AU2013224705A1 - A drill bit and method for producing a drill bit - Google Patents

Abstract

Abstract The present invention provides a drill bit comprising a shaft having a drilling end defining a drill point; at least one face that extends to at least partially define the drill point, the or each face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute defined in the shaft for directing away debris produced during drilling. Fig. 1 1 109a 105 109b 107b 115 111a r1T

Description

- 1 A DRILL BIT AND METHOD FOR PRODUCING A DRILL BIT Field of the Invention [0001] The present invention relates to a drill bit and method for producing a drill bit, and is of particular but by no means exclusive application to drilling bones, cartilage and similar structures during orthopaedic surgery. Background of the Invention [0002] The use of drill bits for orthopaedic surgery is known. However, a problem can occur with existing orthopaedic drill bits when drilling through bone and cartilage. Specifically, bone has a covering known as periosteum which has a slippery characteristic. When drilling, particularly in difficult surgical procedures, it has been known for drill bits to slip off the periosteum, potentially causing damage to the periosteum and bone, and to adjacent body parts including muscles, tendons, skin, organs etc. Summary of the Invention [0003] In accordance with a first aspect, the present invention provides drill bit comprising: a shaft having a pyramidal shaped end defining a drill point; at least one face that extends to at least partially define the drill point, the or each face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute defined in the shaft for directing away debris produced during drilling; wherein the at least one flute intersects with the at least one face, such that, in end view, the flute is offset from a central part of the face; and wherein the flute intersects the face in a manner that defines a continuous curve at the flute-face intersection. [0004] Preferably, each edge defines a cutting edge and preferably the or each recess is located to further define the cutting edge.

-2 [0005] Preferably each edge extends from the shaft to a remote point of the drill tip. [0006] By employing a cutting edge the drill tip can quickly create a securing hole which secures the drill bit in position so as to prevent the drill bit from moving over the surface of the material when starting to drill. [0007] Preferably, the depth of the second portion of each of the recesses varies along a length thereof relative to a surface of the drill tip so that the cutting ability of the edge adjacent to the point of the drill bit is less than the cutting ability of the edge adjacent to the shaft. [0008] By reducing the cutting ability of the cutting edge adjacent to the point, the drill bit is less likely to break when drilling is commenced. This is because the edge adjacent to the point is less likely to lock with the material into which the drill is entering. [0009] Preferably, the first portion of the or each recess is substantially helical in shape, whilst the second portion of the or each recess is substantially straight. [0010] Preferably, the drill tip includes at least three edges which define the pyramidal shape of the drill tip. [0011] Preferably, at least three corresponding surfaces extend between the three edges. Prior to forming the or each recess the surfaces may be flat (planar) or concave with respect to the drill bit. [0012] Preferably, the second portion of the or each recess extends along a respective one of the surfaces. [0013] Preferably, the edge of the drill tip is bevelled so as to enhance the cutting ability of the cutting edge. [0014] In accordance with a second aspect, the present invention provides a drill bit comprising: a shaft having a pyramidal shaped end defining a drill point; at least one face that extends to and helps define the drill point, the or each -3 face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute defined in the shaft for directing away debris produced during drilling, with the at least one flute intersecting with the at least one face, wherein the or each face: (a) is curved or v-shaped concavely into the shaft; and (b) has a chamfer or a v-shaped groove along one edge thereof. [0015] Preferably, the step of forming the one or more recesses includes moving a grinding element outwardly from the drill tip as it moves therealong such that the depth of the second portion of each of the recesses varies along a length thereof relative to a surface of the drill tip. [0016] Preferably, the or each recess is formed adjacent to a respective edge such that the cutting ability of the edge adjacent to a point of the drill tip is less than the cutting ability of the edge adjacent to the shaft. [0017] In accordance with a third aspect, the present invention provides a drill bit comprising: a shaft having a pyramidal shaped end defining a drill point; at least one face that extends to and helps define the drill point, the or each face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute defined in the shaft for directing away debris produced during drilling, with the at least one flute intersecting with the at least one face, such that, in end view, the flute is offset from a central part of the face. [0018] By offsetting the flute in this manner, the present inventor has discovered that e.g. bone debris can be rapidly released and directed away from the drill end, and yet a strong drill point can be formed which can be securely located at the bone. The inventor has observed that a strong point can be forced through the periosteum to provide a means against slippage and to then enable rapid drilling of the bone. Such a drill point may also preliminarily puncture the bone and then, when driven, cut away the bone, the flute location then rapidly directing away debris produced during such cutting. [0019] Preferably, the flute intersects the face in a manner that defines a continuous curve at the flute-face intersection.

