Abstract: The disclosure relates to a device for deburring at least one borehole opening of a metal workpiece, wherein the device has a rotationally symmetrical countersink bit. The countersink bit of the device is designed to remove at least one burr of the at least one borehole opening. The countersink bit can be introduced into an opening forming the at least one borehole opening and rotated. The disclosure also relates to a corresponding method.

Abstract: In this drill, a wall face of a chip removal groove includes a first wall face having a concave curve shape and a second wall face having a straight line shape in a cross section orthogonal to an axis of the drill main body, an extension line of a straight line of the second wall face extends in a direction opposite to a drill rotation direction as the straight line of the second wall face goes to an outer periphery side of the drill main body with respect to a radius line connecting an outer peripheral end of the second wall face and the axis with each other, the cutting edge includes a first cutting edge having a concave curve shape and a second cutting edge having a straight line shape which intersects with the first cutting edge at an obtuse angle.

Abstract: A cutting insert for a rotary drill tool and a drill tool assembly in which an insert and a support body are coupled via cooperative contact surfaces and a mounting screw. The contact surfaces provide a dual function to axially and rotationally lock the insert at the support body in addition to providing a centring function of the insert.

Abstract: Drills and methods of removing material using drills are disclosed. Drills may include a plurality of lands that extend to a cutting edge, where adjacent lands are separated by flutes comprising a base contour arranged in a generally helical configuration along a centerline axis of a drill body. The drill also includes a plurality of contoured drill points each having a linear portion that extends towards an outer diameter of the drill body, and an arcuate portion that extends from the linear portion and towards a chisel of the drill body. The drill further includes a plurality of gash contours positioned within the plurality of flutes. The gash contours extend from the chisel of the drill body, and the gash contours are oblique to the base contours of the flutes.

Abstract: A rotary cutter with hemispherical shaped head and a plurality of blades mounted in said head, wherein each of said blades has securement means for securing each blade in position in said head by interacting with an inner surface of said head.

Abstract: A drill bit that serves to remove mineral materials and that consecutively has on a longitudinal axis (6) a drill head (2), a helix (3), an insertion end (4) and an impact surface (7) on the end face of the insertion end (4) that faces away from the drill head (2) and that serves to absorb impact along a direction of impact (8), is provided. The drill head (2) has at least two cutting edges (13) and at least two blades (20). The cutting edges (13) each have a cutting face (16) and a free face (17). The blades (20) run parallel to the longitudinal axis (6) and adjoin the cutting edges (13). The blades (20) each have a radially projecting tooth (24) that adjoins the cutting face (16), whereas it adjoins the free face (17) either only partially or not at all. The axial dimension (29) of the tooth (24) is smaller than the axial dimension (25) of the blade (20).

Abstract: The negative land includes: a first region in which a space between the upper cutting edge and the lower cutting edge becomes wider toward the outer circumferential surface; and a second region which is continuous to the first region and in which the space becomes wider toward the rotation axis. In a cross section perpendicular to the rotation axis, the rake face includes a return face continuous to the outer circumferential surface, the return face being recessed opposite to a rotation direction of the drill. When a first boundary represents a boundary between the outer circumferential surface and the first region and a second boundary represents a boundary between the first region and the second region, a length of the first boundary is larger than a length of the second boundary in a direction parallel to the rotation axis. The second boundary is continuous to the return face.

Abstract: A bone broach is formed from a plurality of substantially planar members which are positioned adjacent to each other with each of the substantially planar members attached to at least one other substantially planar member. At least some of the substantially planar members defines at least one cutting profile at its perimeter. The plurality of substantially planar members include a first group of substantially planar members defining planes which are substantially parallel to each other, and at least one additional substantially planar member defining a plane which is angled relative to the planes defined by the first group of substantially planar members.

Abstract: A drill according to an embodiment of the present invention has a pair of main cutting edges positioned at a front end of a drill body, a pair of first chisel edges each extending from the pair of main cutting edges toward a rotation axis, and a second chisel edge positioned between the pair of first chisel edges and intersecting with the rotation axis of the drill body. When viewing a locus of rotation of the pair of first chisel edges and a locus of rotation of the second chisel edge in a cross section taken so as to include the rotation axis, the respective locus of rotation of the pair of first chisel edges have a rectilinear shape, and respective imaginary straight lines obtained by extending the locus of rotation of the pair of first chisel edges toward the rotation axis are positioned further to a rear end side of the drill body than the locus of rotation of the second chisel edge.

