GB2546102A

GB2546102A - Door latch installation jig

Info

Publication number: GB2546102A
Application number: GB1600370.9A
Authority: GB
Inventors: Stem Tim; Wilkinson Ben; Warmer Verity
Original assignee: Progress Ventures Ltd
Current assignee: Progress Ventures Ltd
Priority date: 2015-08-20
Filing date: 2016-01-08
Publication date: 2017-07-12
Anticipated expiration: 2036-01-08
Also published as: GB2546102B; GB201514817D0; GB201600370D0

Abstract

A jig 120 for cutting holes in the edge and side face of a door panel comprises an edge guide boring hole 126 between first and second clamping jaws. A cross drilling guide body 156 is rotatably mounted to the first jaw and adjusted between first and second positions providing two different backset distances. The guide body 156 has a guide hole 162 offset from the rotational axis of the guide body providing eccentric movement of the guide hole 162. A latch 160 or detents may retain the guide body in one of two positions. In a preferred arrangement radial protrusions (146C, fig.8A) in the first jaw or guide body are retained in circular groove (193, fig.8) in the other of the first jaw and guide body, a wall of the channel having a notch allowing axial insertion of the guide body to the first jaw; subsequent mounting of a thumb-grip on the guide body may prevent disassembly. In an alternative arrangement guide body 156 is rotational sandwiched between two circular ring elements 152, 154 of the jaw.

Description

Door Latch Installation Jig [0001] The present invention relates to a jig for use in door latch installation for personnel doors for domestic or other applications.

BACKGROUND

[0002] Installation of door latches in the edges of door panels, and the associated handles on either side of the panel for operation of the latch, has evolved over time. A presently employed construction in some territories, for example in the United States of America, involves drilling an edge-hole in the edge of the door to receive a latch body, and a cross-drilling through the side of the door panel to intersect the edge-hole, on a centre line of the cross-drilling that is either 60 mm or 70 mm distance from the door edge at which the edge-hole opens. This distance (the backset) dictates the latch to be used, which latch has an operation aperture at one of these distances from a face plate of the latch, the face plate being intended to be flush with the door edge. The operation aperture is adapted to receive a handle spindle of a door handle, which is either in the form of a knob or a lever. Knob handles have handle spindles employing a large backset (57mm, 70mm or over), so as to give room for a user’s hand to engage the handle without contact with a doorjamb when the door is closed. Lever handles employ a latch with a small backset (45 mm - 57mm), since the lever should not project near the centre of the door and the user’s hand does not need to envelope the lever near the doorjamb. Which back set is preferred is frequently a matter of choice.

[0003] In the United States, the diameter of the cross-drilling is typically 55mm. The handles are secured to each other by cross screws that pass through the body of the latch. The cross screws (passing through the body of the latch) serve to further secure the position of the latch where its body is otherwise unsupported in the cross-drilling (although the latch is to some extent also supported by the handle spindle in the operation aperture of the latch). More importantly, however, they secure the position of the handles with respect to the door.

[0004] The handles each comprise a rose base in which is disposed the lever or knob with at least some degree of rotation ability with respect to the rose base, so that the lever/knob can rotate the handle spindle for operating the door latch. Usually, the knob or lever is spring-biased by a spring mounted in the rose base to return the knob or lever to a neutral position. This is generally horizontal with lever handles, but is not often relevant with knob handles (if they have rotational symmetry). Since the door latch is operated by turning the knob or handle, there is a corresponding rotational moment imposed on the rose base due to friction, so that, if the latter is not well secured it can, over time, come loose and rotate also, leading to potential movement of the handle neutral position. The rose base must be larger (in diameter) than the diameter of the cross drilling, so that the edges of the facing rose bases on either side of the door panel can clamp the door panel when the cross screws are engaged between the two handles. The cross screws, on passing through apertures in the latch body, are retained by the latch body to prevent the rose bases from rotation.

[0005] US2014366395A discloses a jig for cutting holes in the edge and sides of door panels. The jig comprises a clamp, having first and second jaws, for gripping the edge of a door, wherein an edge-bore guide is arranged to be central between said first and second jaws in all operational positions of the jaws and wherein one of the first and second jaws carries a cross-drilling guide, which cross-drilling guide is slidable in the jaw between a short backset and a long backset position.

[0006] It is an object of the present invention to provide an arrangement whereby a smaller diameter rose base may be employed.

