GB2238749A - Mortice cutting jig - Google Patents

Abstract

A jig, for use in cutting a mortice lock aperture into a workpiece such as a door, has a pair of cheek plates 12, 14 and a clamping plate 64 by means of which the jig may be clamped to the workpiece. A drill bit guide 28, 30 is mounted on guide rods 16, 18 connecting the cheek plates and is positionable centrally with respect to the workpiece by a centralizing screw 50. Further guides may be provided for use in drilling a hole transversely through a door for the spindle of a lock and also for the lock skudgeon. <IMAGE>

Description

APPARATUS FOR USE IN CUTTING A MORTICE The present invention relates to apparatus for use in cutting a mortice, and in particular for cutting a mortice in a door edge to receive a lock or other door closing means.

It has long been recognised by carpenters that installation of mortice locks can be difficult and time consuming. Doors usually made of timber are supplied by the manufacturer without any lock or latching device. As a result, various types of door are likely to be fitted with varying types of mortice lock. In addition, the receiving plate on the door frame needs to be acurately aligned with the mortice lock. In any particular location, this is likely to be fitted at different points. Thus it is not possible to have a standard door with a pre-cut mortice lock position and each door must be prepared individually by a carpenter.

In order to prepare a door to receive a mortice lock, normally a row of holes are drilled along the plane of the door and the remaining wood between the holes is chislled out. This is a time consuming process and often results in inaccurate lock fittings.

A number of solutions to the problem have been proposed. For example GB 1450020 describes a morticing machine which includes two guides and a router. The guides are clamped to the plane of the door and the router is guided such that it cuts the required hole to receive the lock within the door.

GB 2075911 describes a complicated mortice cutting apparatus having a clamping guide which again requires the use of a rotatable cutting tool in the form of a router.

The lever 32 guides the cutting tool 10 within a guide portion 15.

GB 2123338 provides a guide arrangement to provide a hole in the plane of the door by means of a routing cutter operated by an electric drill. One of the problems with this apparatus is that the electric drill cannot rotate the router cutting blade at a sufficient speed to provide a clean cut within the door. Although the apparatus is significantly better than the two prior art cutting machines described, the appratus is difficult to operate and does not provide a clean hole.

The present invention attempts to overcome the problems of the prior art by providing a jig which follows the more commonly used methods of carpenters when cutting mortice locks.

According to the present invention there is provided a jig comprising a pair of opposed clamps capable of being clamped to opposed faces of a door and being adjustable according to the width of the door, the jig comprising a plate having a plurality of holes therein, the holes being of sufficient size to allow a drill to pass there through to drill along the plane of the door a sufficient depth, the plate being slideable and lockable within the clamp to allow alternative hole position to be drilled.

The apparatus of the present invention also includes a device for centering the plate with respect to the plane of the door.

The apparatus of the present invention optionally includes a side plate attached to one of the clamps having a hole therein to act as a guide for a drill to drill a hole to accomodate the spindle of lock.

In a further embodiment the side plate may also include a hole therein to allow the drilling of the skudgeon of a lock.

In a further optional embodiment the side plate may have a backing plate to prevent the drill from damaging the wood when either or both the spindle hole and the skudgeon.

are drilled.

In a further optional embodiment, the present invention may have a hardened bush for guiding the drill and an adjusting mechanism whereby the bush may be mechanically adjusted without unclamping the jig from the opposing faces of the door.

An embodiment of the invention will now be described by way of example only, with reference to the accompanhing drawings in which: Figure 1 is a front elevation of a mortice jig according to the invention; Figure 2 is a rear elevation; Figure 3 is a plan view; Figure 4 is a left hand side elevation; Figure 5 is a right hand side elevation; Figure 6, 7 & 8 are scrap section views showing detail parts of the invention.

As seen in the drawings a door lock mortice drilling jig 10 is provided with side plates 12 & 14, and rods 16, 18 are secured by dowel pins 20, 22 to the plate 12. The plate 14 is removably secured to rods 16, 18 by set screws 24, 26, the plate 14 being spaced from the plate 12.