Abstract: A cutting insert for metalworking operations is retained within a cutting insert holder by a resilient tab on the holder that engages a recess on the stem of the insert. The cutting insert and the holder may be fabricated using rapid prototyping techniques such as 3D printing.

Abstract: The coupling part, in particular cutting head for a drilling tool for the interchangeable fastening in a coupling receptacle, has a coupling pin which is enclosed by a head support surface, wherein the coupling pin has a plurality of types of functional surfaces, namely stop surfaces for transmitting a torque between the cutting head and the carrier, and clamping surfaces for centering and clamping the cutting head in the coupling receptacle. The coupling pin has an axially front pin region and an adjoining, axially rear pin region, and the clamping surfaces and the stop surfaces are arranged in different pin regions. This decoupling and distribution of the functional surfaces to the various pin regions permits simpler production of the coupling pin and an overall more robust configuration.

Abstract: A drill configured for drilling ductile materials includes a drill margin with a margin extremity adjacent to a relief surface. The drill includes a drill body and a drill head secured to the drill body via rotational coupling of the drill head on the drill body.

Abstract: For enabling accurate and efficient cutting work on a narrow area, in a hydraulic chuck configured such that a pressurization fluid pressurized by a push member (8b) is fed through a pressurization passage (8) to a pressurization chamber (6) to reduce a diameter of an elastic deformable part (2b), the hydraulic chuck includes a body (1) having a flange accommodating part (5a) opening at a small-diameter portion at a tip end of the body and a sleeve accommodating part (5b) opening in a bottom face of the flange accommodating part (5a), and a sleeve (2) having a hole (2a) in which a gripped object is inserted, the sleeve being engageable and insertable with/to the sleeve accommodating part (5b) from a leading end side of the flange accommodating part (5a), the sleeve (2) forming the pressurization chamber (6) reserving therein an amount of the pressurization fluid between this sleeve (2) and the sleeve accommodating part (5b), the sleeve (2) having a flange (7) engageable with the flange accommodating part (5a)

Abstract: The present disclosure provides a quadrangular indexable drill insert comprising a substantially flat top surface and bottom surface, a side surface adjoining the top and bottom surfaces; four identical cutting edges formed at intersection of side surface and top surface, each cutting edge comprising, a concave curved part edge of predetermined radius at corner of the insert; a first part edge oriented towards axis of drill body and is having negative slope, said first part edge is connected to the concave curved part edge through a nose portion; a second part edge connected to first part edge through a transitional edge, said second part edge is tangentially oriented to an imaginary inscribed circle; a third part edge connected to the second part edge through a transitional edge, and a nose portion of adjoining the third part edge with concave curved part edge of succeeding cutting edge.

Abstract: A rotary drill bit for engaging an earth strata material includes a cutting insert attached to an axial forward end of an elongate drill bit body. The cutting insert includes an elongate insert body rotatable about a central axis with a pair of symmetrical halves symmetrical about the central axis, each symmetrical half comprising: a leading face; a top surface having a primary relief surface; a web thinning gash extending between the leading face and the primary relief surface, the web thinning gash having a debris evacuation portion centrally disposed adjacent the central axis and a distal transition portion disposed adjacent the debris evacuation portion; a first leading cutting edge at the intersection of the leading face and the primary relief surface; and a second leading cutting edge at the intersection of the web thinning gash and the primary relief surface of the top surface.

Abstract: A manufacturing process for a chain tool attached to a bicycle folding tool included the following steps: Material preparing step: a rod with a length is prepared. Manufacturing step: the rod is milled via a milling cutting step to form a chain fixing groove, a detaching portion, an axial groove and a screwing portion, the chain fixing groove having a retaining wall, the retaining wall being milled to form an arc notch, the screwing portion being threaded to form a threaded hole via a drilling and tapping step. Heat treatment step: after the manufacturing process, the rod is heat treated. Sheet metal part assembling step: a sheet metal part is assembled to the chain tool by at least one connecting part; therefore, the chain tool is attachable to the sheet metal part.

Abstract: A drill bit configured for use with a rotary power tool including a chuck. The drill bit includes a shank including a first end and a second end, and a paddle that extends from the second end of the shank. The paddle includes a first face including a concave portion, a second face opposite the first face and the second face including a convex portion opposite the concave portion, a cutting surface, a cutting edge located at an end of the cutting surface, a relief angle defined by the cutting surface, and an angled rake face adjacent the cutting surface that defines a rake angle that is between about 5 degrees and about 45 degrees.

