GB2137929A

GB2137929A - A Saw Table

Info

Publication number: GB2137929A
Application number: GB08310372A
Authority: GB
Inventors: Robert Scott Simon; Colin Edwin Brooks
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-04-16
Filing date: 1983-04-16
Publication date: 1984-10-17
Also published as: GB8310372D0

Abstract

A saw table for use with a portable power- driven circular saw comprises a work table 10 on which are mounted two fences 15 and 16, at right angles. A saw guide extends over the table 10 above the fences 15 and 16, and is pivoted adjacent one end to the table, and the other end of the guide runs along an arcuate track 28. The guide comprises two angle sections 26 held spaced apart by cross members 25,27 whereby a portable circular saw may be slid therealong with the saw sole plate accurately located by the sections 26. <IMAGE>

Description

SPECIFICATION A Saw Table This invention relates to a saw table suitable for use with a portable power-driven circular saw, particularly-but not exclusively-to permit the cutting of lengths of timber accurately at a predetermined angle.

Saw tables suitable for use with conventional hand tenon saws are well known, and comprise a work table having a workpiece guide arrangement adapted to support a workpiece, and a saw guide arrangement adapted to hold the blade of a tenon saw. Satisfactory results can be obtained with such a saw table when relatively small sections are to be cut-for example, picture framing-but it is found that considerable operator skill is still required. Moreover, when a large section is to be cut, the manual operation of the tenon saw tends to cause minor but nevertheless significant variations over the cut face of the timber, and this may spoil the quality of a resultant joint, especially in the case of a mitred corner.Also, if the workpiece and saw guide arrangements are not set precisely at the required angle, any errors will be compounded-for example, in the case of a mitred corner joint, if the two guide arrangements are not at exactly 450, the completed joint will not be an exact right angle.

Whenever possible, people tend to use poweroperated tools in preference to manual tools, but up to now there has been no entirely satisfactory proposal for a portable power tool suitable for the cutting of lengths of timber with a high degree of accuracy. Very expensive tools for this purpose are available, such as radial arm saws, and also power tools especially designed solely to fulfil this purpose. A general purpose circular saw table also can be used to perform this task, but less conveniently, and generally with less accuracy, for the use of a circular saw table requires the timber to be moved relative to the saw blade, and only short timber guides ordinarily are provided. In any event, a radial arm saw or a circular saw table is a relatively expensive and heavy item, not suitable for portable or domestic use.

Power-driven portable electric circular saws are most common-place, and are widely used both by professional craftsmen and domestically.

Such saws are quite unsuitable for the cutting of lengths of timber at exact angles-for example, 900 or 450 to the length of the timber-in view of the fact that no accurate timber guides are provided. It is however an object of this invention to provide a saw table suitable for use with such a saw, to permit the accurate cutting of timber.

Accordingly, this invention provides a saw table suitable for use with a portable power driven circular saw, comprising a work table on which are mounted a saw guide and a fence against which a workpiece may be held, the saw guide being arranged to support a portable power-driven circular saw and to define a guide path along which a supported saw may be slid, the saw guide extending over the work table above the fence, and one of the fence and the saw guide being mounted for adjustment with respect to the other of the fence and saw guide, to permit a cut to be made across a workpiece at a selected angle.

It will be appreciated that the saw table of this invention permits a conventional portable circular saw to be used to effect a cut across a length of timber or other material at a precise predetermined angle, by initially pre-setting the relative disposition of the saw guide and the fence. This is achieved by accurately constraining the movement of the circular saw, whilst also providing an accurate reference for locating the workpiece.

The saw table of this invention must be adapted for use with a particular saw, by appropriately configuring the saw guide to accept and accurately guide the saw. It is convenient, therefore, to provide means allowing the adjustment of the saw guide both to accept a given saw and relative to the work table, thereby to permit the accommodation of different designs of circular saw, and in particular different widths of saw sole plate, different spacings between the saw blade and the sole plate edges and different depths of cut below the sole plate.

Preferably, the saw guide comprises two spaced parallel rails, for example each of angle section and appropriately supported at or adjacent the ends thereof, with one flange of each section lying substantially horizontal (in the normal operating position of the saw table) and directed towards the other section, and the other flange of each section projecting upwardly from the one flange. A saw may then be supported by its sole plate on the two horizontal flanges and guided by the two vertical flanges, as the saw is slid along the rails. Adjustable means may then be provided to permit the spacing between the two sections to be varied to suit a given circular saw-for instance by means of a slotted spacer bar extending between the two sections and to which the sections are clamped by means of nuts and bolts.

