EP0042244B1

EP0042244B1 - Saw guide apparatus

Info

Publication number: EP0042244B1
Application number: EP81302539A
Authority: EP
Inventors: Gordon Williams Wynn
Original assignee: G W WYNN Ltd
Current assignee: G W WYNN LIMITED
Priority date: 1980-06-07
Filing date: 1981-06-08
Publication date: 1986-04-09
Also published as: EP0042244A1; DE3174301D1

Description

This invention relates to saw guide apparatus for use with handsaws of various kinds.
Guide apparatus for sawing operations is known in many different forms. The conventional mitre box, for example, is often employed for preparing mitre joints of frames but is limited in its applications and also in the size of workpiece that it will accept. It is still widely used because of its robust nature, but even when attempts have been made to make more versatile forms of apparatus in which a workpiece can be placed for sawing, the incorporation of further facilities can make them cumbersome, and they remain extremely limited as regards the maximum size of workpiece that can be accommodated.
Other saw guide apparatus has been developed that is adapted to be placed upon the workpiece, this resulting in a more compact form of apparatus, and also generally allowing it to be used with larger sizes of work. However, such apparatus often has only limited capabilities, such as the saw guides of UK Patents 620650 and 904254. Thus, although these saw guides can be placed against the side faces of a workpiece to guide the saw at specific angles to those side faces, they do not provide any means of con- trollably locating the position of the saw longitudinally of said side faces.
There is known (UK patent 1 502 596) a relatively robust form of saw guide apparatus that is adapted to be supported on a workpiece which is capable of a number of different functions. This comprises bearer means that are adapted to be placed on a workpiece with a forwardly facing guide face behind which the bearer means extend to engage longitudinal side faces of the workpiece, and a transverse location device can provide a datum at an adjustable distance in front of the guide face, but this is of limited practical value as a means of locating the saw guide plane at desired positions longitudinally of said side faces. Also, while it is able to be supported upon relatively large workpieces, it can only make a limited depth of cut. Moreover, the setting arrangements for making oblique cuts are complicated and, indeed, it is not possible to use the apparatus practically for making 45° mitre cuts.
This last form of apparatus, like other known apparatus that is adapted to be placed upon a workpiece, is primarily useful for making cuts across the width of an elongate workpiece and cannot be readily adapted to making cuts longitudinally of the workpiece. Even in an example of known apparatus, such as UK patent 620650, in which a rotatable saw guide is employed that can be disposed longitudinally to the bearer means by which the apparatus is supported on the workpiece, there is no practical value to be derived from this as there is no way of adjusting the spacing of the saw guide relative to the workpiece side faces.
US―A―1 535 042 discloses a saw guide apparatus wherein saw guide means are secured to a first of two bearer members providing planar locations for mutually transverse faces of the workpiece. The second of the bearer members is adjustably securable to the first bearer member such that it can be used as a clamping plate adapted to extend across a workpiece and to engage against the remote end of the workpiece. The features of the pre-characterising part of Claim 1 are known from this document.
In the saw guide apparatus according to the present invention, on said first member of the bearer means there is a further member which is positively securable against rotation relative to the first bearer member and forms a depending portion of the bearer means that provides a location face rearwards of the saw guide plane and at an adjustable distance therefrom.
The invention will be described in more detail by way of example with reference to the accompanying drawings, wherein:

Fig. 1 illustrates a first embodiment of saw guide apparatus according to the invention,
Fig. 1a is a transverse section of the apparatus in Fig. 1.
Figs. 1 b and 1c are front and plan views of the supporting bracket of the saw guide means in the apparatus of Fig. 1,
Figs. 2 and 3 show the apparatus of Fig. 1 in two different modes of use,
Fig. 4 illustrates a further form of apparatus according to the invention,
Fig. 5 illustrates the apparatus of Fig. 4 in another mode of use,
Fig. 6 illustrates the apparatus of Fig. 4 with modified saw guide means,
Figs. 7 and 8 are side and plan views illustrating a further modification of the apparatus of the preceding figures, and
Fig. 9 illustrates a further modified form of apparatus according to the invention.