-4 [0020] This curving further enhances and smooths the directing away of debris produced during bone drilling. [0021] Preferably the or each face: (a) is flat, being defined as a bevel; (b) is curved or v-shaped concavely into the shaft; (c) has a chamfer or a v-shaped groove along one edge thereof. [0022] In accordance with a fourth aspect, the present invention provides drill bit comprising: a shaft having a drilling end, the drill having: a drilling end point; a distal portion having three faces meeting at a common point, the three faces arranged in a pyramid shape and the three faces defining cutting edges; a proximal portion extending away from the distal portion, the proximal portion including a continuing portion of at least one face; the shaft including: a flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with the said face to form a first portion of a trailing edge of at least one face; and a v-shaped groove surface disposed between the drilling end point and the flute surface, said v-shaped groove intersecting with the continuous portion of the at least one face to form a second portion of the trailing edge of the face, the v-shaped groove surface intersecting the flute surface and arranged to direct debris into the flute surface, the second portion of the trailing edge defining a piercing edge, the piercing edge enhancing insertion of the drilling end point along the longitudinal axis and into the surface of the material being drilled. a drilling end point; a distal portion having three faces meeting at a common point, the three faces arranged in a pyramid shape and the three faces defining cutting edges; a proximal portion extending away from the distal portion, the proximal portion including a continuing portion of at least one face; the shaft including: a flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with the said face to form a first portion of a trailing edge of at least one face; and -5 a v-shaped groove surface disposed between the drilling end point and the flute surface, said v-shaped groove intersecting with the continuous portion of the at least one face to form a second portion of the trailing edge of the face, the v-shaped groove surface intersecting the flute surface and arranged to direct debris into the flute surface, the second portion of the trailing edge defining a piercing edge, the piercing edge enhancing insertion of the drilling end point along the longitudinal axis and into the surface of the material being drilled. [0023] In accordance with a fifth aspect, the present invention provides a drill bit comprising: a shaft having a pyramid shaped drilling end; at least one face that extends from said end point and defining a cutting edge, said one face disposed at an acute angle with the longitudinal axis of said shaft; a flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with the said face; and a second surface disposed between said end point at said flute surface, said second surface extending along a portion of said cutting edge and affecting the sharpness of said cutting edge. [0024] In accordance with a sixth aspect, the present invention provides a drill bit comprising: a shaft having a drill end, the drill end having: a drilling point; a distal portion having a plurality of faces extending from the drilling point, each face defining a respective cutting edge and the plurality of faces arranged in a pyramidal structure, such that the pyramidal structure defines the drill end point; a proximal portion extending away from the distal portion, the proximal portion including a continuing portion of at least one face; the shaft further having: a flute surface defined in the shaft for directing away debris produced during drilling, the flute surface intersecting with the continuing portion of the at least one face to form a first portion of a trailing edge of the at least one face and a terminal end; and a second surface located at the terminal end of said flute surface and disposed between the drilling end point and the terminal end, the second surface intersecting with the continuing portion of the at least one face to form a second portion -6 of the trailing edge of the at least one face, the second surface intersecting the flute surface and arrange to direct debris into the flute, the second portion of the trailing edge defining a piercing edge supplementing the respective cutting edges formed by the plurality of faces, the piercing edge enhancing insertion if the drilling end point along the longitudinal axis and into a surface of a material being drilled. [0025] In accordance with a seventh aspect, the present invention provides a drill bit comprising: a cylindrical shaft and a drill tip, the drill tip comprising: a pyramidal shaped end, the pyramidal shaped end having a distal portion comprising a plurality of faces, the faces meeting at a common point and defining a drill terminal point on the longitudinal axis of the shaft; and the drill tip comprising a proximal portion having the cutting edges extending therealong; a plurality of recesses for directing debris produced while drilling, each recess having two portions; a first recess portion extending along the shaft, the first recess portion extending adjacent the proximal portion and intersecting one of the cutting edges of the plurality of the cutting edges to terminate one of the cutting edges at a point spaced within the outer periphery of the shaft, the first recess portion providing a leading edge disposed at a negative cutting angle relative to the cutting surface at the outer periphery; and a second recess portion formed in the proximal portion of the pyramidal shaped end, the second recess portion extending toward another cutting edge of the plurality of cutting edges. [0026] In accordance with an eighth aspect, the present invention provides a drill bit comprising: a shaft and a pyramidal shaped end defining a drill point; at least one face on said pyramidal end that at least in part defines the drill point, the at least one face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute disposed substantially along the shaft and extending away from said pyramidal end, said at least one flute aligned with said at least one face for directing away debris produced during drilling, said at least one flute intersecting with -7 said at least one face, such that, in end view, the flute is offset from a center line of the face, and wherein the flute intersects the face in a non-abrupt manner defining a continuous curved surface at the flute-face intersection, said curved surface leading from the face into the flute whereby channeling of debris into the flute is enhanced, wherein the at least one flute extends generally spirally away from its respective face and substantially along the shaft. [0027] In accordance with a ninth aspect, the present invention provides a drill bit comprising: a shaft and a drill tip, said drill tip having three cutting edges defining a pyramidal shaped end, said pyramidal shaped end having three faces, said three faces being uniform in shape and defining said cutting edges, said pyramidal shaped end having: (a) a distal portion comprised of said three faces meeting at a common point defining said drill end point located on the longitudinal axis of said shaft; and (b) a proximal portion; each of said cutting edges of both said distal portion and said proximal portion being defined as straight and extending along both said distal portion and said proximal portion, from said end point to said shaft; a plurality of recesses for directing away debris produced during drilling, each of said recesses having: (a) a first recess portion extending along a substantial length of the shaft; and (b) a second recess portion located in said proximal portion of said pyramidal shaped end, said second recess portion extending from said first recess and terminating in said proximal portion, and extending adjacent to a portion of one of said cutting edges in said proximal portion; and wherein the depth of said second recess portion varies along its length, relative to the surface of the drill tip so that the portion of said cutting edge located adjacent said second recess has a lesser cutting ability nearer said end point than said shaft. [0028] In accordance with a tenth aspect, the present invention provides an orthopedic drill bit for drilling brittle material, such as bone, comprising (A) a shaft and (B) a drill tip, A. said shaft having (1) a shaft end, and -8 (2) at least one first recess for directing away debris produced while drilling, said first recess is helical in shape and having a constant depth throughout a substantial portion of its length, said first recess forming a lateral cutting edge along said shaft; B. said drill tip located at said shaft end, said drill tip having: (a) a distal portion; and (b) a proximal portion; said distal portion having a pyramidal shape and comprising: (i) three faces that are planar and of uniform shape, meeting at a common point; (ii) three straight first cutting edges defined by said three faces, each said first cutting edges having a first cutting ability which is uniform along each said first cutting edge and; (iii) a drill end point defined by the meeting of said three faces at said common point, said drill end point located on the longitudinal axis of said shaft, said first cutting edges extending from said drill end point to said proximal portion; said proximal portion of said drill tip having (i) three straight second cutting edges, each said second cutting edge extending from a said first cutting edge to the periphery of the