The present invention relates to apparatus for use in cutting a workpiece In particular but not exclusively, the invention relates to apparatus for cutting a mortice pocket, hinge recess or latch plate recess in a vertical edge of a door. The invention further relates to apparatus for cutting an aperture such as a cylindrical cylinder lock aperture or circular handle shaft aperture in a face of a door

The cutting of a mortice pocket or a front plate recess in an edge of a door, or the cutting of a hinge rebate, or of a cylindrical aperture in a face of a door, are known to be challenging tasks even to a skilled worker The problem is particularly acute if cutting takes place in-situ, such as when installing a lock in a door that has already been hung Mistakes in chiselling or machining may require the entire door to be discarded and replaced

GB2238749 discloses a jig, for use in cutting a mortice lock aperture into a workpiece such as a door, having 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, A mortice is cut by sequentially drilling holes using a series of apertures in the drill bit guide 30 to guide the drill bit The invention suffers the disadvantage that materia! remaining between the drilled holes must be cut away using a chisel before a mortice lock can be fitted.

WO 88/10177 discloses a guide for cutting a mortise comprising a drill guide part 2 having a drill guide aperture 21 passing therethrough, the aperture 21 comprising a plurality of overlapping cylindrical shapes 20 A mortice may be cut by using the guide to drill a sequence of holes The guide suffers the disadvantage that arcuateSy pointed parts are left around the edge of the aperture as drilled, which must subsequently be removed using a chisel.

According to the present invention there is provided an apparatus for use in cutting a mortice pocket in a leading edge of a door in-situ, the apparatus comprising, at least one elongate guide means; clamping means for clamping the elongate guide means to a door or other workpiece such that the elongate guide means is substantially parallel to a leading edge thereof,

and a drill guide means mounted on the elongate guide means so as to be reciprocally moveable therealong, the apparatus further comprising means for translating the drill guide means in a direction having a resolved component norma! to the elongate guide means

The direction having a resolved component normal to the elongate guide means may itself be substantially normal to the elongate guide means {this is generally preferred), or may be disposed at an angle of less than 90° thereto

The means for translating the drill guide means may be arranged to translate both the elongate guide means and the drill guide means together, or may be arranged to translate the drill guide means independently of the elongate guide means

The apparatus has the advantage that different thicknesses of mortice may be cut by translating the drill guide means between predetermined limits Moreover, the apparatus may be used to cut rebates (e g. for face-plates or hinges) on sides parts of the door or workpiece, or even hinge rebates on parts of a door frame

Preferably, first and second adjustable stopping means are provided on the elongate guide means so as to define limits of travel of the drill guide means along the elongate guide means.

A rack and pinion or worm screw or similar mechanism may be provided for moving the drill guide means along the elongate guide means This type of mechanism may also be used for effecting translation of the drill guide from side to side This has the advantage that smooth, controlled movement of the drill guide means along the elongate guide means may be effected

At least first and second elongate guide means may be provided. The first elongate guide means may include a rack of said rack and pinion mechanism The stopping means may be mounted on the second elongate guide means

A pinion of said rack and pinion mechanism may be located in the drill guide means.

The clamping means are configured such that the elongate guide means may be moved in a direction substantially perpendicular to their extent In addition, the clamping means

may be configured to allow controlled lateral movement of the drill guide means, in addition to reciprocal movement along the elongate guide means

The drill guide means may comprise a bearing block, the bearing block having a hole therethrough, adapted snugly to receive a drill shaft such that the drill shaft may be supported, directly or indirectly, by bearings of the bearing block and rotate therein

Preferably, the bearing block is releasably secured to the drill guide means, for example by a key and twist mechanism This helps to prevent the bearing block and any drill shaft held thereby from accidentally disengaging from the drill guide means The apparatus may further comprise a drill shaft received in the drill guide means, the drill shaft being provided with a drill bit

Alternatively, the drill guide means may include a cylindrical aperture configured rotatably to receive a bobbin The bobbin may be provided a through hole adapted to receive a drill shaft

The bobbin may be made of or coated with a low-friction material, or be provided with a collar made of a low-friction material Alternatively or in addition the bobbin may be made of an elastomeric material