Slidably mounted on the rods 16, 18 between the side plates is a drill guide plate 28 having a drill guide block 30 slidably located within an elongate slot 32. The guide block is provided with a number of holes 34 and may be positioned at any one of a number of positions with respect to the slot 32 by means of a locating pin 36 which engages within one of a series of holes 38 formed in one side of the block 30. The locating pin 36 passes freely through a first wall 40 between the slot 32 and one edge of the guide plate 28 when the pin is in its block engaging position. The pin is urged into that position by a spring 42 which is seated in a hole 44 in the plate 12 and acts against a flange 46 on the locating pin.The pin extends outwardly from the flange through a hole in the side plate 12 and is provided with a knob 48 by means of which the pin may be withdrawn from its block engaging position to allow movement of the block 30 within the slot 32.

The guide plate 28 is adjustable along the rods 16, 18 by means of an adjusting screw 50, which is screwed into a threaded hole 52 in the plate 14.

One end of the adjusting screw has a knurled knob 54 and the other end has a reduced diameter portion 56 which passes freely through a hole 58 formed in a second wall 60 between the slot 32 and a second edge of the guide plate 28. Washers 60, 62 enable the reduced portion 56 of the screw 50 to engage the guide 28 so that turning the screw in either direction, by means of the knob 54 causes the guide plate 28 to slide along the rods 16, 18.

A clamping plate 64 is provided adjacent the plate 14 and a screw 66, is rotatably secured to the plate 64 at 66. The end of the screw 66 remote from the plate 64 is provided with a knob 68 and rotation of the knob causes the clamping plate to move towards or away from the side plate 12 in order to impart a door engaging and clamping action.

Pivotally mounted on the drill guide plate 28 are two centralising members 70, 72. Each of these members comprises a two-armed lever 74 pivoted at 76 and having an outwardly depending peg 78 at the end of each of its arms.

A torsion spring, not shown, is provided in the area of the pivot 76 to urge the lever 74 in a rotational direction such that one of the pegs 78 engages an inner surface of a recessessed portio+n 80 of the side plate 12. The diameter of the pegs 78 is such that the inner surface 82 of each peg 78 is always aligned with the unrecessed surface 84 of the side plate 12, as seen clearly in Figure 2.

In use the jig is placed on the edge portion of a door D that is to be provided with a lock containing mortice recess, the jig being positioned in its correct heightwise position, the front and rear faces of the door being located between the pegs 78 on the centralizing members 70,72. The knob 68 is then turned in the direction to close the clamping plate 64 towards the side plate 12. The jig is thus clamped in position on the door.

Next, the knob 54 is turned in the direction to move the drill guide plate 28 to locate the holes 34 centrally of the thickness of the door. In so moving, the axes of the pivots 76 move towards the side plate 12, and contact of the pegs 78 with the recessed portions 80 causes the two-armed levers 74 to rotate about their pivots 76.

The inner faces of the pegs 78 thus remain equidistant from the centre line joining the pivots 76 and the holes 34 in the drill guide block 30. Rotation of the knob 54 is continued until the inner faces of all the pegs 78 engage the front and rear faces of the door. The holes 34 are then positioned centrally with respect to the thickness of the door D.

A drill bit in a powered or hand operated drill is then passed in turn through each of the holes 34 and into the door to the depth suitable for the size of the lock casing. The knob 48 is then pulled to withdraw the pin 36 from its location in one of the holes 38 in the block 30, and the block is moved longitudinally along the slot 32 of the guide plate 28 and the pin 36 is located in a different hole 38, thus positioning the holes 34 out of alignment with the holes already drilled in the door. This operation may be repeated severally according to the size of mortice required, when it will be found that almost all of the wood has been cleared from the recess and only a small amount, if any, remains to be chiselled out before the lock is fitted.

