AU2013204287A1

AU2013204287A1 - Improvements in or relating to the assembly of a shearing handpiece body

Info

Publication number: AU2013204287A1
Application number: AU2013204287A
Authority: AU
Inventors: Robin James Howell; Wayne Thomas Mason; Jamie William Michael Stanfield; John Alun Harris Williams
Original assignee: Lister Shearing Equipment Ltd
Current assignee: Lister Shearing Equipment Ltd
Priority date: 2012-04-12
Filing date: 2013-04-12
Publication date: 2013-10-31
Anticipated expiration: 2033-04-12
Also published as: GB2502877A; GB201206451D0; GB2502877B; GB201306644D0; GB2501100A; AU2013204287B2

Abstract

Abstract The present invention provides a shearing handpiece body (10) having a through bore (21) defining a longitudinal space within which there is provided a sleeve bush (30), an inner back half joint (40) and a spindle (50). The sleeve bush (30) has a proximal end (32) and a distal end (34). The inner back half joint (40) is rotatable relative to 10 the handpiece body (10), and the spindle (50) is also rotatable relative to the handpiece body (10) and the inner back half joint (40). The spindle (50) has forward, intermediate and rearward portions (52,54,56). The shearing handpiece body (10) further includes a first bearing (60) retained within the interior of the sleeve bush (30). 15 Fig. 1 '-s r4A

Description

Our ref: P338414AU Improvements In or Relating To the Assembly of a Shearing Handpiece Body 5 The present invention relates to a shearing handpiece and particularly to the retention of a sleeve bush and associated bearings within the shearing handpiece body. The present invention further relates to an improved sleeve bush for a shearing handpiece. A shearing handpiece typically includes a handpiece body having a crank spindle 10 which drives a crank pin. The crank pin carries a crank roller. The crank roller, in turn, drives a fork assembly which converts the rotational motion of the crank pin into reciprocal lateral motion. The crank spindle is typically supported within the handpiece body by a front bearing which is mounted to the handpiece body, and a rear bearing which is mounted to a portion of the shearing handpiece known as the back 15 joint. In the prior art the front bearing is typically seated against a forward shoulder within the handpiece body. During assembly of the shearing handpiece, the front bearing is inserted into the handpiece body from the rear and moved into engagement with the forward shoulder. The shoulder thus prevents further axial movement in a forward direction. 20 The outer diameter of the front bearing is mounted into a forward bearing seat within the shearing handpiece body. Behind the forward bearing seat within the shearing handpiece body is a larger diameter rear bore into which the external diameter of a sleeve bush is mounted. The external diameter of the inner back half joint is then 25 assembled within the internal bore of the sleeve bush such that the inner back half joint is free to rotate. The rear bearing is mounted into a rear bearing seat within the inner back half joint. In order for the handpiece to operate reliably, it is important that the front and rear 30 bearings are in very close axial alignment and concentric with one another such that the crank spindle and inner back half joint can rotate freely. It follows therefore that, amongst other requirements, the front bearing seat and rear bore of the shearing handpiece body, along with the external diameter and internal bore of the sleeve bush, 2 along with the external diameter and rear bearing seat of the inner back half joint, must all have close axial alignment and be concentric with each other. During the manufacturing process of a handpiece it is very difficult to achieve perfect 5 alignment and concentricity between all six of the above specified 'critical diameters', firstly due to limitations in the processes used to manufacture the shearing handpiece body and sleeve bush, and secondly due to misalignment errors which may be introduced during the assembly procedure. 10 The present invention seeks to improve the alignment between the front bearing and rear bearing of a handpiece. It does this firstly by eliminating the requirement for (at least) two of the 'critical diameters' to either exist or else to be aligned and concentric with the other 'critical diameters', and secondly by enabling the two critical diameters into which the front bearing and inner back half joint are assembled to be ground / 15 machined concurrently into a separate cylindrical 'cartridge', thereby simplifying the machining operations required during production of the complex shaped shearing handpiece body. The present invention also seeks to ease the assembly procedures by reducing the number of operations that require accurate alignment to be maintained. 20 According to the first aspect of the present invention there is provided a shearing handpiece including body having a through bore defining a longitudinal space within which there is provided a sleeve bush, an inner back half joint and a spindle, the sleeve bush having a proximal end and a distal end, the inner back half joint being positioned within a through bore of the sleeve bush and rotatable relative to the 25 handpiece body, the spindle also being rotatable relative to the handpiece body and the inner back half joint, and the spindle having forward, intermediate and rearward portions, wherein the shearing handpiece body includes a first bearing retained within the interior of the sleeve bush. 30 The intermediate portion of the spindle nay have a larger diameter than both the forward and rearward portions of the spindle. Steps or shoulders may thus be defined at the interface of the forward and intermediate portions, and the intermediate and rearward portions respectively.