Alternatively, a carrier may be supported by the rails for sliding movement therealong, the carrier being provided with means adapted to support and locate a power-driven circular saw. The rails may thus each be in the form of a channel member, with the open side thereof facing the other member, the carrier being a plate slidable along the channels. Adjustable abutments may be fastened to the plate, a slot being formed in the plate through which the saw blade may project.

Most preferably, there are provided two fences, each secured to the work table such that the angle therebetween is exactly 900. There should be a clearance between the adjacent ends of the two fences at least sufficient to accommodate the circular saw blade-but it is convenient to allow the said spacing to be adjustable by sliding movement of the fences, whereby a workpiece may extend beyond both sides of the work table when supported against a fence.

For the just-described arrangement, the saw guide should adjustably be mounted on the work table, for instance by pivoting the guide to the table at the end thereof adjacent the two fences, and providing an arcuate track on the table adjacent the other end, along which track the guide may be slid. A screw threaded or other clamping mechanism may serve to hold the guide at a selected position, and conveniently the track has at least some graduations thereon to indicate the angle of cut relative to the fences. Also, at least one but preferably two pre-set indexing arrangements may be provided, for example at 450 and 900, to allow accurate pre-setting of the saw guide for cutting mitres and square ends.

The above-described arrangement may be modified by mounting the saw guide in a fixed manner on the work table, and mounting the pair of fences on a sub-assembly which is pivoted to the work table. Again, suitable markings and possibly also a pre-set indexing arrangement should be provided, but for co-operation with the sub-assembly, rather than with the saw guide.

It will be appreciated that the arrangements of saw table described above and having two fences accurately pre-set at 900 to one another, the production of a mitred corner joint is possible with exactly 900 between the component members, even though the saw guide may have been set imprecisely, provided that the two workpieces are held respectively one against each fence, in turn.

Moreover, in view of the rapidly-rotating blade of the circular saw, a clean and accurate cut can be obtained, with a minimum of operator skill.

The saw table of this invention may be used for cutting lengths of material to accurate predetermined lengths. This may be achieved by means of an end stop adjustably mounted on the work table or on one of the fences, and against which the workpiece may be abutted, before a cut is made. Calibration means conveniently are provided in association with the end-stop, to obviate the need to mark the workpiece itself with the required length.

To ensure reliable and repeatable operation, it is preferred for the work table to be rigid-for example by making the table from a cast aluminium alloy, with the fences bolted thereto ina secure manner. Also, clamping devices may be provided to hold workpieces to the fences during a cutting operation, to facilitate. the operation of the device.

By way of example only, one specific embodiment of saw table of this inventionwill now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a plan view of the saw table arranged in accordance with the invention; Figure 2 is an end view of the table of Figure 1; Figure 3 is a view similar to that of Figure 2, but with the saw guides raised; Figure 4 is a sectional view of the saw table, taken on line A-A marked on Figure 1; and Figure 5 is a perspective view of an alternative form of saw guide, adaptable for a variety of divers saws.

The embodiment of saw table of this invention and illustrated in the drawings comprises a cast aluminium alloy base or work table 10 having four downwardly projecting feet 11, disposed one at each corner and cast integrally with the work table 10. In plan, the work table 10 is square and has formed in the upper surface two grooves 12 and 13 which extend respectively parallel to an adjacent edge of the work table 10, the two grooves being formed by a machining operation so as to be precisely at right angles to one another. Located in the two grooves 12 and 13 are fences 14 and 15 respectively, each fence being a snug fit in its associated groove so as to be supported thereby in an upright disposition, with the faces 16 and 17 respectively of the fences perpendicular to the main plane of the work table 10.Suitably formed in the work table 10 are two pairs 18 and 19 of threaded holes, the two pairs of holes being associated respectively with the grooves 12 and 13. The holes extend substantially horizontally within the thickness of the work table, from an adjacent edge thereof, such that the associated fence 1 6 or 1 7 may be clamped at a selected position along the length of the groove, by means of thumb screws threaded into the holes.

A mounting plate 22 is pivoted to the work table 10 by means of a bolt 23, extending through a hole provided at the intersection of the grooves 12 and 13. The mounting plate 22 extends beyond the periphery of the work table 10, and has at its outer end-a pair of upstanding lugs 24.

