WO2009153602A1

WO2009153602A1 - Saw guides

Info

Publication number: WO2009153602A1
Application number: PCT/GB2009/050706
Authority: WO
Inventors: Liam James Murphy
Original assignee: Liam James Murphy
Priority date: 2008-06-21
Filing date: 2009-06-19
Publication date: 2009-12-23
Also published as: GB0811491D0

Abstract

A saw guide comprising a cutting block (2) characterised in that the cutting block (2) defines a principle bore (4), a cutting slot (8) that intersects the principle bore (4), and a sighting bore (10) in which the sighting bore (10) is so positioned that a first end of the sighting bore (10) mouths into the principle bore (4) and the second end mouths on to at least one outer face (12) of the cutting block (2), and the cutting slot(8) intersects the first end of the sighting bore (10) at the sighting bore's intersection with the principle bore (4).

Description

Saw Guides

This invention relates to saw guides, and in particular to saw guides for manual use.

Saw guides are generally used to guide the blade of a saw when sawing through an object. When the object is a straight bar, tube (of circular or other cross-section) or other elongate member (hereafter collectively referred to as tubes), and it is desired that the cut is to be perpendicular to the principle axis of the tube, a known saw guide is comprised of a pair of substantially parallel metal plates in which each plate defines an aperture of a shape and size the same as the cross section of the tube be cut perpendicular to the principle axis of that tube. The apertures in each plate are aligned and the plates fixed to each other to one side of the aperture by suitable fixing means such as a pair of bolts. The fixing of the plates to each other is such that the plates are spaced apart from each other by the width of the blade of a saw suitable for the material of the tube being sawn so creating a cutting slot. One of the plates is larger than the other and includes a grip portion which is not overlaid by the smaller plate. The plates are fixed to each other in such a fashion that the grip portion extends from the fixing means and away from the aperture. Where the tube to be cut is threaded, the edges of one or both of the plates defining the aperture may also be threaded with a thread of the same characteristics as that on the tube.

In use, the grip portion of the saw guide is gripped by a vice. The tube is passed through the aperture until the line of the desired cut is in alignment with the cutting slot. The blade of a suitable saw is introduced into the cutting slot and the tube cut.

An alternative known saw guide, is a saw guide as described above to which a retaining block is attached to one of the plates, said retaining block defining an aperture of similar shape and size to that defined by the metal plates with that aperture being aligned with the apertures in the metal plates. The retaining block is provided with one means for gripping a tube introduced into the apertures so as to retain that tube in position when the tube is being cut. Most typically, that gripping means is a threaded screw which, when tightened, pushes the tube against the retaining block. According to the present invention there is provided a saw guide comprising a cutting block characterised in that the cutting block defines a principle bore, a cutting slot that intersects the principle bore, and a sighting bore in which the sighting bore is so positioned that a first end of the sighting bore mouths into the principle bore and the second end mouths on to at least one outer face of the cutting block, and the cutting slot intersects the first end of the sighting bore at the sighting bore's intersection with the principle bore.

In a particularly preferred embodiment of the present invention the cutting slot is planar and the plane of that slot is substantially perpendicular to the principle axis of the principle bore.

In a particularly preferred embodiment of the present invention the sighting bore has a principle axis on/or substantially parallel to the plane of the cutting slot.

In a further preferred embodiment of the present invention both the principle bore and the sighting bore are of substantially circular cross section. In alternative embodiments of the present invention one or both of the principle bore and sighting bore are of a non-circular cross section. In a further alternative embodiment of the present invention the sighting bore may consist of a slot or other shaped aperture and the second end of the sighting bore mouths on to at least one outer face of the cutting block.

The advantage of the saw guide of the present invention lies in the presence of the sighting bore which allows a mark indicating the exact position at which the tube must be cut to be accurately aligned with the cutting slot. This ease of alignment is highly advantageous over the known prior art where it is difficult to line up a cutting mark.

The cutting block of the present invention may be further provided with one or more means for reversibly engaging with a tube passing through the principle bore so as to allow the releasable retention of such a tube in a fixed position within the saw guide. In a preferred embodiment of the present invention there is provided at least one such engaging means to either side of the cutting slot. In a particularly preferred embodiment of the invention, three such engaging means are provided each side of the cutting slot. In preferred embodiments of the present invention the engaging means comprise of grub screws which may be reversibly screwed towards or away from the principle bore. Alternative engaging means may be used.

The cutting block of the present invention may be a single block of material suitably shaped, bored and cut or it may be comprised of a plurality of suitably shaped parts fixed to each other. In either instance, the block or the parts thereof may be made by known casting and/or milling techniques.