The drill shaft may be adapted for connection to a power drill Alternatively, the apparatus may further comprise an integral motor for rotating the drill shaft

Advantageously the drill bit is adapted to produce small swarf. This permits a mortice pocket to be cut without the need to withdraw the rotary cutting means at intervals during cutting of a mortice pocket, since the small swarf is readily ejected from the mortice pocket during rotation of the cutting means

Preferably, the drill bit comprises a shaft, the shaft having a major axis along a length of the shaft about which the drill bit is rotated in normal operation, the shaft having a leading end and a trailing end, the trailing end being adapted to be gripped in the chuck of a drill, wherein the leading end of the shaft is provided with a plurality of blades disposed radially with respect to the major axis of the shaft, the blades having a leading edge and a leading surface, wherein the leading edge is shaped to provide a cutting

edge, and the leading surface is disposed on the side of the blade that faces a direction of rotation of the drill bit

The leading end of the shaft may be provided with a spike, the spike lying along the major axis and protruding away from the drill bit, each blade further comprising a longitudinal edge distal the major axis, the longitudinal edge describing a substantially helical form, coaxial with said major axis The blades may be provided with a plurality of teeth along said longitudinal edge. The teeth enable the driil bit to cut along a radial direction when the bit is translated in a radial direction,

Alternatively, the leading surface may be generally planar and the blades disposed such that an angle between the plane of the surface of the workpiece to be cut and the plane of the leading surface is greater than substantially 90°

Preferably the drill bit has four blades

Preferably the clamping means comprises at least one clamp, the at least one damp being operable to grip opposite faces of a door.

The clamping means may be further operable to grip a clamp adaptor, the clamp adaptor comprising means for attachment to the leading edge of a door

The clamp adaptor may be configured to grip opposite faces of a door, wherein, with the apparatus clamped to the clamp adaptor, the apparatus is mountable with the drill guide means in juxtaposition with a face of the door

This feature has the advantage that the apparatus may be mounted to a face of the door thereby to allow an aperture to be cut through the thickness of the door

An aperture of oval cross-section corresponding to that of a cylinder lock may be made by reciprocal movement of the drill guide means parallel to a leading edge of the door

The clamp adaptor may be provided with at least one hook means, the at least one hook means being configured to hook around a portion of the apparatus thereby to restrain movement of the guide means relative to the adaptor

For a better understanding of the present invention and to show how it may be carried into effect, reference shall now be made by way of example to the accompanying drawings, in which.

FIGURE 1 is a perspective view of a mortice cutter of a first embodiment of the invention mounted to a door;

FIGURE 2 is a perspective view of a mortice cutter of the first embodiment of the invention with the carrier positioned at an extreme end of the lateral slide means;

FIGURE 3 is a perspective view of a mortice cutter of a second embodiment of the invention;

FIGURE 4 is a perspective view of a mortice cutter of the second embodiment of the invention with a bobbin, drill bit and hand drill mounted to the carrier;

FIGURE 5 is a perspective view of a mortice cutter of a third embodiment of the invention,

FIGURE 6 is a view of a first embodiment of a drill bit for use with the mortice cutter with a bobbin mounted thereon;

FIGURE 7 is an axial view of the first embodiment of a drill bit for use with the mortice cutter,

FIGURE 8 is a side view of a first embodiment of a drii! bit for use with the mortice cutter;

FIGURE 9 is a perspective view of a first embodiment of a drill bit for use with the mortice cutter,

FIGURE 10 is a perspective view of a second embodiment of drill bit for use with the mortice cutter,

FIGURE 1 1 is a perspective view of a clamp adaptor;

FIGURE 12 is a perspective view of a clamp adaptor being installed between clamp members of a mortice cutter of a first embodiment of the invention;

FIGURE 13 shows a mortice cutter of the first embodiment of the invention mounted to a face of a door

