APPARATUS FOR LOCATING A WORKPIECE

Abstract: A saw guide apparatus has pairs of rollers (7) defining a guide plane for a saw cut on a workpiece (W) placed on a base (2) of the apparatus. Bosses (6) between the rollers and the base project a small distance radially of the rollers to keep the workpiece out of contact from the rollers so that it does not impede their free rotation by the reciprocating saw blade. The rollers (7) comprise detachable fixed pillars (10) on which rotatable tubes (9) are supported and the pillars have an increased diameter at their upper ends to prevent lifting of the tubes.

Description: Apparatus for Locating a Workpiece The present invention relates to an apparatus for locating a workpiece for sawing, and more particularly for locating a workpiece to be cut at a chosen angle and at a chosen position along its length. Devices for locating an elongated workpiece for the purpose of making a saw cut at a chosen angle are already known, such as those disclosed in U.K. Patent No. 1358251. To hold the saw, guide means are provided comprising pairs of spaced parallel members, two members of a pair having a small gap between them in which the saw blade is located. To reduce the wear on these members from the rubbing of the saw teeth against them it is also known to form them as rollers to be rotated by the movement of the saw blade, e.g. U.K. Patent No. 1307164. It is generally desirable to locate the workpiece as close as possible to the guide means and particularly when sawing a small cross-section workpiece it can be helpful to place it against the guide means to prevent clatter. If the workpiece bears against quick rollers, however, it will hinder or prevent rotation, so losing the advantage that could otherwise be obtained from this form of guide means. By means of the present invention, it is possible to locate a workpiece very close to guide means in the form of rollers, without hindering the rollers in any way. According to the present invention, there is provided a location apparatus for use in making a saw cut in a workpiece, comprising a base on which the workpiece can be placed, and a saw guide defining a saw guide plane extending upwardly from the base, the guide comprising at least one pair of rollers rotatably mounted on parallel axes and between which the saw guide plane passes, at least one of the rollers being raised above the base with a boss or other protuberance below it forming a locating abutment for a face of the workpiece for fixing the workpiece close to the at least one roller but spaced therefrom, whereby rotation of the roller is not impeded by the workpiece. Preferably, the or each roller comprises a fixed support and an outer tube, rotatably located on the support. The tube may rest upon the boss or protuberance and a radial projection may be provided at the upper end of the support to retain the tube thereon. Preferably, the support is releasably secured to the base by fixing means on the underside of the base. The or each boss or protuberance is preferably integrally formed with the base. A specific embodiment of the invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is a plan view of a location apparatus, with a fragmented view of a workpiece in position on the apparatus; and Figure 2 is a section along the line T-T of Figure 1. The location apparatus according to the invention has a base 1 on which is mounted an adjustable fence 12 for locating a workpiece which is to be cut by a saw guided by two pairs of rollers 7. The base 1 provides a platform 2 resting on a peripheral flange 3,the sides of which have cut-away portions 4. A vertical hole 5 extends through the base 1 at each corner thereof into which can be inserted bench stops (not shown) to position the apparatus on a work top. The rollers 7 are mounted on bosses 6 projecting from the platform 2, the rollers 7 of each pair being separated by a gap 8 whose width is approximately equal to the thickness of a typical sawblade (not shown). The gaps 8 together define a plane within which movement of the blade is restricted when it is inserted between the rollers 7 of each pair. As can be seen from the drawings, the circular bosses 6 are concentric with the rollers 7 to project radially beyond the periphery of the rollers except at the gap between the rollers where flat ledges on the bosses maintain the width of the gap and thereby allow the saw blade to pass between the bosses. Each roller 7 comprises a tube 9 rotatably mounted on a fixed pillar 10 which has an increased diameter at its upper end to prevent the tube from being lifted relative to the pillar. Each pillar 10 is secured to the platform 2 by a nut 11 located underneath the boss 6, and is of slightly smaller diameter than the boss. The fence 12 for locating the workpiece on the platform has an interrupted side wall 12a and an opposite side wall 12b each providing a locating face for a side face of a workpiece (not shown). Downwardly projection pegs 13, 14 at each end of the fence, offset towards the side face 12a, and an intermediate locking screw 15 adjustably locate the fence on the platform using either of two sets of apertures in the platform, each set comprising a circular hole 16 and two slots 17, 18 concentric with the hole. The angular orientation of the fence 12 can be adjusted by pivoting the fence on the peg 13 in the hole 16, the other peg 14 and the screw 15 sliding in their respective slots 17, 18. The slot 18 has a T-shaped cross-section in order to locate a nut (not shown) beneath the platform 2, which is threaded onto the locking screw 15. The locking screw can then be twisted onto the nut to fix the fence in a chosen position. It is alternatively possible to dispose a locking screw below the platform with its engaging nut above the platform. The two sets of apertures 16, 17, 18 are disposed symmetrically with respect to a line perpendicular to the saw guide plane and midway between the pairs of rollers 7. The hole 16 in each set of apertures is adjacent to the pair of rollers 7 associated with that set. Figure 1 shows the fence 12 located with the peg 13 in the hole 16 and the peg 14 in the slot 17; in this configuration, the side 12a of the fence faces the middle region of the platform 2 and provides the workpiece guide plane. The locking screw 15 io Odib4D1 equidistant from the pegs 13, 14, so that the fence 12 may equally be positioned with its ends reversed. In this alternative configuration, the side 12b will then face the middle of the platform 2 and will provide a workpiece guide plane which, for any given angular orientation of the fence, is located nearer the centre of the platform. The fence 12 is provided with two pointers 20, 21 and the platform 2 is provided with a scale 22 adjacent to each slot 18, for indicating the angle between the workpiece guide plane and the saw guide plane. Depending on the configuration, one or other of the pointers 20, 21 will provide a reading on the associated scale 22. The scale may be used in either configuration because the pointers 20, 21 both lie on the line joining the centres of the pegs 13, 14, parallel to the fence sides. In order to make a cut at the required angle at any arbitrary point along the length of the workpiece W, the fence is positioned with its peg 14 in one of the holes 16 and locked in position by tightening the locking screw 15 by hand. The pointer 21 indicates on the scale 22 the angle of cut, which may be from 0o to 4¯16ih401 side 12b of the fence then provides the location face, which over this range of adjustment defines a space for the workpiece clear of the adjacent pair of saw guide rollers. Because the workpiece is sufficiently displaced laterally from these rollers, it can project past them to bring the location for the cut into the saw guide place. The workpiece is cut by a saw guided by the rollers 7 the tubes 9 of which rotate about the pillars 10 as the saw moves. In order to make a feathered cut of 45 , at the squared end of the workpiece, for example the workpiece being first cut with the scale pointer at 00, the fence 12 is positioned with the peg 13 in one of the two holes 16, e.g. as shown in Figure 1, and pivoted to the 450 position. The workpiece W is located by its side face against the wall 12a and by its end face against the further of the two bosses 6. The workpiece is thus fixed lengthwise by abutment of its end face against a boss 6 with the result that it is appropriately positioned for a feathered cut, but does not contact the rollers so that they can still rotate freely. This configuration may also be used for making cuts of 0 angles other than 45 but the saw cut will not of course pass exactly through the end edge when the workpiece is at an angle such that its end face abuts a boss. For all the above-described methods of using this embodiment of the invention, the fence may be positioned using either of the sets of apertures and, accordingly, locating the workpiece close to or against either of. the pairs of rollers. The provision of the two alternative configurations firstly allows an angled cut to be made in either sense relative to a side face of the workpiece, which is useful for cutting picture frame mouldings, for example, that can only be located securely by one of their side faces, and also maes the apparatus equally convenient for right - or lef4;-handed use.