Referring mainly to Figs. 1 and 1a to 1c of the drawings, the apparatus there comprises a two- member bearing means 2, this having a lower angle-section member 4 and an upper shallow channel-section member 6. The members are secured together by a clamping screw 8 that passes through a longitudinal slot 10 in the member 6 to engage a tapped hole 12 in the lower member. The slot 10 is enlarged at its rear end to allow the members to be separated without removing the screw. As can be seen in Fig. 1a the screw can be used to hold the members parallel, with the flanges 14 of the channel-section member seating in longitudinal recesses 16 in the top face of the member 4.
Beyond the forward end of the slot the upper member 6 projects past the lower member and has a nut and screw fixing 18 for a saw guide device 20. The guide device comprises a right- angle bracket 22, with a horizontal limb 24 held by the screw and nut fixing and a vertical limb 26 on which a saw guide element 28 is secured by a screw 32 having its head recessed into the element to be clear of a planar front guide face 30 of the element that defines a saw guide plane. The vertical limb 26 has front flanges 26a that seat in a recess 34 in the rear face of the element 28 to locate the bottom edge of that element horizontally. The screw 32 passes through an elongate slot 26b in the limb 26 allowing the element to be adjusted upwardly and downwardly on the limb before it is secured by a nut on the screw. A guide spring 38 is provided to hold a saw blade (not shown) against the guide face 30. The guide spring is formed by stainless steel or aluminium alloy strip in the form of an inverted narrow "U" with a bifurcated rear leg 40 received in the slot between the limb 26 and the element 28. The spring 38 is adjustable upwardly and downwardly and is secured by a further screw 33, recessed into the front face 30, like the screw 32. A nut 33a retaining the screw 33 is disposed in the top recess 27 in the limb 26 and the spring is therefore not clamped directly to the limb 26 although the sides of the flanges 26a will prevent the spring element rocking about the screw 33. The manner of attachment of the spring allows its height to be adjusted relative to the saw guide element and it can also be inserted into its slot from above or from below. The forward leg 42 of the spring overlies the front guide face 30 and the free end of the forward leg is formed in a shallow "V" to bear resiliently against the guide face.
Fig. 1 illustrates the use of the apparatus to make a saw cut in an elongate workpiece W at 90° to its main faces. The user holds the bearer means with one hand against the workpiece so that horizontal and vertical limbs 4a, 4b of the angle-section member 4 bears firmly against the abutting workpiece top and side faces respectively, and with the blade of a handsaw (not shown) retained against the saw guide face by the spring 38, the 90° saw cut is made.
Angular adjustment is possible about the axes of the screw and nut fixings of the saw guide device 20 to the upper bearer member 6 and of the upper bearer member 6 to the lower bearer member 4. Preferably, for both such adjustments location means are provided whereby specific angular orientations can be obtained. Thus, additional grooves can be formed in the upper face of the member 4 to receive the flanges 14 of the upper bearer member, and Fig. 1 shows a pair of such grooves 48 directed at right-angles to the angle member. These can be used, in the manner illustrated in Fig. 2, to locate the two bearer members at right-angles to each other, so that the vertical limb 4b of the angle member locates against an edge of a workpiece W rearwards of the saw guide means, while the bottom face of the upper member 6 locates on the top face of the workpiece. This arrangement is particularly suitable for making saw cuts in relatively wide workpieces, such as boards.
The bottom edge of the saw guide element 28 can also engage the workpiece top face to assist in supporting the apparatus stably. In the different modes of use shown in Figs. 1 and 2 the element 28 must be at different levels relative to the bearer means to do this, but the elongation of the slot 26b permits the necessary adjustment.
By means of further slots similar to the slots 48 but set obliquely in the lower member 4, it is possible to adjust the two bearer members to make oblique cuts in the workpiece. However, it is more appropriate, when there is a need for making such oblique cuts in elongate workpieces, e.g. for framing, to make use of the angular adjustability of the saw guide device. In the forward end of the upper bearer member 6 beyond the slot there is a longitudinal rib 50 that can seat in alternative slots 24a in the underside of the horizontal limb 24 of the bracket 22 and Fig. 3 illustrates how the bracket 22 can be rotated through 45° on the upper member 6 to be located obliquely by the rib 50. The slots illustrated allow adjustment through 45° and 90° in both directions, but other angles can be provided.
Further modes of operation are possible using bearer means of greater depth than those illustrated in Figs. 1 to 3. Fig. 4 illustrates an example, in which the same upper bearer member 6 is employed with a lower bearer member 54 that now takes the form of an I-section strip bent to a right-angled "S"; a screw and nut fixing 56 is provided, with a plurality of alternative receiving holes 58 in the lower member horizontal limbs. In this embodiment the lower S-form member 54 the workpiece W, and the I-section of the lower member is disposed symmetrically between the flanges 14 of the upper channel-section member 6 so that the bottom face of one of those flanges locates on the top face of the workpiece.
