Background of Invention Extension tables for use with table saws and spindle molders are common accessories particularly with the more massive industrial versions of such machines where an extension table acts to effectively extend the primary working surface of such a machine in a manner to allow the machining of large work pieces accurately and confidently across the primary working surface. In addition, such extension tables extend the distance at which a fence can be mounted from the cutting tool of such a machine thereby greatly increasing the ability of such a machine to perform rip cutting operations with a parallel fence mounted at greater distance than would otherwise be available from the cutting tool.

Extension tables come in either fixed or sliding configurations with the fixed configuration providing all the foregoing benefits including use for square cuts on large work pieces with the work piece sliding on the fixed table and against the fixed fence. Sliding extension tables similarly provide a physical extension of the primary working surface of the machine however they also incorporate a longitudinal track system parallel with the sides of the primary working surface to carry the extension table along a predetermined path to facilitate smooth and highly accurate processing of work pieces relative to the tool of such a machine.

Sliding extension tables may be fitted with a fence arrangement and a means for clamping or securing the workpiece to the sliding extension table thereby allowing the sliding extension table and its inherent accuracy to be translated to a work piece moving across the tool. Sliding extension tables may also be fitted with a means for clamping or securing the workpiece to the

sliding extension table further ensuring the sliding extension table and its inherent accuracy will be faithfully and confidently translated to a workpiece moving across the tool.

Guidance throughout such a cutting arrangement is provided by the longitudinal tracks and not by a random datum point or face on the workpiece thereby allowing straight cuts to be achieved parallel to the datum face of the fence allowing straight or taper ripping cuts dependent on the positioning to the fence.

Conventional sliding extension tables fall into two basic design forms: 1. Sawbench mounted - where an inner guidance track is rigidly mounted to the machine chassis and an outer support is provided by counterleaver swinging arm pivotally mounted to the machine chassis. This arrangement is totally dependent on the mass of the machine to ensure that a work piece placed on the sliding table does not overbalance the machine or cause the assembly to tilt. Some machine mounted sliding extension tables are provided with an out rigger foot in order to secure the cantilever swinging arm if necessary, however, such provisions are only intended for use when the extension table is subject to considerable weight and generally limit the extension table to a fixed mode.

Such arrangements permit the operator to follow the workpiece without impediment as the swinging arm follows the movement of the operator.

However, such arrangements are unsuitable for lightweight portable machinery of the type found in common use in home workshops as such machinery does not have the substantial mass of industrial machines to resist tilting.

2. Freestanding sliding extension table frames are also known which incorporate inner and outer guide tracks. Such prior art frames have an inner guide track fitted to the machine and an outer guide track also fitted to the machine at a distance by way of cross-bracing as a means of secure connection to the machine chassis. This arrangement permits fitting to lightweight portable saw benches as the outer guide track is supported on the ground, but the

necessity of providing cross-bracing and the inherent need for such guidance tracks to be precisely positioned greatly limits the application of such freestanding assemblies to lightweight portable machines. Furthermore, the necessary cross-bracing and complex configurations required to ensure the precision necessary to allow such frame assemblies to operate interferes with the ability of operator to follow the workpiece through the full available table travel as this area is occupied with cross bracing etc. Accordingly the currently available sliding extension table assemblies for use on lightweight machines suffer major problems of ensuring precision of set up as well as interfering with the operators preferred ability to closely follow through on the workpiece during a cutting operation.

The increasing demand for lightweight portable home workshop machine which are capable of providing high levels of accuracy and increasing standards and scope of work would greatly benefit from the provision of a sliding extension table assembly adapted for use with lightweight portable machinery which could overcome all foregoing problems.

Object and Statement of Invention One object of this invention is to provide an improved sliding extension table assembly and accessories for use therewith.