In a further preferred embodiment of the present invention the cutting block is provided with at least one pair of opposed clamping faces. Most preferably those clamping faces are substantially parallel to each other and are suitable for clamping between the jaws of a clamping means such as a bench vice. In a particularly preferred embodiment of the present invention, the clamping faces are substantially perpendicular to the plane of the cutting slot. The clamping faces are most preferably adjacent to the blind edge of the cutting slot.

The cutting block of the present invention may be further provided with one or more threaded blind bores, the diameter and thread of those blind bores being suitable to receive a first end of a threaded bar. The blind bores most preferable mouth onto an outer surface of the cutting block. When such a threaded bar is engaged in the blind bore then the other end of the threaded bar may be used to engage with a star nut and the cutting block used to drive or set the star nut in a tube using known techniques. Alternatively, one or more threaded bores may be provided in such positions as to allow the cutting block to be releasably fixed against or to a support surface. Such a support surface may be the upper surface of a work bench.

The dimensions of the principle bore may, in one embodiment, be of a shape and size suitable to allow the insertion of the tube to be cut along the principle axis of the tube but to allow little or no lateral movement. In an alternative preferred embodiment the dimensions of the principle bore may be larger than the tube to be cut so that a collar may be inserted between the face of the principle bore and the tube to be cut. Such an arrangement is particularly advantageous because the collar can have a smooth inner face or, should this be required, a threaded inner face, the thread being appropriate to engage with the external thread of a tube to be cut. In such an embodiment, the engagement means may be used to retain the collar within the principle bore. The collar may be located in the principle bore on either or both sides of the cutting slot.

In the alternative preferred embodiment where the dimensions of the principle bore are larger than the tube to be cut so that a collar may be inserted between the face of the principle bore and the tube to be cut, the cutting block of the present invention may be used to retain alternatively configured collars. The alternatively configured collars may be configured that they may be used for purposes other than the cutting of tubes. One particularly preferred alternative use will be when the collar is so configured to act as a guide for a push rod or use in driving objects such as a star nut into a tube the end of which is partially inserted into the principle bore. The advantage of such an arrangement is that there may be an automatic alignment of the principle axis of the collar, the push rod and the tube, or some predetermined relationship between the principle axis of the collar, the push rod and the tube. Again the collar may be retained in the principle bore by the engagement means.

The present invention is further described and explained by way of example and with reference to the accompanying drawings in which

Figure 1 shows a first embodiment of a saw guide according to the present invention; and

Figure 2 shows a second embodiment of a saw guide according to the present invention.

With reference to Figure 1 , a saw guide according to the present invention is comprised of a cutting block (2) which defines a principle bore (4) which passes from a first face (6) of the cutting block to a second, opposite face (not illustrated). The cross section of the principle bore (4) is substantially a circular. The cutting block (2) further defines a cutting slot (8) which is planar and has a plane substantially perpendicular to the principle axis of the principle bore (4). Cutting slot (8) intersects principle bore (4). Cutting slot (8) is of a Width, in the direction of the principle axis of principle bore (4), suitable to allow the introduction of a saw blade (not shown) and for that saw blade to be used. It is more preferred that the width of slot (8) is just large enough to allow the use of the saw blade but not large enough to allow the teeth of the saw blade to travel in a direction that is not in the plane of cutting slot (8).

Cutting block (2) further defines a sighting bore (10) which extends from an outer face (12) of the cutting block to the principle bore (4). The principle axis of sighting bore (10) lies on the plane of the cutting slot (8).

The cutting block (2) further defines six engagement bores (14) each of which are threaded and suitable for engagement with grub screws or bolts (now shown). As may be seen, three engagement bores (14) are located to either side of the cutting slot (8).

Cutting block (2) further defines a pair of clamping faces (16), the plane of those clamping faces being substantially perpendicular to the plane of the cutting slot (8) and the clamping faces being adjacent to the blind edge (18) of the cutting slot (8). The cutting block (2) is further provided with a second pair of clamping faces (20) which are substantially parallel to each other and to the plane of cutting slot (8).

In use, a user will take the cutting block (2) to a bench vice or other suitable clamping means. In the case of a bench vice the user will determine whether the bench vice is so positioned on the bench that they find it easier to saw in a direction substantially perpendicular to the jaws of the bench vice, in which case cutting block (2) will be clamped by the bench vice on clamp faces (16) or substantially parallel to the jaws of the bench vice in which case cutting block (2) will be clamped by the bench vice on clamp faces (20). The user will then take the tube to be cut which has been suitable marked as to where the cut should be made. The tube is introduced into principle bore (4) and slid along that bore until the cutting mark is visible through sighting bore (10). The user will then be able to visually align the cutting mark and the cutting slot (8). Grub screws or bolts are then introduced into as many of threaded bore (14) as the user wishes to use. It is particularly envisaged that where the surface of the tube may be damaged by the engagement of the tube with the ends of the bolts of grub screws only the grub screws on the sides of the cutting slot (8) that corresponds to the waste or unwanted portion of the tube will be engaged with the tube.

