Introduction This invention relates to a workpiece clamping apparatus.

Workpiece clamping apparatus are used to hold workpieces in position so that they can be worked upon. For example, workpiece clamping apparatus are commonly used to secure tree branches and tree trunks in position while the branch or trunk is cut into a number of smaller pieces by an operator using a chainsaw. The present invention is directed to such a workpiece clamping apparatus.

There are numerous different workpiece clamping apparatus available on the market. However, there are problems with the known workpiece clamping apparatus. Generally speaking, there is a trade-off between stability and usability with the known workpiece clamping apparatus. Often, the more stable the workpiece clamping apparatus, the more cumbersome the frame becomes. A cumbersome frame requires special care to ensure that the chainsaw or other cutting device does not come into contact with the frame. If the chainsaw should come into contact with the frame, this can cause damage to the frame, the chainsaw or can cause injury to the operator. Furthermore, a cumbersome frame typically creates obstacles which have to be avoided particularly when cutting the last few pieces.

However, more compact frames are typically less stable. If the frame is unstable and the workpiece has a tendency to move, this makes working on the workpiece more difficult and can present a danger to the operator. This problem is exacerbated by the fact that the work often involves removing part of the workpiece resulting in a shift in the centre of gravity of the workpiece which itself has a tendency to cause the workpiece to move about further. In combination, this can lead to a highly unstable and often dangerous workpiece clamping apparatus.

Another problem with the known workpiece clamping apparatus is that many do not readily receive workpieces in a variety of different shapes and sizes and they require significant adjustment in order to secure workpieces of varying shapes and sizes. With the known apparatus, it is usually time consuming to have to adjust the workpiece clamping apparatus. Often, a degree of trial and error is required in order to adjust the workpiece clamping apparatus so that it is able to receive a workpiece. This can entail lifting the workpiece up on to the apparatus two or more times until the apparatus has been adjusted appropriately to receive the workpiece. As the workpieces are often heavy, this repetitive lifting and putting down of the workpiece can cause discomfort or injury to the operator. Both of these drawbacks are highly undesirable.

It is an object of the present invention to provide a workpiece clamping apparatus that overcomes at least some of the problems with the known apparatus.

Statements of Invention

According to the invention there is provided a workpiece clamping apparatus comprising a central upright column supporting a compact workpiece receiving cradle, the upright column having a pair of legs connected to the column adjacent the base of the upright column and extending outwardly therefrom, each leg having a ground engaging foot at its end remote from the upright column to support the workpiece clamping apparatus and in which there is provided a clamping device mounted on the column operable to releasably secure a workpiece in position on the workpiece receiving cradle.

By having such a workpiece clamping apparatus, the workpiece clamping apparatus will be stable yet will also be compact in construction. This provides a workpiece clamping apparatus that is safe to use as well as being relatively simple to operate. By having a central upright column with a compact workpiece receiving cradle, the frame will not have a tendency to get in the way of a chainsaw or other cutting implement thereby obviating the possibility of injury to the user and allowing the user to cut the entire workpiece into relatively small pieces. By having the legs connected to the central column in the manner described, the centre of gravity of the apparatus will be lowered and the legs will provide a stable base for the entire apparatus.

In one embodiment of the invention there is provided a workpiece clamping apparatus in which the workpiece clamping device comprises a flexible bracing member. A flexible bracing member is seen as particularly useful as it will allow for quick and simple adjustment. Furthermore, the flexible bracing member will have a tendency to follow more closely the contours of unevenly shaped workpieces and will therefore have a tendency to create a more secure connection with the workpiece. In one embodiment of the invention there is provided a workpiece clamping apparatus in which the clamping device comprises a coarse adjustment means of the flexible bracing member and a fine adjustment means of the flexible bracing member. This is seen as a particularly advantageous aspect of the present invention. By providing both a coarse adjustment means and a fine adjustment means, it will be possible to engage many different shapes and sizes of workpiece simply with the minimum of difficulty. This will not require the workpiece to be placed onto the cradle and removed from the cradle repetitively and will also allow the apparatus to be used with a wide range of different sizes of workpiece. In one embodiment of the invention there is provided a workpiece clamping apparatus in which the fine adjustment means comprises a handle connected to one end of the flexible bracing member, and a handle receiving plate mounted on the column, the handle receiving plate having a plurality of mounting points formed along its length, each of which provide a receiving location for the handle. This is seen as a simple construction of fine adjustment means that will be simple to operate and inexpensive to manufacture.

