Abstract: A drill has a shank with a central axis of rotation and at least one insert on one end of the shank. The insert has at least two cutting edges. The first and second cutting edges cooperate to form a hole when rotated about the central axis. One of the top and bottom faces acts as a seating face and the other acts as a cutting face. Cutting edges are formed on opposite sides of the cutting face. One end of each of the first cutting edges terminates in a juncture with a second cutting edge that extends from the cutting face toward the seating face. The first and second cutting edges cooperate to form a radiused hole when rotated about a central axis. The bottom of said hole is cut continuously across its entire area.

Abstract: A drill for chipforming machining comprising a drill body (11), two cutting inserts (12, 13) and screws (14, 15). The cutting inserts are screwed to cutting insert sites (18, 19) in the axially forward end of the drill (10). The screws force the cutting inserts radially outwardly during tightening until a shoulder (28) at the lower side of each cutting insert abuts against a vertical support surface (22) on the drill body (11). The cutting inserts are tangentially mounted, i.e. they have holes for accomodating the screws, which terminates in the chip surfaces of the cutting inserts.

Abstract: A precision boring tool for the machining of inner faces of bores with at least one cutting plate, supported by a bracing claw, is disclosed. The cutting plate (2) is tilted versus the plane running through the cutting edge (11) of the cutting plate (2) and the longitudinal axis (17) of the precision boring tool (1). Thus, the bracing claw (3) can be disposed such that it does not protrude into the chip space (4).

Abstract: A milling and countersinking fixture for machining cylindrical openings includes a spindle head having a central opening formed therein and a tool holder disposed on the spindle head having an end surface and having a central opening formed therein defining an inner surface. A clamping mandrel is supported in the central opening formed in the spindle head and guided through the central opening formed in the tool holder. The tool holder has at least one recess formed therein having a given cross-sectional shape and is open only toward the end surface and toward the inner surface. At least one cutting body has a cross-sectional shape adapted to the given cross-sectional shape for insertion in the at least one recess.

Abstract: In a ball end mill, a rotational locus is described by cutting edges of respective throw-away tips mounted to a tool body. The cutting edge of one of the tips and the cutting edge of the adjacent tip overlap with each other, and the center of the overlapping portion is located at a position that is substantially 45.degree. from a forward end of the cutting edge along a 1/4 arc of the rotational locus therefrom. The overlapping length is 1/4 to 1/3 of a diameter of the rotational locus in an arcuate length thereof. A planar section is formed at a side surface of at least one of the tips, which is located at a forward end of the tool body. The side surface is located adjacent a forward end of the cutting edge. A planar surface is formed at at least one of the tip pockets formed in the tool body, at a position facing toward the planar section. The planar surface is subject to a radial cutting force acting from the throw-away tip having the planar section. The planar section is abutted against the planar surface.

Abstract: Tooling to form a countersink and counterbore in a workpiece includes:(a) a first part defining an axis and that extends axially forwardly in a bore hole in the workpiece,(b) a rotatable carrier connected with that first part,(c) and a cutter blade on the carrier, the blade projecting radially relative to the first part forming at least one cutting edge spaced outwardly of a cylinder defined by that first part, the cutting edge shaped to form the countersink and counterbore at one end of the bore hole.

Abstract: A drill for stack drilling comprises a drill body, a central cutting insert, and a peripheral cutting insert. The inserts have active cutting edges arranged such that the drill successively cuts radially outwardly from the center of the drill in order to avoid the formation of break-out slugs. The active cutting edge of the central insert has three cutting edge portions forming obtuse angles with one another. The radially innermost one of those cutting edge portions is shorter than each of the other two cutting edge portions.

Abstract: In a drill bar having a transverse slot, in which a cutter assembly having two diametrically oppositely positioned cutters is inserted, the cutter assembly has a housing from which the outer cutting edges of the cutters are outwardly extended. Each cutter is formed of a one-piece made of high-strength material and has an inner cutting edge and an inner and outer inclined wall adjusted to an inclined wall of the tapered tip of the adjustment bolt which is inserted into the recess formed in the housing to adjust the distance between the outer cutting edges of the two cutters in dependence on a hole to be drilled.

Abstract: An elongated grooving or threading tool has a cutting section and a rearward cemented carbide section which are, respectively, held together in axial alignment by a threaded fastener and a drawbolt which engage the intermediate section and hold the respective connections under compression.