Besides cutting out a mortice recess to receive the lock casing when fitting a new door, it is also necessary to provide a hole in the door through which the spindle of a door knob will pass, and also for the lock skudgeon. The invention may include an extension 86 on the side plate 12 and a drill guide 88 is slidably mounted on a rod 90 within a through recess 92 formed in the extension. The drill guide is provided with a hole 94 of a size suitable for a drill to suit the size of the lock spindle.

Two further holes 96 are provided in the drill guide of a size and in a position suitable for the lock skudgeon.

As seen clearly in Figure 4 the clamping plate 64 is provided with cut out portions 98 and 100 which substantially align with the drill guide holes 94 and 96.

In use, the spindle and skudgeon drill guide is adjusted along the guide rod 90 to suit the position of the spindle and skudgeon, being secured in place by a set screw 102. Appropriate sized drills are then passed through the holes 94 and 96 to drill through the door, the plate 64 acting as a braker plate to prevent the drill splintering the wood as it emerges through the door.

The slot 32 may advantageously employed as a guide for a router used to cut a recess in the edge face of the door to accomodate the face plate of the lock. The shank of the router cutter is guided in close contact with the faces of the slot 32, the plate 30 having first been removed, and the required recess is neatly cut out without the need of recourse to manual chiselling.

For such use, the slot is appropriately dimensioned for the common size of face plate, but if smaller face plates are to be accomodated, a thin walled collar may be placed around the shank of the cutter in accordance with normal practice.

Although the invention has been described with reference to its use in drilling out the recess for a mortice lock, it has at least one other use. For example, it may be used as a jig for drilling matching dowel holes for joining lengths of wooden boards edge to edge and the self-centring facility is of considerable advantage for this purpose. With this in mind, a number of interchangeable plates 30 may be provided, each having an appropriate sized hole or a selection of sizes of holes 34, according to the thickness of boards being drilled and dowelled.

Claims (11)

1. A jig for use in drilling holes in a workpiece such as a door, the jig being adapted for clamping to opposed faces of the workpiece and comprising a pair of cheek plates, guide rods extending between the cheek plates, a clamping plate moveable between the cheek plates and adapted to clamp the jig onto the workpiece, a drill bit guide member located between the cheek plates and slideably mounted on the guide rods, the drill bit guide member being adjust able with respect to the cheek plates so as to be positionable width-wise of the edge of the workpiece.

2. A jig according to claim 1 wherein the drill bit guide member is adjustable by means of an adjusting screw threaded into one of the cheek plates.

3. A jig according to claim 1 or claim 2 wherein the drill bit guide member is provided with a block slideable longitudinally within a slot formed in the guide member and having at least one hole therein corresponding in size to the drill bit to be guided, the block being adjustable longitudinally within the slot.

4. A jig according to claim 3 wherein a locating peg is provided in one of the cheek plates to locate in one of a number of locating holes formed in the side of the block.

5. A jig according to any of the above claims wherein means are provided to centralise the guide member with respect to the workpiece.

6. A jig according to claim 5 wherein the means for centralising the guide member comprises at least one 2-armed lever, being pivoted about its centre on a pivot pin located on the central median line of the guide member and having an upstanding finger at the end of each arm, an innermost part of each finger being adapted to engage respective faces of the workpiece when the guide member is positioned centrally of the width of the workpiece.

7. A jig according to any of the above claims where the clamping plate is moveable with respect to the work piece by means of a clamping screw threaded into one of the cheek plates and engaging with said clamping plate.

8. A jig according to any of the above claims wherein there is provided at least one transverse drill guide formed with holes for passage therethrough of a drill bit arranged to drill one or more holes transversely through the workpiece.

9. A jig according to claim 8 wherein the said transverse drill guide is located within a guideway formed in one of the cheek members.

10. A jig according to claim 8 wherein the clamping plate is provided with apertures adapted to align with the holes in the transverse drill guide to act as a breaker plate.

11. A jig for use in drilling holes in a workpiece such as a door, substantially as described herein with reference to the accompanying drawings.