GB2440919A

GB2440919A - Saw guide for making mitre cuts

Info

Publication number: GB2440919A
Application number: GB0615661A
Authority: GB
Inventors: Keith Andrew Marley
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-08-07
Filing date: 2006-08-07
Publication date: 2008-02-20
Also published as: GB0615661D0

Abstract

A saw guide apparatus which comprises a base 1 and a backplate 2 and 3 upstanding from a periphery thereof. The backplate 2 and 3 contains a saw guide assembly having a vertical open ended slot formed between two saw guide members 6 and 7 which are rotatable relative to the backplate 2 and base 1. The base 1 comprises at least one aperture through which a saw blade can extend. The figures show an open-ended sector-shaped aperture extending into the base 1 from the saw guide members 6 and 7, with the saw guide assembly further comprising a horizontal arm 8 extending from the saw guide members 6 and 7 to the edge of the aperture where it is supported. The arm 8 comprises a slit through which the saw blade can extend when the guide is used. Alternatively the at least one aperture may comprise a series of slits in the base (not shown).

Description

Saw Guide This application relates to saw guides, and in particular to

a saw guide apparatus for making mitre cuts in a work piece.

Prior art saw guides for making mitre cuts include simple mitre boxes, which comprise a base and at least one upstanding member, the base and the upstanding member having slots therein in order to guide a saw to cut the work piece at a chosen angle. An example of a mitre box can be found in US6662699. Such mitre boxes suffer various disadvantages such as: being difficult to use, having inadequate provision for holding the work piece, only allowing cutting at predetermined angles and only accommodating small work pieces. Other devices are known in which a saw is held at a particular angle to the side of the base of the device by a pair of saw guides which are mounted to the base of the device. These saw guides allow forward and backward sawing motion of the saw as well as some motion up and down and a degree of tiltability, and are used in combination with a large hacksaw. Such a device is described in GB2361667A or US6698328. However devices of this type also have certain disadvantages, for instance, they will only accept certain types of saw, for example tenon saws having the correct dimensions to fit the guide, so that in practice such devices are generally sold together with the saw: This means that the operator cannot choose the saw he or she feels suits the job best and in addition, such devices are generally only capable of holding small work pieces. Also they tend to restrict the saw to an angle close to the horizontal, by the time the bottom of the work piece is neared, limiting the effectiveness of the sawing action.

In the light of these disadvantages there is provided a saw guide apparatus comprising a base and an upstanding saw guide assembly, the saw guide assembly being rotatably attached to the base and having a vertical open ended slot for guiding the blade of a saw such that in use the blade of the saw can extend through an aperture of the base whereby rotation of the saw guide assembly allows the angle of cut to be varied.

In a preferred embodiment the saw guide assembly is attached to the periphery of the base and further comprises a horizontal extension extending from the upstanding saw guide assembly, the horizontal extension having a horizontal slot extending through part of the horizontal extension and cooperating with the vertical slot to guide the blade of a saw extending through the plane of the base.

In a more preferred embodiment the apparatus includes a wheel disposed at the end of the horizontal slot furthest from the saw guide assembly.

In a most preferred embodiment the sides of the slot are formed by replaceable inserts.

An embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of the saw guide apparatus forming the top of a workbench; Figure 2 shows an exploded perspective view of the saw guide apparatus; Figure 3 shows a partially exploded view of the saw guide assembly; Figure 4 shows a back view of the saw guide apparatus forming the top of a As shown in figures 1 and 4 it is convenient for the saw guide apparatus to form the top of a workbench, although this is not necessarily the case and the apparatus could be sold separately and mounted on legs at a later point. This would be particularly advantageous if the workbench was sold as a modular system having different tops suited for the different jobs to be done.

The apparatus comprises a flat base 1, with a backplate 2, 3 at a right angle to the base and a pair of adjustable blocks 15, 16 to clamp the work piece against the backplate 2, 3. The blocks are connected to threaded components 17, 20, which extend through slots in the base 1 and are mounted on threaded rods 18, 21 having handles 19, 22 at one end. The blocks 15, 16 are moved towards and away from the backplate, 2, 3 by turning the handles 19, 22.

The legs and supporting framework may be of a known type, although the preferred arrangement has a pair of extra supporting members 46, 47 which serve to keep the base rigid.

