GB2210580A

GB2210580A - Mitre joint cutting guide

Info

Publication number: GB2210580A
Application number: GB8723280A
Authority: GB
Inventors: Gordon Hague; Keith Hague
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-10-05
Filing date: 1987-10-05
Publication date: 1989-06-14
Anticipated expiration: 2007-10-05
Also published as: GB2210580B; GB8723280D0

Abstract

A mitre joint cutting guide comprises a first wall 20 fixed longitudinally to a planar base 10 which has at least one saw guide edge 16, 18 extending at 45 degrees to its longitudinal direction. A second wall 30 is slidingly mounted on shafts 26, 28 so that a workpiece can be held between the walls 20, 30. In use, the cutting guide can be inverted from its illustrated orientation and placed over an elongate timber workpiece. The second wall 30 is slid towards the first wall 20 to hold the workpiece. In a further embodiment, the cutting guide includes saw guide slits (70, 72, 74, 76, Fig 4). A clamping insert (62) is adjustable by using nuts (68) engaged on threaded shafts (56, 58). <IMAGE>

Description

MITRE JOINT CUTTING GUIDE This invention relates to a mitre joint cutting guide.

A conventional mitre box or mitre block consists of a channel-section device having a base and opposed vertical side walls which are provided with respective saw guide slits enabling a timber workpiece, such as a length of coving, which is placed on the base, between the walls, to be cut at an ankle of 450 or 90 , as required. With such a device, the workpiece must always be placed therein and held steady by hand as it is worked upon. This is not always convenient, particularly for pieces of extreme length.

It is an object of the present invention to provide a compact and universally useful mitre joint cutting device, which is more convenient to use than a conventional mitre box.

With this object in view, the present invention provides a mitre joint cutting guide comprising a planar base having a longitudinal direction and at least one edge-extending at 450 to said longitudinal direction, a first wall fixed to the base and extending substantially perpendicular thereto in said longitudinal direction, and a second wall which also extends substantially perpendicular to the base in the longitudinal direction, parallel to the first wall, but which is mounted on the base so as to be slidably adjustable in its spacing from said first wall.

Thus the proposed device can be placed over any workpiece and the second wall slid towards the first wall to hold the workpiece securely therebetween so that it can be cut in line with the 450 edge of the base.

Preferably the second wall or a support element on which the second wall is mounted is slidable in a recess or aperture in the base. In this respect, the second wall or its support element are advantageously slidingly mounted on one or more shafts or rails which project into the recess or aperture. In this way there are no components, save the walls, projecting above the surface of the base to interfere with workpieces placed thereon or over which the device is placed.

Preferably the shaft(s) or rail(s) extend(s) across the recess or aperture substantially at right angles to the longitudinal direction of the base, the second wall or its support element sliding axially of the shaft or rail.

Two shafts or rails are preferably provided for mounting of the second wall or its support element. Such an arrangement provides stability and prevents pivoting of the wall, and more than two shafts or rails would probably be superfluous for the expecting size of the cutting guide device and hence the recess.

The second wall or its support element may be retained on the shafts or rails by provision of stop means in the form of a crosspiece or enlargement on each of the shafts or rails. Such stcr means define the maxi spacing of the second wall from the first wall.

Alternatively, the shaft or shafts may be threaded, in which case stop means in the form of threaded members, e.g. wing nuts, may be provided. These nuts enable adjustment of the maximum spacing of the second wall from the first wall. They also enable a workpiece to be fixedly (yet releasably) clamped between the first and second walls of the device. Furthermore, such nuts, if they can be released from the ends of the shafts, will also enable the second wall or its support element to be removed from the shafts and replaced, or perhaps reversed, to provide a further wall of different configuration or different spacing from the first wall.