Accordingly in one aspect the invention provides a sliding extension table assembly adapted for cooperation with a machine having a primary working surface said assembly including a slidable table; an inner support for placement proximate to the machine, an outer support for placement substantially parallel to the inner support at a distance removed from and independent of said machine, said inner and outer supports being provided with inner and outer guides respectively for sliding movement of the table substantially co-planar with the primary working surface of the machine.

When cooperating with the machine, the sliding table preferably abuts

against or is adjacent to an adjoining edge of the primary working surface of the machine, the sliding table being movable in a direction parallel to the adjoining edge.

The inner support is preferably attachable to the machine to enable the inner guide to extend substantially parallel to the adjoining edge of the primary working surface.

By providing guides for sliding movement of slidable table directly onto the inner support and independent free standing outer support, no cross bracing or other linking structure apart from the table is necessary in the area between the inner and outer supports. Thus the operator is able to remain in an upright position and follow the workpiece through its full available travel.

In one preferred form of the invention, the guide for the outer support includes an outer supporting track and the inner guide includes an inner supporting track. The table will most preferably include journal bearings positioned on the underside thereof wherein said journal bearings are open to allow free vertical engagement with the inner and outer supporting tracks. The bearings preferably include at least two first bearings adapted for snug lateral engagement with the inner supporting track and at least two second bearings adapted for tolerant lateral engagement with the outer supporting track so as to allow the outer supporting track a measure of latitude without affecting the accuracy of the movement of said table. The bearings may be arcuate low friction dry bearings shaped to substantially conform to the shape of said tracks with the tracks most preferably adopting a substantially circular cross-section configuration as an elongate, hollow cylindrical pipe or tube.

The outer support preferably includes an elongate cylindrical shaped supporting track and at least two legs for holding the track in the desired position wherein the legs are independently stable in a direction transverse to the track, that being a direction toward and away from the machine, and dependently stable in the longitudinal direction of said track when fitted thereto.

The legs are preferably fitted to the track at or near a first end thereof so as to allow independent vertical height adjustment of the track on each leg.

The second end of each leg may be fitted with a foot to provide the aforesaid transverse stability and the foot is preferably pivotally fitted to the leg and movable from a first position providing stable support for the leg which is held at an angle acute to the vertical, through to a second position folded back upon and parallel to the leg. Each leg may be fitted to the track by the free clampable passage of the first end of the leg through an aperture formed toward both ends of the support track. The support track apertures incorporates a clamping means for the leg which preferably includes a clamping plate adapted to fit within the hollow support track and having an aperture corresponding to the aperture formed through the track. The clamping plate is adapted for longitudinal movement back and forth within the track such that the relative movement of the track aperture and the clamping plate aperture applies a clamping force to a leg inserted through the track apertures by drawing the leg against the track aperture at the required and selected height therein.

This provides a means of independently clamping the two end legs at the required height to ensure that the outer track remains substantially parallel to the primary working surface of the machine notwithstanding any undulations or variations in the ground upon which the machine and the sliding table extension are placed.

In another aspect, the invention provides a sliding extension table for use in the previously described assembly wherein the sliding extension table includes open journal bearings positioned at the underside thereof located at the extreme corners of the rectangular sliding extension table. The sliding extension table may be formed from a rectangular frame having a continuous Tee slot formed therein for captively receiving one or a plurality of inverted bolts. The captive bolts are preferably capable of following the entire perimeter of the rectangular frame of the table.

The provision of the Tee slot in the perimeter enables objects to be

secured to the table. If the object is an article such as a fence which is long enough to extend across a diagonal of the table, then the article can be secured to the table with a clamp and inverted bolt at each end and be oriented at any angle within the plane of the table.

In another aspect, the invention provides a fence for use in conjunction with the previously described sliding table. The fence include a longitudinal through slot formed along a substantial length of the fence. The through slot is preferably adapted to receive one or a plurality of inverted bolts for engagement with the Tee slot so as to form a means of fitting the fence to the table. The inverted bolt or bolts may be secured to the fence by at least one positioning clamp. The fence may be formed of two elongate rails held apart by end spacers so as to form a longitudinal slot and if necessary a central spacer may be fitted to ensure adequate rigidity of the fence.