Abstract: An insert boring tool includes radially outward and inward cutting inserts mounted thereon. The radially outward and inward inserts are arranged such that end cutting edges of the respective inserts are intersected with each other at a point of intersection in loci of rotation of the respective inserts in a plane containing an axis of a tool body. The radially outward and inward inserts are positioned such that, assuming that a radial distance between the point of intersection and a radially outermost end of the end cutting edge of the radially outward insert is A, and a radial distance between the point of intersection and a radially innermost end of the end cutting edge of the radially inward insert is B, a ratio of A/B takes a value of from 2/8 to 45/55.

Abstract: A cutting tool assembly and, more particularly, a novel holding device for cutting tools, especially such as flat beaded drill bits which are employed in the drilling of track rail. A tool holder possessing a generally solid cylindrical construction, having a first cylindrical shank portion is adapted to be fixedly installed in the rotary drive unit of a rail drill, and wherein the tool holder includes a second cylindrical shank portion coaxial with the first shank portion having a tool-mounting projection end. A clamping member extends transversely across a longitudinal slot formed in the second shank portion whereby actuation of the clamping member, such as a screw or the like, will selectively widen or narrow the slot. The shank end of a flat beaded track drill is inserted into the slot, with raised longitudinal beads on the opposite surfaces of the drill bit engaging into complementary longitudinal grooves formed in the facing surfaces of slot in the tool holder.

Abstract: An insert boring tool includes a tool body and a cutting insert releasably mounted thereon. The insert includes a plate defined by front and rear surfaces and a plurality of side faces and having a plurality of corners where adjacent side faces intersect one another. At least one of the corners is removed to provide a corner face. A first cutting edge is defined by the front surface and one of the side faces adjacent to the corner face, and a straight second cutting edge is defined by the front surface and the corner side face. The first and second cutting edges intersect each other at an obtuse angle, and are indexed in an end cutting position. The front surface has a marginal portion extending along the second cutting edge and inclined in such a manner that a thickness of the plate between the marginal portion and the rear surface is progressively reduced toward the second cutting edge.

Abstract: A cutting tool assembly including an elongated pilot holder and a cutter blade adapted to be transversely positioned in a transverse slot in the pilot holder. The cutter blade includes cutting edges along one transverse edge of the blade and notches in the upper and lower transverse edges of the blade for respective coaction with a set scrw received in a threaded central axial bore in the lower pilot end of the pilot holder. In use, the lower pilot portion of the pilot holder is positioned in a previously provided pilot hole in a plate member, and the pilot holder is lowered and simultaneously rotated to move the cutting edge of the cutter blade into the upper face of the plate member to perform a cutting operation in the upper face, whereafter the pilot holder and cutter blade are raised, the set screw is loosened to allow removal of the cutter blade from the pilot holder, the pilot holder is lowered to dispose the slot below the lower face of the plate member, the cutter blade is rotated through 180.degree.

Abstract: A single-lip solid drilling tool has a one-piece shank with an integral head having a radially or diametrically extending groove for a blade with an eccentric tip. The blade is held in its groove by several clamping screws so that it can be removed for sharpening or for replacement with a fresh blade. One or both lateral portions of the blade extend beyond the periphery of the head to guide the tool in actual use. The shank has an eccentric coolant hole whose discharge end is adjacent the blade and which is formed by providing a short cylindrical hard-metal blank with an eccentric axially parallel bore before the blank is stretched to reduce its diameter to a requisite value and to simultaneously reduce the diameter of the bore. The stretched blank is then machined to provide it with one or more chip evacuating flutes and, if necessary, with one or more grooves for discrete guide members which extend beyond the peripheral surface of the head.

Abstract: A cutting tool especially for use on KEVLAR comprises a rotatable holder and an insert which is attached on the holder. The insert has a particular shape useful for shearing the KEVLAR fibers and forming a countersink.

Abstract: A tenon forming tool which is an attachment for a powered hand drill.

Abstract: A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting edges formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first cutting edge tip to the axis of rotation plus the distance from the second cutting edge tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second cutting edge tip to the axis of rotation minus one-half the distance from the first cutting edge tip to the axis of rotation.

Abstract: A drill comprises a holder (1) and a cutting member in the form of a pair of discs (2,3). Each disc (2,3) has at least five facets (11,12) arranged along its periphery and symmetrically with respect to its center line (13, 14), the discs (2, 3) being mounted in such a manner that angles (.phi.) of inclination of their facets (11, 12) with respect to an axis (4) of the holder (1) are equal to one another.