shaft, and (ii) a second recess aligned with and extending from said first recess and terminating in said proximal portion, said second recess forming a surface varying in depth and extending along a portion of a said second cutting edge, said second cutting edge along which said surface extends having a second and varied cutting ability defined by the depth of said second recess, said second and varied cutting ability having a lesser cutting ability nearest said drill end point than said shaft; and wherein said shaft has a longitudinal axis and wherein each of said first cutting edges in said distal portion has a greater acute angle with the longitudinal axis of the shaft than each of said second cutting edges in said proximal portion. [0029] In accordance with an eleventh aspect, the present invention provides a drill bit for drilling into a surface of a material comprising: a shaft having a drill end, said drill end having: (1) a drilling end point; (2) a distal portion having three faces meeting at a common point defining said drill end point located on the longitudinal axis of said shaft, said three faces arranged in a pyramidal shape, said three faces defining three cutting edges; and (3) a proximal portion extending away from said distal portion, said proximal portion including a continuing portion of at least one face of said three faces; -9 said shaft further including: (a) at least one flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with said continuing portion of said one face of said three faces to form a first portion of a trailing edge of said one face; and (b) a V-shaped groove surface disposed between said drilling end point and said flute surface, said V-shaped groove surface intersecting with said continuing portion of said one face to form a second portion of the trailing edge of said one face, said V-shaped groove surface intersecting said flute surface and arranged to direct debris into said flute surface, said second portion of said trailing edge defining a piercing edge, said piercing edge enhancing insertion of said drilling end point along said longitudinal axis and into the surface of the material being drilled. [0030] In accordance with a twelfth aspect, the present invention provides a drill bit comprising: a shaft having a drill end, said drill end having: (1) a drilling end point; (2) a distal portion having a plurality of faces extending from said drilling end point, each face of the plurality of faces defining a respective cutting edge, said plurality of faces arranged in a pyramidal structure; and (3) a proximal portion extending away from said distal portion, said proximal portion including a continuing portion of at least one face of said plurality of faces; said shaft further including: a flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with said continuing portion of said at least one face to form a first portion of a trailing edge of said at least one face and forming a terminal end; and a second, grooved surface located at the terminal end of said flute surface and disposed between said drilling end point and said terminal end, said second, grooved surface intersecting with said continuing portion of said at least one face to form a second portion of the trailing edge of said at least one face, said second, grooved surface intersecting said flute surface and arranged to direct debris into said flute, said second portion of said trailing edge defining a piercing edge supplementing the respective cutting edges formed by the plurality of faces, said piercing edge enhancing -10 insertion of said drilling end point along said longitudinal axis and into a surface of a material being drilled. [0031] In accordance with a thirteenth aspect, the present invention provides an orthopedic drill bit comprising: a cylindrical shaft and a drill tip, said drill tip comprising: a pyramidal shaped end having a plurality of cutting edges, said pyramidal shaped end having (a) a distal portion comprising a plurality of faces defining said cutting edges, said faces meeting at a common point and defining a drill end point located on the longitudinal axis of said shaft; and (b) a proximal portion having said cutting edges extending therealong; a plurality of recesses for directing away debris produced while drilling, each said recess having two portions: (1) a first recess portion extending along said shaft, said first recess portion extending adjacent said proximal portion and intersecting one of said cutting edges of said plurality of cutting edges to terminate said one of said cutting edges at a point spaced within the outer periphery of said shaft, said first recess portion providing a leading edge disposed at a negative cutting angle to the cutting surface at said outer periphery; and (2) a second recess portion formed in said proximal portion of said pyramidal shaped end, said second recess portion extending toward another cutting edge of said plurality of cutting edges of said pyramidal shaped end. [0032] In accordance with a fourteenth aspect, the present invention provides a drill tipped shaft for use during surgery for initial longitudinal insertion into periosteum and other body material, such as cartilage and bone material, followed by rotational movement to a further depth in the body material, said drill tipped shaft comprising a shaft having: (1) an end portion defining a drill tip for creating a securing hole in the body material to prevent the end portion from slipping on periosteum and other body material as the shaft begins to rotate, said end portion having a pyramidal shaped end formed from three faces intersecting to form three first cutting edges disposed relative to one another to provide for initial longitudinal insertion of said shaft into the body material and to cut away bone material during rotation of said shaft, each of said three faces - 11 intersecting with two of the other faces so as to define two of said three first cutting edges; (2) a second portion extending rearwardly of said end portion, said second portion having a. three chamfered faces defining three second cutting edges, each of said second cutting edges extending from one of said first cutting edges; and b. three curved faces, each of said curved faces having a concave shape and intersecting with two of said chamfered faces so as to define both a said second cutting edge of one of said chamfered faces and a trailing edge of another of said chamfered faces; and (3) a third portion extending rearwardly of said second portion, said third portion having three recess surfaces for directing away debris produced during rotational movement of the shaft, each of said three recess surfaces intersecting with one of said curved faces for directing debris from one of said curved faces into said one of said recess surfaces. [0033] In accordance with a fifteenth aspect, the present invention provides a drill tipped shaft for use during surgery for initial longitudinal insertion into periosteum and other body material, such as cartilage and bone material, followed by rotational movement to a further depth in the body material, said drill tipped shaft comprising a shaft having: (1) an end portion defining a drill tip for creating a securing hole in the body material to prevent the end portion from slipping on periosteum and other body material as the shaft begins to rotate, said end portion having a pyramidal shaped end formed from three faces intersecting to form three first edges disposed relative to one another to provide for initial longitudinal insertion of said shaft into the body material and to cut away bone material during rotation of said shaft, each of said three faces intersecting with two of the other faces so as to define two of said three first edges; (2) a second portion extending rearwardly of said end portion, said second portion havinga. three ground faces defining three second edges, each of said second edges extending from one of said first edges; andb. three curved faces, each of said curved faces having a concave shape and intersecting with two of said ground faces so as to define both a said second edge of one of said ground faces and a trailing edge of another of said ground faces; and (3) a third portion extending rearwardly of said second portion, said third - 12 portion having three recess surfaces for directing away debris produced during rotational movement of the shaft, each of said three recess surfaces intersecting with one of said curved faces for directing debris from one of said curved faces into said one of said recess surfaces. [0034] In accordance with a sixteenth aspect, the present invention provides a drill tipped shaft for use during surgery for initial longitudinal insertion into periosteum and other body material, such as cartilage and bone material, followed by rotational movement to a further depth in the body material, said drill tipped shaft comprising a shaft having: (1) an end portion defining a drill tip for creating a securing hole in the body material to prevent the end portion from slipping on periosteum and other body material as the shaft begins to rotate, said end portion formed from three faces intersecting to form three first edges disposed relative to one another to provide for initial longitudinal insertion of said shaft into the body material and to cut away bone material during rotation of said shaft, each of said three faces intersecting with two of the other faces so as to define two of said three first edges; (2) a second portion extending rearwardly of said end portion, said second portion having a. three ground faces defining