Referring particularly to figures 2 and 3, it can be seen that the backplate 2, 3 is made from two pieces, 2 and 3 which have a gap between them in which the saw guide assembly is located. As shown in figure 2 (and partially in figure 3) the opposing faces of backplate pieces 2 and 3 have arcuate plates 27 and 28 attached to them, in this case by screws 36 and 37, although any other suitable fastening method would be appropriate. The arcuate faces could also be formed integrally with each backplate piece 2 and 3. However since the preferable materials for the pieces differ, with the backplate 2, 3 and base 1 preferably being made from a relatively lightweight material such as wood and the other parts mainly being made from steel or another metal, the preferred embodiment has plates attached to the backplate pieces 2, 3.

The saw guide assembly includes two vertical saw guide members 6 and 7 which as shown in all the figures (but perhaps most clearly in figure 3) and define a vertical slot for guiding a saw blade (as shown in figure 1). Auxiliary vertical saw guides 24 and 25 may also be provided and are preferably replaceable. Preferably auxiliary saw guides 24 and 25 are plastic or another material which will not damage the blade of a saw.

It can be seen that the pair of vertical saw guide members 6 and 7 define an open ended cylinder, with a vertical slot in it. Throughout this application reference may be made to the "axis" of the saw guide assembly, and this refers to the axis of symmetry of the cylinder assembly.

In order that the vertical saw guide members 6 and 7 are held a constant distance apart, and allowed to rotate about the axis, the top of each vertical member 6, 7 is provided with semi-cylindrical clamp members 11, 12, 13, 14 for attaching itto the top of the arcuate plates 27 and 28, which it should be noted extend further upwards than the backplates 2, 3. The description of the clamp on vertical saw guide member 6 will be described referring to figure 3 but it will be understood that both clamps operate the same way. As can be seen, the clamp is formed by an arcuate inner component 12, and an arcuate outer component 11. The arcuate inner component 12 has the same thickness and degree of curvature as arcuate plate 27 and when fully assembled rests with its lower surface on the upper surface of arcuate plate 27. The outer arcuate component 11 is curved to conform with the outermost surfaces (i.e.the surfaces furthest from the axis) of inner component 12 and plate 27, and is longer than inner arcuate component 11 so that when assembled (conveniently with screws 41 and 42) with its top surface at the same level as the top surface of inner component 12 it extends down alongside curved plate 27 and clamps the vertical member 6 parallel with the plate 27.

Preferably the arcuate components 11, 12, 13, 14 extend substantially completely round the outer surfaces of vertical members 6 and 7 so that even at the extremes of rotational movement the greatest possible surface area of plates 27 and 28 remain in contact with the vertical members and arcuate components 11, 12, 13, 14 so that pressure is well distributed.

The bottom of the saw guide assembly is rotatably held in place in a similar fashion, this time by clamp members 23 and 24 having a slightly more complex shape.

As can be seen each of the clamp members 23, 24 has a flat portion which is attached to the lower surface of the base 1 (conveniently by screws 45) and an arcuate upwardly extending portion. The outer surface of the upwardly extending portion has the same degree of curvature as the inner surface of the vertical saw guide members 26 and 27.

In the same way as plates 27 and 28, it is preferable that the upwardly extending portions of clamp members 23 and 24 are curved so that there is a relatively large contact area between the outer surfaces of the upwardly extending portions of the clamp members 23, 24. It is imperative however that the upwardly extending portions of clamp members 23, 24 do not extend circumferentially too far round the axis of the saw guide assembly as if they were to do so they would obstruct the saw when the assembly was rotated. Preferably the plates 27, 28 and upwardly extending portions of the clamp members 23, 24 extend circumferentially between 10 and 150 degrees, more preferably between 20 and 90 degrees and most preferably approximately 45 degrees.

Of course both the top and bottom of the vertical saw guide members 6 and 7 could be held with similar clamp members of either type, or the top could be held with the type described for the bottom and the bottom with the type described for the top. In addition any other suitable construction which allows for a rotatable saw guide assembly having an open ended slot so that a saw can extend beneath the plane of the base 1 to cut a work piece could be adopted.