Claims: CLAIMS 1. A location apparatus for use in making a saw cut in a workpiece, comprising a base (1) on which the workpiece can be placed, and a saw guide (7) defining a saw guide plane extending upwardly from the base, characterised in that the guide (7) comprises at least one pair of rollers (7,9) rotatably mounted on parallel axes and between which the saw guide plane passes, at least one of the rollers (7,9) being raised above the base (1) with a boss (6) or other protuberance below it forming a locating abutment for a face of the workpiece for fixing the workpiece close to the at least one roller (7, 9) but spaced therefrom, whereby rotation of the roller (7,9) is not impeded by the workpiece. 2. Apparatus according to claim 1 characterised in that the or each roller (7,9) comprises a fixed support (10) and an outer tube (9) rotatably located on the support (10). 3. Apparatus according to claim 2 characterised in that the tube(9) rests upon the boss (6) or protuberance. 4. Apparatus according to claim 2 or claim 3 characterised in that a radial projection is provided at the upper end of the support (10) to retain the tube (9) thereon, 5. Apparatus according to any one of claims 2 to 4 characterised in that the support (10) is releasably secured to the base (1) by fixing means (11) on the underside of the base. 6. Apparatus according to any one of the preceding claims characterised in that the or each boss (6) has a circular form concentric with its roller (7,9) and with its side facing the saw guide plane relieved so that it does not protude beyond a tangent plane to the roller (7,9) in the direction of the saw guide plane. 7. Apparatus according to any one of the preceding claims characterised in that the or each boss (6) or protuberance is integrally formed with the base (1).

Inventors: ADAMS, SIDNEY JAMES, GRIMES, DAVID KENNETH
Applicants: GRIPPERRODS INTERNATIONAL PLC
Application year: 1985
Main classification: B27G5
IPC codes: B27G5, B23D51