Abstract: This document provides novel drills and/or reamers that are well-suited for making holes in a variety of materials including, but not limited to, metals, ceramics, glass, wood, plasterboard, plastics, stone, composites, synthetics, silicon or multi-layered or hybridized substrates. In some embodiments, these drilling devices have some centers of mass that are offset from the axis of rotation. Accordingly, such drills and/or reamers may rotate and cut using a precessional pattern of motion. Precessional cutting devices may display a mechanical wave pattern in relationship to the longitudinal axis of the device. If the cutting device is fabricated from a flexible material, for example Nickel-Titanium, bodily deflection of the device may result during rotation.

Abstract: In a method for a finishing work of a spray-coated surface, an inner surface of a cylindrical hollow member is roughened by forming a helical groove thereon. A thermal spray coating is formed on the inner surface that is roughened, and a finishing work is carried out by cutting the thermal spray coating along a helix of the groove by use of a cutting tool. According to the method for a finishing work, a finishing work of a thermal spray coating with non-uniform hardness can be carried out efficiently.

Abstract: A drill, such as a spade drill, is provided. The drill includes a drill body that includes a mounting end and a cutting end. The cutting end includes first and second cutting edges that are generally curved along the entirety of the cutting end of the drill body, removing any sort of cutting corner. The curved cutting edge provides a more resilient drill for removing material from a workpiece. The cutting edges may also include a drilling point at a distal end and at least partially between the first and second edges, along with webs extending from the drilling point to the cutting edges. The mounting portion includes structure to attach the drill to a holder, which can connect to a rotating apparatus for rotating the holder and drill.

Abstract: A rotating tool includes a plurality of elongated members, a cutting edge extending from at least one of the elongated members. A support is attached to each of the elongated members for holding the elongated members at a distance relative to an axis of rotation of the tool. A guiding pad extends radially outwardly from the axis relative to at least one of the elongated members. The tool is particularly useful for reaming operations in which it can be useful to have a tool with a large diameter and/or length.

Abstract: In order to allow high-precision machining of the inner surface of a pipe using little machining time, the draw broach has a cutting part having a plurality of cutters extending in the axial draw direction. The cutting part is divided into a main part and an insertion part tapering conically in the draw direction. The insertion part in turn is divided into a front region, viewed in the draw direction, forming a pre-cutting stage, and a rear region, wherein the conicity of the pre-cutting stage is less than that of the rear region.

Abstract: One non-limiting aspect of the present disclosure is directed to a multi-piece twist drill head. The multi-piece twist drill head includes a core piece formed from a first hard material, and a peripheral piece formed from a second hard material. The core piece and peripheral piece each comprise a cutting edge and are adapted to mate to provide a central region and a peripheral region, respectively, of the multi-piece twist drill head. A twist drill including the multi-piece twist drill head is also disclosed.

Abstract: A cutting insert for a drill of the present invention comprises an upper face having a first side and a second side respectively disposed on both sides of a first corner portion, a bottom face corresponding to the upper face, and a side face located between the upper face and the bottom face. The insert has a first cutting edge formed along the first side, and a second cutting edge formed along the second side. The side face has a first region corresponding to the first cutting edge, a second region corresponding to the second cutting edge, and a third region corresponding to the first corner portion. The third region has an upper region which is adjacent to the first corner portion and disposed toward the upper face, and a lower region located below the upper region. An inclination angle ?3 of the lower region to the bottom face is larger than each of an inclination angle ?1 of the first region to the bottom face and an inclination angle ?2 of the second region to the bottom face.

Abstract: The invention relates to a reaming tool, comprising a rotationally drivable main body (16) and at least one cutting body (18) fastened thereto. The at least one cutting body has at least one reaming blade (26) at the edge of a rake face (28). According to the invention, a chip-forming step (32) and/or chip-breaking elements (34) are formed in the rake face (28) and the reaming blade (26) has a ground cutting edge (40, 42, 44).

Abstract: Some embodiments pertain to a tool that includes a first arm and a second arm that is rotatably connected to the first arm. The first arm includes an opening and the second arm includes a projection that engages threads on a fastener which is installed within the opening in the first arm. During operation of the tool, a fastener is inserted into the opening in the first arm. Pressure is applied to bring the first and second arms together such that the projection engages the threads of the fastener and then deforms the threads. The first arm may include a plurality of threaded openings such that each opening is adapted to receive a different diameter fastener. In addition, the second arm may include a plurality of projections such that each projection is a different size and is aligned relative to one of the openings in the first arm.