The invention will be described further, by way of example, with reference to the accompanying drawings, it being understood that the following is illustrative and not limitative of the scope of the invention. In the drawings: Fig. 1 is a perspective view showing the underside of a first practical embodiment of the mitre joint cutting guide of the invention; Fig. 2 is a similar perspective view showing the upper side of the same device as in Fig. 1; Fig. 3 is a perspective view of a second practical embodiment of the mitre joint cutting guide of the invention in a position with the respective walls at their minimum spacing apart; and Fig. 4 is a view similar to Fig. 3 showing the same embodiment in a different position, with the respective walls at their maximum spacing apart.

With reference to Figs. 1 and 2, a first embodiment of the device of the invention comprises a base in the form of a trapezoidal block 10 having long and short parallel side edges 12, 14 and symmetrical ends 16, 18 extending at 450 to the side edges 12, 14. On one surface, which may be termed the top surface, of the block 10 an upstanding first wall 20 is fixed along the edge margin at the short side edge 14. This wall is, of course, substantially parallel to the longitudinal extent of the base. A rectangular recess 22 is provided in the central region of the base 10. This recess 22 is cut in from the long side edge 12 and extends inwards to an inner edge 24 closely adjacent the first wall 20.A pair of spaced apart, smooth surfaced shafts 26, 28 project, perpendicularly to the first wall 20 and the longitudinal extent of the base 10, from the said inner edge 24 of the recess 22 to the mouth thereof, adjacent the long side edge 12. A second wall 30 is slidably mounted on these shafts 26, 28. The second wall 30 has a lower shorter region which fits into the recess 22 and is provided with the holes through which the shafts 26, 28 extend with reasonable play, and an upper longer region, having respective end portions which project beyond the lower region and rest upon the top surface of the base 10.

The outer ends of the shafts 26, 28 are provided with stops, such as friction fit or welded on ferrules 32, which prevent removal of the second wall 30 from the shafts 26, 28. These stops 32 define the maximum spacing between the first and second walls 20, 30, which may be approximately 7.5 or 8 cm. They may fit into countersunk bores in the lower region of the second wall 30 and thus permit the second wall 30 to be moved to a position where its surface remote from the first wall 20 is substantially flush with the long side 12 of the base 10, as shown in Figs. 1 and 2.

The mode of use of the aforesaid embodiment will readily be appreciated. It can be placed over a workpiece, such as an elongate timber coving, in the manner shown in Fig. 1. In this respect, the second wall 30 is manually slid away from the fixed first wall sufficiently to allow the coving to fit between the walls 20, 30 which project downwardly at either side thereof. The second wall 30 can then be slid towards the first wall 20 and used to hold the coving thereagainst as a mitre edge is cut thereacross by using one of the 450 edges 16 or 18 as a saw guide.

The aforesaid device is much more convenient to use than a conventional mitre box.

Numerous modifications are possible in the shape of the base, the walls and the recess. For example, the base may have only one 450 end with the other end straight (i.e. perpendicular to the longitudinal extent of the base). Also, instead of ferrules, or comparable stop means, a crosspiece may extend over the mouth of the recess to prevent removal of the second wall from the shafts.

If the slidable second wall is not formed in the manner described a wall upstanding from the base surface may be mounted upon a support element which is accommodated in the recess and slidably mounted on the shafts.

In a further development, the second wall may be springbiassed towards the first wall, e.g. by helical springs mounted on the shafts between the second wall, or its support element, and the stop means.

Figs. 3 and 4 show a more complex embodiment of the mitre joint cutting guide of the invention. This again comprises a planar base 40 with a fixed first wall 50 extending along one longitudinal edge and a second wall 60 which is parallel to the first wall and is mounted so as to be slidable in a direction perpendicular thereto.

The planar base 40 has long and short parallel side edges, one end 42 which is perpendicular thereto and one end 44 which extends at 450 thereto. The first wall 50 extends the entire length of the longest side edge of the base, but overhangs beyond the edge by a part of its width. A further wall 52, corresponding in all respects, extends along the opposing surface of the base 40 and projects side-by-side with the first wall 50.