three second edges, each of said second edges extending from one of said first edges; and b. three curved faces, each of said curved faces having a concave shape and intersecting with two of said ground faces so as to sharpen the said second edge of one of said ground faces to enhance cutting during shaft rotation and to define a trailing edge of another of said ground faces; and (3) a third portion extending rearwardly of said second portion, said third portion having three recess surfaces for directing away debris produced during rotational movement of the shaft, each of said three recess surfaces intersecting with one of said curved faces for directing debris from one of said curved faces into said one of said recess surfaces. Brief Description of the Drawings [0035] Notwithstanding any other embodiments which may fall within the scope of the present invention, a preferred embodiment of the present invention will now be -13 described, by way of example only, with reference to the accompanying drawings, in which: [0036] Figure 1 illustrates a perspective view of a first drill bit according to a preferred embodiment of the present invention; and [0037] Figure 2 illustrates an end view of the first drill bit shown in Figure 1. [0038] Figures 3A to 3C respectively show an enlarged end, and side and perspective views of a second drill bit in accordance with the preferred embodiment of the present invention; [0039] Figures 4A to 4D respectively show front, end, side and perspective views of the second drill bit of Figure 3, but in outline; [0040] Figures 5A to 5C respectively show an enlarged end, and side and perspective views of a third drill bit in accordance with the preferred embodiment of the present invention; [0041] Figures 6A to 6C respectively show an enlarged end, and side and perspective views of a fourth drill bit in accordance with the preferred embodiment of the present invention; [0042] Figures 7A to 7D respectively show an enlarged end, and side, perspective and reverse perspective views of a fifth drill bit in accordance with the preferred embodiment of the present invention; [0043] Figures 8A to 8C respectively show an enlarged end, and side and perspective views of a sixth drill bit in accordance with the preferred embodiment of the present invention; [0044] Figures 9A to 9C respectively show an enlarged end, and side and perspective views of a seventh drill bit in accordance with the preferred embodiment of the present invention; and -14 [0045] Figures 10A to 10C respectively show an enlarged end, and side and perspective views of a eighth drill bit in accordance with the preferred embodiment of the present invention. Preferred Embodiment of the Present Invention [0046] Figure 1 shows, a first drill bit 101 according to the preferred embodiment of the present invention. The drill bit 101 includes a shaft 103 which has a pyramidal shaped end 105 defining a drill tip. The material from which the drill bit 101 is made depends on the intended application of the drill bit 101. However, for orthopaedic surgery, the drill bit 101 is made from surgical quality stainless steel. Whilst not illustrated in the figures, the other end of the drill bit 101 is adapted for mounting in a motorized drill chuck. For example, the other end of the drill bit 101 can be provided with a series of graduations, a cut-away and a circumferential groove in the shaft 103 adjacent the other end so as to facilitate its coupling in the chuck of a drive of a motorised surgical drill. The graduations can be used to indicate depth of insertion of the drill bit into the drive chuck and into the patient. [0047] The drill bit 101 also includes one or more recesses in the form of grooves 107, each of which includes a first portion 109 extending at least partway along the shaft 103 and a second portion 111 which extends along an edge 113 of the drill tip. Typically edge 113 defines a cutting edge. The edge 113 also includes bevelling so as to enhance the cutting ability of the cutting edge. The grooves 107 allow debris which is produced whilst drilling to be channelled away from the hole while being drilled. The first portion 109 of each of the grooves 107 spirals along the shaft 103 so as to form of a helix, whilst the second portion 111 is substantially straight (that is, tending to align with a longitudinal axis of the shaft). Each of the grooves 107 typically has an arcuate semi cylindrical shape in cross-section and along its length. However, other suitable profiles such a V-shape or square shape may be employed. [0048] The depth of the second portion 111 of each of the grooves 107 varies along the length of the second portion 111 relative to the surface of the drill tip in which the second portion 111 is located. More specifically, the depth of the second portion 111 of each of the grooves 107 becomes shallower towards the point 115 of the drill bit 101. This provides the cutting edge located nearer the point 115 with a lesser cutting ability -15 than the portion of the cutting edge 119 located nearer the shaft. The advantage of this is that the drill tip is less likely to break as a result of locking with the material into which the drill bit 101 is entering. [0049] The pyramidal shaped end 105 is formed from three elongate surfaces, but more surfaces can be employed if desired. Increasing the number of surfaces to define the pyramidal shaped end 105 results in more edges 113 which can define more cutting edges. [0050] Also, the pyramidal shaped end 105 is relatively longer than the drill tip of existing drills. This provides an extreme point 115 which assists in securely locating the drill bit 101 so as to prevent movement thereof when drilling is started. The assistance is provided as a result of the extreme point 115 piercing the periosteum and puncturing the outer surface of the bone, thereby locating the drill bit 101 in place prior to drilling. Each of the surfaces forming the pyramidal shaped end 105 subtends an angle with the longitudinal axis of the drill bit 101. The angle is typically around 300, but may be varied depending on the application (for example, hardness of the material to be drilled). [0051] As mentioned previously, the drill bit 101 is made from a material that is suitable for the intended application. For example, where the drill bit 101 is intended to be used in orthopaedic surgery the drill bit 101 is made from surgical quality stainless steel. The drill bit 101 is made from a blank rod of the appropriate material. Using a suitable grinder, one of the ends of the blank rod can be ground down so as to form the pyramidal shaped end 105 and adapt the other end of the drill bit 101 so that the drill bit 101 can be retained by a chuck of a drill. [0052] The grinding machine can also be used to form the grooves 107. When forming the first portion 109 of each of the grooves 107, the grinding wheel of the machine remains fixed so that the first portion 109 has a constant depth. However, when forming the second portion 111 of the grooves 107, the grinding wheel is gradually moved outwardly from the drill tip as it moves towards the point 115. Moving the grinding wheel outwardly results in the second portion 111 having a depth that varies along the length of the drill tip. This characteristic produces a cutting edge which has a lesser cutting ability about the point 115 and which increases in cutting ability towards the shaft 103. Having a lesser cutting ability at the point 115 reduces the likelihood of - 16 the point 115 breaking off when drilling is commenced due to the cutting edge locking with the material into which the hole is being drilled. [0053] Referring to figure 3, which shows a second drill bit 310, the drill bit 310 includes a drill shaft 312, the opposite end 313 of which is adapted for mounting in a motorised drill chuck. For example, for orthopaedic procedures, the opposite end of the shaft can be provided with a series of gradations 314, a cut-away 315 and a circumferential groove 316 adjacent to end 313 to facilitate its coupling in the chuck of a drive of a motorised surgical drill. The gradations can be used to indicate depth of insertion of the drill bit in both the drive chuck and into a patient. [0054] A plurality of spiral flutes 317 extend from near the drilling end 318 and part way along the shaft 312. Each flute is typically an arcuate semi-cylindrical groove extending in the shaft, but may be V-shaped, square shaped etc. in cross-section. Each flute provides a passageway for the release of debris cut by the drill bit as it is inserted through a substrate (typically a bone). Usually two or three such spiral flutes are provided in the drill bit to maximise debris release. [0055] A drill point 319 is provided at drilling end 318, the drill point being substantially elongated, tapered and pointed when compared with a conventional drill bit. In effect, the drill point is provided as a trocar-type formation. [0056] Further, one or more, and typically three, bevelled faces 320 are provided and combine to define the drill point 319 at drilling end 316, each face subtending an angle a with a longitudinal axis AX through the shaft 312. Typically, the subtended angle a is around 300, although it may be varied depending on the application (e.g. hardness of material to be drilled). The three faces generally provide end 318 with a triangular pyramidal appearance. [0057] Advantageously, the formation of bevelled faces 320 define cutting edges 322 along the side of each bevelled face which facilitate cutting and thus drilling into a bone or similar when the drill bit is rotated.