In one embodiment of the invention there is provided a workpiece clamping apparatus in which the handle receiving plate comprises a pair of substantially parallel plates spaced apart from each other, each of which having a plurality of notches formed along its length and in which the handle is provided with a pair of protrusions extending outwardly from opposite sides of the handle for releasable engagement in the notches to secure the handle in position relative to the receiving plate. In one embodiment of the invention there is provided a workpiece clamping apparatus in which the handle receiving plate is mounted on a track on the central upright column for limited movement along the track relative the central upright column. In one embodiment of the invention there is provided a workpiece clamping apparatus in which there is provided a biasing means biasing the handle receiving plate in a given direction along the track and operable to exert a clamping force on a workpiece secured in place by the clamping device. In this way, the fine adjustment means will operate in a manner similar to an over center latch. The biasing means may be provided by one or more springs or one or more gas struts. The biasing means will ensure that a constant force is maintained on the workpiece.

In one embodiment of the invention there is provided a workpiece clamping apparatus in which the coarse adjustment means comprises an anchoring plate having means to releasably engage the flexible bracing member intermediate its ends and anchor the flexible bracing member relative thereto. An anchoring plate is a simple device to use as the coarse adjustment means. In one embodiment of the invention there is provided a workpiece clamping apparatus in which the flexible bracing member comprises a chain and the means to engage the flexible bracing member comprises a notch formed in the anchoring plate dimensioned to receive a link of the chain. Again, this is seen as a simple way of anchoring the chain in position. If it is desired to loosen the coarse adjustment means, the chain may be released from the notch and paid out the desired amount before being reinserted into the notch. The chain will be held in place by the link abutting against the anchoring plate.

In one embodiment of the invention there is provided a workpiece clamping apparatus in which there is provided a guide member for leading the flexible bracing member from one side of the column to the opposite side of the column and in which the coarse adjustment means and the fine adjustment means are located on the same side of the column. This is also seen as an advantageous aspect of the present invention as this will enable quick and efficient adjustment of the flexible bracing member to match the dimensions of the workpiece.

In one embodiment of the invention there is provided a workpiece clamping apparatus in which the legs are pivotably connected to the upright column and are pivotal to and from a working position extending outwardly from the upright column and a stowed position substantially in line with and alongside the upright column. This is particularly desirable as the entire workpiece clamping apparatus can be stored compactly. When it is desired to use the apparatus, the legs can be pivoted about the pivot point, which preferably will be a hinge or the like, into an operating position. In one embodiment of the invention there is provided a workpiece clamping apparatus in which each leg is provided with a corresponding strut, each of the struts being pivotably mounted on the column and in which the strut and the leg are each provided with complementary locking members to releasably secure the strut to the leg. In one embodiment of the invention there is provided a workpiece clamping apparatus in which the ground engaging foot is moveable to and from an operating position and a stowed position. Again, this is a useful way of minimizing the amount of space required for the apparatus when it is being stored. In one embodiment of the invention there is provided a workpiece clamping apparatus in which the ground engaging foot is rotatably mounted relative to the leg to allow rotation of the foot to and from the operating position and the stowed position.

In one embodiment of the invention there is provided a workpiece clamping apparatus in which the cradle comprises a pair of substantially Y-shaped workpiece receiving members spaced apart from each other. These are seen as simple and inexpensive to provide and furthermore will allow most shapes of workpiece to be held in place securely. In one embodiment of the invention there is provided a workpiece clamping apparatus in which the workpiece receiving members are spaced apart from each other by a distance of the order of less than 0.5m, preferably less than 0.3m. By having a small separation between the workpiece receiving members, the workpiece, including the final piece of the workpiece left on the apparatus, can be cut into relatively small pieces and there will not be an oversized piece at the end. Furthermore, there will not be the danger of cutting into the frame in order to reduce the size of the last piece.