In a central region of the base 40, a rectangular recess 46 is cut in from the shorter of the longitudinal edges. The recess 46 has symmetrical, oblique side edges 48, so that in transverse cross-section, it is dove-tail shaped, and an inner edge 54 parallel to the walls 50, 52. A pair of threaded shafts 56, 58 project, perpendicular to the walls 50, 52, from the inner edge 54 of the recess 46 and extend out of the recess 46 well beyond the shorter side edge of the base 40.

A support element 62 in the form of a block of dovetail cross-section and equal thickness to the base 40 (i.e. matching the shape of the recess 46) is slidably mounted on the shafts 56, 58 and capable of fitting into the recess 46 in abutment against the inner edge 54 thereof.

On opposing surfaces and along opposing edges of this element 62 there are respective upstanding second walls 60' and 60". In theorientationof the element 62 illustrated in Figs. 3 and 4, the wall 60' extends along that edge of the element 62 which is closest to the first wall 50 whilst the wall 60" extends along the edge thereof which is furthest from the wall 50 and also projects from the opposing surface of said element, that is to say on the same side of the base 40 as the further wall 52. At each side of the recess 46, respective additional wall portions 64, 66 extend along the shorter side edge of the base 40, parallel to and on the same surface of the base 40 as the first wall 50.

Finally, respective wing nuts 68 are located on the shafts 56, 58 outwardly of the element 62. These retain the element 62 and determine the maximum extent to which it can slide away from the inner edge 54 of the recess 46 i.e. maximum spacing between the second wall 60' and the first wall 50, and the second wall 50" and the further wall 52. However, as the > ing nuts 68 are threadedl# adjv able, the aforesaid maximum positions can be adjusted to meet the circumstances of use of the device.

As indicated in the drawings, various saw guide slits 70, 72, 74 are provided in the walls 50, 60', 62 and 64 at 450 and 900 to the longitudinal extent of the base 40 and of the walls 50, 52, 60, 62, 64. Further saw guide slits 76 extend in line with the oblique side edges 48 of the recess 46 from the inner edge 54 of the recess to the walls 50, 52.

Again, the mode of use of the aforesaid embodiment will be readily understood. For use in a similar manner to the previous embodiment, the wing nuts 68 can be moved to a location at or near the ends of the shafts 56, 58 and a workpiece (not shown) can be placed on the base 40 and retained between the first and second walls 50, 60', by sliding of the element 62. With this embodiment, however, the user has a choice as to which surface of the base 40 should receive the workpiece. It can either be held between the wall 60' and the first wall 50, as just mentionedr or, at the other side, it can be held between the wall 60" and the further wall 52, the former being used for narrower workpieces, and the latter for wider workpieces since the wall 60' is closer to the wall 50 than the wall 60" is to the wall 52.In this respect, the maximum spacing between the second wall 60' and the first wall 50 when the wing nuts 68 are still located on the shafts is when the wall 60' is approximately in line with the additional walls 62, 64, as shown in Fig.

4, and this may be in the region of 7.5 to 8 cm. At the same position of the element 62, the spacing between the wall 60" and the wall 52 is almost twice as large.

Since the wing nuts 68 are adjustable on the shafts 56, 58 (and these preferably have a rapid threading) the workpieces can be firmly clamped between the respective walls 60', 50 or 60", 52. This is not possible with the previous embodiment. Also, of course, the device can be placed onto the workpiece or vice versa prior to cutting mitre joints or straight cuts using the edges 44 or 42, respectively as saw guide. In addition, however, the user has the option of using saw guide slits 70, 72 or 74, or where appropriate 76.

In view of the facility of fixedly clamping. items between the slidable walls 60' or 60" and 50 or 52 respect- ively, this embodiment is particularly suited to being clamped to the edge of a workbench, then used, in any of the ways mentioned above as a cutting guide.

Many variations are possible. If the further wall 52 is omitted (or even if it is not), the support element 62 may be removed, by release of the wing nuts, and reversed so that a wider workpiece or fixed member, such as a workbench edge, may be clamped between the wall 60" and the wall 50. However, if release of the wing nut 68 is not necessary, stop means at the ends of the shafts may be provided in addition to the wing nuts.