-17 [0058] The formation of an extreme drill point 319 at drilling end 318 also enables the drill to be securingly located at a bone, piercing the periosteum and puncturing the outer surface of the bone to locate the drill bit in place prior to drilling. [0059] In accordance with the present invention, and as best shown in Figure 3A, each flute 317 intersects with a respective face 320 at a location that is offset from a centre line CL through the face 320. The advantage of this offsetting is that it facilitates maximum debris removal during cutting of bone, cartilage and other bodily material. [0060] For example, referring to Figure 3A, and assuming a counter clock-wise rotation of the drill, uppermost face 320' defines a leading edge 322' and a trailing edge 322". It will be see that flute 317' is located adjacent to the trailing edge. Thus, as the drill rotates and leading edge 322' cuts through a material, debris passes across and is accommodated by a maximal face area 320', prior to passing into flute 317'. This maximal face area prevents bunching or blocking of debris at the face and enhances debris release away from the drill point. Therefore, an optimal location for the intersection of each flute with its respective face is adjacent to the trailing edge for that face, as shown in Figure 3A. Advantageously, rapid debris removal also facilitates more rapid drilling. [0061] Referring now to Figures 5A to 5C, where like reference numerals are used to denote similar or like parts, drilling end 518 is now provided with four bevelled faces 520 (which in this embodiment are typically flat faces). The four faces generally provide end 518 with a square pyramidal appearance. [0062] As can be clearly seen from Figure 5A, only two of the faces (in this case two opposing faces) are provided with a flute 517 intersecting therewith. Again, these flutes are offset from a central part of their respective face to enhance debris removal as described above. The unfluted faces also provide an enhanced trocar-like affect to the drilling end 518. [0063] It will also be seen in Figure 5 that the flutes 517 are enlarged compared with the flutes of the drill bit of Figures 3 and 4. This is to ensure that the rate of debris release is maintained with the lesser flute number, and this also enables the flutes to pick up debris that passes across the unfluted faces (i.e. as the drill rotates at rapid -18 speeds). Otherwise, the operation of the drill bit is the same as the drill bit of Figures 3 and 4. [0064] Referring now to Figure 6, where like reference numerals are used to denote similar or like parts, a surgical drill bit having three faces at drilling end 618, similar to the drill bit of Figures 3 and 4, is shown. Each face also has a respective flute intersecting therewith, however, in this embodiment the intersection between the flute and its respective face is not abrupt but is gradual as facilitated by a continuous curved region 626. This region provides a kind of scalloping or concavity in each face 620, thus enhancing the definition of the drill point 619, but also providing a more pronounced channelling affect into each flute to guide and enhance the removal of debris cut by the rotating drill bit. [0065] The more pronounced drill point facilitates easier drill bit location at slippery cutting surfaces and easier penetration. The region 626 facilitates more rapid removal of debris and thus even faster drill cutting. [0066] Referring now to Figures 7A to 7D, the drill bit of Figure 6 is further modified in that each face 720 is concaved inwardly with respect to the drill bit, defining an arcuate 3D scalloped surface. This is best seen with reference to Figure 7D. [0067] The effect of this scalloping is that the drill point 719 is even further pointed or sharpened, and the cutting edges become curved along their length and again are further sharpened (i.e. because of the more rapid dropping away of each face 720 on either side of the cutting edge). [0068] The drill bit of Figure 7 also employs the continuous curved region 726 at the intersection of flute 717 and face 720 so that debris cut by the drilling end is rapidly conveyed away therefrom in use. [0069] In figure 7, in end view (i.e. Figure 7A) the concave face is typically symmetrical about face centre line CL. However, the concave face can be defined asymmetrically about the centre line, for example, so that adjacent to the leading edge 722', the face slopes more steeply away, and slopes more gradually up towards the trailing edge 722". This asymmetric offset of the concavity at each face can sharpen the -19 leading edge relative to the trailing edge and can enhance debris being directed towards flute 717 (i.e. by pressure differentials etc.). The operation of the drill bit of Figure 7 is in other respects similar to that previously described. [0070] Referring now to Figure 8, the inwardly concave curved face of Figure 7 is replaced by two flat sub-faces 827 and 828. The sub-faces 827 and 828 in end view (i.e. Figure 8A) define face 820 as a type of tapering V-shaped groove (i.e. tapering down to drill point 819). Again, the employment of a concave V-shaped face 820 sharpens or pronounces the edges 822, and also assists in directing debris towards flute 817 via curved region 826. [0071] Again, typically the sub-faces 827 and 828 are arranged symmetrically about face centre line CL, but may be asymmetrically offset to e.g. more steeply slope away from the leading edge 822' as opposed to the trailing edge 822". Again, this can define a sharper cutting edge and assist with the distribution of debris away from the drilling end 818. [0072] Referring now to Figures 9A to 9C, where like reference numerals are used to denote similar or like parts, a drill bit having either flat faces 920 as shown in Figure 6, or curved faces as shown in Figure 7 is depicted. In any case, in this embodiment a chamfer 930 is provided that slopes away from the leading edge 922 and into its respective face as best shown in Figure 9A. As also best shown in Figure 9A, a small section 931 of chamfer 930 continues on and extends partway up trailing edge 922", so that drill point 919 is defined by the merging of three chamfered faces and thus is unitary and pyramidal in shape (i.e. trocar-like). [0073] This chamfering arrangement increases the strength of the drill point and prevents it from breaking away where other point configurations might otherwise fail in extreme situations. Otherwise, the drill bit of Figure 9 is similar in construction to the drill bit of Figures 6 and 7 and operates in a similar manner to the drill bits previously described. [0074] Referring now to Figures 1OA to 10C, where like reference numerals are used to denote similar or like parts, a further modified drill bit is shown. In this embodiment, the faces 1020 are typically flat (although may be slightly concave) in a similar manner - 20 to Figure 3. Also, in this embodiment no continuous curve region at the intersection of flute 1017 and face 1020 is depicted, although such a region may be provided as appropriate. [0075] Unique to this embodiment is the provision of a V-shaped groove 1032 running along the trailing edge 1022", from the drill point 1019 to the flute 1017. The V-shaped groove 1032 terminates in the flute 1017 and provides a further means for the channelling and directing of debris into the flute. In addition, it sharpens the leading edge 1022' of each face 1020, thus enhancing cutting. It also provides for the release of debris entrained in front of the leading edge as the drill bit rotates. The V-shaped groove 1032 can be symmetric or asymmetric as described above, with the advantages as described above. [0076] Furthermore, in this embodiment at drill point 1019, in effect six cutting edges are provided to further enhance insertion of the drill bit through the periosteum and to promulgate rapid cutting of the drill bit into bone etc. [0077] The operation of the drill bit of Figure 10 is otherwise as described for the previous drill bits. [0078] Typically the flutes, faces and grooves are machined onto the shaft 1012, and typically the shaft 1012 is formed from surgical stainless steel. [0079] The shaft is typically cylindrical and circular in cross-section, although other cross-sectional shapes (e.g. hexagonal or octagonal) may be employed. [0080] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It should be understood that the invention includes all such variations and modifications which fall within the spirit and scope of the invention.