3 The sleeve bush may feature a flange at its proximal end which abuts the shearing handpiece body so as to prevent axial movement of the sleeve bush relative to the shearing handpiece body in the distal direction. Here the terms distal and proximal 5 refer to the two ends of the shearing handpiece body, with the proximal end being commonly referred to as the "back end" where the handpiece connects to a drive arrangement, and the distal end being commonly referred to as the "front end" where the comb and cutter are located. 10 In an alternative embodiment axial movement of the sleeve bush relative to the handpiece body may be prevented by other means. For example, a threaded portion of the sleeve bush may be received in and mated to a complementarily threaded portion of the handpiece body. 15 The front bearing is pre-assembled into the sleeve bush and held in place between two bearing retainers, preferably circlips, within the sleeve before the sleeve is inserted into the handpiece. Movement of the bearing in an axial direction relative to the sleeve bush is prevented by these bearing retainers. 20 The front bearing may be a double row bearing. In an alternative embodiment the sleeve may be provided with multiple single row front bearings. Advantageously the through bore of the shearing handpiece body is straight and requires neither a shoulder nor a recess, leading to simpler machining of the part and 25 less wastage of material during manufacture. Also it will be appreciated that the present invention eliminates the front bearing seat found in handpiece bodies known from the prior art. This thereby removes one of the diameters within the handpiecce body which, as mentioned above, was previously critical to the alignment and concentricity of the front and rear bearings. Further it will be appreciated that in the 30 present invention the alignment and concentricity of the external diameter of the sleeve bush is no longer critical to the alignment and concentricity of the front and rear bearings.

4 Preferably the distal portion of the bore of the sleeve bush where the front bearing is mounted has the same diameter as the proximal portion of the sleeve bush bore into which the back joint is assembled. This further minimises the number of 'critical diameters' within the shearing handpiece which must be within very close axial 5 alignment and concentric with respect to each other. According to an alternative embodiment of the present invention, the shearing handpiece body may include an inner shoulder which abuts the distal end of the sleeve bush so as to prevent axial movement of the sleeve bush relative to the shearing 10 handpiece body in the distal direction. The shearing handpiece body may further include a recess in its bore such that when the sleeve bush is inserted into said bore, a resilient retaining means can located in said recess and abut the proximal end of the sleeve bush, to substantially prevent axial 15 movement of said sleeve bush relative to the shearing handpiece body when the shearing handpiece body is loaded axially through a forward stroke of the shearing handpiece body. An elastomeric o-ring may be provided which surrounds the sleeve bush and is 20 located between the sleeve bush and the handpiece body. Such an o-ring is compressed when the sleeve bush is introduced into the handpiece body. The o-ring in the compressed state may act to prevent rotation of the sleeve bush relative to the handpiece body. 25 The elastomeric o-ring may received in a circumferential recess of the sleeve bush. Alternatively, the elastomeric o-ring is received in a circumferential recess of the handpiece body. According to a second aspect of the present invention there is provided a shearing 30 handpiece sleeve bush comprising a tubular member and a bearing, the tubular member having first and second ends and a through bore, and wherein the bearing is retained in the through bore at a location closer to one of the ends than the other.

