Field of the Invention

The present invention relates to a workpiece positioning device, and more particularly to a work length stop and barb device for positioning a workpiece easily and accurately, say, on a working surface of a portable, multi-purpose apparatus for controlling power tools as described in my International patent application Background

When articles require operations using power/machine tools such as circular saws, routers, drill presses and the like, it is desirable to be able to position a workpiece rapidly, accurately, and repeatably in relation to an operative member of a power/machine tool or the like. Various methods are employed to do this with the amount of time required to setup for that being amortised over the number of parts requiring the particular operation eg. cutting, drilling or whatever. The greater the speed, convenience and accuracy with which a setup can be established and used, the more efficiency is achieved. The more this efficiency can be applied to a lesser number of articles requiring such operations, as is the case when doing very small production runs and in situations requiring constant changes in setup, the improvement in efficiency becomes increasingly more significant.

A problem with setting up a worklength stop to an accurate length occurs in quickly locating the appropriate position with repeatable accuracy; this is often done simply by measuring between the stopping member and the operative member of the power/machine tool, normally requiring a test cut and then usually needing readjustment, with the whole process being repeated with each subsequent setting. A part solution to this is sometimes achieved by fixing a measuring tape to the

workpiece support with time consuming regard to the accurate location of the tape and requiring great care that the tape's end does not interfere with the operative member. This works adequately for a cutting machine while the same angle of cut is used, but when changing from say a 90° square cut to, for example, 45 mitre, the previous setting is of no value and is in danger of enmeshing the tape with the operative member of the power/machine tool, and so another time consuming setup is required each time this is done.

Further, it is generally more desirable to use a worklength stop on a flat work piece support to provide constant support for sometimes flexible materials that require the operation; but when doing so, there is often a problem with a build up of debris at the stopping member; this can cause inaccuracies and also considerable inconvenience in having to watch for that effect and by the constant need to interrupt the work to clear the debris. A device that is substantially self clearing of such debris would provide considerably increased efficiency.

Furthermore, it would be advantageous if a worklength stop could be adapted for accurately spacing trenches, grooves and holes in relation to an operative member of a power/machine tool and therefore each other on a workpiece. The present invention is concerned with a distance locating device of the form of device 80 shown in Figs 11-13 of PCT/AU88/00499, but in a preferred form has the added benefit of being adapted to act as a work length stop and barb without reorientation as required for the bar 90 as shown between Figs 13 and 14 of PCT/AU88/00499. Summary of the Invention

In one form the present invention consists in a distance locating device or work length stop adapted to be attached to a machine tool apparatus said device being

adapted to support a measuring tape and including an index positioned to align with measurements on the tape, a stopping member of said device being positioned so that a distance between ends of the stopping member and an operative member of a machine tool attached to the apparatus corresponds to a measurement simultaneously read at the index.

In another form the present invention consists in a distance locating device or work length stop, adapted to be attached to a machine tool apparatus comprising a support adapted to be adjustably fixed to a workpiece guide of the machine tool apparatus, a rigid member secured to the support for movement within a plane and a stopping member adjustably securable along the rigid member and extending a transverse length from the rigid member in a direction towards the machine tool when attached to the apparatus, a barb projecting from and in the reverse direction of the stopping member, said barb being adapted in use to contact an end face of a trench formed in a workpiece while maintaining the stopping member out of contact with said trench.

Preferably, the rigid member allows the device to rotate about a first axis substantially perpendicular to a longitudinal axis of the stopping member so that the positioning device may be used to position workpieces in at least two orientations with respect to the first axis.

Preferably, the rigid member further allows the device to be rotated about a second axis substantially parallel to the longitudinal axis of the stopping member, and the device further comprises a projection on said stopping member projecting away from the rigid member and wherein said projection is adapted to perform as a stop or as a barb when the device is rotated about the second axis. Preferably, the projection extends to an effective centre of the rigid member such that when the device is

rotated about the second axis, the projection may act at a fixed position as a stop for the workpiece in a first orientation or as a barb for the workpiece in a second orientation, and the device may also be rotated about the first axis such that the projection may act substantially at the fixed position as a barb for the workpiece in the first orientation or as a stop for the workpiece in the second orientation.