Abstract: A drill having two or more cutting edges is provided with interchangeable cutting members. The cutting members are fastened by screws in corresponding recesses formed in the drill bit. The cutting members are embodied by interchangeable plates and provided with fastening portions behind the main cutting edge, in the direction of cutting. The screws engage through these fastening portions in threaded bores formed in the front face of the drill bit.

Abstract: A drill comprising a drill body (11) and a drill tip (22). The drill tip is detachably secured in a slot in the drill body. The drill tip (22) consists of a tip body and cutting portions. The drill body (11) and the tip body comprise cooperating surfaces in order to receive the radial and axial forces acting on the cutting portions.

Abstract: A two piece boring bar, one piece of which provides a recessed free end to which a cutting bar extension member is attached. When a cutting element as a separated component is used it may be removably secured upon the free end of the boring bar extension by a clamp that in turn provides a conically shaped socket which receives the similarly shaped head of a connecting member, threadable into the end portion of the boring bar extension, outside the boundaries of the recess formed therein. The clamp is also provided with a bendable depending stud projectable into an aperture formed outside the recess in parallel relation to the threaded connection of the clamp fastener, for locating and maintaining the clamp in position prior to its clamping engagement with the cutting element.

Abstract: The invention provides a specialty tool useful for cleaning out broken off or cut off plastic pipe and glue in plastic fittings and plastic couplers. An arbor for use with a manual or electrical operated drill is provided with a smooth portion and a threaded portion. The threaded portion terminates in a screw head. Positioned on the arbor adjacent the screw head is an internal guide disc sized to fit inside the broken off or cut off plastic pipe to be removed from the plastic fitting or coupler. A circular cutting head having sharpened protrusions along the circumference is positioned next to the internal guide disc. A retaining nut slipped down over the smooth arbor shaft is tightened down against the circular cutter and retains both the cutter and the internal guide disc firmly on the arbor shaft. The assembled device is useful for the removal of broken off or cut off plastic pipe remaining in an otherwise useable plastic fitting or coupling.

Abstract: An insert rotary cutter for processing a metal workpiece includes a cutter body of a generally circular cross-section having an axis of rotation therethrough. The cutter includes one or more cutter inserts releasably mounted on a periphery of the cutter body. The insert includes a generally quadrilateral plate defined by a front face, a rear face disposed generally parallel to the front face and four side faces. The insert has a pair of main cutting edges defined by the front face and one pair of the opposite side faces. The pair of opposite side faces serve as respective rake surfaces for the main cutting edges. Each of the rake surfaces is convexly curved in such a manner that the width of the insert between the rake surfaces is larger at a central portion of each main cutting edge than at opposite ends of the main cutting edge.

Abstract: A metal cutting tool having an exchangeable cutting insert mounted on a replaceable cartridge seat releasably fitted in a tool holder of the cutting, the cartridge seat comprising a body portion with a receiving pocket formed therein, an axially directed external surface of the body portion and a substantially planar rear surface thereof; the receiving pocket being formed with a substantially planar insert receiving surface; the tool holder being formed with an insert receiving cavity having an axially directed internal surface adapted to receive the body portion and a substantially planar end surface adapted to abut said rear surface; one of said axially directed surfaces being substantially cylindrical and the other being formed with three suitably located, axially directed protrusions so that upon the screw coupling together of the cartridge seat in the receiving pocket the body portion pivots about its region of abutment so as to be clamped against the protrusions.

Abstract: An insert rotary cutter for processing a metal workpiece includes a cutter body having an axis of rotation therethrough. The cutter includes at least one cutter insert releasably mounted on an outer periphery of the body. The insert is of a generally polygonal shape having a curved front face. The front face has a pair of opposed marginal ridges serving as respective main cutting edges. The front face has marginal portions disposed adjacent and extending along the main cutting edges, and the marginal portions serve as respective rake surfaces for the main cutting edges. Each of the rake surface is convexly curved as viewed from a respective one of the main cutting edges and is concavely curved as viewed along a respective one of the main cutting edges.

Abstract: An end mill comprises an end mill body and a throw-away tip mounted on a forward end of the end mill body so as to be spaced from an axis thereof. A core receiving recess is formed at a center of a forward end face of the end mill body and has a size equal to or greater than a distance between the throw-away tip and the axis of the end mill body. The throw-away tip has an end cutting edge formed by a cutting edge ridge located adjacent the forward end of the end mill body and extending from an outer peripheral side of the end mill body toward an inner peripheral side thereof, and outer and inner peripheral cutting edges respectively formed by cutting edge ridges respectively extending from outer and inner peripheral ends of the end cutting edge toward a rearward end of the end mill body. The end mill body may mount at least two throw-away tips disposed symmetrically with respect to the axis thereof.

