flank surface.

Abstract: A long bone reamer apparatus is assembled from a plurality of blades that interlink with each other. According to a first embodiment, six long cutting blades are held in position by a plurality of disks, each having six blade receiving slots spaced at 60 degrees with respect to each other. The longitudinal axis of each of the blade receiving slots is slightly offset from the center of the disk so that tabs on opposing blades contact and are welded to each other. According to a second embodiment of the invention, four blades are connected together in a boxlike arrangement having a long rod in the center thereof for support. A first set of the blades includes an interior aperture with a plurality of tabs which engage with a plurality of tab receiving slots in the second set of blades. Both sets of reamers have a head with blade portions arranged to lie along the surface of a semi-circle and, moreover, both embodiments have longitudinal sidewalls having cutting edges, which lie in the plane of a cylinder.

Abstract: A plumbing tool for providing a passageway through a blockage, such as a test cap or other blockage, in a fluid-carrying line. During the rough-in plumbing phase of construction, the drain pipe leading from the plumbing system in a building to the city sewer main in the street is positively sealed off by a test cap welded in the pipe at the location of the clean-out. Pressurizing the rough-in plumbing to test the same can then proceed knowing that if any leaks occur, they are in the branch plumbing on the building side of the test cap and not at or in the test cap. Following successful completion of the initial test, the top-out plumbing is completed, leaving the test cap welded in the clean-out or drain pipe. After the roof vents are in, the top-out test of the plumbing system is made, again knowing that if the system shows any leaks, they are the result of a failure in the plumbing work and not a failure of the test cap.

Abstract: The present invention is a drilling system for cutting flat bottomed holes in work pieces. The tool has two opposing angled cutting edges extending from a rotational axis, with the inner portions of these cutting edges extending upwardly to create an overlapping web at the center. The overlapping web strengthens the center portion of the cuttings edges of the tool. The angle at which the inner portion of the cutting edge is inclined can be increased to create a center point on the cutting surface of the tool. The center point adds stability to the tool as it rotates along its longitudinal axis. The cutting edge has a rake surface with a positive rake angle that lessens the forces on the insert and also allows for better formation of chips of stock material being removed. Chip breakers can be cut into the cutting edges of the insert, further aiding in the removal of stock material.

Abstract: A boring tool is provided with rotary cutting inserts which rotate as a result of the forces which act on the inserts as the tool bores a workpiece. The inserts are positioned on the tool so that the cutting point of each insert is located in a different radial plane along the axis of the tool. The inserts are also positioned on the tool so that the radial distance of the cutting point of each insert from the axis of the tool is different. The non-symmetrical positioning of the inserts on the boring tool provides improved performance of the tool over a tool in which the inserts are symmetrically positioned.

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.

Abstract: The present invention pertains to a drill bit tip portion (3) comprising a drill bit body having an axis of symmetry (1). The drill bit body having lands (2) symmetrically displaced around the symmetry axis (1) has axial clearance faces (6) forming main cutting edges (5) and back edges (7). The main cutting edges (5) are connected with axial rake faces (4). The axial clearance faces (6) are crossed beginning from the axial rake faces (4) throughout the back edges (7) till the drill apex (9) by the oval cross section grooves (10) forming symmetrically central cutting edges (11). The central cutting edges (11), being connected to one another at a drill apex (9), are connected to corresponding main cutting edges (5). The corresponding surfaces of the grooves (10) are smoothly connected with the axial rake faces (4), and the central cutting edges (11) are smoothly connected with the corresponding main cutting edges.

Abstract: A reamer for material-removing finishing machining of drilled surfaces in workpieces made of metal. The reamer has a blade insert and two guide bars associated with the blade insert. The first guide bar trails the blade insert, as seen in the direction of rotation of the reamer, by approximately 40.degree. and the second guide bar is arranged opposite the blade insert. The reamer has at least one additional blade insert that leads the second guide bar by approximately 40.degree..

Abstract: Drilling tool with a drill head with an end face pointing in the feed direction and which has a main bit, which forms a drill point located in the drill axis and the bit is inclined on either side in a substantially roof-shaped manner and the tool has drilling dust grooves. The main bit has a primary cutting edge, which extends radially over at least one side of the main bit, and a secondary cutting edge, which extends radially over substantially the remaining length of the main bit and is axially set back with respect to the primary cutting edge counter to the feed direction by at least the amount of feed in millimeters per revolution.

Abstract: A drilling tool comprises a drill tip, a chip removal part which axially adjoins the drill tip, and a drill shank which is positioned at the end of the chip removal part. Two chip flutes extend in a helical manner over the chip removal part starting at the main cutting edges of the drill tip. The drilling tool is separated into two parts in the region of the chip removal part and consists of a base body which is connected to the drill shank as one part and an exchangeable tip made of a harder material which is connected to the drill tip as another part. The exchangeable tip is connectable to the base body in a form-fitting and/or frictional-fitting manner at an axial separation point.