An auto trench locator/work length stop of the invention has the ability to maintain correct separations of trenches when operating. As well it can be connected to a measuring tape to provide fast settings and have a micro adjustable zero when used as a work length stop. Brief Description of the Drawings

The invention will be described with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of a distance locating device in accordance with the prior art;

Fig. 2 is a perspective view showing the device of Fig. 1 clamped to the workpiece support guide of an apparatus as disclosed in Figs. 1-10 of International patent application PCT/AU88/00499;

Fig. 3 is a front elevation showing one method of operation using the device of Fig. 1;

Fig. 4 is another front elevation showing another method of operation using the device of Fig. 1;

Fig. 5 is a side view of an embodiment of a workpiece positioning device in accordance with the present invention;

Fig. 6 is a perspective view of the Fig. 5 embodiment; Fig. 7 is a side view of a part of the workpiece positioning device of Figs. 5 and 6 showing an outer surface of a workpiece being positioned;

Fig. 8 is a side view of a part of the workpiece positioning device of Figs. 5 and 6 showing an inner

surface of a workpiece being positioned; and

Fig. 9 is a side view of the embodiment of the workpiece positioning device of Figs. 5 and 6 in which the device has been rotated so that a web acts as a stop. Detailed Description

The disclosure of International patent application PCT/AU88/00499 is incorporated herein by reference to assist in appreciation of apparatus to which the present invention is applicable. Fig. 1 illustrates a distance locating device 80 in accordance with the disclosure of my International patent application PCT/AU88/00499, device 80 being able to be secured to the workpiece support guide 25 by means of a clamp 81 formed from L-shaped flange 82 and a plate 83 mounted on a slidable central rod 84. The distance between the lower surface of the flange 82 and the upper surface of the plate 83 is governed by a central threaded bar connected to the rod 84 and which carries a wing nut 84A. A tape measure receiving bracket 85 is also located on the flange 82.

Pivotally mounted at the top of the device 80 is an arm 86 which can be swung through the positions illustrated by broken lines in Fig. 1 with the lowered position being adjustably set by the screw 87. Slidably and adjustably mounted on the arm 86 is a bridle 88 through which a threaded bar 90 is screwed on a substantially downward angle.

A wing nut 91 releasably locks the bridle 88 and threaded bar 90 at any desired position along the arm 86. The threaded bar 90 (when released) is able to be rotated to determine precisely the distance between the point 92 of the bar and the operative member of the power tool.

A fine saw cut is placed at say, any point along the fence of the workpiece support at a distance from the cutter of the power tool not exceeding the distance

between the point 92 and the cursor 89. By this means the free end of the tape has been adjusted to suit the application. In the described embodiment of Fig. 3 this is approx. 150mm. The tape's own hook is inserted into this saw cut and the main body of the tape measure is then clipped onto the receiving bracket 85 by it's own clip. The bracket 85 is rotatable to allow the attachment of "right-handed" and "left-handed" tapes. The adjustable cursor 89 is then set to indicate on the tape the measurement between the point 92 and the operative member of the power tool and locked with wing nut 93. Any discrepancy can be finely adjusted by rotation of the threaded bar 90. From then on any length can be rapidly selected and set by relocating the device 80 with the cursor 89 indicating upon the tape the precise length to be cut.

This same application of "referred" measure can also be applied for example, to the cutting of architraves of numerous and varying lengths with a mitre at each end requiring the measure of length to be taken from the

"short corners" by simply relocating the tape's own hook an appropriate amount and then reading the length of cut indicated by the cursor on the tape.

Fig. 2 illustrates the device 80 clamped to the workpiece support guide 25. The bridle 88 with the bar 90 are set on the arm 86 in the operative position for use as a work length stop.

As illustrated in Fig. 3, in this configuration a conventional tape measure 95 can be clipped by its own clip (not illustrated) onto the bracket 85 and adjusted and then used in the manner previously described. This is particularly useful for rapid setup when cutting a number of pieces of material 96 at multiples of varying lengths from a long piece of stock material. Such cut to length material 96 for example being timber as required for the

noggings of a timber framed wall.

Finally Fig. 4 illustrates a method of using device 80 together with a power tool using a trenching head 98 to cut trenches 99 at a predetermined spacing from each other. In this use, the direction of the bar 90 is reversed by end inverting the bridle 88 and slidably setting it at the required position along arm 86 and at a suitable height by adjustment of screw 87. One trench is cut in the correct position, then, with the device 80 at the predetermined space from the trenching head 98, the work material, say a piece of timber is moved from left to right as seen in Fig. 4. The point 92 slides along the top of the timber until it drops into the cut trench 99. A short push to the left brings the point 92 into abutment with the right hand edge of the cut trench 99. Then the trenching head 98 is moved past the timber to cut the next trench 99. The timber is then again moved from left to right thereby bouncing the arm 86 (and hence point 92) out of the previously cut trench 99. The timber is moved further from left to right until the point 92 is located in the last cut trench 99, the next trench 99 is cut, and so on. This method is particularly useful in cutting trenches in wall plates for studs, for example.