Abstract: A drill of the present invention includes a first cutting edge and a second cutting edge each located at a front end of a cylindrical cutting part; a first flute and a second flute connected to the first cutting edge and the second cutting edge, respectively, in which the first and second flutes are positioned helically from a front end to a rear end on a peripheral section of the cutting part; and a first land and a second land each extended from the front end to the rear end on the peripheral section of the cutting part, in which the first and second lands are being located portions between the first flute and the second flute, respectively. The first flute and the second flute are separately extended from the front end to the rear end. The cutting part includes a first region in which a diameter of an inscribed circle in a cross section perpendicular to a rotation axis of the cutting part increases in a direction away from the front end and toward the rear end.

Abstract: A guide portion prevents the drilling hole from curving due to a skipping rope phenomenon, and also prevents the inner wall face of the drilling hole from being damaged, so that its surface roughness can be improved. Chip evacuating flutes 4 are formed in the periphery of a drill body 1 which has a stick shape and is rotatable on its axis O, from its front flank 3 toward the rear side. Cutting edges 2A are formed along ridge lines where the front flanks 3 intersect with wall faces 4A which are in the chip evacuating flutes 4 and face in a drill rotational direction T. A cutting edge section 2, where the cutting edges 2A are formed, is provided in the front side of the drill body 1. A cutting edge section 2 has an external diameter which is smaller toward the rear side in the axis O direction than the external diameter D at the cutting edges 2A. A guide portion 6 has a maximum external diameter part 6A at the front periphery side, and is provided to the rear side of the cutting edge section 2.

Abstract: A tool head includes a main body having a nominal diameter, a face end center formed on the main body, and at least two major cutting edges which each run radially outward from and adjoin the face end center. The face end center is formed by a cone of circular cross-sectional area, which cone extends from a cone apex through to a cone base.

Abstract: A tool head includes an ovoid basic element disposed about a center axis, at least two chip grooves formed in the basic element, and a number of major cutting edges. Each major cutting edge is disposed in a convex course along a respective chip groove of the at least two chip grooves. The major cutting edges define with their radially outermost region a nominal diameter. A radial distance from each major cutting edge to the center axis in a front, tip-side, arc portion increases up to the nominal diameter and in a rear, shank-side, arc portion decreases back down to a minimum diameter.

Abstract: A drill bit, has a front side (5) and a circumferential surface (19) adjoining the front side (5). The front side (5) has a main cutting edge (7) including a transverse cutting edge (3) extending through a center axis (11) of the drill bit (1), and has two first and second main cutting-edge regions (13, 15) adjoining the transverse cutting edge (9) and extending radially toward the circumferential surface (19). The circumferential surface (19) comprises at least two chip flutes (21, 23), which between them delimit a first and a second web (25, 27), and three lands, of which a first land adjoins the end of the first main cutting-edge region (13) facing away from the transverse cutting edge (9), and serves as a free cutting-edge land (33), and additionally has a free cutting edge (39), a second land adjoins the end of the second main cutting-edge region (15) facing away from the transverse cutting edge (9), and serves as a guide land (35), and a third land serves as a support land (37).

Abstract: One non-limiting aspect of the present disclosure is directed to a multi-piece spade drill head for a spade drill, wherein the spade drill includes an elongate body portion and a cutting portion removably secured to an end of the body portion. The multi-piece spade drill head includes at least two insert pieces, each piece including a cutting edge. The at least two insert pieces are configured to be removably secured to the body portion of the spade drill adjacent one another and with the cutting edges of the insert pieces aligned to together form a cutting edge on an end of the spade drill.

Abstract: A loose top for drilling tools, including front and rear ends, a pair of envelope part surfaces concentric with a center axis, and two chip flutes countersunk in relation to the pair of envelope part surfaces between which two bars project radially from a central core, the front end including a cutting edge and at least one clearance surface positioned rotationally behind the cutting edge, the rear end forming an axial contact surface.