5 The sleeve bush and bearing thus form a sub assembly which can be inserted and subsequently removed from a shearing handpiece. This facilitates easier servicing of the shearing handpiece with respect to bearing replacement. 5 The through bore may have a substantially constant diameter along the length of the sleeve bush. The outer surface of the tubular member may be provided with a circumferential recess within which an elastomeric o-ring can be received. Such an o ring is compressed when the sleeve bush is introduced into the handpiece body. The o-ring in the compressed state may act to prevent rotation of the sleeve bush relative 10 to the handpiece body. The tubular member may be provided with a flange which, in use, abuts an abutment feature of a shearing handpiece body. A portion of the outer surface of the tubular member may be threaded. 15 An end of the tubular member is chamfered. Such a chamfer assists with the insertion of the sleeve bush into the shearing handpiece body. The bearing may be retained within the through bore by retaining means provided on 20 opposing sides of the bearing. The retaining means may be circlips. Advantageously the sleeve bush, front bearing, bearing retaining means and spindle can be loaded and unloaded in the manner akin to a cartridge to allow for simple cleaning, replacement and maintenance. Furthermore this 'cartridge' sub-assembly 25 minimises the number of 'critical diameters' within the shearing handpiece which must be within very close axial alignment and concentric with respect to each other. According to a third aspect of the present invention there is provided a method of assembling a sleeve bush and a bearing to a shearing handpiece body, the method 30 comprising the steps of: providing a sleeve bush as described above with reference to the second aspect; and 6 axially locating the sleeve bush within a through bore of the shearing handpiece body.. Embodiments of the present invention will now be described with reference to the 5 accompanying drawings in which: Figure 1 shows a cross-sectional view of the rear portion of a shearing handpiece body; Figure 2 shows a cross-sectional view of the rear portion of a shearing 10 handpiece body according to a first embodiment of the present invention; Figure 3 shows a cross-sectional view of the rear portion a shearing handpiece body shown in figure 2 having an alternative configuration. Figure 4 shows a cross-sectional view of the rear portion of a shearing handpiece body according to a second embodiment of the present invention; 15 Figure 5 shows a cross-sectional view of the rear portion a shearing handpiece body shown in figure 4 having an alternative configuration; Figure 6 shows a cross-sectional view of the rear portion of another shearing handpiece body; and Figure 7 shows a cross-sectional view of a combined bearing and sleeve bush 20 assembly of the shearing handpiece body of figure 6. Referring firstly to figure 1 there is shown a cross-sectional view of a shearing handpiece generally designated 10. The shearing handpiece includes a handpiece body 20 having a through bore 21 defining a longitudinal space, a sleeve bush 30, an inner 25 back half joint 40 and a crank spindle 50, all retained within the longitudinal space. The crank spindle 50 includes a crank pin 51 which is offset in relation to the rotational axis 53 of the crank spindle 50. The crank spindle 50 is supported by a first or front bearing 60 and a second or rear bearing 80. The first bearing 60 may be a double row bearing. Alternatively, the first bearing 60 may be defined by multiple 30 single row bearings. The crank spindle 50 has a forward portion 52, an intermediate portion 54 and a rearward portion 56. In the embodiment shown the intermediate portion 54 has a 7 greater diameter than the forward and rearward portions 54,56. Steps 58,59 are thus defined in the spindle 50 at the interface of the forward and rearward portions 52,56 and the intermediate portion 56. In the embodiment shown the intermediate portion 54 has the greater diameter along its entire lenght. It will be appreciated the greater 5 diameter is necessary only in the vicinity of the aforementioned interfaces and thus the intermediate portion may have a reduced diameter at its mid section. The sleeve bush 30 has a proximal end 32 and a distal end 34. The terms "proximal" and "distal" are construed with reference to an operator who holds the shearing 10 handpiece body 20 in use. Alternatively, the terms "proximal" and "distal" may be construed with reference to their proximity to the inner back half joint 40. The sleeve bush 30 is dimensioned so as to be a sliding fit in the bore 21 of the handpiece body 20. The proximal end 32 of the sleeve bush 30 features a flange 36, 15 which abuts the shearing handpiece body 20 so as to prevent axial movement of the sleeve bush 30 relative to the shearing handpiece body 20 in the distal direction. It will be noted that the outer diameter of the sleeve bush flange 36 is approximately equivalent to the outer diameter of the shearing handpiece body 20 at the interface with the flange 36. The