SUMMARY OF THE INVENTION

[0007] In one aspect the present invention provides a jig for guiding cutting of holes in the edge and side of a door panel, comprising: a clamp, the clamp having first and second jaws and means to urge the jaws together to grip the edge of a door panel; an edge-bore guide, being arranged between the jaws and having an edge-bore guide bore to guide cutting of a bore along an edge-bore axis in the edge of the door panel; and a cross-drilling guide, being arranged in the first jaw, having a cross-drilling guide bore to guide cutting of a bore along a cross-drilling axis orthogonal to said edge-bore axis in the side of the door panel, wherein the first jaw comprises a body, the cross-drilling guide being mounted in the body for rotation of the cross-drilling guide about a rotation axis lying parallel to said crossdrilling axis, the cross-drilling guide bore being arranged in the cross-drilling guide so that the cross-drilling axis is eccentric with respect to the rotation axis, whereby a backset of the jig, being the distance along said edge-bore axis from the edge-bore guide where it abuts a door edge to the cross-drilling axis, is variable, between a long backset and a short backset, by rotating the cross-drilling guide in said body so that the cross-drilling axis is moved between two opposite positions intersecting said edge-bore axis on either side of said rotation axis, stops being provided between the jaw body and the cross-drilling guide to positively locate the cross-drilling guide in each of said positions.

[0008] Said rotation of the cross-drilling guide between said long and short backset positions may conveniently be a rotation of 180 degrees, the centre of said rotation being on said edge-bore axis. Thus, merely by rotating the cross-drilling guide in the body through 180 degrees the jig may be adjusted between its long and short backset positions.

[0009] Said stops may be provided by co-operating spring plungers and concavities in the cross-drilling guide and body, whereby the cross-drilling guide positively adopts and is retained in said long or short backset positions when the spring plungers are engaged with said concavities.

[0010] Alternatively, said cross-drilling guide and body may be provided with cooperating notches and detents, whereby the cross-drilling guide positively adopts and is retained in said long and short backset positions.

[0011] A spring biased latch may be provided between the body and cross-drilling guide that must be released before the cross-drilling guide can be rotated in the body between said positions.

[0012] In one embodiment, the body is hollow and comprises two circular ring elements that between them retain the cross-drilling guide for rotation therein.

[0013] In some embodiments, a circular groove is provided on one of said cross-drilling guide and body and protrusions are provided on the other of said cross-drilling guide and body, such that, when the cross-drilling guide is engaged with the body, the protrusions slide in the groove when the cross-drilling guide is rotated relative to the body and retain the cross-drilling guide in engagement with the body, notches being provided in a wall of the groove so that, when the protrusions are aligned with the notches, the protrusions can pass through the notches and the cross-drilling guide can be withdrawn in an axial direction with respect to said rotation axis to release the cross-drilling guide from engagement with the body.

[0014] Said cross-drilling guide may comprise a front portion and a rear portion, one of said protrusions and groove being mounted on the front portion. Preferably, it is the front portion that carries the groove, and said protrusions are on the body.

[0015] The jig may further include a thumb grip releasably engageable with a socket in the cross-drilling guide, adapted to engage stop parts of the body to prevent rotation of the cross-drilling guide with respect to the body so far beyond said first and second positions that said cross-drilling guide can adopt a release position with respect to the body at which said protrusions are aligned with and can pass through said notches to release the crossdrilling guide from the body.

[0016] That is to say, the thumb grip must first be removed in order to dismantle the jig. Or, putting it another way, to assemble the jig, the cross-drilling guide must be engaged with the body by orienting the protrusions with respect to the notches, moving the crossdrilling guide axially with respect to the axis of rotation to move the protrusions into the groove, rotating the cross-drilling guide with respect to the body to a position in which the thumb grip can be engaged with a socket on the cross-drilling guide, said stop parts on the body being arranged to abut the thumb grip when the thumb grip is disposed in the socket.

[0017] The thumb grip may include a pair of opposed feet engageable with corresponding recesses of the socket, said recesses each having a lip on the edge thereof, such that when the feet are inserted in the recesses, the thumb grip is retained in the cross-drilling guide. Optionally, the feet of the thumb grip each include a ledge engageable with the lip of each recess of the cross-drilling guide, such that the ledges are retained by the lips via a snap fit relationship.

[0018] Preferably, the thumb grip is adapted to be friction-gripped by a user to rotate the cross-drilling guides between said first and second positions.