Abstract: A three-way indexable throwaway tip for deep-hole drilling can be used as a center cutting blade body for a drill head in either whole cutting type or uncut core break-off type applications. The throwaway tip for deep-hole drilling is of a thick plate body having a three-fold symmetry with three cutting sections that are rotationally spaced apart at a central angle of 120 degrees. When mounted on a drill head, one cutting section of the throwaway tip faces a drilling direction. The forward facing blade edge of that cutting section includes an inner blade edge shorter in blade length and an outer blade edge longer in blade length forming an apex. The outer blade edge is composed of two consecutive blade edge portions of a peak-side outer blade edge portion having a smaller outer blade edge angle and a corner-side outer blade edge portion having a larger outer blade edge angle.

Abstract: Embodiments of the invention relate to a reamer for machining a workpiece by chip removal. Embodiments of the reamer can incorporate a holder, having a receiving opening disposed on a workpiece-side end face and having an internal thread, a holder bore extending inside the holder in a longitudinal direction thereof and opening into the receiving opening, an exchangeable head, having a cutting-nose element having a plurality of cutting noses disposed in a distributed manner in a circumferential direction, an exchangeable-head shank having an external thread corresponding to the internal thread disposed in the receiving opening, a bearing contact element disposed between the cutting-nose element and the exchangeable-head shank and having a first bearing contact surface for bearing contact on a first support surface disposed on the workpiece-side end face, with an exchangeable-head bore corresponding to the holder bore extends through the exchangeable head in a longitudinal direction thereof.

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: A cutting insert has a head portion and a coupling portion protruding rearwards from the head portion, along a longitudinal insert axis. The head portion has a base surface at a rearward end thereof, defining a base plane, and two major surfaces. A coupling portion rear surface is longitudinally spaced apart from the base surface and a cylindrical coupling peripheral surface extends between the coupling portion rear surface and the base surface. A resilience slit has two opposite inner walls converging forwards towards a slit inner end terminating at a slit inner end plane. The slit inner end plane is parallel to the base plane and spaced apart therefrom by a longitudinal distance. The inner walls of the resilience slit form an acute slit angle therebetween.

Abstract: A cutting tool having a shaft with a longitudinal axis, wherein the cutting tool includes a first flute extending about the longitudinal shaft along a helix angle and a first cutting edge adjacent the first flute. The cutting tool also includes a second flute extending about the longitudinal shaft along a helix angle and a second cutting edge adjacent a second flute. The cutting tool further includes a third flute extending about the longitudinal shaft along a helix angle and a third cutting edge adjacent the third flute. The first cutting edge, the second cutting edge, and the third cutting edge are unequally angularly spaced from each other.

Abstract: A boring bit includes a shank and a drilling head coupled to the shank. The drilling head includes a center tip and a pair of flanges. Each flange includes a cylindrical sidewall section, a cutting edge extending radially outward from the center tip to the sidewall section, a bottom face extending radially outward from the shank to the sidewall section, a rake face extending axially from the cutting edge to the bottom face, a rearward edge extending radially outward from the shank to the sidewall section and defining a boundary of the bottom face opposite the rake face, a spur extending axially from the sidewall section, and a chip channel defined at least in part by the sidewall section. The sidewall section of each flange extends through a sweep angle from the cutting edge to the rearward edge. The sweep angle is between about 30 degrees and about 60 degrees.

Abstract: A cutting drill includes a shank having a hole and formed to be gripped in a tool holder, and a drill body having a rod shape and locked into the hole of the shank. The shank has an axis around which the drill body rotates. The drill body has a cutting-edge portion forming a tip portion of the drill body and a neck portion having a diameter smaller than a diameter of the cutting-edge portion. The cutting-edge portion has a first cutting-edge portion and a second cutting-edge portion formed between the first cutting-edge portion and the neck portion. The first cutting-edge portion is contiguous to the second cutting-edge portion by a step portion such that the second cutting-edge portion has a diameter which is smaller than a diameter of the first cutting-edge portion.

Abstract: A drill tool including a drill body having an inner insert and an outer insert at an end portion of the drill body. The distance from a central axis of the drill body to the outer insert is greater than the distance from the central axis to the inner insert. The cutting edges of the inner and outer inserts can be chamfered with the inner insert chambered at a radially inward portion and the outer insert chamfered at a radially outward portion. The inner insert and the outer insert can be mirror symmetric to one another. The inner insert and the outer insert are mounted to the drill body such that an effective cutting length of the inner insert equals an effective cutting length of the outer insert, the effective cutting lengths being measured in a direction perpendicular to the central axis.

