GB2137137A - Improvements in or relating to jigs - Google Patents

Abstract

A jig comprises two quadrant shaped frameworks 10, 11 pivoted together. One framework carries 11 a groove cutting tool 15 to cut a groove in, for example, a rebate surface of a frame of a wooden window having two further mutually inclined surfaces. The other framework 10 carries two guide surfaces 25, 29 for engagement with the two mutually inclined surfaces of the frame. The frameworks can be moved to an operative position in which the cutter of the tool is held orientated at the required angle relatively to the guide surfaces so that, with the cutting tool operating, the guide surfaces can be slid along the frame surfaces to cut the required groove at the correct angle. <IMAGE>

Description

SPECIFICATION Improvements in or relating to jigs The invention relates to jigs and to jig and groove cutting tool combinations.

According to a first aspect of the invention, there is provided a jig for holding a groove cutting tool to form a groove in one surface of an elongate member having at least three mutually inclined surfaces, the groove extending along and at an angle to said one surface, the jig comprising a tool carrying arm, a first guide surface for guiding engagement with one of the other surfaces of the elongate member and a second guide surface for guiding engagement with the or another of the other surfaces of the elongate member, the first and second guide surfaces having the same mutual inclination as the surfaces of the member which they engage and the tool carrying arm being so arranged relatively to the two guide surfaces that a cutter carried thereby cuts a groove in said one surface of the required angle.

Preferably the tool carrying arm forms part of a first framework and the guide surfaces are carried on a second framework, the two frameworks being pivoted together so that the tool carrying arm can be pivoted into and out of an operative position for cutting the groove.

The two frameworks may be of generally quadrant shape pivotably connected at their respective apices and be so arranged that, when in the operative position, the quadrants are generally in register.

The frameworks may be urged by spring means out of the operative position and a microswitch may be provided for switching-on the tool as the frameworks reach the operative position, and for switching-off the tool as the frameworks leave the operative position.

The two frameworks may be provided with respective parts which together form a manual grip to allow manual relative movement of the frameworks into the operative position.

Preferably, the guide surfaces and the cutter are arranged as respective corresponding corners of the generally quadrant-shaped frameworks.

The first guide surface may be rigidly connected to one member of the second framework with the second guide surface being mounted on a second such member.

The position of the second guide surface may be adjustable relatively to the first guide surface.

The adjustment may be in a direction normal to the plane of said second guide surface.

The second member of the second framework preferably extends in a direction normal to the plane of said second guide surface and is adjustable relatively to the remainder of the second framework to adjust the position of the second guide surface, the tool carrying arm and the second arm being pivoted together to allow adjustment of the length of the third arm.

According to a second aspect of the invention, there is provided a jig and groove cutting tool combination comprising a jig according to the first aspect of the invention and a groove cutting tool mounted on the tool carrying arm thereof.

The groove cutting tool preferably comprises an elongate body extending parallel to the length of the tool cutting arm and a tool at the end of the body adjacent the guide surfaces.

The tool may comprise a circular cutter lying in a plane normal to the length of the tool.

There may also be provided an outlet adjacent the tool for connection to the supply of air under pressure to blew away cut material.

The following is a more detailed description of one embodiment of the invention, by way of example, reference being made to the accompanying drawing which is a side elevation of a jig carrying a groove cutting tool.

The jig comprises first and second frameworks 10, 11 of generally quadrant shape connected together by a pivot 12 at one corner.

The first framework 10 includes a tool carrying arm in the form of a sleeve 14. A groove cutting tool 15 extends through the sleeve 14. The body of the tool extends generally parallel to the sleeve 14 and has at one end, remote from the pivot 12, a cutter 16 which lies in a plane normal to the length of the tool 15. A flexible drive powers the tool 1 5 from a remote power source.

The sleeve 14 also includes a passage 17 having an outlet 18 for connection to a compressed air source and an outlet 19 through which the compressed air can emerge.

The first framework 10 is completed by a handgrip member 20, connected at one end to the tool carrying sleeve 14 at the pivot 12, and an arnuate spacing member 21 connected between the sleeve 14 and the handgrip 20 at their ends remote from the pivot 12.

The second framework 12 is of generally quadrant shape and comprises three members 22, 23, 24. The first and third of these members 22, 24 are rigidly connected together at the pivot 12.

The first member 22 extends generally parallel to the tool carrying sleeve 14 and is so shaped as to receive the base of this sleeve when the frameworks 1 0, 11 are in the operative position shown in the drawing. At the end opposite the pivot 12, the first member 22 carries a first guide surface 25 which lies in a plane transverse to the length of the member.

The third member 24 co-operates with the handgrip member 20 to form together a manual grip by which the frameworks can be moved relative to one another.

The second member 23 interconnects the first and third members 22, 24 at their ends remote from the pivot 12. This member 23 is formed by two parallel rods 26 which, at one end, extend through respective holes which are provided in a block 27 at the end of the third member 24 and in which the rods are lockable by a locking device 28. At their other ends, the rods 26 carry a second guide surface 29 which is adjacent the first guide surface 25 but which lies in a plane transverse to the plane of the first guide surface 25.

The second guide surface 29 is also connected to a mounting 30 which includes an aperture in sliding engagement with a third rod 31 parallel to said two parallel rods 26 and fixed at the end of the first member 22 adjacent the first guide surface 25.

A spring (not shown) is provided between the frameworks 1 0, 11 and tends to pivot the frameworks 10, 11 out of the operative in-register position shown in the drawing. A micro-switch (not shown) for controlling the tool 15 is also provided between the frameworks 10, 11, the micro-switch acting to operate the tool 15 as the frameworks 1 0, 11 reach the operative position and acting to render the tool 1 5 inoperative as the frameworks 10,11 separate.