[0019] Typically, the long backset is 57 mm and the short backset is 45 mm.

[0020] The diameter of the cross-drilling bore of the cross-drilling guide may be 44mm, and the diameter of the edge-bore guide bore may be 25 mm. A conversion sleeve may be introduced in the edge-bore guide bore to reduce its bore diameter, optionally to 22mm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a door panel showing the holes to be cut;

Figure 2 is a perspective view of an assembled door latch arrangement to which the present invention relates, and adapted to fit in the holes shown in Figure 1;

Figures 3a and b are perspective views of a jig being an embodiment in accordance with an aspect of the present invention, respectively in closed and open positions;

Figure 4 is a side view of the jig shown in Figure 3b; and

Figure 5 is a view similar to Figure 4, but in a long backset position of the jig, as it is in Figure 3a (the jig in Figures 3b and 4 being in short backset positions of the jig);

Figure 6 is a perspective view of the inside of a jig in accordance with an aspect of the present invention;

Figure 7 is an exploded view of a jig in accordance with an aspect of the present invention; and

Figures 8A - 8D are perspective partial views of the assembly of a jig (some components not shown) in accordance with an aspect of the present invention.

DETAILED DESCRIPTION

[0022] Figure 2 shows a latch system 1 with which the present invention is concerned. This is more fully described in our copending application filed contemporaneously herewith under the title “Door Latch Installation” (and incorporated in its entirety by this reference thereto). The latch system 1 has a latch 10, known per se, having a latch body 12 and an end plate 14. The end plate 14 is round and has a cylindrical section 16 adapted to be received in an edge bore 110 (shown in Figure 1) in the edge 112 of a door panel 52. The section 16 has knurls 18 adapted to be a press fit in the edge bore 110 if that is appropriately sized. Typically, the section 16 and the edge bore have a diameter of about 25 mm. The end of the latch 10 has the usual latch member 20, adapted to engage a keeper (not shown) in a doorjamb and to retain the door closed, in known fashion. The latch body 12 has a longitudinal axis X. It also has operation aperture (not visible), which is rotatable in the body about an operation axis A which is orthogonal to the longitudinal axis X. The operation aperture has a “backset” BS, being the separation of the axis A from the end plate 14. This is typically either 45 mm or 57mm, depending on the handle (not shown) to be employed with the door.

[0023] In a door with an edge bore 110, a cross drilling 50 is provided whereby the axis of the cross-drilling is arranged to be coincident with the axis A of the operation aperture.

In the cross drilling 50, an adaptor 40 is first fitted, in a close sliding fit in the cross drilling.

It has a latch bore arranged to be coincident with the latch axis X when inserted and with a cross section to receive the latch body (in this case substantially rectangular) when the latch is inserted in the edge bore. The adaptor also has a spindle hole. When the latch 10 and adaptor 40 are in place, the operation aperture 22 is adapted to receive in a sliding fit a square-section handle spindle 30, which has a longitudinal spindle axis coincident, when assembled, with the operation axis A.

[0024] Two rose bases 60A,B are provided. The rose bases 60A,B each have screw holes to receive screws 80 having screw heads 81. The screw holes are diametrically opposed. They are received in a boss 94, which is internally threaded at both ends. When they are tightened, the rose bases 60A,B clamp the door panel around the cross-drilling 50. It is evident that the thickness T of the door panel is a variable parameter and the lengths of the screws and boss 94 can accommodate door panels of thickness between about 35 and 45mm.

[0025] Thus, to accommodate the latch 1, two drillings 110, 50 are required in the door 52. A jig 120 in accordance with embodiments of the present invention are illustrated in Figures 3 to 8D. Here, the jig comprises a clamp, having first and second jaws 122,124, for gripping the edge of a door. Between the jaws 122,124 there is arranged an edge-bore guide 126, provided with a guide bore 176. The clamp jaws 122,124 and edge-bore guide 126 are interconnected by a threaded stud 128 and an unthreaded rod 130. Both stud and rod have central circular flanges or grooves (not visible) engaged by corresponding internal grooves or flanges in the edge-bore guide 126 (also not visible). The rod and stud are both arranged freely rotatable in the edge-bore guide 126, whereby the position of the stud and rod in their respective axial directions, and regardless of their rotational positions, remains the same in the edge-bore guide 126. The stud 128 is threaded either side of the edge-bore guide 126 and received in correspondingly threaded bores 132,134 of the clamp jaws 122,124 respectively. The threads 132,134 in each clamp jaw 122,124 are in the opposite sense. The thread in the bore 132 may be a normal right-hand thread, and the stud 128 has a knob 136 by which it can be rotated (clockwise) by a user to screw the stud into the jaw 124, drawing the jaw towards the edge-bore guide 126 (moving as between Figures 3b and 3a). The thread in the bore 132, on the other hand, would in this event be a left-hand thread, so that clockwise rotation of the stud 128 unscrews the stud from the clamp jaw 122 pushing it towards the edge-bore guide 126, and at the same rate that the clamp jaw 124 is pulled towards the edge-bore guide 126.