Abstract: A reamer for the precision machining of a drilled hole, having a plurality of cutting bars which are separated from one another by chip grooves and extend in the longitudinal direction of the tool, wherein a plurality of chip divider grooves which run in the transverse direction of the tool and divide each cutting bar into cutting segments are provided.

Abstract: One non-limiting aspect of the present disclosure is directed to a multi-piece spade drill head for a spade drill, wherein the spade drill includes an elongate body portion and a cutting portion removably secured to an end of the body portion. The multi-piece spade drill head includes at least two insert pieces, each piece including a cutting edge. The at least two insert pieces are configured to be removably secured to the body portion of the spade drill adjacent one another and with the cutting edges of the insert pieces aligned to together form a cutting edge on an end of the spade drill.

Abstract: Reaming tool includes a head and a detachable cutting insert fixed in a seat. The seat includes radial, tangential, and axial support surfaces, while the cutting insert has a mirror-symmetrical polyhedron shape comprising six limiting surfaces, viz. two chip surfaces and at least two clearance surfaces, a number of alternately usable, identical cutting edges formed in transitions between the chip and clearance surfaces. A female- or male-like securing means co-operates with a complementary, male- or female-like securing means in the seat, more precisely in an inactive, contactless state as long as the cutting insert is held pressed by the cutting forces against the axial support surface. The securing means is activatable when the cutting insert is unintentionally distanced from the axial support surface against the action of a clamping member. Tool head and reaming insert for the tool are disclosed.

Abstract: A holder of the present invention has a first insert pocket and a second insert pocket at the tip end thereof. The first insert pocket is located closer to the central axis thereof than the second insert pocket. The axial rake of the first insert pocket is larger than the axial rake of the second insert pocket.

Abstract: A cutting head includes a drill tip having a chisel edge, at least two main cutting edges, each extending between a central end at the chisel edge and an outer end. A recess is associated with each main cutting edge and located at each side of the chisel edge. Each recess includes a chip breaking groove extending along the main cutting edge and spaced from the main cutting edge by a distance. Furthermore, a twist drill has a cutting head and drill tip.

Abstract: The thread generating tool for producing a thread in a workpiece has the following features: a) the tool is rotatable about a tool axis (A), b) the tool has a number n?1 of groove generating regions for generating in each case one groove in the workpiece and a number m?1 of thread generating regions for generating the thread in the workpiece, c) each of the m thread generating regions is arranged behind one of the n groove generating regions as viewed in an axial projection parallel to the tool axis (A), and has a smaller extent than said groove generating region as viewed in cross section in the axial projection.

Abstract: [Problem] To provide a drill which enables a great reduction in cutting resistance and easy performance of a drilling operation by human power using a hand drill, a drilling machine, or the like. [Solution] A drill has two cutting edges formed symmetrically with respect to a rotation axis, and is subjected to thinning at the tip thereof. The cutting edge is configured from a thinned cutting edge (1) which extends in a shape including a curved line from a chisel edge to the outer peripheral side of the drill, and a main cutting edge (2) which extends from the end of the thinned cutting edge to the outer peripheral end of the drill when viewed from the tip side of the drill, and a thinned surface formed by the thinned cutting edge is formed into an approximately parabolic shape inclined in a drill axis direction when viewed from the front side of the drill.

Abstract: An end mill includes first cutting edges which spiral in a direction defining a positive helix angle and second cutting edges which spiral in a direction defining a negative helix angle, the first cutting edges and the second cutting edges being disposed at positions shifted in a circumferential direction. The first cutting edges and the second cutting edges are each configured to be continuous over an effective cutting edge length. At an axially forward end of the end mill, a first phase angle between one of the first cutting edges and its adjacent second cutting edge located adjacent to the first cutting edges in an opposite direction to a tool rotation direction is set to be different from a second phase angle between the second cutting edge and its adjacent first cutting edge located adjacent to the second cutting edges in the opposite direction to the tool rotation direction.

Abstract: A drill having a replaceable cutting head, modified to eliminate forces which would distort the pocket of the drill shank and otherwise concentrate stresses which would cause failure of the drill. The cutting head has a frustoconical depending connecting member received in a receptacle formed in the shank. In different embodiments, contact between the pocket formed in the shank and the cutting head connecting member is limited. In one embodiment, angle of drive surfaces is modified from prior art practice. In another embodiment, transition of at curved joints between vertical and horizontal surfaces is made more gradual. The drill preferably has flutes formed collectively by the shank and cutting head when assembled.