Abstract: A rotary tool with a shank comprises a tool body and a tip member Joined to the tool body. A narrow hole starts at an inlet port positioned at an end surface or an outer peripheral surface of the shank to run along the axis of rotation of the tool up to a tip end of said tool body and communicates at the boundary of the tip member and the tool body with an outlet port which opens to the terminal ends of ejection grooves.

Abstract: The drill bit according to the present invention provides an advanced, carbide tipped, coolant feed, two-fluted deep hole drill capable of drilling a wider variety of materials deeper and faster than presently known drills of similar construction. Specifically, a deep hole drill bit includes a cutting tip with a fitting end having "V" shaped profile with an apex edge extending along a plane which is substantially aligned with the cutting edges of the cutting tip. The drill bit additionally includes a drill shaft having a distal end adapted to be matingly fitted to the fitting end of the cutting tip. This joint structure allows the shaft to naturally push behind the drill tip to provide enhanced strength and support during drilling. In this manner, the contact area between the drill tip and the shaft is maximized, with the contact area being greatest towards the base of the "V", where the compressive forces are also greatest, i.e., along the cutting edges.

Abstract: An improved self centering spade drill having at least three cutting blades extending radially outward from the center of the drill, the front edge of the blade constituting the cutting portion of the drill, the rear edge of the blade constituting the port end of the drill which are adapted to be received and supported by a drill holder.

Abstract: A cutting tool such as a drill or reamer for machining a bore in a workpiece is provided with at least one chamfered cutting edge on its distal end having an enlarged radial extent. The chamfered edge is defined between a tapered leading end, and an undercut end, and has a radial extent about 2.5% greater than the radial extent of the shaft of the tool. At least 40% of the length of the chamfered edge is substantially parallel to the axis of rotation of the tool shaft. The tapered and radially enlarged geometry of the chamfered cutting edge advantageously allows the drill or reamer to machine a bore in a workpiece formed from materials having significant spring-back characteristics, such as aluminum, titanium, or nickel alloys without sticking or galling during the machining operation, thereby greatly increasing tool life.

Abstract: A centrifugal rotational countersink reamer for three-dimensional bores, being comprised mainly of an axial screw typed spring and an encircling screw typed spring, the encircling screw typed spring loosely slips over and encircles the threads of the axial screw typed spring, one end of the axial screw typed spring forms a central rod mounted in a cylindrical seat, the countersink reamer is inserted and fixedly mounted on an electric or pneumatic hand tool or a claw on a drilling machine; then the countersink reamer can be inserted into a rough bore, the hand tool is activated to rotate the countersink reamer, thus the axial screw typed spring creates a centrifugal swivelling wiping action during rotation, the threads of the encircling screw typed spring form grinding blades to abrase during rotation rough edges, especially the rough edges in the rough bore or on the three-dimensional interior/exterior bore rims located in a narrow area which makes the rough edges hard to be accessed for grinding.

Abstract: A drilling tool includes a one-piece drill body having axially spaced front and rear ends. The front end includes pockets for receiving cutting inserts spaced by respective radial distances from a center axis of rotation of the drill body. Chip canals are formed in the front end, and a frustoconical chip space is formed in the drill body for connecting the chip canals to an axial passage which discharges chips through the rear end of the drill body.

Abstract: In the production of rotor grooves, between the usual undercut-free opening of the groove with a disk milling cutter and profile milling by means of a high speed, high performance steel profile shaft milling cutter, a preliminary fine cutting operation is inserted, in which the profile form is premachined with a profile shaft milling cutter equipped with indexable cutting bits. The profile shaft milling cutter used for the purpose has a greater number of cutting surfaces at its tooth tips than at its tooth flanks. The cutting surfaces defined by overlapping, in circumferential direction, of the cutting edges of the indexable cutting bits are interrupted, so that substantially flat and hardly stiff chips are produced.

Abstract: A finish reamer adapted to finish ream bronze-based valve guides and valve inserts is disclosed. The reamer includes a body section having a plurality of spiral flutes formed therein. The flutes define a plurality of cutting blades. Each cutting blade has an axially extending radial relief formed therein, and a land with a margin having a non-uniform width that is smaller near its leading end and larger near its trailing end.

Abstract: A reamer for finish machining a bore formed in a workpiece and method for providing a reamer with an abrasion resistant material. The reamer includes a body defining an outer surface, a cutting blade and guide member each coupled to the body, and an abrasion resistant material coupled to the reamer to form a friction resistant layer having a contact surface thereon. The abrasion resistant material impregnates the reamer to define an intermediate layer of abrasion resistant material intermixed with the reamer. The method includes the steps of assembling the reamer, applying an abrasion resistant material to said reamer, and allowing the abrasion resistant material to impregnate the reamer to define an intermediate layer of abrasion resistant material intermixed with the reamer.

Abstract: A method that eliminates or reduces chatter when plunge cutting with boring cutters at different diameters, different tool geometries, different chip loads and different cutting depths, by computing optimal cutting insert locations and relocating such inserts to such optimal cutting locations with different phase angles therebetween; this minimizes the resultant radial force of the combined cutters.