It will be clear that, as compared with Fig. 1, the increased depth of the S-section member gives substantially greater stability when the apparatus is held against a workpiece, which may be particularly important when making saw cuts on members with a relatively narrow top face, such as the moulding illustrated in Fig. 4. In fact, because the lower member there extends below the workpiece, for firmer location it can be used as a bench stop or can be gripped in a vice on which the workpiece rests. The location of the apparatus may be assisted by the provision of transverse projections such as pins 60 on the forward limb of the S-form member having their bottom face in the same plane as the bottom faces of the upper member channel flanges.
The form of the lower member in this modified apparatus provides for other modes of use of the apparatus, as will now be described. In the mode shown in Fig. 4, the forward limb 62 projects upwards to above the level of the upper bearer member 6, and thus has its rear face directly opposed to the saw guide face 30. By setting the spacing between the saw guide face and the forward limb, and the aligning the rear face of that limb to a datum on the workpiece, e.g. the end face of a workpiece or a previous saw cut, a saw cut can be made at a required distance from that datum. The displaceability of the spring 38 allows it to be moved clear of the saw guide face to facilitate setting the spacing. If the workpiece is to have a halved joint with another elongate member, simply by gripping that other member lightly between the forward limb and the guide face before tightening the screw 56, this distance can be set to its width. Fig. 4 also illustrates how the relatively deep lower bearer member may depend below a workpiece and be used as a bench stop, or may have its bottom portions held in a vice.
The overall longitudinal and vertical extent of the lower member 54 is sufficient for it to provide support for the apparatus against the workpiece in either of these directions. Fig. 5 shows the S-form member reversed as compared with Fig. 4, so that top face of a workpiece W is engaged by the upper bearer member 6 and/or the lower edge of the saw guide element, and the workpiece side face by end face 65 of the shorter end limb 64 of the lower member 54, now located rearwards of the saw guide plane. With the apparatus held by clamping the end limb 64 against the workpiece side face this is suitable for making a saw cut vertically or nearly vertically in the end face of an elongate member in a position spaced forwards from the locating side face. In the example of Fig. 5, if the workpiece W is to be one part of a halved joint, the position of the vertical saw cut in the other part of the joint can be gauged using the vertical cut face in the workpiece W after the waste has been removed at one side of the first saw cut. To do this the spacing between the limb 64 and the saw guide face 30 is set at the distance between the first saw cut and the opposite face of the workpiece to that with which the limb 64 is shown in contact in Fig. 5.
When sawing wide workpieces, it will be understood that the mode of operation shown in Fig. 2 may be employed using the modified form of the apparatus of Figs. 4 and 5, with the S-form member 54 turned at right-angles to the upper member. Slots can be provided in either or both horizontal limbs of the S-form member, like the grooves 48 in the bearer member 4, to give a positive angular setting.
Referring again to Fig. 4, this also illustrates a modification of the saw guide device in that a guide element 28a is provided with grooves in its rear face for two spaced guide springs 38, both vertically adjustable and reversible (as will be described below). Furthermore, to increase wear resistance a facing sheet 30a, e.g. of a plastics laminate, can be adhered to the front face of the saw guide element in this and other embodiments. If required, interchangeable saw guide elements may be provided for specialised functions, e.g. for hacksaws for coping saws, for tile cutters etc.
Referring to Fig. 6, another modification of the saw guide device is shown in which a guide face element 70 is provided having an oblique front face. The rear face is still located vertically by the bracket but the element has a tapered thickness so that the front face is inclined at a small angle to allow it to be used for cutting the pins and slots of dovetail joints. Preferably an inclination of 8° is provided, a conventional angle for dovetails. The guide element is shown in position for cutting the sides of dovetail pins that must have their faces inclined to the longitudinal (vertical) axis from the joint end face of the workpiece W. To cut the opposite sides of the dovetail pins the element 70 is turned through 180°. To cut the sides of the dovetail slots on a similarly located second workpiece the element is turned through 90° and 270°. Mutually transverse grooves 34 allow the guide spring 38 to be inserted from the uppermost edge of the guide element 70 as it is turned to each new position: preferably in each case the bottoms of the spring grooves are at a uniform distance from the guide face.
Fig. 6 shows a further modification of the apparatus to incorporate two saw guide devices at opposite ends of the bearer means. As illustrated the upper bearer member 72, otherwise similar to the member 6, is cranked at its rear end to form an integral saw guide bracket 74 on which the additional saw guide element 28 is mounted, with a guide spring 38 if required. This may be of particular advantage when it is required to make saw cuts at two different settings (as in the case of dovetail pins and slots) and it is then possible to preserve the settings while all the cuts are being made. It will be understood that this second saw guide device may be mounted on a pivotable bracket also if required. It is alternatively possible to form the saw guide bracket in the previously described embodiments as an integral part of the upper bearer member. Although some modes of adjustment may not be possible this will be a more economical construction.