Pivoted to these lugs is a U-shaped bracket 25, there being a pair of saw guide rails 26 attached to the web of the bracket 25 in a parallel spacedapart disposition, so as to extend over the work table 10. The opposed ends of the two rails 26 are attached one to each limb of a U-shaped block 27 the base portion of which is .adapted to slide over the work table 10.Each rail 26 is of right angle section, and is-attached to the bracket 25 and the block 27 such that one flange of each rail is substantially horizontal (with the saw table in its normal operating position) and directed towards the other rail; and with the other flange extending upwardly, whereby a guide channel for a portable electric circular saw (such as that shown in.broken lines in Figure 4) may be slid along the rails 26, whilst being accurately located thereby.

The mounting plate 22, bracket 25, rails 26 and block 27 are all appropriately designed for use with a particular type of portable electric circular saw, such that the line of movement of the circular sawtlade,- when slid along the rails 26, will intersect the pivotal axis of the mounting plate 22 and the intersection of the grooves 12 and 13. Thus, if the saw table is to be used with a different circular saw, the mounting plate 22, bracket 25, rails 26 and block 27 may be replaced by simi!ar components but.apprnpriately configured for the different circular saw.

An arcuate guide rib 28 is attached to the upper surface of the work table 10, so as to have its centre of curvature on the axis of the bolt 23.

The block 27 has a groove 27a (Figure 3) formed therein and in which may be accommodated the guide rib 28, the block 27 also being provided with a clamp screw 29, arranged so as to allow clamping of the block 27 to the guide rib 28 at a selected angular position. The guide block 27 has an index mark 30 which may be aligned with calibrated graduations marked on the upper surface of the work table 10, for example at 450, 60/300, 75/150 and 900, with respect to the fences 14 and 15.

As shown in Figure 1, there is a cut-out portion 31 in the work table, adjacent the arcuate rib 28.

This portion allows the easy location of a circular saw at the ends of the rails 26 by the block 27, and also edge 32 of the cut-out portion serves to deflect the conventional saw guard upwardly, as the saw is advanced towards the other end of the rails 26.

A graduated rule 33 is clamped to the work table 10 by means of a pair of screws 34, which rule may be used in conjunction either with the end of the adjacent fence 14 or with index marks provided on the fence. In this way the end of the fence 14 may be pre-set at some required distance from the line of cut of a saw on the rails 26, such that a workpiece having one end aligned with the end of the fence will be cut to the pre-set length. The end of the fence may be provided with an end-stop or abutment, to assist the alignment of the workpiece with the end of the fence. The rule 33 itself may be adjusted with respect to the actual line of the saw cut, by releasing the screws 34.

An alternative form of end-stop (not shown) may be mounted.directly on the work table, to extend parallel to the length of the fence 14. Such an end-stop also may be calibrated, to facilitate adjustment and the cutting of workpieces to predetermined lengths.

In operation, the fences 14 and 15 are secured at the required positions by means of the thumb screws 20 and 21, with a sufficient gap between the adjacent ends of the two fences to accommodate the workpieces. The rails 26 and block 27 are then pivoted upwardly about the connection to lugs 24, and a first piece of timber to be cut is positioned on the work table 10, so as to bear against face 1 of fence 1 4-such astimber 33 illustrated in Figure 1. The rails 26 are then lowered, and the clamp screw 29 tightened to hold the rails 26 at the desired angle relative to the fences-and in the illustration of Figure 1 ,'at 450 to both fences. The circular saw is then engaged with the rails 26, operated and slid along the rails, so as to cut the first piece of timber, at 450 to its length.The first piece of timber is then removed from the work table 10, and a second piece offered to the table as illustrated at 34 in Figure 1, engagedwith face 17 of thefence 15.

The second piece of timber is then cut in precisely the same manner as the first piece, so completing mitering of the timbers .to form a corner joint.

It will be appreciated that because the fences 14 and 15 are accurately located by the grooves 12 and 13 disposed precisely at right angles, and each fence is used one for each of two members to be joined together, the final joint will have the two members disposed precisely at right angles, even though the rails 26 may not be disposed at precisely 450 to either fence. Thus, the circular saw table of this invention as described above particularly facilitates the rapid production of mitred corners with a minimum of operator effort and skill.

Figure 5 shows in part a modification of the saw table described above with reference to Figures 1 to 4. This modification, when incorporated in the saw table, permits the table to be used with a very wide variety of designs of circular saw.

In the modification of Figure 5, the rails 26 of Figures 1 to 4 are replaced by rails 40 (only one of which is shown in Figure 5) which rails 40 are of channel-shaped cross-section, with the open sides of the channels facing each other. Between the rails 40 is slidably mounted a carrier 41, which carrier has an opening 42 formed therein.