In one embodiment of the invention there is provided a workpiece clamping apparatus in which the flexible bracing member comprises a chain. Detailed Description of the Invention

The invention will now be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawings, in which:-

Figure 1 is an isometric view of a workpiece clamping apparatus according to the invention;

Figure 2 is an end view of the apparatus of Figure 1 ;

Figure 3 is a front view of the apparatus of Figure 1 ; Figure 4 is a top plan view of the apparatus of Figure 1 ;

Figure 5 is an isometric view of the workpiece clamping apparatus according to the invention in a stowed configuration; Figure 6 is an end view of the apparatus of Figure 5;

Figure 7 is a front view of the apparatus of Figure 5;

Figure 8 is a top plan view of the apparatus of Figure 5;

Figure 9 is an isometric view of the workpiece clamping apparatus with a workpiece mounted thereon;

Figure 10 is an end view of the apparatus shown in Figure 9;

Figure 1 1 is an isometric view of the central column of the workpiece clamping apparatus according to the invention; Figure 12 is a front view of the column shown in Figure 1 1 with upright bars mounted on the central column;

Figure 13 is a front view of the handle receiving plate of the workpiece clamping apparatus according to the invention;

Figure 14 is a side view of the handle receiving plate shown in Figure 13;

Figure 15 is a side view of the handle of the workpiece clamping apparatus according to the invention; and

Figure 16 is a side view of the handle engaging the handle receiving plate.

Referring to Figures 1 to 10 inclusive, there is shown a workpiece clamping apparatus, indicated generally by the reference numeral 1 , comprising a central upright column 3 supporting a compact workpiece receiving cradle 5. The upright column 3 has a pair of legs 7, 9 connected to the column adjacent to the base 1 1 of the upright column. The legs 7, 9 extend outwardly from the central column and each leg 7, 9 has a ground engaging foot 13, 15 respectively, at the end of the leg 7, 9 remote from the upright column 3 to support the workpiece clamping apparatus 1 . The compact workpiece receiving cradle comprises a pair of Y-shaped workpiece receiving members 17, 19 spaced apart from each other and dimensioned to receive a workpiece 21 between the arms 23, 25, 27, 29 of the Y-shaped workpiece receiving members. There is provided a clamping device, indicated generally by the reference numeral 31 mounted on the column 3 operable to releasably secure a workpiece 21 in position on the workpiece receiving cradle 5. The clamping device 31 comprises a flexible bracing member, in this case provided by a chain 33, that is able to assume closely the profile of the surface of the workpiece 21 to facilitate secure engagement of the workpiece. The clamping device comprises both a coarse adjustment means 35 of the flexible bracing member and a fine adjustment means 36 of the flexible bracing member, both of which will be described in more detail below. The coarse adjustment means 35 comprises an anchoring plate 37 that can releasably engage the flexible bracing member 33, in this case a chain, intermediate its ends and anchor the chain to the anchoring plate. In the embodiment shown, the anchoring plate 37 comprises a notch 39 formed in the anchoring plate. The notch is dimensioned to receive a link of the chain 33 which is in a substantially vertical plane. As the links of a chain are generally offset with respect to the next adjacent links by 90°, the next link will be in a substantially horizontal plane. Accordingly, the shoulders of the next link in the chain adjacent to the link located in the notch will abut against the anchoring plate and will be unable to pass through the notch when a pulling force is exerted on the chain. The anchoring plate 37 and hence the notch are inclined upwardly and outwardly from the central column to prevent inadvertent disengagement of the chain from the notch. In order to pay out more chain to facilitate a larger workpiece, the chain 33 is lifted upwards until it is free of the notch 39 and a link further down the chain is inserted into the notch. If it is desired to reel in more chain to ensure secure fastening of a narrower workpiece, the chain is lifted upwards until it is free of the notch and the desired amount of chain is pulled through beyond the anchoring plate before a link of the chain is inserted into the notch.

The coarse adjustment means further comprises a guide member, in this case, a hollow pipe 41 cranked intermediate its ends into a curved pipe which acts to lead the flexible bracing member from one side of the column 3 to the opposite side of the column to the anchoring plate 37. In this way, both the coarse adjustment means 35 and the fine adjustment means 36 are located on the same side of the column 3 which will facilitate adjustment of the flexible bracing member 33 by the operator of the apparatus 1.

The fine adjustment means 36 comprises a handle 43 connected to one end of the flexible bracing member 33, and a handle receiving plate 45 mounted on the column 3. The handle receiving plate 45 comprises a pair of substantially parallel plates 47, 49 that are spaced apart from each other. The plates 47, 49 each have a plurality of notches 51 (a), 51 (b), 51 (c), 51 (d) and 51 (e) formed along their length which act as a plurality of mounting points for reception of the handle. The handle 43 is provided with a pair of protrusions 53, 55 extending outwardly from opposite sides of the handle 43 for releasable engagement of the notches 51 (a) - 51 (e) to secure the handle in position relative the receiving plate. In the embodiment shown, there are five notches in each plate, however, it will be understood that more or less notches could be provided.