Figs. 7 and 8 illustrate an alternative modification for use in cutting dovetail joints. In this case a modified lower bearer member 76 is of inverted U-form with dependent limbs 78a, 78b one of which is perpendicular to the horizontal intermediate section and the other of which is at an angle of 8° to the vertical. The limb 78a can be used in the same way as the limb 64 (Fig. 5). The limb 78b can be set against a side face of a workpiece W, as illustrated in Fig. 7, to locate the saw guide plane at 8° to that side face. The figure shows one side of a dovetail pin being cut and the oppositely inclined other side is cut after reversing the workpiece W to locate against the opposite side face.
For cutting the dovetail slot as shown in plan in Fig. 8 the lower member has two pairs of grooves 80a, 80b oppositely inclined at 8° to the longitudinal axis, so that the saw guide face can be located at an oblique position to the vertical side face of the workpiece W for the mating part of the joint.
It may be noted here that although for firmer guidance the lower part of a saw blade should be kept in contact with the guide element as it cuts through the workpiece, this may introduce a very slight inaccuracy in the saw cut, due to the fact that the saw blade will be held slightly out of the vertical (as represented by the saw guide face) due to the set of its teeth. To ensure that the face of the saw blade is in planar contact with the saw guide face, the guide element above the workpiece should have a recessed lower edge, as illustrated at 92 in Fig. 7, so that the laterally projecting tips of the teeth do not contact the saw guide element. Generally, however, it is unnecessary to try to avoid this source of minor inaccuracy.
The saw guide device may incorporate means acting as a depth stop to limit the depth of saw cut. For example, if used with a backsaw, the saw guide element may be so adjustable in height so that the saw movement downwards is limited by engagement of the spine of the saw with the upper edge of the element. In some modes of use the guide spring 38 can be used as a depth stop by reversing it from the illustrated position so that it is upwardly open. Near their junction the two vertical limbs of the spring are joined by a screw bolt 94 (Fig. 1) that forms an axle for a hard plastics roller 96 and when the saw teeth engage the roller further downwards movement of the saw is prevented. The roller rotates freely and therefore little or no damage is caused to it or the saw teeth. The screw bolt 94 can help to draw the two limbs of the guide spring together and so be used to adjust the spring pressure with which a saw blade is held against the guide element. In its inverted orientation, when sawing relatively small section workpieces, it may also be possible to locate a guide spring (or a single bifurcated bar) behind the workpiece as a supporting leg for the apparatus resting on the surface on which the workpiece is placed.
Fig. 9 shows a further modified apparatus according to the invention. The upper bearer member 6 and saw guide device 20 are as described before but a longitudinally and rotatably adjustable intermediate box frame member 102, is clamped to the upper member by the screw 8, and to a planar bottom element 102a of the member 102 a lower L-shaped member is secured to be longitudinally adjustable. Location against a workpiece top face is provided by the upper bearer member 6, and side face location by the side edges 102b of the intermediate member 102 together with the lower member 104 if this is present. The upper member is held in longitudinal alignment with the intermediate member by grooves (as in the previously described embodiments). Auxiliary grooves 110 are illustrated for receiving the channel section flanges of the upper member to locate the upper and intermediate members at right angles to each other and there may of course be similar pairs of grooves for other angular orientations. The lower member 104 is slidable longitudinally on the intermediate member and is secured by a further clamping screw 112. It is therefore adjustable independently of the relative positions of the upper and intermediate members, and its upright terminal limb 104a can be employed in the same way as the limb 62 shown in Fig. 4. With the lower member 104 removed, the forward end face 102c of the intermediate member can be employed in the same way as the shorter vertical limb 64 shown in Fig. 5.
With the lower member removed, if the intermediate member is inverted, as shown in broken lines in Fig. 9, its lugs 108 depend a short distance below the upper member to function as a side location for the workpiece. In this configuration the apparatus can be used for, e.g. a workpiece held in a bench vice, where there is not enough clearance for the lugs of the intermediate member.
It is a feature of all the apparatus described that it is possible to assemble and adjust it to use it either right-handed or left-handed. In the example of Fig. 9 by re-assembling the bearer members with the upper member 6 reversed, but on the same side of the lugs 108 as illustrated, and with the lower member 104 also reversed, the saw guide means 20 and the vertical limb 104a will face in the opposite direction to that shown in the drawing.
It will be understood that in all instances in which the bearer means comprises a member having an upright limb disposed forwardly beyond the saw guide plane, means can be provided for attaching a selector head, as is described in UK patent specification 1 502 596, for assisting the location of a saw cut relative to an existing cut or end face as described in that earlier patent specification.
While the saw guide elements have been illustrated with retaining springs to hold the saw blades against the guide faces, it is possible to use other saw retaining means known in the art, such as inset magnets, or fixed or sprung rollers, but is it generally desirable to provide means that allow the user to use the apparatus with the entire guide face unobstructed if desired. Other modifications are also possible: for example the saw guide carrier and planar element can be a single member and the guide element if detachable can also be reversible. The parts of the apparatus can also be adapted for more effective co-operation with other apparatus: for example special guide springs may be provided for engagement of a hacksaw blade.