[0026] Consequently, regardless of the rotational position of the stud 128, the jaws remain equidistant from the edge-bore guide 126. The rod 130 is unthreaded, but is a close sliding fit in bores in the clamp jaws, only one, 142, being visible in the drawings.

The rod 130 serves to keep the jaws square with respect to one another and to the edge-bore guide 126.

[0027] Thus, in Figure 3b, the jaws 122,124 are shown separated and can be positioned around a door edge 112,52 with a rear face 138 of the edge-bore guide 126 lying flush against the edge 112. The knob 136 is then turned until the door 52 is clamped by the jaws 122,124, the position of the jig being checked periodically by reference, for example to guide grooves 144 to ensure correct positioning of the jig to the intended location of the holes 110,50.

[0028] Only one jaw, jaw 124, serves as a guide for cutting the cross drilling 50. It comprises a hollow body 146 comprising two circular ring elements 152,154 which retain between them a circular guide body 156, the circular body and ring elements being centred at C and the body 156 being rotatable within the ring elements about an axis A’ that passes through the centre C. A raised thumb-grip 158 is provided on the guide 156 by which the guide may be rotated by the user about the axis A’. A spring biased latch 160 firstly requires displacing (leftwardly in Figure 4) to release a catch (not shown) from a detent (also not shown) on the guide 156 before the guide can be rotated. In Figure 3a and 5, the grip is shown at the 12 o’clock position. Here one detent on the guide 156 can be engaged by the catch on the latch 160. When the catch is released by displacing the latch 160, the guide can be rotated through 180 degrees to the position shown in Figures 3b and 4, where another detent on the guide 156 can be engaged by the catch on the latch 160. Thus the guide 156 has two positions mutually displaced by 180 degrees of rotation within the ring elements 152,154.

[0029] An alternative arrangement to the spring biased latch 160 for retaining the guide body 156 in either of the two positions, is shown in a different embodiment illustrated in Figure 7. Here, a spring plunger 146D is received in a bore (not shown) in an internal face 190 of the hollow body 146 of the jaw 124. The spring plunger 146D includes a sprung ball bearing (not shown) on the free end thereof. When the hollow body 146 and guide body 156 are aligned such that the guide 156 is in one of the two positions described above, the ball bearing of the spring plunger 146D engages with one of a corresponding pair of concavities or recesses 156D (as shown in Figure 7 and 8A), hereinafter referred to as a “dimple”, on an internal face 195 of the guide body 156. The spring plunger 146D is biased such that when the ball bearing is engaged in the corresponding dimple 156D, the guide body 156 is retained, or “locked” in position. In order to “unlock” the guide body 156, a significant rotational force must be applied on the thumb-grip 158, which force must be sufficient to press the ball bearing into the spring plunger 146D, thereby disengaging the ball from the dimple 156D and allowing the guide body 156 to be rotated about the axis A’. The embodiment of Figures 7 and 8 differs in other ways described further below.

[0030] Returning to the embodiment shown in Figures 3 to 6, the guide 156 has a circular guide hole or bore 162 which is eccentric with respect to the centre C, being displaced therefrom to B, when the grip 158 is in the 6 o’clock position shown in Figures 3b and 4, or to B’ when the grip 158 is in the 12 o’clock position shown in Figure 3a.

[0031] The lateral displacement between B and B’ is typically 12 mm, with the centre at B being spaced from rear face 138 of the edge-bore guide 126 by a distance of 45 mm, whereas the centre at B’ being spaced from face 138 of the edge-bore guide 126 by a distance of 57 mm. Of course, provided the centres B,B’ are both on the axis X and separated by the correct offset (typically 12 mm), it is not essential that the centre C be also on the axis X or that the rotation be of 180 degrees.