Abstract: The invention covers the control of the horizontal position of a reamer cutting tool in relation to a tool-holder pin.A support is surmounted by a core which slides sideways in the pin. The slide is controlled by a screw whose head forms a vernier, while its crown wheel is engaged tangentially by a worm screw. A flange holds the whole mechanism in place horizontally. A locking screw locks the support into position once an angle has been fixed.The invention has the following features: reduction in the overall diameter of the tool; and increase in precision by the suppression of action which would interfere with the precision adjustment and throw it out of tolerance at the moment the device is finally locked into position.

Abstract: A cutting tool, a drill for instance, having a drill body and a cutting portion. The cutting portion comprises a central cutting insert and two peripheral cutting inserts. A cutting edge extends along the three inserts. The inserts comprise surfaces for facilitating a tight connection between the parts of the cutting edge. The peripheral inserts consist of a material of greater hardness than the material in the central insert, and therefore the cutting edge is adapted for the varying cutting speeds in the radial direction of the tool.

Abstract: The invention relates to a drill for metal drilling, comprising a drill body and a drill tip provided with cutting portions. The drill tip is detachably secured to the drill body by means of fastening devices, which are arranged on opposite sides of the centerline (CL) of the drill. The planar lower face of the drill tip is provided with a central tap which engages in a central recess in the mainly planar front surface of the drill body in order to center the drill tip relative to the drill body. A central fluid passage is formed in the drill body, which transforms into eccentrically arranged fluid passages in the drill tip. The fastening devices form at least partly walls in the eccentrical fluid passages.

Abstract: A conical cutting insert. The insert is comprised of a body member with first and second end sections oppositely disposed from a median plane. One or both of the end sections may be provided with a cutting edge. The cutting edge is formed by the intersection of an interior outwardly tapered cutting surface and an exterior inwardly tapered flank surface. The cutting surface may be frustro-conical or one or more planar surfaces. The flank surface may be frustro-conical or one or more planar surfaces. Where planar surfaces are utilized, the cutting edges are linear. Where frustro-conical surfaces are utilized, the cutting edge is circular. A plurality of coolant flow orifices are provided to allow the flow of coolant on one or both of the flank surface and cutting surface. Chip flow grooves may be provided on the cutting surface to guide and/or break chips during the cutting operation. Lobes may be provided on the flank surface to provide a constant flank angle during the cutting operation.

Abstract: A cutter insert of the indexable type for a rotary cutter includes a body of a plate of a generally circular shape and having three notches of a V-shape formed in a circumferential face of the body in equally circumferentially spaced relation, each V-shaped notch being defined by a pair of first and second opposed walls. A front face of the body cooperates with the circumferential face, interrupted by the three V-shaped notches, to define three arcuate convex cutting edges each having a leading and a trialing end. A marginal portion of the front face disposed adjacent to and extending along each cutting edge serves as a rake surface for the cutting edge, the rake surface being recessed adjacent to the first wall of the V-shaped notch so as to slope toward a rear face of the body toward the first wall to provide a convex portion extending between the front face and the first wall.

Abstract: An insert for a drill including a carbide body having a generally polygonal perimeter with three pairs of sides, the sides of each pair being of an equal length.

Abstract: A drill has a shank with a central axis of rotation and at least one insert on one end of the shank. The insert has at least two cutting edges. The first cutting edge has a negative radial rake and the second cutting edge has negative axial and positive radial rake surface. The first and second cutting edges cooperate to form a radiused hole when rotated about the central axis. Also, the cutting insert is composed of hard wear resistant material. The insert has top and bottom faces and a peripheral wall joining the top and bottom faces. The insert body is polygonal when viewed in plan. One of the top and bottom faces acts as a seating face and the other acts as a cutting face. There are first cutting edges formed on opposite sides of the cutting face at the juncture of the cutting face with the peripheral wall. One end of each of the first cutting edges terminates in a juncture with a second cutting edge that extends from the cutting face toward the seating face.

Abstract: The invention pertains to a self-cleaning high speed core boring tool for enlarging an existing deep hole. The elongated tool includes a shank held within a rotating tool holder, a central portion upon which cutting elements are mounted in diametrically located relationship, and the forward end of the tool comprises a cylindrical extension having a pair of spiral flutes defined therein each of which communicates with a cutting element for receiving chips. The flutes spiral in a direction opposite to the direction of tool rotation during boring whereby chips received within the flutes are displaced forwardly of the cutting elements to keep the cutting area free of chips.