Once the tube to be cut has been clamped into position, a saw blade is introduced into cutting slot (8) and the tube cut using that saw blade.

The diameter of principle bore (4) is such that the tube to be cut using the apparatus of the present invention is a sliding fit within principle bore (4). In an alternative, unillustrated, embodiment of the present invention the principle bore (4) is of a larger diameter than the tube to be cut and a collar or bush is inserted into principle bore (4). In such an embodiment the radially outer diameter of that collar or bush has a is a sliding fit with the principle bore (4) and the radially inner face of the collar or bush has a diameter that is a sliding fit with the tube which is to be cut. Such a collar or bush arrangement allows a variety of collars/bushes to be used so allowing the same cutting block (2) to be used to cut a variety of differently diametered tubes. The inner face of the collar of bush may also be threaded if it is to be used in connection with a tube which has an outer face which is threaded.

With reference to Figure 2, a cutting block (28) is comprised of a first and second part (22) and (24) respectively which are rigidly joined to each other by bolts (26). In such an embodiment, the cutting slot (8) is created at the interface of parts (22) and (24). The rest of the features of the embodiment of the present invention illustrated in Figure 2 are as those illustrated in Figure 1 and are similarly numbered. The use of cutting block (28) is as the use of cutting block (2) illustrated in Figure 1.

It is a particular advantage of a cutting block of the present invention that by use of clamping faces (16) and (20) a user may ensure that he/she may use a natural sawing action without undue twisting or leaning of the user's body when cutting the tube to be cut. The use of such a natural sawing action is particularly beneficial because it will have the effect that the use if less likely to inadvertently force the saw in any direction out of the plane of cutting slot (8) than would be the case if the user were not using a natural sawing action. This results in decreased damage to the faces of cutting slot (8) by the saw blade which increases the life and accuracy of the cutting block (2).

It will be appreciated that the illustrated embodiments of the saw guide of the present invention are all dedicated towards the cutting of a tube perpendicular to the principle axis of that tube. If it were desired that the tube were cut at a predetermined angle to the principle axis of the tube (other than perpendicular) then it will be appreciated that the cutting slot (8) can be orientated at the preferred angle relative to the principle axis of the principle bore.

Claims

1 A saw guide comprising a cutting block characterised in that the cutting block defines a principle bore, a cutting slot that intersects the principle bore, and a sighting bore in which the sighting bore is so positioned that a first end of the sighting bore mouths into the principle bore and the second end mouths on to at least one outer face of the cutting block, and the cutting slot intersects the first end of the sighting bore at the sighting bore's intersection with the principle bore.

2 A saw guide according to claim 1 in which the cutting slot is planar and the plane of that slot is substantially perpendicular to the principle axis of the principle bore.

3 A saw guide according to claim 1 or 2 in which the sighting bore has a principle axis on/or substantially parallel to the plane of the cutting slot.

4 A saw guide according to any of claims 1 to 3 in which both the principle bore and the sighting bore are of substantially circular cross section.

5 A saw guide according to any of claims 1 to 4 in which the cutting block further comprises one or more engaging means for reversible engaging with a tube passing through the principle bore.

6 A saw guide according to claim 5 in which the cutting block further comprises at least one engaging means on either side of the cutting slot.

7 A saw guide according to claim 6 in which the cutting block further comprises three engaging means on either side of the cutting slot.

8 A saw guide according to any of claims 1 to 7 in which the cutting block is a single block of material.

9 A saw guide according to any of claims 1 to 7 in which the cutting block is a plurality of suitably shaped parts fixed to each other. A saw guide according to any of claims 1 to 9 in which the cutting block is provided with at least one pair of opposed clamping faces.

A saw guide according to claim 10 in which the opposed clamping faces are parallel and the plane of the clamping faces is substantially perpendicular to the plane of the cutting slot.

A saw guide according to any of claims 1 to 11 in which the cutting block further comprises one or more threaded blind bores.

A saw guide according to any of claims 1 to 12 in which the cutting block is further provided with at least one removable collar in which the collar is so configured and dimensioned that the collar may be introduced into the principle bore with the outer face of the collar having a sliding fit with the inner face of the principle bore.

A saw guide according to claim 13 in which the inner face of the collar defines a bore through which a tube may be passed.

A saw guide according to claim 13 in which the collar retains a push rod that may slide through the collar along the principle axis of the principle bore.