[0032] The guide 156 has the indicia “45mm” and “57mm” (assuming these are the separations just discussed) printed or embossed on it, one dimension being visible through a window 164 in a flange 166A of the ring element 154. The corresponding flange 166B has no such window, so that the indicium under it on the guide 156 is not visible (shown in dotted lines in Figure 4). The indicium visible through the window 164 indicates the backset currently applying. Of course the backsets are not limited to 45 and 57 mm, and nor is the offset B-B’ limited to 12 mm.

[0033] In the alternative embodiment mentioned above and shown in Figures 7 and 8, instead of the guide body 156 being retained in the hollow body 146 between two circular ring elements 152,154, the guide body 156 is retained in the hollow body 146 by means of protrusions 146C,146B in the internal face 190 of the hollow body 146 engaging and sliding in a circular groove or recess 193 in a front portion 195 of the guide body 156. This enables rotation of the guide body 156 relative to the hollow body 146 about axis A’ whilst retaining them in engagement with one another (see especially Figure 8A). In the example illustrated in Figure 8A, notches 156C,156B, adjacent to the “45mm” and “57mm” indicia on the front portion 195 of the guide body 156, correspond with the protrusions 146C.146B on the internal face 190 of the hollow body 146. When assembling the jig clamp jaw 124, the notches 156C,156B are aligned with protrusions 146C.146B and in this position, the guide body 156 can be inserted axially into engagement with the hollow body. When the guide body 156 is rotated about axis A’, such that the notches 156C, 156B and protrusions 146C, 146B are not aligned, the guide body 156 is retained in the hollow body 146.

[0034] In this embodiment, the thumb-grip 158 is provided as a separate component prior to assembly. As shown in Figures 7 and 8A - 8D, the grip 158 includes a pair of opposed feet 158A engageable with a socket 156A on the edge of the rear portion 198 of the guide body 156. When assembling the second jaw 124, and the protrusions 146C,146B are retained in the groove 193, the guide body 156 is then rotated about the axis A’ to expose access to recesses 156A, as shown in Figure 8C. Grip 158 is then fitted such that feet 158A are located in socket 156A. The feet may further include ledges 158E that are retained by corresponding lips 156E located at the opening of socket 156A of the guide body 156. In other words, the grip 158 is clipped into the guide body 156 via a snap fit relationship between the feet 158A and the lips 156E. When assembled (shown in Figure 8D), the grip 158 prevents the guide body 156 from being rotated about the A’ axis to a position wherein the notches 156C, 156B and protrusions 146C, 146B can be aligned. Indeed, they are shaped and sized so that they can only be withdrawn in one rotational release position around 360 degrees. Moreover the two protrusions 146B are shorter, circumferentially, than the single protrusion 146C, so that there is always engagement between both protrusions 146B,146C and groove 193, even at the 180 degree position opposite the release position at which the notches and protrusions are properly (ie releasably) aligned.

[0035] As shown in Figure 8D, once the grip 158 is fitted, the guide body 156 cannot be rotated in direction 201 past stop point 200 on the hollow body 146, due to the raised profile of the grip 158. When rotated in the opposite direction, the guide body 156 cannot be rotated past point 202 for the same reason. In this way, the grip 158 retains the guide body 156 in the hollow body 146, whilst allowing the guide body 156 to be rotated between the two backset positions, mutually displaced in this embodiment from one another by 180 degrees of rotation.

[0036] Also in this embodiment, a door facing cover 153 may optionally be included.

Door facing cover 153 is fitted to a rear face 199 of the guide body 156 by means of pegs 153A, which pegs are a snap fit with recesses 153B in the rear face 199 of the guide body 156. Door facing cover has a guide hole 162A corresponding with the guide hole 162 of the guide body 156.

[0037] The guide hole 162 is arranged to receive and guide the position of a hole saw (not shown) of diameter corresponding to the guide hole 162 and equal, of course, to the desired diameter of the cross drilling 50. The guide hole 162 does not guide a hole saw in a rubbing sense; rather, it serves only as a guide to the point on the door152 at which to direct a pilot bit that normally serves the guiding purpose for a hole saw. In that respect, a guide hole 162 and associated mechanism is not provided on the other jaw 122 because, when the pilot penetrates the far side of the door, that pilot hole provides all the hole saw guidance needed from that side.