shearing handpiece body 20 also features a hole 23 which 20 aligns with a recess 37 in the sleeve bush 30 so that a connector 38 can be fitted in order to prevent axial movement of the sleeve bush 30 relative to the shearing handpiece body 20 in the proximal direction. The hole 23 is threaded and in the embodiment shown the connector 38 is a screw. It will be appreciated that other forms of connector may be used to secure the sleeve bush 30 against axial movement relative 25 to the handpiece body 20, for example a roll pin. It will be appreciated that the connector 38 also prevents relative rotation of the handpiece body 20 and the sleeve bush 30. The distal end 34 of the sleeve bush 30 is chamfered 39 to assist insertion of the 30 sleeve bush 30 into the through bore 21 defined by the shearing handpiece body 20. The first bearing 60 is prevented from moving axially relative to the sleeve bush 30 by a first retaining means 70, in the form of a circlip, abutting its forward or distal face 8 62 and a second retaining means 72, also in the form of a circlip, abutting its rearward face 64. The first bearing 60 further acts to axially locate the crank spindle 50 and inner back half joint 40 within the handpiece body 20. A step 58 provided between the crank spindle forward portion 52 and the crank spindle intermediate portion 54 5 abuts the rearward or proximal face 64 of the first bearing 60. The first and second circlips 70 and 72 are located in respective first and second annular recesses 71,73 of the sleeve bush 30. The second bearing 80 is prevented from moving axially relative to the sleeve bush 30 10 by a step 59 provided between the crank spindle intermediate portion 54 and the crank spindle rearward or proximal portion 56 which also abuts the second bearing 80 forward face 82. A third retaining means 74, also in the form of a circlip, abuts the rearward or 15 proximal face 84 of the second bearing 80. An abutment surface of the inner back half joint 40 which abuts the forward or distal face 82 of the second bearing 80. The third circlip 74 is located in an annular recess 75 provided in the inner back half joint 40. The inner back half joint 40 is rotatable with respect to the sleeve bush 30. 20 At the proximal end 32 of the sleeve bush 30 there is provided a dust seal 45, located between the flange 36 of the sleeve bush and the inner back half joint 40. It will be appreciated that the sleeve bush 30 serves to both carry the first bearing 60 and to position the first bearing 60 at a desired axial location within the shearing 25 handpiece body 20. The bore of the sleeve bush 30 further serves to locate the inner back half joint 40 within the shearing handpiece body 20 and thus ensures correct alignment of the first and second bearings 60,80. Referring now to Figure 2, there is shown a first embodiment of the present invention 30 generally designated 110. Features similar to the embodiment of figure 1 are identified with like reference numerals prefixed with 1. The shearing handpiece includes a handpiece body 120 having a through bore 121 9 defining a longitudinal space, a sleeve bush 130, an inner back half joint 140 and a crank spindle 150, all retained within the longitudinal space. The crank spindle 150 includes a crank pin 151 which is offset in relation to the rotational axis 153 of the crank spindle 150. The crank spindle 150 is supported by a first bearing 160 and a 5 second bearing 180. The sleeve bush 130 has a proximal end 132 and a distal end 134. As before, the terms "proximal" and "distal" are construed with reference to an operator who holds the shearing handpiece body in use or proximity to the inner back half joint 140. 10 Again as before, the sleeve bush 130 is dimensioned so as to be a sliding fit in the bore 121 of the handpiece body 120. The shearing handpiece body 120 includes an internal shoulder 22 which abuts the distal end 134 of the sleeve bush 130 once the sleeve bush 130 has been inserted into the bore 121. . This prevents axial movement 15 of the sleeve bush 130 relative to the shearing handpiece body 120 in the distal direction. The shearing handpiece body 120 further including an annular recess 24 in its through bore 121 such that when the sleeve bush 130 is inserted into said through bore 121, a resilient retaining means 90 is located in said annular recess 24 and abuts the proximal end 132 of the sleeve bush 130, thereby preventing axial movement of 20 the sleeve bush 130 relative to the shearing handpiece body 120 in the proximal direction. At the proximal end 132 of the sleeve bush 130 there is provided a dust seal 145, which is located between the shearing handpiece body 120 and the inner back half 25 joint 140. It will be appreciated that the arrangement of the first and second bearings 160, 180 of the embodiment of figure 2 are essentially the same as those for the first and second bearings 60, 80 described with reference to figure 1. 30 Figure 3 shows a slightly revised embodiment of the invention to that shown in figure 2 and generally designated 11 A . Common features are identified with like reference numerals.