Claims (40)

1. A drill bit comprising: a shaft having a pyramidal shaped end defining a drill point; at least one face that extends to at least partially define the drill point, the or each face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute defined in the shaft for directing away debris produced during drilling; wherein the at least one flute intersects with the at least one face, such that, in end view, the flute is offset from a central part of the face; and wherein the flute intersects the face in a manner that defines a continuous curve at the flute-face intersection.

2. A drill bit in accordance with Claim 1, wherein the drill tip has a distinct pyramidal head located at the drill point.

3. A drill bit in accordance with Claim 2, wherein the distinct pyramidal head is integrally formed with the drill tip.

4. A drill bit in accordance with any one of the above claims wherein the or each face: (a) is flat, being defined as a bevel; (b) is curved or v-shaped concavely into the shaft; and (c) has a chamfer or a v-shaped groove along one edge thereof.

5. A drill bit in accordance with Claim 4, wherein in (c) the flute extends into the face adjacent to said one edge.

6. A drill bit in accordance with Claim 5, wherein the flute intersects with the v-shaped groove.

7. A drill bit in accordance with any one of Claims 2 to 6, wherein three faces are provided at the drilling end, each evenly offset with respect to the other two and each tapering down to the drill point to provide the drill tip with the appearance of a triangular pyramid. - 22

8. A drill bit in accordance with Claim 7, wherein the pyramidal drill head is in the form of a triangular pyramid.

9. A drill bit in accordance with Claim 7 or 8, wherein a respective flute is provided to intersect with each face.

10. A drill bit in accordance with any one of Claims 2 to 6, wherein four faces are provided at the drilling end, each evenly offset with respect to adjacent faces on either side thereof and each tapering down to the drill point to provide the drill tip with the appearance of a square pyramid.

11. A drill bit in accordance with Claim 10, wherein the pyramidal drill end is in the form of a square pyramid.

12. A drill bit in accordance with Claims 10 or 11, wherein a respective flute is provided to intersect with each of only two of the faces, being opposing faces at the drill tip.

13. A drill bit in accordance with any one of the above claims, wherein each flute extends generally spirally away from its respective face and at least part way along the shaft.

14. A drill bit comprising: a shaft having a pyramidal shaped end defining a drill point; at least one face that extends to and helps define the drill point, the or each face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute defined in the shaft for directing away debris produced during drilling, with the at least one flute intersecting with the at least one face, wherein the or each face: (a) is curved or v-shaped concavely into the shaft; and (b) has a chamfer or a v-shaped groove along one edge thereof.

15. A drill bit comprising: a shaft having a pyramidal shaped end defining a drill point; at least one face that extends to and helps define the drill point, the or each - 23 face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute defined in the shaft for directing away debris produced during drilling, with the at least one flute intersecting with the at least one face, such that, in end view, the flute is offset from a central part of the face.

16. A bit as claimed in any one of Claims 15 to 22, wherein the or each flute extends generally spirally away from its respective face and at least part way along the shaft.

17. A drill bit comprising: a shaft having a drilling end, the drill having: a drilling end point; a distal portion having three faces meeting at a common point, the three faces arranged in a pyramid shape and the three faces defining cutting edges; a proximal portion extending away from the distal portion, the proximal portion including a continuing portion of at least one face; the shaft including: a flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with the said face to form a first portion of a trailing edge of at least one face; and a v-shaped groove surface disposed between the drilling end point and the flute surface, said v-shaped groove intersecting with the continuous portion of the at least one face to form a second portion of the trailing edge of the face, the v-shaped groove surface intersecting the flute surface and arranged to direct debris into the flute surface, the second portion of the trailing edge defining a piercing edge, the piercing edge enhancing insertion of the drilling end point along the longitudinal axis and into the surface of the material being drilled. a drilling end point; a distal portion having three faces meeting at a common point, the three faces arranged in a pyramid shape and the three faces defining cutting edges; a proximal portion extending away from the distal portion, the proximal portion including a continuing portion of at least one face; the shaft including: a flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with the said face to form a first portion of a trailing edge of at least one face; and - 24 a v-shaped groove surface disposed between the drilling end point and the flute surface, said v-shaped groove intersecting with the continuous portion of the at least one face to form a second portion of the trailing edge of the face, the v-shaped groove surface intersecting the flute surface and arranged to direct debris into the flute surface, the second portion of the trailing edge defining a piercing edge, the piercing edge enhancing insertion of the drilling end point along the longitudinal axis and into the surface of the material being drilled.

18. A drill bit comprising: a shaft having a pyramid shaped drilling end; at least one face that extends from said end point and defining a cutting edge, said one face disposed at an acute angle with the longitudinal axis of said shaft; a flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with the said face; and a second surface disposed between said end point at said flute surface, said second surface extending along a portion of said cutting edge and affecting the sharpness of said cutting edge.