[0038] The other jaw 122 can however provide another function, namely as a tool holder for Allen keys 172 that are useful for adjusting hole saws. Also visible in Figures 5 and 7, is an elastomeric surround 170, which provides better grip for the jig 120 on a door and prevents the door surface from being scratched by the jaw member 124.

[0039] Either before or after the cross-drilling 50 is cut, the edge-bore 110 is also cut, but using a hole saw of smaller diameter and guided by guide hole 176 in the edge-bore guide 126. Guide hole 176 will typically have a diameter of 25 mm, but smaller latches 10 are available to fit 22 mm bores. Therefore, a conversion sleeve 178 is provided with a bore 176A of 22 mm whereby such smaller bores can be guided by the jig 120.

[0040] Finally, the jig is provided with a further guide window 180 (see Figures 6, 7 and 8A) to enable the jig to be positioned vertically on a door panel.

[0041] Any of the above-described features can be used in any suitable combination with any of the other above-described features, and the present invention is not necessarily limited to the specifically described combinations.

[0042] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0043] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments.

The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0044] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

1. A jig for guiding cutting of holes in the edge and side of a door panel, comprising: a clamp, the clamp having first and second jaws and means to urge the jaws together to grip the edge of a door panel; an edge-bore guide, being arranged between the jaws and having an edge-bore guide bore to guide cutting of a bore along an edge-bore axis in the edge of the door panel; and a cross-drilling guide, being arranged in the first jaw, having a cross-drilling guide bore to guide cutting of a bore along a cross-drilling axis orthogonal to said edge-bore axis in the side of the door panel, wherein the first jaw comprises a body, the cross-drilling guide being mounted in the body for rotation of the cross-drilling guide about a rotation axis lying parallel to said crossdrilling axis, the cross-drilling guide bore being arranged in the cross-drilling guide so that the cross-drilling axis is eccentric with respect to the rotation axis, whereby a backset of the jig, being the distance along said edge-bore axis from the edge-bore guide where it abuts a door edge to the cross-drilling axis, is variable, between a long backset and a short backset, by rotating the cross-drilling guide in said body so that the cross-drilling axis is moved between two opposite positions intersecting said edge-bore axis on either side of said rotation axis, stops being provided between the jaw body and the cross-drilling guide to positively locate the cross-drilling guide in each of said positions.

2. A jig as claimed in claim 1, wherein said rotation of the cross-drilling guide between said long and short backset positions is a rotation of 180 degrees, the centre of said rotation being on said edge-bore axis.

3. A jig as claimed in claim 1 or 2, wherein said cross-drilling guide and body are provided with co-operating notches and detents, whereby the cross-drilling guide positively adopts and is retained in said long and short backset positions.

4. A jig as claimed in claim 3, wherein a spring biased latch is provided between the body and cross-drilling guide that must be released before the cross-drilling guide can be rotated in the body between said positions.

5. A jig as claimed in any of claims 1 - 3, wherein cross-drilling guide and body are provided with a co-operating spring plunger and concavities, whereby the cross-drilling guide positively adopts and is retained in said long or short backset positions when the spring plungers are engaged with said concavities.

6. A jig as claimed in any preceding claim, wherein the body is hollow and comprises two circular ring elements that between them retain the cross-drilling guide for rotation therein.

7. A jig as claimed in any one of claims 1 - 5, wherein a circular groove is provided on one of said cross-drilling guide and body and protrusions are provided on the other of said cross-drilling guide and body, such that, when the cross-drilling guide is engaged with the body, the protrusions slide in the groove when the cross-drilling guide is rotated relative to the body and retain the cross-drilling guide in engagement with the body, notches being provided in a wall of the groove so that, when the protrusions are aligned with the notches, the protrusions can pass through the notches and the cross-drilling guide can be withdrawn in an axial direction with respect to said rotation axis to release the cross-drilling guide from engagement with the body.

8. A jig as claimed in claim 7, wherein said cross-drilling guide comprises a front portion and a rear portion, one of said protrusions and groove being mounted on the front portion.

9. A jig as claimed in claim 8, wherein the front portion carries the groove, and said protrusions are on the body.

10. A jig as claimed in claim 7, 8 or 9, further comprising a thumb grip releasably engageable with a socket in the cross-drilling guide and adapted to engage stop parts of the body to prevent rotation of the cross-drilling guide with respect to the body so far beyond said first and second positions that said cross-drilling guide can adopt a release position with respect to the body at which said protrusions are aligned with and can pass through said notches to release the cross-drilling guide from the body.