The features objects and advantages of the invention will become more apparent from the following description of the preferred embodiment and drawings in which: Figure 1 is a perspective view of the sliding extension table assembly; Figure 2 provides details of the outer supporting track means; Figure 3 provides details of the inner supporting track; Figure 4 is details of the inner track fitting to a machine; Figure 5 is an exploded view of the table; Figure 6 is a perspective view of the table and fence; Figure 7 is a perspective view of the table with the fence fitted thereto; Figure 8 provides perspective views of work piece clamping means; and Figure 9 is a selection of configured uses of the sliding extension table assembly.

Referring firstly to Figure 1, the sliding extension table assembly can be seen assembled for co-operation with a light weight portable machine 1, in this case a portable table saw, with the table saw having a primary work surface in the form of a top 2. The sliding table assembly includes an inner support for

placement proximate to the machine. In the embodiment showing Figure 1, the inner support is secured to the machine and includes a guide in the form of an inner supporting track 4 preferably of an elongate cylindrical shape held in position by brackets 24. The assembly also includes an independent or free standing outer support having an outer guide in the form of outer supporting track 7 which is shown as being an elongate cylindrical shape. The outer supporting track 7 is held at the appropriate position by two legs 8 which are leaning slightly off the vertical and dependent on the feet 11. The outer supporting track 7 can be moved up and down the leg 8 as required in order to ensure that the outer supporting track 7 can be positioned substantially parallel to the face primary working surface 2. The completely independent and free standing nature of the outer support allows the outer supporting track to be positioned or placed at a distance removed from and completely independent of the machine 1 so as to allow completely free access between the inner and outer tracks.

The inner supporting track 4 may be placed substantially parallel to the adjoining edge 2A and face of the primary working surface 2 and proximate to the machine. As the outer supporting track 7 is positioned substantially parallel to the inner supporting track 4 the assembly is able to provide an inner and an outer supporting track parallel to the primary working surfaces of the machine 1. With the outer support being placed at a distance from the machine full and unimpeded access between the inner and outer supporting tracks is allowed.

The sliding extension table assembly further includes a table 5 which is provided with open bearings 6 (6A and 6B) positioned underside at each extreme corner such that the table can be made to slide along the outer and inner tracks with the bearings following the tracks so as to provide the table with a movement substantially co-planar with the primary working surface of the machine, and parallel to the adjoining edge 2A.

The outer support is shown in more detail with reference to Figure 2 and can be seen to be made up of outer supporting track 7 in the form of an

elongate cylindrical tube which is supported at the required height by way of two legs 8. The outer supporting track 7 is provided with a through aperture 13 at or near each end with the aperture being made up to two holes on either side of the cylinder providing an aperture through which the first end 9 of each leg 8 can pass. The free movement of the leg through the supporting track aperture provides the means for height adjustment of the supporting track and the height adjustment is independent in both legs so as to provide a ready means of adjusting the configuration of the supporting track to ensure that it remains parallel with the face of the primary working surface of the machine.

In order to ensure the stability of the outer track means, independent of any structural reliance on the machine 1, the legs are provided with feet 11 which are pivoted to a second end 10 of the legs via a crank 22. One end of the crank 22 is attached to the foot and the other end of the crank is pivoted on the second end of the leg so as to provide a means of moving the foot from a first position with the foot bearing against the leg and providing a type of A- frame assembly to a second position where the foot 11 can be pivoted through a wide arc around the bottom of the leg 8 so as to return to a second position folded back upon and parallel to said leg.