Abstract: The invention relates to a short-hole drill and a cutting insert therefor, for drilling of metallic work pieces. The drill comprises a drill shank with two chip flutes formed therein and with two cutting insert sites and two mainly rectangular cutting inserts having mutually identical shaping. The cutting inserts are accommodated in the cutting insert sites and secured thereto by means of lock screws such that the broken non-active cutting edge abuts against a broken support surface in each cutting insert site while the active cutting edge projects axially forwards. The cutting insert which is arranged radially outermost is inclined such that it determines the size of the bore while the longitudinal axis of the other cutting insert is arranged parallel to the center line (CL) of the drill. The distance between the outermost parts of each cutting edge is longer than the shortest distance between the long side surfaces of the cutting insert.

Abstract: An insert cutter includes a body having at least one generally radially outwardly-opening recess disposed adjacent a forward end face thereof. A cutter insert is received in the recess. The insert is a polygonal shape having a front face, a rear face and side faces. Each corner portion where adjacent side faces intersect each other is removed to provide first and second corner faces. The insert has main cutting edges each defined by the front face and a respective one of the side faces, auxiliary cutting edges each defined by the front face and a respective one of the first corner faces, and corner cutting edges each defined by the front face and a respective one of the second corner faces. Each side face serves as a flank of a respective one of the main cutting edges with a positive clearance angle A. Each first corner face serves as a flank of a respective one of the auxiliary cutting edges with a positive clearance angle B.

Abstract: This spade drill has an elongated holder with a standard driving configuration at one end, and adapted at the axially opposite end to receive a carrier block provided with receptacles for receiving indexable standard cutting inserts of extremely hard alloy.

Abstract: To achieve reliable fastening of a toothed cutter carrier on the toothed bearing surface of a tool body, and to achieve favorable force ratios, in a rotary cutting tool, in particular a drilling head, the tooth formation of the bearing surface is constructed in a sawtooth shape with steep tooth flanks and inclined tooth flanks, the steep tooth flanks being disposed substantially on that side of the teeth which is orientated towards the cutting element of the cutter carrier. The tooth formation on the cutter carrier is constructed so that it is substantially similar to the tooth formation of the bearing surface for interengagement therewith.

Abstract: A boring block and tool holder is disclosed having an opening therein. The block is made of a thick rectangular plate having inserts set into its front corners and inclined surfaces adjacent its rear edge forming a noncircular tang part having two rearwardly facing shoulders adjacent the tang portion which is received in a slot in a boring bar. The shape of the slot is complimentary to the shape of the tang part of the block. A tapered hole through the tang aligns with a tapered hole in the boring bar and the tapered hole in the block receives a taper pin which forces the block rearward bringing the block into firm rigid relationship with the end of the bar thereby clamping the block in positive rigid relation to the bar. The block has more strength than previous blocks because the block is thicker below the cutting inserts and there is more metal below the cutting insert, yet it can use the same bar and same slot width as rectangular blocks.

Abstract: An inverted cutter or a backspotfacer 100 having indexible, lockable, rotatable carbide cutter inserts 120 whereby in use an operator can reposition the inserts 120, as necessary, to assure a sharp cutting edge 175.

Abstract: A conical cutting insert. The insert is comprised of a body member with first and second end sections oppositely disposed from a median plane. One or both of the end sections may be provided with a cutting edge. The cutting edge is formed by the intersection of an interior outwardly tapered cutting surface and an exterior inwardly tapered flank surface. The cutting surface may be frustro-conical or one or more planar surfaces. The flank surface may be frustro-conical or one or more planar surfaces. Where planar surfaces are utilized, the cutting edges are linear. Where frustro-conical surfaces are utilized, the cutting edge is circular. A plurality of coolant flow orifices are provided to allow the flow of coolant on one or both of the flank surface and cutting surface. Chip flow grooves may be provided on the cutting surface to guide and/or break chips during the cutting operation. Lobes may be provided on the flank surface to provide a constant flank angle during the cutting operation.