The handle receiving plate 45 is mounted on a track, in this case a pair of substantially upright parallel bars 57, 59 which in turn are mounted on the central upright column. In this way, the handle receiving plate is able to move along the track relative the central upright column. As well as the handle receiving plate 45, there is provided a pair of springs 61 , 63 that provide a biasing force to urge the handle receiving plate downwards relative the upright column. When a workpiece is mounted in the cradle, this force exerted by the springs 61 , 63 is operable to exert a clamping force on a workpiece secured in place by the clamping device and also allows the fine adjustment.

Referring specifically to Figure 3, the legs 7, 9 are hingedly mounted to the central column 3 about hinges 71 , 73 respectively. There are provided a pair of struts 75, 77 which in turn are also hingedly mounted to the central column about hinges 79, 81 respectively. The struts 75, 77 each have slider 83, 85 respectively at their end remote from the central column. The sliders 83, 85 are dimensioned to releasably engage a complementary abutment 87, 89 on the legs 7, 9 and prevent further movement of the strut along the leg.

In order to collapse the apparatus from the operating configuration (as shown in Figures 1 to 4) to the collapsed or stowed configuration (as shown in Figures 5 to 8), the central column 3 is lifted upwards. As the central column is lifted upwards, the sliders 83, 85 will disengage the abutments 87, 89 and the struts 75, 77 will be free to rotate upwards about the hinges 79, 81 to a position alongside and substantially in line with the central column 3. Once the struts 75, 77 have been pivoted upwards about the hinges 79, 81 , the legs 7, 9 can also be pivoted upwards about the hinges 71 , 73 to a position alongside and substantially in line with the central column 3. A pair of bolts 91 , 93 secured to the central column are provided to engage a bracket 95, 97 on the legs 7, 9 respectively and an internally threaded knob (not shown) is provided on each bolt to secure the bracket to the bolt and by extension to secure the legs 7, 9 in position relative to the central column 3. ln order to expand the apparatus from a collapsed configuration (as shown in Figures 5 to 8) to an operating configuration (as shown in Figures 1 to 4), the above steps are reversed. First of all, the internally threaded knobs are loosened and the legs 7, 9 are lowered about their hinges 71 , 73 to a position where the legs form an angle with the central column of slightly greater than 90°. Once in this position, the struts 75, 77 are lowered about their hinges 79, 81 until the sliders 83, 85 rest on the top surface of the legs 7, 9. Once the sliders 83, 85 are resting on the legs, the central column is lowered thereby causing the sliders 83, 85 to move outwardly along the legs 7, 9 until the sliders engage the abutments 87, 89. The abutments 87, 89 prevent further movement of the struts and the weight of the column and any workpiece mounted thereon will hold the workpiece clamping apparatus in the operating configuration.

Referring specifically to Figures 9 and 10, there is shown a pair of views with a workpiece, in this case a tree trunk 21 , mounted in the cradle 5. The workpiece 21 is lifted up onto the cradle. The handle 45, with one end of the chain 33 connected thereto, is drawn over the workpiece and the protrusions 53, 55 extending outwardly from opposite sides of the handle 43 are located in one of the pairs of notches 51 (a), 51 (b), 51 (c), 51 (d) and 51 (e) formed along the length of the handle receiving plate 47. Preferably, the handle is lowered as much as possible and the chain is pulled as taut as possible prior to engaging the protrusions in the lowest possible pair of notches. Once the protrusions of the handle 45 are engaged in a pair of notches 51 (a)-51 (e), the handle is rotated downwards about the protrusions in the direction indicated by the arrow A in Figure 10. The fine tuning member operates in a fashion similar to an over-centre latch. As the handle is rotated in the direction of the arrow A, the handle receiving plate 47 will be urged upwards along the pair of bars 57, 59 against the force of the springs 61 , 63. When the handle has been rotated fully, it will be "over-centre" and the springs 61 , 63 that urge the handle receiving plate downwards will prevent disengagement of the clamping device. The workpiece can then be cut into a number of smaller pieces without becoming dislodged from the apparatus. The size of the cradle and the fact that the Y- shaped workpiece receiving members are relatively close to each other allows the final piece of the workpiece to be relatively small.