The fitting of the leg to the supporting track 7 is provided by a clamping means in the form of a clamping plate 15 which is adapted to fit within the hollow supporting track 7 at the end thereof such that the clamping plate has its own aperture 16 corresponding to the aperture formed through the track. The clamping plate is fitted to the end of the track 7 preferably by way of a screw threaded arrangement 23 such that it can be moved longitudinally within the track so as to apply a clamping force to one side of a leg inserted through the track apertures 13 and corresponding clamp aperture 16. The first end of the leg may also be provided with a sliding height adjustment including bolt 40 received within a slot 41 in the leg 10 clamping nut 42 and level setting washer 43.

Accordingly the height adjustment of the leg is effected by loosening the

screw arrangement 23 which releases the clamping pressure on the leg 8 inserted through the apertures 13 of the track 7. The height can then be adjusted to whatever is necessary and set by tightening screw 13 to draw the clamping means back on the leg such that that part of the leg within the confines of the track 7 is made to bear upon the extreme edges of the apertures 13 and therein clamped at the desired height. The level setting washer may then be moved up to abut against the bottom surface of the track 7 to set the height on the leg.

Alternatively the height of the outer supporting track can first be set by adjusting the position of bolt 40 and washer 43 to the desired level, inserting the first end of the leg into the track apertures 13 and tightening the screw threaded arrangement 23 as described above. By providing a separate height setting, the outer support can be dismantled and later reassembled with the track 7 at precisely the same height.

The inner supporting track is detailed in Figures 3 and 4 where the inner supporting track 4 is rigidly attached to the machine via removable brackets 24.

The brackets may be adjustable to ensure that the supporting track is preferably maintained parallel to face and adjoining edge of the primary working surface such that the sliding table, when fitted, is co-planar with the primary working surface. The brackets are fitted to the machine via mounts 25 and once the mounts are precisely aligned to the machine chassis 1, the removable brackets 24 can be readily removed and replaced at leisure knowing that the accuracy of the arrangement will be maintained notwithstanding repeated removal of the inner track. The inner supporting track 4 can additionally be provided with terminal skids 26 which act as travel stops for the sliding table and also provide added support for large overhanging work pieces. In addition, the inner supporting track 4 includes a pivoting latch 27 which is adapted to locate around a bearing block of the sliding table therein locking the sliding table in mid-stroke position to enable the sliding extension table to be used as a conventional fixed rip extension table when the length of the cut required

exceeds the available travel of the sliding table.

Referring now to Figure 5 the extension table takes a substantially rectangular configuration including an outer frame 27. The outer frame 27 has a continuous Tee slot 28 formed therein (see insert 1). In the particularly preferred embodiment, the rectangular frame consists of four frame members 45 connected by corner brackets 29. The continuity of the Tee slot 28 is preferably ensured by the formation of corresponding Tee slot in the corner bracket such that the rectangular frame 27 when assembled provides for the continuous Tee slot 28 extending right around the rectangular frame so formed.

Referring now to Figures 6 and 7, a perspective view of the table and fence is shown. The rectangular frame of the table is provided with open bearings be made up of a at least two first open bearings 6a being shaped so as to provide a snug lateral engagement with the inner supporting track, this provides the precise datum relative to the primary working surface of the machine 1 to allow the table to move in an accurate parallel motion relative to the adjoining edge 2A of the primary working surface 2. The outer side of the table is provided with at least two second bearings 6B which are adapted for tolerant lateral engagement with the outer supporting track. To achieve this, the second bearings 6B provide a shape faithful with but a laterally extended template of the outer supporting track 7. In this manner, the outer supporting track is provided with considerable latitude in terms of its position such that the outer support whilst precisely levelled parallel for the table to be co-planar with the top of the primary working surface 2, does not have to be similarly precisely located parallel to the adjoining edge 2A of the primary working surface along which the table will travel. The latitude so provided ensures that the sliding extension table assembly is readily adapted to lightweight machines in a variety of environments particularly where such light weight machinery is adapted for transport and location in a variety of environments on a variety of terrain. The particular features of the invention allow the sliding extension table

assembly to be readily adapted to a variety of terrain in the minimum of time relying on a minimum of precision whilst ensuring the greatest possible accuracy.