11. A jig as claimed in claim 10, wherein the thumb grip includes a pair of opposed feet engageable with corresponding recesses of the socket, said recesses each having a lip on the edge thereof, such that when the feet are inserted in the recesses, the thumb grip is retained in the cross-drilling guide.

12. A jig as claimed in claim 11, wherein the feet of the thumb grip each include a ledge engageable with the lip of each recess of the cross-drilling guide, such that the ledges are retained by the lips via a snap fit relationship.

13. A jig as claimed in claim 10, 11 or 12, wherein, the thumb grip is adapted to be friction-gripped by a user to rotate the cross-drilling guides between said first and second positions.

14. A jig as claimed in any preceding claim, wherein the diameter of the cross-drilling bore of the cross-drilling guide is 44mm.

14. A jig as claimed in any preceding claim, wherein said long backset is 57 mm and wherein said short backset is 45 mm.

15. A jig as claimed in any preceding claim, wherein the diameter of the cross-drilling bore of the cross-drilling guide is 44mm. CLAIMS

1. A jig for guiding cutting of holes in the edge and side of a door panel, comprising: a clamp, the clamp having first and second jaws and means to urge the jaws together to grip the edge of a door panel; an edge-bore guide, being arranged between the jaws and having an edge-bore guide bore to guide cutting of a bore along an edge-bore axis in the edge of the door panel; and a cross-drilling guide, being arranged in the first jaw, having a cross-drilling guide bore to guide cutting of a bore along a cross-drilling axis orthogonal to said edge-bore axis in the side of the door panel, wherein the first jaw comprises a body, the cross-drilling guide being mounted in the body for rotation of the cross-drilling guide about a rotation axis lying parallel to said crossdrilling axis, the cross-drilling guide bore being arranged in the cross-drilling guide so that the cross-drilling axis is eccentric with respect to the rotation axis, whereby a backset of the jig, being the distance along said edge-bore axis from the edge-bore guide where it abuts a door edge to the cross-drilling axis, is variable, between a long backset and a short backset, by rotating the cross-drilling guide in said body so that the cross-drilling axis is moved between two opposite positions intersecting said edge-bore axis on either side of said rotation axis, stops being provided between the jaw body and the cross-drilling guide to positively locate the cross-drilling guide in each of said positions; and wherein a circular groove is provided on one of said cross-drilling guide and body and protrusions are provided on the other of said cross-drilling guide and body, such that, when the cross-drilling guide is engaged with the body, the protrusions slide in the groove when the cross-drilling guide is rotated relative to the body and retain the cross-drilling guide in engagement with the body, notches being provided in a wall of the groove so that, when the protrusions are aligned with the notches, the protrusions can pass through the notches and the cross-drilling guide can be withdrawn in an axial direction with respect to said rotation axis to release the cross-drilling guide from engagement with the body.

7. A jig as claimed in any preceding claim, wherein said cross-drilling guide comprises a front portion and a rear portion, one of said protrusions and groove being mounted on the front portion.

8. A jig as claimed in claim 7, wherein the front portion carries the groove, and said protrusions are on the body.

9. A jig as claimed in claim 7 or 8 , further comprising a thumb grip releasably engageable with a socket in the cross-drilling guide and adapted to engage stop parts of the body to prevent rotation of the cross-drilling guide with respect to the body so far beyond said first and second positions that said cross-drilling guide can adopt a release position with respect to the body at which said protrusions are aligned with and can pass through said notches to release the cross-drilling guide from the body.

10. A jig as claimed in claim 9, wherein the thumb grip includes a pair of opposed feet engageable with corresponding recesses of the socket, said recesses each having a lip on the edge thereof, such that when the feet are inserted in the recesses, the thumb grip is retained in the cross-drilling guide.

11. A jig as claimed in claim 10, wherein the feet of the thumb grip each include a ledge engageable with the lip of each recess of the cross-drilling guide, such that the ledges are retained by the lips via a snap fit relationship.

12. A jig as claimed in claim 9, 10 or 11, wherein, the thumb grip is adapted to be friction-gripped by a user to rotate the cross-drilling guides between said first and second positions.

13. A jig as claimed in any preceding claim, wherein said long backset is 57 mm and wherein said short backset is 45 mm.