The jig and groove cutting tool combination described above with reference to the drawing is for forming a groove in one surface of an elongate member having at least three mutually inclined surfaces, the groove extending along and at an angle to said surface. For example, such a surface may be a surface 32 of a casement receiving rebate 33 in a frame member 34 of a wooden window. In this case, the groove 35 is for receiving the angled foot of a flexible sealing strip (not shown). The groove 35 is angled so that the presence of the groove in the rebate does not unduly weaken the edge of the rebate 33, so preventing the frame splintering. The frame member has two further surfaces 36 and 37 which form guides for the jig.

The first and second guide surfaces 25, 29 have the same mutual inclination as the surfaces 36, 37 which they engage. Variations in the spacing of the rebate surface 33 and the second surface 37 are accommodated by adjustment of the rods 26 using the locking device 28. Differing relative angular orientations between the surfaces can be accommodated by the use of appropriately shaped guide surfaces 25, 29.

As will be seen, the tool carrying sleeve 14 is so arranged relatively to the two guide surfaces 25, 29 that, when the framework 10, 11 are in the operative position shown, the cutter 16 is positioned to cut the groove 35 in the rebate surface 32 at the required position and at the required angle.

in use, the jig is brought to the window with the framework 1 0, 11 separated under the action of the spring. The guide surfaces 2-5, 29 are placed flat on the respective frame surfaces 36, 37. The manual grip 20, 24 is then gripped to draw the two frameworks 10, 11 together. As they reach the in-register position, the micro-switch starts the tool 15 which cuts into the rebate surface 32 under the grip pressure. The jig is then simply slid along the surfaces 36, 37, with the guide surfaces 25. 29 being kept flat on these surfaces at all times. The cutter 16 is rotated and the passage 17 emits a blast of air from the outlet 1 9 which blows dust and cuttings away from the cutting zone, so allowing the operator a clear view.

The cutter 16 is provided with a bevelled rear cutting surface 38 that cuts away the rebate surface 32 between the groove 35 and the edge of the surface 32. This allows a portion of the sealing strip to be accommodated below the level of the surface 32 thus allowing the sealing strip to be used even where the casement is a very tight fit on the rebate surface 32.

When the groove 35 has been cut, the grip pressure is released so that the cutter 16 moves away from the rebate surface 32 and the tool 1 5 is switched-off by the micro-switch. It will be appreciated that this provides a safety feature because, if the grip is relaxed accidentally, the tool 15 will stop.

It will be appreciated that cutting tools other than the tool 15 described above with the reference to the drawings may be carried by the jig. In addition, it is not essential that the second member 23 be adjustable; it could be rigidly arranged to deal with only particular sizes of cut member. Only a single framework could be provided carrying both the tool 15 and the guide surfaces 25, 29.

Claims (16)

1. A jig for holding a groove cutting tool to form a groove in a first of at least three mutually inclined surfaces provided on an elongate member, the groove extending along and at an angle to said first surface, the jig comprising a tool carrying arm, a first guide surface for guiding engagement with a second of said at least three mutually inclined surfaces of the elongate member and a second guide surface for guiding engagement with the second or third of the other surfaces of the elongate member, the first and second guide surfaces having the same mutual inclination as the surface of the member which they engage and the tool carrying arm being so arranged relatively to the two guide surfaces that a cutter carreid thereby cuts a groove in one said surface at a required angle.

2. A jig according to claim 1, wherein the tool carrying arm forms part of a first framework and the guide surfaces are carried on a second framework, the two frameworks being pivoted together so that the tool carrying arm can be pivoted into and out of an operative position for cutting the groove.

3. A jig according to claim 2, wherien the two frameworks are of generally quadrant shape pivotably connected at their respective apices and are so arranged that, when in the operative position, the quadrants are generally in register.

4. A jig according to claim 2 or claim 3, wherein the frameworks are urged by spring means out of the operative position and a microswitch is provided for switching-on the tool as the frameworks reach the operative position, and for switching-off the tool as the frameworks leave the operative position.

5. A jig according to any one of claims 2 to 4, wherein the two frameworks are provided with respective parts which together form a hand grip to allow manual relative movement of the frameworks into the operative position.

6. A jig according to any one of claims 2 to 5 wherein the guide surfaces and the cutter are arranged at corresponding corners of their associated generally quadrant-shaped frameworks.

7. A jig according to claim 6, wherein the first guide surface is rigidly connected to one member of the second framework with the second guide surface being mounted on a second such member

8. A jig according to claim 7, wherein the position of the second guide surface is adjustable relatively to the first guide surface.

9. A jig according to claim 8, wherein the adjustment is in a direction normal to the plane of said second guide surface.

10. A jig according to claim 8 or claim 9, wherein the second member of the second framework extends in a direction normal to the plane of said second guide surface and is adjustable relatively to the remainder of the second framework to adjust the position of the second guide surface.

11. A jig for holding a groove cutting tool substantially as hereinbefore described with reference to the accompanying drawings.

12. A jig and groove cutting tool combination comprising a jig according to any one of claims 1 to 11 and a groove cutting tool mounted on the tool carrying arm thereof.

13. A combination according to claim 12, wherein the groove cutting tool comprises an elongate body extending parallel to the length of the tool cutting arm and a tool at the end of the body adjacent the guide surfaces.

14. A combination according to claim 13, wherein the tool comprises a circular cutter lying in a plane normal to the length of the tool.

15. A combination according to any one of claims 12 to 14, wherein there is provided an outlet adjacent the tool for connection to the supply of air under pressure to blow away cut material.

16. A jig and groove cutting tool combination substantially as hereinbefore described with reference to the accompanying drawings.