Claims

1. Saw guide apparatus arranged to be placed upon a workpiece (W), comprising bearer means having faces for locating mutually transverse faces of the workpiece, including a bottom location face arranged to bear against a top face of the workpiece, saw guide means (20) arranged to be disposed wholly above the top face of the workpiece and defining the orientation of a saw guide plane relative to said workpiece location faces, the bearer means comprising at least two members (4, 6 or 6, 54 or 6, 76 or 6, 102, 104) that are adjustably secured together, and the saw guide means (20) being part of or being secured to a first of the bearer members (6),
characterised in that a further one (4, or 54 or 76 or 102) of the bearer members is positively securable against rotation relative to the first bearer member and forms a depending portion of the bearer means that provides a location face rearwards of the saw guide plane and at an adjustable distance therefrom.

2. Apparatus according to Claim 1, wherein said rearwards location face is lower than the portion of the first bearer member extending between a plane including said rearwards location face and the saw guide plane.

3. Apparatus according to Claim 1 or 2, wherein the first bearer member has in the space between said rearwards location face and the saw guide plane a bottommost face that does not project below said bottom location face.

4. Apparatus according to any preceding claim, wherein said rearwards location face is disposed parallel to the saw guide plane.

5. Apparatus according to any preceding claim, wherein the horizontal extent of the further member in providing said rearwards location face is greater than the horizontal extent of the saw guide means.