In a first embodiment of the invention, an apparatus 10 comprises an upper transverse slide 20 and a lower transverse slide 3O ₁ each slide 20, 30 comprising a pair of clamps 22 having rotary handles 25 Carriages 4O ₁ 50 slide within tracks 27, 37 of each slide 20, 30 The carriages 40, 50 are connected to opposite ends of a toothed bar 60 and a parallel slide bar 70 such that the toothed bar 60 and slide bar 70 are perpendicular to the slides 20, 30. The clamps 22 allow the apparatus to be mounted in juxtaposition with a leading surface 310 of a door 300, the leading surface 310 being the surface between a front side 320 (Figure 1) and a back side 330 (Figure 2) of the door The apparatus is oriented such that the toothed bar 60 and slide bar 70 are parallel to the surface 310

The toothed bar 60 and slide bar 70 each pass through cylindrical passages of a carrier 80, such that the carrier 80 may slide along the toothed bar 40 and slide bar 50 The carrier 80 is machined from a block of aluminium

The carrier 80 has a bearing block 150 mounted therein, for receiving a shaft 200 of a cutting tool 250. The bearing block 150 is oriented such that the axis of rotation of the shaft is substantially normal to the slide bar 70 and transverse slides 2O ₁ 30 The bearing block is located between the toothed bar 60 and slide bar 70..

A rotary handle 65 projects from a side of the carrier 80 and is connected, within the carrier, to a toothed wheel (not shown) which engages teeth 62 of the toothed bar 60 Rotation of the handle 65 results in translation of the carrier 80 along the toothed bar 60 and slide bar 70

The carrier 80 is also fitted with a friction adjustment mechanism which comprises a screw 84 fixedly connected to a rotary handle 85 The screw 84 may be screwed into the carrier 80 so as to abut the slide bar 70 A frictional force may thereby be applied between the carrier 60 and the siide bar 70

An upper stop 1 10 and a lower stop 120 comprise annular rings 1 16, 126 through which the slide bar 70 passes, and are positioned at locations of the slide bar 70 either side of the carrier 80 The stops 1 10, 120 may be moved along the slide bar 50 so as to bracket the length of the slide bar 70 along which travel of the carrier 80 is required The stops 110, 120 each have a screw 1 12, each having a rotary handle 114 that may be used to tighten the screws against the slide bar 70 so as to lock the position of the stops 11O ₁ 120

The lateral position of the carrier 80 may be varied by sliding along the transverse slides 20, 30 When a cutting operation is being performed, the carrier 80 may be locked in position using the upper and lower friction grips 21 , 31 , respectively

When cutting a mortice pocket, the carrier will typically be positioned midway between opposite faces 320, 330 of the door 300 When cutting a hinge rebate, the carrier will typically be positioned such that the recess is made towards an edge of the trailing surface (not shown) of the door 300

In a second embodiment of the invention (Figure 3), the carrier 80 is provided with a cylindrical cut-out 81 for rotatably receiving an elastomeric bobbin 710 The bobbin 710 has a central hole 720 for rotatably receiving a shaft of a drill 200 The other components of the second embodiment are generally similar to those of the first embodiment, and the general description in connection with the first embodiment applies also to the second embodiment.

In a third embodiment of the invention (Figure 4), lateral movement of the carrier 80 may be effected by means of damps 810 provided with rotary handles 820 By adjusting the positions of the clamps 810 in relation to clamp brackets 830, the lateral position of the carrier 80 may be adjusted

A drill bit 200 suitable for use with the apparatus 10 is shown in Figure 3 The drill bit comprises a cutting element 400 at a leading end 405 of the drill bit 200, designed to produce small swarf when cutting A cylindrical PTFE collar 220 is fitted to the bit 200 behind the cutting element 400, the diameter of the collar corresponding to that of the cylindrical cut-out 70 such that the collar may be inserted into the cut-out 70

Upon insertion into the cut-out 70, the collar 220 abuts a circumferential shoulder of the cut-out (not shown) proximate a rear face of the carrier 60, which faces the leading surface 310 of the door 300. The shoulder prevents the collar from sliding past the rear face of the carrier 60, but still permits the cutting element 210 to pass through the carrier 60 to cut the leading surface 310 of the door 300.

The collar 220 acts as a friction reducing element and a vibration damper. In use, the drill bit rotates within the collar 220, which provides both lateral and longitudinal stability to the drill bit, since substantially lateral forces are encountered as the cutting element 300 is moved along the edge of the door 300 The presence of the collar 220 enables an accurate cut to be made, with a high quality surface finish.