It can be seen from Figures 9 and 10 that both the fine adjustment means and the coarse adjustment means are located on the same side of the column. This allows the operator to adjust the clamping device with ease. If it is necessary to adjust the coarse adjustment means, before engaging the handle in one of the pairs of notches, the operator grasps the tail of flexible bracing member and adjusts the flexible bracing member in the manner described above by paying out or retrieving the flexible bracing member and securing the flexible bracing member in position once more to the anchoring plate. Once the flexible bracing member has been secured in position to the anchoring plate, the fine adjustment means is then operated to securely fasten the workpiece to the apparatus. It will be noted from the drawings that at least one of the ends of the arms 23, 29 of the Y-shaped workpiece receiving members 17, 19 is open to allow insertion and temporary storage of the handle. This is a simple way of keeping the handle to hand and will facilitate faster engagement of a workpiece.

Referring to Figures 1 1 and 12, there is shown a pair of views of the upright central column without the legs, struts and parts of the clamping device attached. It can be seen that the central upright column consists of a frame work including a pair of substantially parallel uprights 101 , 103 bridged along its length by a plurality of bracing members, an upper bracing member 105, a middle bracing member 107 and a lower bracing member 109. In Figure 1 1 , there is shown a plurality of apertures in both the upper bracing member and the middle bracing member. These apertures are suitable to receive the pair of substantially upright parallel bars 57, 59 (Figure 12). The upright parallel bars 57, 59 form the track for the handle receiving plate 47. The upright parallel bars are provided by bolts and there are provided a pair of nuts, an upper nut 1 1 1 and a lower nut 1 13 on each of the upright parallel bars. The lower nut 1 13 operates to secure the upright parallel bar in position on the bracing member. The upper nut 1 11 operates to adjust the amount of force exerted by the springs (not shown) on the handle receiving plate, as will be more clearly described with reference to Figures 13 and 14 below.

Referring to Figures 13 to 16 inclusive and first of all specifically to Figures 13 and 14, some parts of the clamping device are shown. Only the bolts comprising the upright parallel bars 57, 59, the springs 61 , 63, the upper bracing member 105, the middle bracing member 107, the upper nuts 1 1 1 , the lower nuts 1 13 and the handle receiving plate 47 are shown. It can be seen that the handle receiving plate 47 is mounted on the upright parallel bars 57, 59 and rests on the upper nuts 1 1 1. The handle receiving plate is urged downwards by the springs 61 , 63. Referring to Figure 15, there is shown a side view, partially in outline of the handle 45 which in turn comprises a pivot pin 121 and a pivot arm 123. One end 125 of the pivot arm is mounted on the pivot pin 121 . The end of the chain (not shown) is attached to the other, free end 127 of the pivot arm 123. Referring to Figure 16, as the handle 45 is rotated downwards in the direction of the arrow B, and the chain (not shown) becomes taut, the handle receiving plate 47 will be urged upwards along the track against the action of the springs 61 , 63. Once the handle 47 has been rotated by a predetermined amount, the pivot arm will go "over-centre" and further rotation of the handle will cause the springs to at least partially relax. In order to release the handle, this spring force will have to be overcome and the springs now work to hold the handle in the workpiece clamping position. Therefore the handle is kept in position until it is desired to release the handle.

Referring again to Figure 1 , there is provided an internally threaded knob 131 securing the foot 13, 15 in a fixed relationship with its respective leg 7, 9. It is possible to rotate the foot on the leg for more compact storage (as shown in Figures 4 to 8 inclusive). The foot has a box shaped section along part of its length which corresponds and fits inside a box-shaped section of the leg. The box shaped section of the leg effectively sleeves the box-shaped section of the foot. Rotation of the foot relative to the leg is achieved by loosening the internally threaded knob and sliding the box-shaped section of the foot outwardly until it is no longer engaged by the box-shaped section of the leg. The foot is then rotated through 180° and the box shaped section of the foot is slid back into the box shaped section of the leg and the wing nut is tightened again. When it is desired to unpack the apparatus, these steps are repeated in order to have the feet facing the correct direction (i.e. towards the ground).

It will be understood, that various modifications could be made to the specific constructions described without departing from the spirit or scope of the invention. For example, various other constructions of flexible bracing members could be used, such as a strap or rope, provided that suitable means are provided on the coarse adjustment means to engage the flexible bracing member.

