GB2228705A - Bench clamp - Google Patents

Abstract

A bench clamp consists of a longitudinal member (2) along the length of which are several holes (4) into a selected one of which may be fitted a dog (18). A slide (8) with an abutment (16) is movable along the length of the clamp by a suitable means such as a screw (10) so as to grip a workpiece between the abutment and dog. The lower surface of the longitudinal member is provided with a protrusion (24) which is preferably longitudinal and can fit into a hole or slot in a bench or be gripped by a vice on the bench. <IMAGE>

Description

BENCH CLAMP The present invention relates to bench clamps suitable for wood working.

Woodworking benches have traditionally been provided with a vice and a single surface mounted stop for use when planing a flat length of wood. Recently the tendency has been to provide holes along the length of the bench into one of which a stop or dog can be inserted. A further stop which can be moved by means of a screw in a direction toward the dog is then used to clamp the wood workpiece.

This arrangement has the advantage over the single stop arrangement in that the workpiece can be worked in both directions along its length. However, such an arrangement is expensive to build into a bench and the dog holes can be damaged by other work processes carried out on the bench.

It is an object of the invention to provide a simple and economic device which can overcome the above disadvantages.

A bench clamp according to the present invention comprises a longitudinal member having a plurality of dog receiving holes along its length, a dog fitting into one of the dog holes, a slide with an abutment movably mounted to the longitudinal member and means for moving the slide towards the dog to grip a workpiece between the abutment and dog, a lower surface of the longitudinal member having a protrusion for passive or active engagement with a bench. In a passive mode the protrusion may be such as will fit into a hole or slot in the bench, the weight of the clamp retaining the clamp in place. In an active mode the protrusion may be gripped into the bench vice or a clamp on the bench such as is provided by a suitable popular portable folding bench.

Preferably the protrusion extends longitudinally or there may be two or more protrusions located in the longitudinal direction of the clamp. In the event of the protrusion extending along the length of the dog holes, the protrusion may be aligned along one edge of the bottom of the dog holes which preferably extend through the longitudinal member. Long shanked dogs can then have additional support from the protrusion(s).

The means for moving the slide is suitably a screw of such a length that the slide member may be moved a distance corresponding to the distance apart or more of the dog holes.

The abutment on the slide may be adjustable in a vertical direction and/or may be removably mounted.

The longitudinal member is preferably made of wood and for ease of manufacture may be formed from two or more longitudinal lengths of wood grooved to receive jointing tongues along part of their length, which tongues or grooves provide in part a slide way or ways for the slide.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a plan view of a bench clamp according to the invention; Figure 2 is a cross-section of the clamp of Figure 1 taken on AA of Figure 1; Figure 3 is an exploded perspective view of a slide and its associated components for the clamp of Figure 1; Figure 4 is a perspective view of a forked blade stop for the slide of Figure 3; Figure 5 is an end elevation of a dog for the clamp of Figure 1 taken along the line AA of Figure 1; Figure 6 is a side elevation of the dog of Figure 5 and Figure 7 is a cross-section of the clamp of Figure 1 taken on BB of Figure 1.

The bench clamp shown in the drawings comprises a longitudinal member 2 formed from several longitudinal lengths of wood as will be described hereafter in detail.

Formed along the length are six dog receiving holes 4 spaced apart along the longitudinal axis 6. A slide 8 is movably mounted to the longitudinal member 2 as will be described in detail. A screw 10 acting in a nut 12 set in a mortice 14 in slide 8 together act as a means for moving the slide along axis 6. The slide has a stop 16 acting as an abutment and a dog 18 is inserted in one of the dog holes 4 which together when the slide is moved toward a workpiece 20 grip the workpiece. The lower surface 22 of the member 2 is provided with a longitudinal protrusion 24 which is clamped in a bench vice or the clamp of suitable popular portable folding bench.

The longitudinal member 2 (see Fig. 7) is formed from a first length of wood 30, a second length 32, a third length 34, a fourth length 36 and a fifth length 38.

Fifth length 38 is vertically thinner than lengths 30-36 so has a length 40 fixed by screws or glued to its underside 41 so as to provide a level base. Lengths 30 and 32 are joined by respective grooves 42 and 44 and a first tongue 46. Similarly lengths 34 and 36 are joined by respective grooves 48 and 50 and a second tongue 52.

In the region of screw 10 tongues 46 and 52 provide slide ways acting with respective grooves 54 and 56 of slide 8. Lengths 36 and 38 are glued together so as to facilitate machining of the dog holes 4.

The slide is recessed at 60 to receive stop 16 which is screwed in place by screws 62. Stop 16 can have a known vertically adjustable camming arrangement.

The screw 10 is rotatably mounted in an angle plate 64 screwed by screws 66 into lengths 30 and 38. A nylon bearing 68 supports one end the screw in length 34 whilst the other end of the screw has a spindle 70 and turn bar 72. Nylon thrust washers 74 are fitted either side of plate 64. The plate 64 has the advantage of strengthening the longitudinal member laterally.

The dog 18 is of an inverted L shape made of marine plywood and is provided with a leaf spring 76 to ensure frictional retention in a dog hole 4. Hole 4 is shaped to receive the head 78 of dog 18 so that it can be flush fitted into the clamp.

In an alternative embodiment (not shown) the protrusion 24 instead of being longitudinally aligned with axis 6 is one or two vertical protrusions which enables the clamp to be "pegged" into a hole or holes in the supporting bends. Generally the weight of the clamp should be sufficient to hold the clamp in place on the bench but the peg(s) could be pinned from the underside of the bench.

Although a generally wooden clamp is preferred which is suitably made of a hard wood such as beech other materials such as plastics could be used.

The clamp is particularly advantageous for cabinet making and other fine working of wood where a fair face to the wood working surface must be maintained. This is not always the case with a bench incorporating a dog and screw arrangement because the bench working surface becomes damaged.

Claims (7)

1. A bench clamp comprising a longitudinal member having a plurality of dog receiving holes along its length, a dog fitting into one of the dog holes, a slide with an abutment movably mounted to the longitudinal member, and means for moving the slide towards the dog to grip the workpiece between the abutment and dog, a lower surface of the longitudinal member having a protrusion for passive or active engagement with a bench.

2. A clamp as claimed in claim 1 wherein the protrusion extends longitudinally along the underside of the longitudinal member.

3. A clamp as claimed in claim 1 wherein the protrusion extends vertically from the underside of the longitudinal member.

4. A clamp as claimed in any one of claims 1 to 3 wherein the longitudinal member comprises two or more longitudinal lengths of wood grooved to receive jointing tongues along at least part of their length, a part of the or each groove or tongue providing a slideway for the slide.

5. A clamp as claimed in any one of claims 1 to 4 wherein the slide is provided with a vertically adjustable abutment stop.

6. A clamp as claimed in any one of claims 1 to 5 wherein the slide moving means comprises a screw mounted towards one end in a plate fastened laterally across the longitudinal member, and a threaded means in the slide.

7. A bench clamp substantially as described with reference to the accompanying drawings.