Claims

1. A mitre joint cutting guide comprising a planar base having a longitudinal direction and at least one edge extending at 450 to said longitudianl direction, a first wall fixed to the base and extending substantially perpendicular thereto in said longitudinal direction, and a second wall which also extends substantially perpendicular to the base in the longitudinal direction, parallel to the first wall, but which is mounted on the base so as to be slidably adjustable in its spacing from said first wall.

2. A cutting guide as claimed in claim 1 wherein the second wall or a support element on which the second wall is mounted is slidable in a recess or aperture in the base.

3. A cutting guide as claimed in claim 2 wherein the second wall or its support element are slidingly mounted on one or more shafts or rails which project into the recess or aperture.

4. A cutting guide as claimed in claim 3 wherein the shaft(s) or rail(s) extend(s) across the recess or aperture substantially at right angles to the longitudinal direction of the base, and the second wall or its support element are slidable axially of the shaft or rail.

5. A cutting guide as claimed in claim 3 or 4 wherein two shafts or rails are provided for mounting of the second wall or its support element.

6. A cutting guide as claimed in claim 3, 4 or 5 wherein the second wall or its support element is retained on the shaft(s) or rail(s) by provision of stop means in the form of a crosspiece or enlargement on the shaft(s) or rail(s).

7. A cutting guide as claimed in claim 6 wherein the second wall is spring biassed towards the first wall by spring means mounted on the shaft(s) or rail(s) between the second wall, or its support element and the stop means.

8. A cutting guide as claimed in claim 3, 4 or 5 wherein the shaft or shafts are, at least partially, threaded, and stop means in the form of threaded members are provided to enable adjustment of the maximum spacing of the second wall from the first wall and to enable a workpiece to be fixedly (yet releasably) clamped between the first and second wall of the device.

9. A cutting guide as claimed in claim 7 wherein the threaded members can be released from the ends of the shafts so that the second wall or its support element can be removed from the shafts and replaced, or reversed, to provide a further wall of different configuration or different spacing from the first wall.

10. A cutting guide as claimed in any of claims 2 to 8 wherein the recess or aperture has oblique side edges and saw guide slits are provided in the base in alignment with these.

11. A cutting guide as claimed in any preceding claim wherein saw guide slits are provided in the first and/or second wall.

12. A cutting guide as claimed in any preceding claim wherein additional wall portions are provided on the base parallel to the first wall.

13. A cutting guide as claimed in any preceding claim wherein a respective first wall and a respective slightly adjustable second wall are provided on each opposing surface of the planar base.

14. A cutting guide as claimed in claim 13 wherein both second walls are provided on a common support element which is slidable in a recess or aperture in the base.

15. A mitre joint cutting guide substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2, or Figs. 3 and 4 of the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS 1. A mitre joint cutting guide comprising a planar base having a longitudinal direction and at least one edge extending at 450 to said longitudinal direction, a first wall fixed to the base and extending substantially perpendicular thereto in said longitudinal direction, a second wall which also extends substantially perpendicular to the base in the longitudinal direction, parallel to the first wall, and which is mounted on the base so as to be slidably adjustable in its spacing from said first wall and clamping means associated with slidable adjustment of the second wall and operative to apply positive clamping force to a work-piece between the first and second walls.

7. A cutting guide as claimed in claim 6 wherein the second wall is spring biassed towards the first wall by spring means of said clamping means, the spring means being mounted on the shaft(s) or rail(s) between the second wall, or its support element and the stop means.

8. A cutting guide as claimed in claim 3, 4 or 5 wherein the shaft or shafts are, at least partially, threaded, and clamping means including of threaded members are provided to enable adjustment of the maximum spacing of the second wall from the first wall and to enable a workpiece to be fixedly (yet releasably) clamped between the first and second wall of the device.