Furthermore, other constructions of coarse adjustment means and fine adjustment means are readily envisaged. For example, a hook could be provided instead of the anchoring plate 37 and notch 39 construction. The hook could engage one of the links and hold it securely in place if desired. Similarly, a clasp or like device could be used to engage a strap if a strap were used instead of a chain and a cleat or like device could be used to engage a rope if a rope were used for the flexible bracing member. In the embodiment shown, the coarse adjustment means and more specifically the hollow pipe 41 and the anchoring plate 37 are mounted about the lower bracing member 109 however these could equally well be mounted elsewhere such as on the middle bracing member 107.

Similarly, other constructions of fine adjustment means are also readily envisaged. Instead of having a plurality of notches on the handle receiving plate and a pair of protrusions on the handle, a plurality of substantially transverse bars or loops on the handle receiving plate and a hook on the handle could be provided. Alternatively, other arrangements of fine adjustment means are envisaged such as a pulley system that may be used to tension the flexible bracing member. As a further still alternative, a spring or other resiliently deformable member, preferably formed as part of the flexible member along at least part of the length of the flexible member, could be used instead of the sliding anchor plate. The spring or other resiliently deformable member would allow the handle to move to the over-centre position creating tension and exerting a clamping force on the workpiece.

In the embodiments shown, an internally threaded knob is provided to secure each of the legs 7, 9 in position relative to the central column and a further internally threaded knob 131 is provided to secure each foot in a fixed relationship with its respective leg 7, 9. Instead of an internally threaded knob, a wing nut or indeed another alternative locking member could be used such as, but not limited to, a bolt or a spring catch.

In addition to the above, the legs are pivotably mounted onto the column and there are provided struts to strengthen the legs. It will be understood that other constructions without struts but with means to lock the legs in position could be provided in its stead. For example, a releasable locking pin that locks the leg relative to a support frame upon which the leg hinges could be used to good effect and other spring loaded constructions that facilitate deployment and stowage of the legs could be provided. It is envisaged that a wheel or more preferably wheels could be provided on the frame to allow for easier transport of the workpiece clamping apparatus from location to location. Preferably, the wheels would be clear of the ground when the workpiece clamping apparatus is in the working configuration and would rest on the ground when the workpiece clamping apparatus is in a folded up, stowed configuration. A small stabilizing leg could be provided that also rests on the ground when the workpiece clamping apparatus is in a folded up, stowed configuration. The stabilizing leg would typically be positioned to one side of the central column opposite the side with the wheels. For example, the stabilizing leg could be positioned at the front of the workpiece clamping apparatus approximately beneath the anchoring plate whereas the wheels would typically be located below the hollow pipe 41. In use, when the workpiece clamping apparatus is leaned backwards slightly, this will cause the stabilizing leg to lift upwards until it is free of the ground and the folded up clamp can be wheeled about on its wheels.

In the embodiments shown, there are provided a pair of Y-shaped workpiece receiving members to receive and support a workpiece therebetween. The Y-shaped workpiece receiving members are suitable to receive a single workpiece in a variety of different sizes. However, other configurations of workpiece receiving members could be provided such as substantially W-shaped workpiece receiving members. A pair of substantially W- shaped workpiece receiving members will be able to receive two workpieces simultaneously. Indeed other shapes of workpiece receiving members with three or more stations for receiving a workpiece therein are envisaged. The workpiece receiving members could be detachably mounted from the uprights so that they are interchangeable or indeed one or more attachments could be provided that can be releasably fitted to a pair of permanently-attached Y-shaped workpiece receiving members, thereby expanding the Y-shaped workpiece receiving members so that they can be used to support many workpieces simultaneously. For example, a fitting with several workpiece receiving stations could be provided to allow multiple workpieces to be placed in the workpiece clamping apparatus simultaneously so that several workpieces could be cut together. The fitting could fit onto the end of the existing Y- shaped workpiece receiving member. In this way, a number of relatively small diameter workpieces could be placed in the workpiece receiving members and clamped simultaneously so that they can be worked on at the same time. ln this specification the terms "comprise, comprises, comprised and comprising" and the terms "include, includes, included and including" are all deemed totally interchangeable and should be afforded the widest possible interpretation.

The invention is in no way limited to the embodiment hereinbefore described but may be varied in both construction and detail within the scope of the claims.