Bars 43 and 44 are bolted to the carrier 41, the bolts passing through transverse slots 44 formed in the carrier such that the bars 43 may be adjusted laterally as shown by arrows A. End stops 45 are similarly bolted to the carrier 41, the bolts extending through slots 46 formed in the carrier 41,so permitting adjustment of the stops 45 as shown by the arrows B.

The arrangement illustrated in Figure 5 is used by loosening the screws such that bars 43 and end stops 46 may be slid to their limiting positions, furthest apart. A circular saw is then positioned on the carrier 41, so that the saw blade projects through the opening 42 and lies in a plane parallel to the rails 40 and extending through the axis of the bolt 23 (Figure 2). The bars 43 and end stops 46 are then adjusted so as to contact the adjacent side edges of the saw sole plate, and clamped in that position by means of the respective bolts. lt may be necessary to adjust the depth of cut of the saw and such adjustment can conveniently be accommodated by packing pieces between the rails 40 and theU-shaped brackets 25 and 27. An alternative would be to provide on the work table itself sheet-like packing material, to lift the work piece to the required height relative to the saw blade.

It will -be appreciated that when the modification of Figure 5 is employed with the saw table, appropriate configuration of the carrier 41 allows the saw table to be used with all commonly available circular saws. Moreover, should the saw blade not be parallel with the side edges of the saw sole plate (due for example to manufacturing tolerances) this may be accommodated by the carrier 41, so as still to give satisfactory operation.

Claims

1. A saw table suitable for use with a portable power-driven circular saw, which saw table comprises a work table on which are mounted a fence against which a workpiece may be held and a saw guide, the saw guide extending over the work table above the fence and being arranged to support a portable power-driven circular saw, the saw guide also defining a guide path along which a supported saw may be slid, and one of the fence and saw guide being mounted for adjustment with respect to the other of the fence and saw guide, to permit a supported saw to make a cut at a selected angle across a workpiece held against the fence.

2. A saw table according to claim 1, wherein the saw guide is adjustable to permit the accommodation of different designs of portable power-driven circular saws.

3. A saw table according to claim 2, wherein the saw guide is adjustable to permit the location of the saw blade of a given portable power-driven circular saw on a cutting line, and to accommodate the depth of cut of that saw.

4. A saw table according to any of the preceding claims, wherein the saw guide comprises two spaced parallel rails each of angle section and appropriately supported at or adjacent the ends thereof, with one flange of each section lying substantially horizontal (in the normal operating position of the saw table) and directed towards the other section, and the other flange of each section projecting upwardly from the one flange.

5. A saw table according to claim 4, wherein means are provided to permit adjustment of the spacing between the two angle sections.

6. A saw table according to claim 5, wherein the adjustment means comprises slotted spacer bars extending between the two angle sections and to which the sections are clamped by means of screw-threaded fasteners.

7. A saw table according to any of claims 1 to 4, wherein there is provided a carrier supported by the saw guide for sliding movement therealong, the carrier being provided with means adapted to support and locate a power-driven circular saw.

8. A saw table according to claim 7, wherein the saw guide comprises two spaced parallel channel members disposed with the open side thereof facing each other, the carrier being in the form of a plate slidable along the channels.

9. A saw table according to claim 8, wherein adjustable abutments are fastened to the plate, a slot being formed in the plate through which the saw blade may project.

10. A saw table according to any of the preceding claims, wherein there are provided two fences, each secured to the work table such that the angle therebetween is exactly 90a

11. A saw table according to claim 10, wherein there is clearance between the adjacent ends of the two fences, at least one fence being slidably mounted on the table to allow the said clearance to be varied.

12. A saw table according to claim 10 or claim 11, wherein the saw guide is adjustably mounted on the work table, by means of a pivot provided at the end of the guide adjacent the two fences, and an arcuate track on the table adjacent the other end of the guide and along which track the guide may be slid.

13. A saw table according to claim 12, wherein a clamping mechanism is provided to hold the guide at a selected position.

14. A saw table according to claim 13, wherein at least one pre-set indexing arrangement is provided to lock the saw guide at a pre-set angle with respect to the fence.

15. A saw table according to any of claims 1 to 9, wherein the saw guide is mounted in a fixed manner on the work table, and the or each fence is mounted on a sub-assembly which is pivoted tothe work table.

1 6. A saw table according to any of the preceding claims, wherein an end stop is adjustably mounted on the work table or on one of the fences and against which a work piece may be abutted.

17. A saw table for a portable power-driven circular saw and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.