In order to cut a mortice pocket having a depth exceeding that of the cutting element 300, a series of cuts are made along the edge of the door, of increasing depth, until the desired pocket depth is achieved

A depth stop 230 is mounted behind the collar 220, and allows the depth to which a cut is to be made to be set. The depth stop 230 comprises an annular ring 235, slidable along the bit 200, with a friction lock comprising a grub screw passing radially through the ring. Tightening of the grub screw against the bit 200 allows the depth stop 230 to be locked in position.

The present embodiment of the invention is designed for use with a standard electric hand drill 400. In alternate embodiments, the apparatus comprises an integral electric motor and drill chuck, eliminating the need to provide a separate hand drill 400.

The cutting element 400 according to the present embodiment (Figures 5 - 7) is provided with four radial blades 420, an outer longitudinal edge 450 of each blade 420 describing a substantially helical form coaxial with the drill bit 200 The longitudinal edge 450 is provided with a plurality of teeth 460 that facilitate cutting of the workpiece when the drill bit is translated in a radial direction

The leading radial edge 430 of each blade 420 is provided with a cutting edge 430 to enable cutting of the workpiece as the drill bit is driven along an axial direction into the workpiece Furthermore, the leading end 405 of the drill bit 200 is provided with an axial spike 410 projecting axially away from the drill bit 200 The spike assists the cutting

element 400 when the cutting element 400 first penetrates into the door 300, by promoting rotational stability,

In an alternative embodiment of the invention (Figure 8), a drill bit 200 is provided with a cutting element 500. The cutting element comprises four blades 520 disposed radially at the leading end 505 of the drill bit 200. A cutting edge 530 is disposed along a radial leading edge of each blade 520. The edge 530 is designed to cut when rotated in an anticlockwise direction when viewed with the leading end 505 towards the viewer Each blade 520 has a leading surface 540 forming an angle generally in excess of 90° with a plane normal to the axis of rotation of the drill bit 200 This plane is generally also the plane of the leading surface 310 of a door 300 to be cut, and this angle enables the blade 520 to slice material from the leading surface 310 and to lift the cut material away from the surface 310 as the bit 200 rotates

A portion 535 of the cutting edge 530 proximate the axis of rotation of the drill bit 200 is shaped so as to provide a slight protrusion axially away from the cutting element 500 This feature provides for smoother entry of the cutting element into the door 300 since the raised portion 535 will enter the leading surface 310 before the remainder of the cutting edge 530

The outer longitudinal edges 550 of the blades 520 are also provided with cutting edges 570 that provide a cutting action when the cutting element is translated in a radial direction.

In an embodiment of the invention a clamp adaptor 700 (Figure 1 1) is provided to enable the apparatus to be mounted in juxtaposition with a front side 320 or a back side 330 of the door Clamp adaptor 700 comprises a G-clamp having a U-shaped body portion 710 and a screw portion 750 Body portion 710 is provided with hook portions 720 (Figures 1 1 and 12). The hook portions 720 are configured to abut clamping members 800 of the apparatus 10 when an end 715 of the body 10 of the clamp adaptor 700 is gripped between clamp members 800 of the apparatus 10. End 715 is an end opposite of the body portion 710 opposite screw member 750.

With clamp adaptor 700 gripped by clamp members 800 of the apparatus 10 and clamp adaptor 700 may be damped about the leading surface 310 of the door 300.. In this configuration, clamp adaptor 700 grips opposite faces 320, 330 of the door 300

Apparatus 10 is thereby secured to the door 300 with carrier 80 in juxtaposition with one of the faces 310, 320 of the door 300

Thus, with a drill mounted to the carrier 80, a hole may be drilled through a thickness of the door from one face of the door to the opposite face. Furthermore, an oval shaped hole may be formed by moving the carrier 80 (and thereby a drill mounted to the carrier) with respect to the door 300 In the event that an oval-shaped hole is required (for example, when installing an oval-shaped cylinder lock such as a Eurolock) a hole of the required shape may be formed by moving a drill bit parallel to the leading surface 310 of the door 300

As shown in Figure 12, hook portions 720 of clamp adaptor 700 assist in preventing apparatus 10 from being pulled away from clamp adaptor 700 in use.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does 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,

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