10 The embodiment of figure 3 differs from that of figure 2 in that a pair elastomeric o rings 191,193 are disposed between the sleeve bush 130 and the bore 121 of the handpiece body 120. In the embodiment shown, there is provided a distal o-ring 191 5 and a proximal o-ring 193. The distal o-ring 191 is located in a recess 195 which extends around the circumference of the bore 121 of the handpiece body 120. The proximal o-ring 193 is located in a recess 197 which extends around the circumference of the sleeve bush 130. It will be appreciated that in alternative embodiments both recesses 195,197 may be provided on either the handpiece body 10 120 or the sleeve bush 130. It will further be appreciated that a greater or lesser number of recesses and o-rings may be provided. The o-rings 191,193 and recesses 195,197 are dimensioned such that the o-rings 191,193 are compressed when the sleeve bush 130 is inserted into the handpiece bore 15 121. The forces generated by compression of the o-rings 191,193 seek to prevent rotation of the sleeve bush 130 relative to handpiece body 120. The embodiment of figure 3 further differs from that of figure 2 in that the inner diameter of the sleeve bush 130 is substantially constant along the length of the sleeve 20 bush 130. It will be noted from figure 2 that the inner diameter of the sleeve bush 130 in the region of the first bearing 160 is greater than the inner diameter of the sleeve bush 130 in the region of the inner back half joint 140. By keeping the diameter substantially constant, then the amount of machining of the sleeve bush 130 during manufacture is reduced and the accuracy of the concentricity between the first and 25 second bearings 160,180 is improved. Figure 4 shows a further embodiment of the present invention generally designated 210. Features common to the embodiment described with reference to figure 1 are identified with like reference numerals. 30 The embodiment of figure 4 differs from the embodiment of figure 1 in that handpiece body and sleeve bush 20,30 are not provided with the respective hole 23 and recess 37, and connector 38. Instead, the distal end 34 of the sleeve bush 30 is provided with 11 a thread 35, while the distal end of the handpiece through bore 21 is provided with a corresponding thread 25. It will be appreciated that the interengagement of the threads 35,25 prevents axial movement of the sleeve bush 30 relative to the shearing handpiece body 20 in the proximal direction. 5 Figure 5 shows a slightly revised embodiment of the invention to that shown in figure 4 and generally designated 210A. Common features are identified with like reference numerals. 10 The embodiment of figure 5 differs from that of figure 4 in that an elastomeric o-ring 191 is disposed between the sleeve bush 30 and the bore 21 of the handpiece body 20. In the embodiment shown, the o-ring 191 is provided at a distal location which aligns approximately with the first bearing 60. The o-ring 191 is located in a recess 195 which extends around the circumference of the sleeve bush 30. It will be appreciated 15 that in alternative embodiments the recess 195 may be provided on the handpiece body 120. It will further be appreciated that a greater number of recesses and o-rings may be provided. The o-ring 191 and recess 195 are dimensioned such that the o-ring 191 is compressed 20 when the sleeve bush 30 is inserted into the handpiece bore 21. The embodiment of figure 5 further differs from that of figure 4 in that the inner diameter of the sleeve bush 30 is substantially constant along the length of the sleeve bush 30. It will be noted from figure 4 that the inner diameter of the sleeve bush 30 in 25 the region of the first bearing 60 is greater than the inner diameter of the sleeve bush 30 in the region of the inner back half joint 40. By keeping the diameter substantially constant, then the amount of machining of the sleeve bush 30 during manufacture is reduced and the accuracy of the concentricity between the first and second bearings 60,80 is improved. 30 The embodiment of figure 5 further differs from that shown in figure 4 in that the respective threaded portions 35,25 of the sleeve bush 30 and handpiece body 20 are 12 relocated from a distal location to a proximal location. In the embodiment shown, the thread 35 of the sleeve bush is located at the proximal end 32 of the sleeve bush 30. Figures 6 and 7 show a further example of shearing handpiece generally designated 5 310. Features common to the embodiment described with reference to figure 2 are identified with like reference numerals. The shearing handpiece 310 of figures 6 and 7 differs from that described with reference to figure 2 in that it is not provided with a separate sleeve bush 130 and 10 bearings 160, where the bearings 160 are retained in the sleeve bush 130 by cirelips 170,172. Instead, the sleeve bush is formed integrally with the bearings 360. More specifically, the outer race 361 of the bearings 360 is extended so as to have a length that is substantially equivalent to that of the sleeve bush 130. 15