It can be seen from the drawings, particularly figures 1-3, that the saw guide assembly also includes a horizontal member 8 which has a slot formed therein corresponding to the slot formed between the vertical saw guide members. Conveniently the horizontal member is made separately from the vertical saw guide members and attached thereto by screws 43 which engage with the horizontal leg at the bottom of each vertical saw guide member 6, 7. However, the entire assembly could be welded together, machined or otherwise manufactured as one piece if so desired. In order to allow the horizontal piece to rotate it is necessary for the base 1 to have a segment removed (or be manufactured with a hole in it). Preferably the segment that is removed forms a sector shaped aperture in the base 1 defining at least a quarter of a circle, so that a cut can be made straight through a work piece perpendicular to the planes of the base and the backplate as well as a 45 degree mitre cut to both the left and the right.

However it will be understood that it would be possible to obtain a similar result by having a smaller sector shaped aperture of such as an eighth of a circle and manipulating the work piece accordingly. A similar result could also be obtained by having a series of slits in the base at particular angles (e.g. 45 degrees, 90 degrees and degrees) to the backplate, although this would require a method for aligning the slot between vertical members 6 and 7 with the slit in the base, and has the disadvantage that it is likely to severely weaken the base.

The provision of a horizontal member 8 provides certain structural benefits since it connects the two vertical members 6 and 7 of the saw guide assembly at the end farthest from the vertical members 6 and 7. The far end of the horizontal member 8 is supported in the base by the lower flat curved plate 5 which is attached to the bottom of the base 1, conveniently by means of screws 29, 30, although other attachment means are possible. The base could alternatively be formed with an integral step providing a supporting surface for the far end of the horizontal member 8. Preferably there is also an upper flat curved plate 4, secured by screws 31 which corresponds with the lower curved plate 5 to provide a channel through which the far end of the horizontal member 8 runs.

Further useful but not optional features of the horizontal member 8 include a spring loaded pin 10 which engages with holes in the base ito lock the saw guide assembly in the required position. Other alternative methods of holding a member in a set position will be known to those skilled in the art and could be appropriate alternatives. An auxiliary horizontal saw guide 38 and wheel 9 are conveniently made of plastic and are easily replaceable, and serve to protect the teeth of a saw from damage due to snagging on the hard edges of horizontal member 8.

Claims

Claims 1. A saw guide apparatus comprising a base and an upstanding saw

guide assembly, the saw guide assembly being rotatably attached to the base and having a vertical open ended slot for guiding the blade of a saw such that in use the blade of the saw can extend through an aperture of the base whereby rotation of the saw guide assembly allows the angle of cut to be varied.

2. A saw guide apparatus according to claim I wherein the saw guide assembly is attached to the periphery of the base and further comprises a horizontal extension of the saw guide assembly extending from the upstanding saw guide assembly into the aperture and cooperating with the vertical slot to guide the blade of the saw through the aperture of the base.

3. A saw guide apparatus according to claim 2 wherein the aperture is sector shaped being narrow but open ended at the periphery of the base and widening inwardly to an arc.

4. A saw guide apparatus according to claim 3 wherein said horizontal extension is supported in the arc.

5. A saw guide apparatus according to claim 1 wherein the saw guide assembly is provided at the periphery of the base and aperture of the base comprises a slot extending inwardly from the saw guide assembly and cooperating with the slot in the saw guide assembly to guide the blade of the saw.

6. OA saw guide apparatus according to claim 3 in which the aperture comprises a plurality of slots.

7. A saw guide apparatus according to either claim 3 or 4 in which the base is provided with an upstanding backplate at the periphery of the base and at least one slot is at 45 degrees to the backplate.

8. A saw guide apparatus according to claim 2 having a wheel disposed at the end of the horizontal slot furthest from the saw guide assembly.

9. A saw guide apparatus according to any one of the preceding claims where the sides of the slot are formed by replaceable inserts.

10. A saw guide apparatus according to any one of the preceding claims further comprising an upstanding backplate at the periphery of the base, into which the saw guide assembly is mounted.

11. A saw guide apparatus according to claim 10 further comprising at least one clamping member for clamping a work piece against the backplate.

12. A saw guide apparatus according to claim 11 wherein the or each clamping member is mounted via a corresponding slot in the base on a threaded rod beneath the base whereby rotation of the rod causes the clamping member to move towards or away from the backplate.

13. A saw guide apparatus according to claim 12 wherein the or each rod is provided with a handle.