Abstract: A cutting tool, for example a milling cutter, capable of omini-directional machining of a workpiece as disclosed. In a preferred form, the cutting tool is embodied as a ball nosed end mill having a cylindrical shank terminating in a spherically shaped cutting end with recesses shaped for receipt of at least two indexable cutting inserts, each insert mounted in lay-down fashion, and providing a portion of an effective overall arcuate cutting edge, the cutting zones of each insert overlapping each other. Each insert has the form of an equilateral polygon bounded by planar flanks, each flank intersecting a convex portion of a major face of an insert to form an arcuate cutting edge. The convex major face portion forms the clearance face and the planar flank portion the rake face for each associated arcuate cutting edge.

Abstract: An indexable shell cutter having an improved cartridge for mounting a cutter insert on the cutting face of the shell cutter body. The cutter body has a plurality of recesses extending rearwardly from the cutting face, each of said recesses being formed by a first surface, a second surface spaced from the first surface, and a base surface extending between the first and second surfaces. The second surface is essentially perpendicular to the plane of the cutting face of the cutter head and is V-shaped in cross-section. A cartridge is removably secured in each of the recesses with the base of the cartridge being in mating engagement with the second surface of the recess.

Abstract: Adjustment of the radial position of the tool bit is accomplished by insertion of the bit in a recess of a clamping shoe which clamps the bit against a shoulder in the cutter head. The clamping shoe has an extension which is rotatably mounted in a recess in the cutter head. A single wedge-shaped adjustment member rotates the clamping shoe with the cutter blade thereby changing the radial distance between the cutting edge and the axis of rotation of the tool.

Abstract: A device for boring holes has a geometrical longitudinal axis, a clamping zone, a shank having a front end zone, two turnover plates fastened on the front end zone of the shank in opposite positions, and a chip space in front of each turnover plate. In the shank, a longitudinal slot runs radially to the geometrical longitudinal axis, which is open towards the front end zone and has a bottom that extends so far towards the clamping zone that the shank halves thus formed can be bent forward at the front end zone to a degree that is sufficient for fine setting the bore diameter. Beyond the bottom of the longitudinal slot, a tapped hole in the shank is coaxial with the longitudinal axis. A coaxial rest hole in the shank in the inner zone of the longitudinal slot is intersected by the longiudinal slot.

Abstract: The operating life of the two guide members in a single bit reamer is increased by shaping the peripheral surface of the guide members with a radius of curvature less than the radius of the bore being machined. Contact between each guide member and the bore wall takes place only along a central quest area extending in the lengthwise direction of each guide member. This allows coating of the peripheral surfaces of the guide members with a hard, wear resistant material. Further, the guide members may be fastened to the cutter head by means of a screw situated in a groove extending in the tangential direction along the peripheral surface of each guide member. This increases the lubricating and cooling effect.

Abstract: The head of this boring tool carries two bit holders, which can be radially adjusted to different cutting widths by tooth systems provided on sloping faces of the head and/or bit holder. To ensure that there is still reciprocal supporting of the bit holders even in the outermost adjustment range thereof, cams are provided for extending the supporting surfaces. As an alternative to or in addition to this measure, the spacing between the front end face of the head and the surface of the bit holder parallel thereto is made so small that when high cutting forces occur these surfaces are supported on one another before the elastic deformation range of the bit holders is exceeded.

Abstract: A countersink utilizes standard, inexpensive inserts for cutting. Thus the tool never needs sharpening. The inserts may be mounted at several locations on the tool, providing a versatile tool that can handle a wide range of hole sizes.

Abstract: A plurality of cutting tips are mounted on the distal end of the cylindrical main body of a drilling tool for performing trepanning. These tips are disposed along the circumferential direction of the main body and equidistantly spaced apart from one another. The force, which is produced by all of the cutting tips and acting at right angles to the axis of the main body, is smaller than the component of the cutting force, which is produced by each tip and acting at right angles to the axis of the main body. The cutting widths of the tips in the radial direction of the main body are substantially equal. One of the tips, which is located at an intermediate position in the radial direction, has a V-shaped leading portion.

Abstract: A cutter insert is provided which is adapted to be supported on a flat platform on a cutter body and abutting edgewise against walls upstanding from said platform. The insert comprises a flat block of cutting material in the geometric shape of a parallelogram having a hole extending therethrough between the upper surface and the mounting surface of the block to receive a screw for securing the block to the platform. The upper surface of the block terminates at opposite ends in radii. The cutter insert further includes a rake face and a clearance face on opposite sides of the hole with said upper surface and said faces constituting cutting edges defined by the intersections of said faces and said upper surface, and an angular facet at diagonally opposed ends of said radii so as to form a chip splitter at the juncture of the cutting edge of the rake face and the cutting edge of the angular facet.