While not illustrated, it is envisaged that the slidable table is provided with an inner and outer sliding track and these tracks co-operate with the guides of the outer and inner supports. In such an embodiment the guides would be bearings which conform to the tracks attached to the table. Such an embodiment would provide still function in accordance with the present invention.

In another aspect the invention provides a fence for use with the table.

The fence includes two elongate rails 20 which are joined by spacers 21 so as to provide an elongate through slot 18 along the substantial length of the entire fence. The elongate through slot 18 is adapted to receive inverted bolts 19 which are inserted in the Tee slot 28 of the table. By way of a suitable clamping means, the fence can be securely fitted to the sliding table in any configuration by virtue of the continuous nature of the Tee slot 28 allowing the fence to be rotated right around the outer perimeter of the table. This arrangement also provides considerable latitude for movement of the fence forward and aft in virtually any position circumscribing the table.

In this manner the fence can be fully utilized in all configurations with respect to the sliding table particularly with regard to the use of the fence when performing angled cuts, for example a miter cross cut where the full reach of the fence allows the extension table to provide confident guidance of a workpiece across a substantial length mating right up to the tool. In order to further assist the user the fence is provided with a sacrificial termination block 29 which when adjusted against the tool provides a datum to align a marked cutting position on a given workpiece.

An additional feature of the invention is the provision of workpiece clamps which are shown in Figure 8. The workpiece clamps 30 include a fixture housing 31 which is adjustably fitted to the fence by way of a Tee bolt

32. The fixture housing can be moved laterally along the length of the fence by adjustment of the turn screw 33. The working clamp piece is activated by the turning of a thumb screw 34 which causes a foot 35 to bear down upon the workpiece 36. The configuration of the fixture housing and foot 35 is provided such that the foot is positioned proximate to the working face 37 of the fence.

This particular configuration has been found to be beneficial particularly upon the completion of a cutting operation where an operator may inadvertently omit to release the thumb screw 34 before removing a work piece from the fence table assembly. Under these circumstances the proximate provision of the foot 35 ensures that the workpiece can be safely removed from the fence/table assembly without risk of damage which may otherwise occur if the foot were positioned further into the workpiece. The workpiece clamps are most useful in performing miter cuts or tapered rips on sheet material where the workpiece has a tendency to slide along the working face 37 of the fence.

The various configurations and modes of operation of the sliding extension table assembly are shown in Figure 9 detailed consecutively as A - stockingsaw, B-a panel saw, C- a taper ripsaw, D- leading angle saw, E - trailing angle saw, F - taper ripsaw, G - fix ripsaw and H - travelling ripsaw.

The advantages provided by the various aspects of the invention are numerous and unique to the art of stationary power tooled machinery, particularly lightweight portable stationary power tool machinery. The limitations of the prior art, in particular, the ability of existing sliding extension table assemblies provide a ready means of providing a quick set up over uneven and unpredictable terrain on a lightweight machine have been comprehensively addressed in the current invention. The sliding extension table assembly of the invention provides a high capacity sliding extension table requiring minimum precision of assembly, ready adjustments with maximum accuracy and performance. The ready set up repeatable fixtures of the assembly including the completely independent nature of the outer supporting track means does not in

any way compromise the ability of an operator to confidently control a workpiece. This is particularly so as the operator is allowed full and ready access between the inner and outer tracks so as to allow the operator in an upright stance to maintain an intimate and close contact with the workpiece as it follows through the whole of a given machining operation. Such intimate contact and the maintenance of such intimate contact with the workpiece throughout the whole of the machining operation in combination with the high level of accuracy provided by the unique features of the assembly provide for the first time a sliding extension table assembly which bridges the gap between the prior art devices available for high mass industrial equipment and low mass portable equipment whilst not sacrificing any aspect of accuracy or safety which are provided in the far more costly alternatives.