Abstract: A drilling tool, in particular a drill, has replaceable cutting elements that form the cutting edges, and chip-removing flutes. A chip shaping area (22) at least partially made of a more wear-resistant material than the drill body itself is arranged next to the faces (11) of the main cutting edges (5) approximately in the chip flow direction. In another embodiment, the chip shaping area if made of the same material as the drill body and is subjected to a subsequent local hardening process that makes it wear-resistant.

Abstract: A device for resurfacing the valve face of a poppet valve in which the pressure between a cutting surface and the valve face is controllable by the operator during the surfacing operation. A bearing case is rotatably attached to a base which is attached to a pair of gripping blocks. A cutting head is rotatably mounted on the bearing case. The cutting head, the bearing case, the base and the gripping blocks define a passage into which a valve stem is inserted. The gripping blocks are clamped in a vise which in turn clamps the valve stem in the device. When the bearing case is rotated, pressure between the cutting surface and the valve face is increased. When the cutting head is rotated, the valve face is resurfaced.

Abstract: A drill according to an exemplary embodiment of the invention comprises a shank from which the drill is driven; a body connected to the shank, the body having a surface; a flute in the body; a cutting edge at a drill point; and a peripheral relief surface which extends outwardly from the surface of the body to an outer circumference of the drill, wherein the peripheral relief surface, for a cross section of the drill perpendicular to a drill axis, intersects the outer circumference at a peripheral point at an edge of the flute. The drill has an improved capacity to withstand a loss of coolant during drilling without severe overheating of the drill or workpiece and with little damage to the drill and workpiece.

Abstract: A self-calibrating countersink tool includes a reusable insert-holder with an axis-defining shank portion and an insert-receiving notch disposed at one end of the holder. The tool also includes at least one selectively attachable insert which is sized and shaped to be received within the insert-receiving notch of the holder. Each disposable insert includes a tapered cutting-edge portion and a notch-mating portion which is complementary in shape to the insert-receiving notch. When the insert is in mating engagement with the holder, the cutting-edge of the insert is disposed forwardly of the holder and defines an angle of between about 105 and 165 degrees relative to the holder axis. The countersink tool also includes an affixation means for affixing a disposable insert to the holder such that the insert is in mating engagement with the insert-receiving notch.

Abstract: A metal cutting drill with replaceable cutting inserts and a length to diameter ratio of four to one or more. Two cutting inserts are positioned in exactly opposed diametric positions, and engage the workpiece in a substantially identical manner to precisely balance the radial forces resulting from drill axially advancing though a workpiece. Through the use of dual cutting inserts, the drill cuts the full circumference of a bore with each one-half revolution and therefore achieves the a faster axial feed rate. By virtue of the inserts being triangular, the curved corners on the cutting edges of the two inserts may be positioned relatively close together and yet sufficient space is left between the inserts to enable the drill shank between the inserts to be relatively thick and strong even at increased length to diameter ratios.

Abstract: A rotary cutting tool includes three complexly-configured, equally-spaced cutting edges. In a first embodiment, which may generally be characterized as an angle milling cutter or countersink, the cutting edges are defined by the intersection of right circular cylinders, offset from the axis of the countersink, with the frustum of a cone. The axes of the cylinders are displaced from the cone axis a distance greater than their radii. The second embodiment, which may generally be characterized as an end mill, also includes three flutes and three cutting edges. Rather than a frustum of a cone, however, the end mill includes a circumferentially radiused edge defining a quarter section of a torus disposed coaxially about the cutter axis. The cutting edges are thus defined by the inter-section of the flutes defined by offset right circular cylinders and the circumferentially radiused edge. A third embodiment is similar to the first embodiment but comprehends a conical milling cutter which converges to a vertex.

Abstract: A drill includes a shank having a tip with two cutting inserts located in a main plane. The cutting inserts have short central cutting edges oriented in a secondary plane. The edges form a pointed center cutting edge for the purpose of entering a workpiece and thereby centering the drill. In the shank two helical flutes are provided, the flutes extending from the tip to the base end. The flutes are located diametrically opposite each other and are separated by two helical lands. The flutes lie in a flute plane that extends at an angle of 90.degree. to the land plane. The secondary plane forms an angle of about 90.degree. to the orientation of the land plane when viewed at the base end of the shank.

Abstract: A drill capable of drilling a deep hole while keeping high chip discharging ability and having a helical flute whose width and helix angle will not change even after the cutting edges have been regenerated by regrinding. The drill has a tip portion formed with a helical flute having a constant width and helix angle, a rear portion formed with a helical flute which are greater in width and smaller in helix angle than the helical flute formed in the tip portion, and a middle portion provided between the tip portion and rear portion and formed with a helical flute smoothly connecting with the helical flutes of the tip portion and rear portion and having a gradually increasing width and a gradually decreasing helix angle from the tip portion toward the rear portion.