Claims

1. A shearing handpiece including body having a through bore defining a longitudinal space within which there is provided a sleeve bush, an inner back half 5 joint and a spindle, the sleeve bush having a proximal end and a distal end, the inner back half joint being positioned within a through bore of the sleeve bush and rotatable relative to the handpiece body, the spindle also being rotatable relative to the handpiece body and the inner back half joint, and the spindle having forward, intermediate and rearward portions, wherein the shearing handpiece body includes a 10 first bearing retained within the interior of the sleeve bush.

2. The shearing handpiece of claim 1 wherein the intermediate portion of the spindle has a larger diameter than both the forward and rearward portions of the spindle. 15

3. The shearing handpiece of any preceding claim wherein the first bearing is prevented from moving axially relative to the sleeve bush by a retaining means, the first bearing and retaining means being located substantially towards the distal end of the sleeve bush. 20

4. The shearing handpiece of the claim 3 wherein the first bearing has a forward face and a rearward face, the first bearing forward face being located against a first retaining means and the first bearing rearward face being located against a second retaining means and a step defined between the spindle forward portion and the 25 spindle intermediate portion.

5. The shearing handpiece of any preceding claim within which there is further provided a second bearing, wherein the second bearing is retained between the spindle and the inner back half joint. 30

6. The shearing handpiece of claim 5 wherein the second bearing has a forward face and a rearward face, the second bearing forward face being located against the inner back half joint and a step defined between the spindle intermediate portion and 14 the spindle rearward portion, and the second bearing rearward face being located against a third retaining means.

7. The shearing handpiece of any preceding claim wherein the distal end of the 5 sleeve bush is chamfered to facilitate insertion of the sleeve bush into the bore of the shearing handpiece body.

8. The shearing handpiece of any preceding claim wherein the sleeve bush further includes a flange at its proximal end which abuts the shearing handpiece body so as to 10 prevent axial movement of the sleeve bush relative to the shearing handpiece body in the distal direction.

9. The shearing handpiece of any of claims 1 to 7 whereby the shearing handpiece body includes a shoulder which abuts the distal end of the sleeve bush so as to prevent 15 axial movement of the sleeve bush relative to the shearing handpiece body in the distal direction.

10. The shearing handpiece of claim 9 wherein the bore of the shearing handpiece body includes a recess and a resilient retaining means located in said recess abutting 20 the proximal end of the sleeve bush to substantially prevent axial movement of said sleeve bush relative to the shearing handpiece body when the shearing handpiece body is loaded axially through a forward stroke of the shearing handpiece body, in use,

11. The shearing handpiece of claim 4 wherein the bearing retaining means are 25 circlips.

12. The shearing handpiece of claim 8, wherein a portion of the sleeve bush is threaded and engaged with a complementarily threaded portion of the shearing handpiece body so as to prevent axial movement of the sleeve bush relative to the 30 shearing handpiece body.

13. The shearing handpiece of any preceding claim wherein the diameter of the bore of the sleeve bush is substantially constant along the length of the sleeve bush. 15

14. The shearing handpiece of any proceeding claim wherein an elastomeric o-ring is provided which surrounds the sleeve bush and is located between the sleeve bush and the handpiece body. 5

15. The shearing handpiece of claim 14 wherein the elastomeric o-ring is received in a circumferential recess of the sleeve bush

16. The shearing handpiece of claim 14 wherein the elastomeric o-ring is received in a circumferential recess of the handpiece body. 10

17. A shearing handpiece sleeve bush comprising a tubular member and a bearing, the tubular member having first and second ends and a through bore, and wherein the bearing is retained in the through bore at a location closer to one of the ends than the other. 15

18. A shearing handpiece sleeve bush as claimed in claim 17, wherein the through bore has a substantially constant diameter along the length of the sleeve bush.

19, A shearing handpiece sleeve bush as claimed in claim 17 or claim 18 wherein 20 the outer surface of the tubular member is provided with a circumferential recess within which an elastomeric o-ring can be received.

20. A shearing handpiece sleeve bush as claimed in any of claims 17 to 19 wherein the tubular member is provided with a flange which, in use, abuts an abutment feature 25 of a shearing handpiece body.

21. A shearing handpiece sleeve bush as claimed in any of claims 17 to 20 wherein a portion of the outer surface of the tubular member is threaded. 30

22. A shearing handpiece sleeve bush as claimed in any of claims 17 to 21 wherein an end of the tubular member is chamfered. 16

23. A shearing handpiece sleeve bush as claimed in any of claims 17 to 22 wherein the bearing is retained within the through bore by retaining means provided on opposing sides of the bearing. 5

24. A shearing handpiece sleeve bush as claimed in claim 23 wherein the retaining means are circlips.

25. A shearing handpiece including a sleeve bush as claimed in any of claims 17 to 24 10

26. A method assembling a sleeve bush and a bearing to a shearing handpiece body, the method comprising the steps of: providing a sleeve bush as claimed in any of claims 17 to 24; and axially locating the sleeve bush within a through bore of the shearing handpiece 15 body.

27. A shearing handpiece substantially as hereinbefore described with reference to or as shown in the accompanying figures. 20

28. A shearing handpiece sleeve bush substantially as hereinbefore described with reference to or as shown in the accompanying figures.