6. Apparatus according to any preceding claim, wherein the further member is positively securable in at least two alternative positions relative to the first member.

7. Apparatus according to any preceding claim, wherein said members of the bearer means are relatively rotatable to adjust the angular orientation of said further member relative to the saw guide plane.

8. Apparatus according to any preceding claim, wherein screw locking means for securing together said first and further members of the bearer means are mounted in said further member with the screw axis extending transversely to said bottom location face, and the first member is adjustable relative thereto.

9. Apparatus according to any preceding claim, wherein said first member is arranged to provide said bottom location face perpendicular to a workpiece location face provided by a side face of said further or another member of the bearer means.

10. Apparatus according to any preceding claim, wherein the first member is wholly disposed so as not to project below said bottom location face.

11. Apparatus according to any preceding claim, wherein said further member (54 or 76 or 102) is of elongate form and has a terminal limb (64 or 78a or 102c) capable of providing said rearward location face.

12. Apparatus according to any preceding claim, wherein said further member (4, 54) or another member (104) of the bearer means is adjustably locatable in a position in which it projects forwardly through the saw guide plane to have a forward terminal portion (62,104a) beyond the saw guide plane, said terminal portion thereby providing an adjustable location spaced forwardly from the saw guide plane.

13. Apparatus according to claim 12, wherein said forwardly projecting member has parallel terminal limbs (62, 64) at opposite ends and is reversible to dispose either of said limbs formost with respect to the saw guide plane, at least one of said limbs being adapted to provide said rearwards location face.

14. Apparatus according to any one of claims 11 to 13, wherein said bearer means comprises three members (6, 102, 104), the first member (6) on which the saw guide means (20) is mounted being attached to the second (102) of said three members providing said rearwards location face, and the third member (104) being slidably adjustable to act as said projecting member providing said location forwards of the saw guide plane.

15. Apparatus according to any preceding claim, wherein said second or further bearer member (54, 76, 102) of the bearer means is of U-form or comprises a U-form portion in which both end limbs of the U-form can be employed as alternative rearwards location faces.

16. Apparatus according to any preceding claim, wherein said further and/or other members (54, or 76 or 102, 104) of the bearer means have a substantial longitudinal and vertical extent such as to provide planar location for the apparatus in both said directions against the workpiece.

17. Apparatus according to any preceding claims, wherein the saw guide means (20) has a forwardly facing guide face (30).

18. Apparatus according to any preceding claim, wherein the saw guide means are positively securable to the first member in a plurality of alternative angular orientations, including one orientation transverse to both location faces and another orientation parallel to one location face and transverse to the other.

19. Apparatus according to any preceding claim, wherein the saw guide means comprises a member having a bottom edge capable of locating a top face of the workpiece.

20. Apparatus according to any preceding claim, wherein there are means for locating the saw guide plane in at least two different angular orientations relative to said two mutually transverse location faces, said two orientations being mutually displaced by 90°, whereby the apparatus can be used for cutting dovetail pins and sockets in workpieces forming the respective members of dovetail corner joints.

21. Apparatus according to any preceding claim, wherein the saw guide means comprises a saw guide element provided with an inclined guide face (30) defining the orientation of the saw guide plane, the guide element being mountable in at least two different angular orientations mutually displaced by 90°, whereby the apparatus can be used for cutting dovetail pins and sockets.

22. Apparatus according to any preceding claim, where the saw guide means is provided with a resilient member (38) for holding the saw blade in the saw guide plane, and said member is removably adjustable in position.

23. Apparatus according to claim 22, wherein said resilient member is of U-form and the saw guide means is provided with means (28) for receiving the resilient member in alternative positions in which the bend of the U-form is located either at the top or the bottom of the saw guide means.

24. Apparatus according to claim 22 or 23, wherein a plurality of said resilient members are provided in the saw guide means in positions spaced transversely across the saw guide face.

25. Apparatus according to any preceding claim which is adjustable to a position in which said location faces are provided other than by the first member of the bearer means, and the first member is displaceable relative to said faces to position the saw guide means at an adjustable distance therefrom.