19. A drill bit comprising: a shaft having a drill end, the drill end having: a drilling point; a distal portion having a plurality of faces extending from the drilling point, each face defining a respective cutting edge and the plurality of faces arranged in a pyramidal structure, such that the pyramidal structure defines the drill end point; a proximal portion extending away from the distal portion, the proximal portion including a continuing portion of at least one face; the shaft further having: a flute surface defined in the shaft for directing away debris produced during drilling, the flute surface intersecting with the continuing portion of the at least one face to form a first portion of a trailing edge of the at least one face and a terminal end; and a second surface located at the terminal end of said flute surface and disposed between the drilling end point and the terminal end, the second surface intersecting with the continuing portion of the at least one face to form a second portion of the trailing edge of the at least one face, the second surface intersecting the flute surface and arrange to direct debris into the flute, the second portion of the trailing edge defining a - 25 piercing edge supplementing the respective cutting edges formed by the plurality of faces, the piercing edge enhancing insertion if the drilling end point along the longitudinal axis and into a surface of a material being drilled.

20. A drill bit comprising: a cylindrical shaft and a drill tip, the drill tip comprising: a pyramidal shaped end, the pyramidal shaped end having a distal portion comprising a plurality of faces, the faces meeting at a common point and defining a drill terminal point on the longitudinal axis of the shaft; and the drill tip comprising a proximal portion having the cutting edges extending therealong; a plurality of recesses for directing debris produced while drilling, each recess having two portions; a first recess portion extending along the shaft, the first recess portion extending adjacent the proximal portion and intersecting one of the cutting edges of the plurality of the cutting edges to terminate one of the cutting edges at a point spaced within the outer periphery of the shaft, the first recess portion providing a leading edge disposed at a negative cutting angle relative to the cutting surface at the outer periphery; and a second recess portion formed in the proximal portion of the pyramidal shaped end, the second recess portion extending toward another cutting edge of the plurality of cutting edges.

21. A drill bit comprising: a shaft and a pyramidal shaped end defining a drill point; at least one face on said pyramidal end that at least in part defines the drill point, the at least one face generally subtending an acute angle with a longitudinal axis of the shaft; and at least one flute disposed substantially along the shaft and extending away from said pyramidal end, said at least one flute aligned with said at least one face for directing away debris produced during drilling, said at least one flute intersecting with said at least one face, such that, in end view, the flute is offset from a center line of the face, and wherein the flute intersects the face in a non-abrupt manner defining a continuous curved surface at the flute-face intersection, said curved surface leading from the face into the flute whereby channeling of debris into the flute is enhanced, - 26 wherein the at least one flute extends generally spirally away from its respective face and substantially along the shaft.

22. A drill bit comprising: a shaft and a drill tip, said drill tip having three cutting edges defining a pyramidal shaped end, said pyramidal shaped end having three faces, said three faces being uniform in shape and defining said cutting edges, said pyramidal shaped end having: (a) a distal portion comprised of said three faces meeting at a common point defining said drill end point located on the longitudinal axis of said shaft; and (b) a proximal portion; each of said cutting edges of both said distal portion and said proximal portion being defined as straight and extending along both said distal portion and said proximal portion, from said end point to said shaft; a plurality of recesses for directing away debris produced during drilling, each of said recesses having: (a) a first recess portion extending along a substantial length of the shaft; and (b) a second recess portion located in said proximal portion of said pyramidal shaped end, said second recess portion extending from said first recess and terminating in said proximal portion, and extending adjacent to a portion of one of said cutting edges in said proximal portion; and wherein the depth of said second recess portion varies along its length, relative to the surface of the drill tip so that the portion of said cutting edge located adjacent said second recess has a lesser cutting ability nearer said end point than said shaft.

23. An orthopedic drill bit for drilling brittle material, such as bone, comprising (A) a shaft and (B) a drill tip, A. said shaft having (1) a shaft end, and (2) at least one first recess for directing away debris produced while drilling, said first recess is helical in shape and having a constant depth throughout a substantial portion of its length, said first recess forming a lateral cutting edge along said shaft; B. said drill tip located at said shaft end, said drill tip having: (a) a distal portion; and - 27 (b) a proximal portion; said distal portion having a pyramidal shape and comprising: (i) three faces that are planar and of uniform shape, meeting at a common point; (ii) three straight first cutting edges defined by said three faces, each said first cutting edges having a first cutting ability which is uniform along each said first cutting edge and; (iii) a drill end point defined by the meeting of said three faces at said common point, said drill end point located on the longitudinal axis of said shaft, said first cutting edges extending from said drill end point to said proximal portion; said proximal portion of said drill tip having (i) three straight second cutting edges, each said second cutting edge extending from a said first cutting edge to the periphery of the shaft, and (ii) a second recess aligned with and extending from said first recess and terminating in said proximal portion, said second recess forming a surface varying in depth and extending along a portion of a said second cutting edge, said second cutting edge along which said surface extends having a second and varied cutting ability defined by the depth of said second recess, said second and varied cutting ability having a lesser cutting ability nearest said drill end point than said shaft; and wherein said shaft has a longitudinal axis and wherein each of said first cutting edges in said distal portion has a greater acute angle with the longitudinal axis of the shaft than each of said second cutting edges in said proximal portion.

24. A drill bit for drilling into a surface of a material comprising: a shaft having a drill end, said drill end having: (1) a drilling end point; (2) a distal portion having three faces meeting at a common point defining said drill end point located on the longitudinal axis of said shaft, said three faces arranged in a pyramidal shape, said three faces defining three cutting edges; and (3) a proximal portion extending away from said distal portion, said proximal portion including a continuing portion of at least one face of said three faces; said shaft further including: (a) at least one flute surface defined in said shaft for directing away debris - 28 produced during drilling, said flute surface intersecting with said continuing portion of said one face of said three faces to form a first portion of a trailing edge of said one face; and (b) a V-shaped groove surface disposed between said drilling end point and said flute surface, said V-shaped groove surface intersecting with said continuing portion of said one face to form a second portion of the trailing edge of said one face, said V shaped groove surface intersecting said flute surface and arranged to direct debris into said flute surface, said second portion of said trailing edge defining a piercing edge, said piercing edge enhancing insertion of said drilling end point along said longitudinal axis and into the surface of the material being drilled.

25. A drill bit according to claim 24 wherein said three faces are all substantially flat.

26. A drill bit according to claim 24 wherein said proximal portion includes a continuing portion of another face of said three faces, and wherein said continuing portion of said another face has a continuing portion of a said cutting edge.

27. A drill bit according to claim 26 wherein said flute surface intersects said continuing portion of said one face.

28. A drill bit according to claim 27 wherein said V-shaped groove surface is disposed between said continuing portion of said one face and said another face, and extends along said continuing portion of said cutting edge of said another face affecting the sharpness of said cutting edge of said another face.