This distance locating device provides the following benefits:- l. Provides a more efficient system of length selection that can be conveniently used with any standard measuring tape.

2. Has micro adjustable zero.

3. Can be quickly fitted to most sizes of material that are likely to be used as the fence of a workpiece support.

4. The location of the point 92 is infinitely adjustable and can be set so as to come into contact at any desired particular point on the

end of the work material and at the same time remain clear of the workpiece support and guide fence, this feature virtually eliminates the need to constantly check for and clean away offcuts and sawdust that normally accumulate against the stop and affect accuracy. For example an aluminium extrusion of hollow section being cut to a work length stop would normally present such a problem. 5. When not in use the arm 86 can be flipped over out of the way, this feature is of great value if more than one stop is desired in use, with the body of the measuring tape attached at an extremity any number of these stops may be fitted to the fence being independently free to slide to any position indicated on the tape by their own cursor and be locked at that location with the arm 86 flipping over into or out of the operable position, thus, leaving a clear path when requiring to use a more remote preset stop at a further length of setting. 6. By end inverting the bridle 88 the device becomes an automatic trench locator having similar advantages as when used in the length stop mode. 7. Because of the. adjustability of the bridle 88 and hence the threaded bar 90 means it can be used also for locating holes at repeated set spacings precisely and automatically. 8. In either mode the feature of "referred" measure read on the tape ensures the tape end is located at a safe distance from the operative member of the power tool. An embodiment of a workpiece positioning device 120 in accord with the present invention is shown in Figs. 5 and 6. Device 120 comprises a sheet made from a

substantially rigid material which is bent to form U-shaped section 121, elongate member 122 and barb 123. Elongate member 122 extends laterally from one of the legs of U-shaped section 121, and barb 123 is formed where elongate member 122 is folded backwards at a first end. Stop 124 is formed by the boundary caused by the fold at the first end of elongate member 122.

The two legs of U-shaped section 121 are pierced by holes through which screw 125 passes. Preferably, screw head 28 is positioned proximate elongate member 122 and butterfly nut 127 can be screwed onto screw 125 so that the distance between the two legs of U-shaped section 121 can be varied. For this purpose, the substantially rigid material should also possess a certain amount of resilience. U-shaped section 121, together with screw 125 and butterfly nut 127 form a mounting means for mounting device 120 on bar 128 which may form part of an associated apparatus.

Device 120 is provided with additional strength by web 129. A first edge of web 129 is attached to a first side of elongate member 122, and a second edge of web 129 is attached to one of the legs of U-shaped section 121. As will be described below, web 129 can also provide device 120 with added versatility. Figs. 7 and 8 show views of the first end of elongate member 122 in operation. In Fig. 7, stop 124 together with support guide 25 is used to position workpiece 96 with reference to outer surface 96 . Such positioning may be required, for example, when cutting workpiece 96 to a certain length. In Fig. 8, barb 123 together with working surface or support guide 25 is used to position workpiece 96 with reference to inner surface 96 . Such positioning may be required, for example, when milling parallel channels in workpiece 96, and when the distance from surface 96 to another reference location is

significant.

Although Figs. 7 and 8 show elongate member 122 projecting towards the left and workpiece 96 positioned essentially to the left of elongate member 122, these orientations are not necessarily fixed. Both the orientation of workpiece 96 and the orientation of device 120 can be reversed. For example, the orientation of device 120 can be reversed by loosening butterfly nut 127, removing device 120 from bar 128, rotating device 120 about a first axis substantially perpendicular to the longitudinal axis of elongate member 122, remounting device 120 on bar 128, and tightening butterfly nut 127.

Some additional versatility provided by web 129 is illustrated in Fig. 9, where device 120 has been rotated about a second axis substantially parallel to the longitudinal axis of elongate member 122. In this rotated position, the apex of substantially-triangular web 129 can act as a stop or a barb for positioning workpiece 96. Although Fig. 9 shows elongate member 122 projecting towards the left and workpiece 96 positioned essentially to the right of U-shaped section 121, these orientations are not necessarily fixed. For example, the orientation of device 120 can be reversed as described above. If the apex of web 129 extends to a point such that projection 130 is substantially aligned with an effective centre line through U-shaped section 121, then device 120 may be rotated about the first axis to reverse the orientation of projection 130, but without substantially altering its position. This may be useful, for example, when workpieces must be positioned with reference to both inner and outer surfaces at a fixed reference location. Thus, there has been described an embodiment of a workpiece positioning device for use with a portable, multi-purpose apparatus for controlling power tools. This

embodiment provides a stop, a barb, and a web which can act as a stop or a barb. In addition, the orientation of the device can be reversed in two planes at least.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.