29. A drill bit according to claim 24 wherein each of said faces is evenly offset with respect to the other two faces.

30. A drill bit according to claim 29 and including two additional flute surfaces.

31. A drill bit according to claim 30 wherein each of said additional flute surfaces intersects a continuing portion of a said face.

32. A drill bit according to claim 24 wherein said V-shaped groove surface terminates in said flute surface. - 29

33. A drill bit according to claim 24 wherein said shaft is cylindrical.

34. A drill bit according to claim 24 wherein said drill bit is formed from stainless steel.

35. A drill bit according to claim 24 wherein said flute surface intersects said V-shaped groove surface.

36. A drill bit comprising: a shaft having a drill end, said drill end having: (1) a drilling end point; (2) a distal portion having a plurality of faces extending from said drilling end point, each face of the plurality of faces defining a respective cutting edge, said plurality of faces arranged in a pyramidal structure; and (3) a proximal portion extending away from said distal portion, said proximal portion including a continuing portion of at least one face of said plurality of faces; said shaft further including: a flute surface defined in said shaft for directing away debris produced during drilling, said flute surface intersecting with said continuing portion of said at least one face to form a first portion of a trailing edge of said at least one face and forming a terminal end; and a second, grooved surface located at the terminal end of said flute surface and disposed between said drilling end point and said terminal end, said second, grooved surface intersecting with said continuing portion of said at least one face to form a second portion of the trailing edge of said at least one face, said second, grooved surface intersecting said flute surface and arranged to direct debris into said flute, said second portion of said trailing edge defining a piercing edge supplementing the respective cutting edges formed by the plurality of faces, said piercing edge enhancing insertion of said drilling end point along said longitudinal axis and into a surface of a material being drilled.

37. An orthopedic drill bit comprising: a cylindrical shaft and a drill tip, said drill tip comprising: a pyramidal shaped end having a plurality of cutting edges, said pyramidal shaped end having (a) a distal portion comprising a plurality of faces defining said cutting edges, - 30 said faces meeting at a common point and defining a drill end point located on the longitudinal axis of said shaft; and (b) a proximal portion having said cutting edges extending therealong; a plurality of recesses for directing away debris produced while drilling, each said recess having two portions: (1) a first recess portion extending along said shaft, said first recess portion extending adjacent said proximal portion and intersecting one of said cutting edges of said plurality of cutting edges to terminate said one of said cutting edges at a point spaced within the outer periphery of said shaft, said first recess portion providing a leading edge disposed at a negative cutting angle to the cutting surface at said outer periphery; and (2) a second recess portion formed in said proximal portion of said pyramidal shaped end, said second recess portion extending toward another cutting edge of said plurality of cutting edges of said pyramidal shaped end.

38. A drill tipped shaft for use during surgery for initial longitudinal insertion into periosteum and other body material, such as cartilage and bone material, followed by rotational movement to a further depth in the body material, said drill tipped shaft comprising a shaft having: (1) an end portion defining a drill tip for creating a securing hole in the body material to prevent the end portion from slipping on periosteum and other body material as the shaft begins to rotate, said end portion having a pyramidal shaped end formed from three faces intersecting to form three first cutting edges disposed relative to one another to provide for initial longitudinal insertion of said shaft into the body material and to cut away bone material during rotation of said shaft, each of said three faces intersecting with two of the other faces so as to define two of said three first cutting edges; (2) a second portion extending rearwardly of said end portion, said second portion having a. three chamfered faces defining three second cutting edges, each of said second cutting edges extending from one of said first cutting edges; and b. three curved faces, each of said curved faces having a concave shape and intersecting with two of said chamfered faces so as to define both a said second cutting edge of one of said chamfered faces and a trailing edge of another of said chamfered faces; and - 31 (3) a third portion extending rearwardly of said second portion, said third portion having three recess surfaces for directing away debris produced during rotational movement of the shaft, each of said three recess surfaces intersecting with one of said curved faces for directing debris from one of said curved faces into said one of said recess surfaces.

39. A drill tipped shaft for use during surgery for initial longitudinal insertion into periosteum and other body material, such as cartilage and bone material, followed by rotational movement to a further depth in the body material, said drill tipped shaft comprising a shaft having: (1) an end portion defining a drill tip for creating a securing hole in the body material to prevent the end portion from slipping on periosteum and other body material as the shaft begins to rotate, said end portion having a pyramidal shaped end formed from three faces intersecting to form three first edges disposed relative to one another to provide for initial longitudinal insertion of said shaft into the body material and to cut away bone material during rotation of said shaft, each of said three faces intersecting with two of the other faces so as to define two of said three first edges; (2) a second portion extending rearwardly of said end portion, said second portion havinga. three ground faces defining three second edges, each of said second edges extending from one of said first edges; andb. three curved faces, each of said curved faces having a concave shape and intersecting with two of said ground faces so as to define both a said second edge of one of said ground faces and a trailing edge of another of said ground faces; and (3) a third portion extending rearwardly of said second portion, said third portion having three recess surfaces for directing away debris produced during rotational movement of the shaft, each of said three recess surfaces intersecting with one of said curved faces for directing debris from one of said curved faces into said one of said recess surfaces.

40. A drill tipped shaft for use during surgery for initial longitudinal insertion into periosteum and other body material, such as cartilage and bone material, followed by rotational movement to a further depth in the body material, said drill tipped shaft comprising a shaft having: (1) an end portion defining a drill tip for creating a securing hole in the body material to prevent the end portion from slipping on periosteum and other body material - 32 as the shaft begins to rotate, said end portion formed from three faces intersecting to form three first edges disposed relative to one another to provide for initial longitudinal insertion of said shaft into the body material and to cut away bone material during rotation of said shaft, each of said three faces intersecting with two of the other faces so as to define two of said three first edges; (2) a second portion extending rearwardly of said end portion, said second portion having a. three ground faces defining three second edges, each of said second edges extending from one of said first edges; and b. three curved faces, each of said curved faces having a concave shape and intersecting with two of said ground faces so as to sharpen the said second edge of one of said ground faces to enhance cutting during shaft rotation and to define a trailing edge of another of said ground faces; and (3) a third portion extending rearwardly of said second portion, said third portion having three recess surfaces for directing away debris produced during rotational movement of the shaft, each of said three recess surfaces intersecting with one of said curved faces for directing debris from one of said curved faces into said one of said recess surfaces.