GB2426729A

GB2426729A - Mortice cutting apparatus

Info

Publication number: GB2426729A
Application number: GB0511283A
Authority: GB
Inventors: Howard George Osborne
Original assignee: W S NORMAN ENGINEERING Ltd
Current assignee: W S NORMAN ENGINEERING Ltd
Priority date: 2005-06-03
Filing date: 2005-06-03
Publication date: 2006-12-06
Also published as: GB0511283D0; WO2006128919A1

Abstract

An apparatus 10 for use in cutting a mortice pocket or a hinge rebate in a leading edge of a door 300 in-situ, the apparatus comprising: at least one elongate guide means 60,70; clamping means 22 for clamping the elongate guide means to a door 300 or other workpiece such that the elongate guide means 60,70 substantially parallel to a leading edge thereof; and a drill guide means 80 mounted on the elongate guide means 60,70 so as to be reciprocally moveable along the elongate guide means 60,70, preferably with a rack and pinion mechanism or worm screw mechanism; and means 20,30 for moving the drill guide means 80 in a direction having a component normal to the elongate guide means 60,70.

Description

I

MORTICE CUTTING APPARATUS

The present invention relates to apparatus for use in cutting a workpiece. In particular, the invention relates to apparatus for cutting a mortice pocket or hinge recess in a vertical edge 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, is known to be a challenging task even to a skilled worker.

The problem is particularly acute if a mortice is to be cut in-situ, such as when installing a lock in a door that has already been hung. Mistakes in chiselling or machining the mortice pocket may require the 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 material 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 arcuately 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 eipngate 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 move,able therealong; the apparatus further comprising means for translating the drill guide means in a direction having a resolved component normal 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 900 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 drill 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.

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

In a first embodiment of the invention, an apparatus 10 comprises an upper transverse slide 20 and a lower transverse slide 30, each slide 20, 30 comprising a pair of clamps 22 having rotary handles 25. Carriages 40, 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 20, 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 slide bar 70.

An upper stop 110 and a lower stop 120 comprise annular rings 116, 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 110, 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 112, 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 stopsllo,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 clamps 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 cutout 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 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 900 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.

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.

Claims

1. 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 normal to the elongate guide means.

2. An apparatus as claimed in claim 1, wherein there is further provided first and second adjustable stopping means on the elongate guide means so as to define limits of travel of the drill guide means.

3. An apparatus as claimed in any preceding claim, wherein a rack and pinion or worm screw mechanism is provided for moving the drill guide means along the elongate guide means.

4. An apparatus as claimed in any preceding claim, wherein a rack and pinion or worm screw mechanism is provided for translating the drill guide means in the direction having a resolved component normal to the elongate guide means.

5. An apparatus as claimed in any one of the preceding claims, wherein there is provided at least first and second elongate guide means.

6. An apparatus as claimed in claim 5, wherein the first elongate guide means comprises a rack of said rack and pinion mechanism or a worm screw of said worm screw mechanism.

7. An apparatus as claimed in claim 6, wherein the stopping means are mounted on the second elongate guide means.

8. An apparatus as claimed in any one of claims I to 3, wherein the means for translating the drill guide means in a lateral direction normal to the elongate guide means is provided by the clamping means.

9. An apparatus as claimed in any preceding claim, wherein the drill guide means comprises a bearing block, the bearing block having a hole therethrough, adapted snugly to receive a drill shaft such that the drill shaft is supported, directly or indirectly, by bearings of the bearing block is rotatable therein.

10. An apparatus as claimed in claim 9, wherein the bearing block is releasably secured to the drill guide means.

11. An apparatus as claimed in any one of claims 1 to 8, wherein the drill guide means includes a cylindrical aperture configured rotatably to receive a bobbin.

12. An apparatus as claimed in claim 11, further including a bobbin rotatably received in the cylindrical aperture of the drill guide means, the bobbin having a through hole adapted to receive a drill shaft.

13. An apparatus as claimed in claim 12, wherein the bobbin is made of or is coated with a low-friction material, or is provided with a collar made of a low-friction material.

14. An apparatus as claimed in claim 12 or claim 13, wherein the bobbin is made of an elastomeric material.

15. An apparatus as claimed in any preceding claim, further comprising a drill shaft received in the drill guide means, the drill shaft being provided with a drill bit.

16. An apparatus as claimed in claim 15, wherein the drill shaft is adapted for connection to a power drill.

17. An apparatus as claimed in a claim 15 or claim 16, further comprising an integral motor for rotating the drill shaft.

18. An apparatus as claimed in claim 15, wherein the drill bit is adapted to produce small swan.

19. An apparatus as claimed in any one of claims 15 to 18 wherein the shaft has a major axis along a length of the shaft about which the drill bit is rotated in normal operation, wherein a 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, a leading surface and a longitudinal edge, wherein the leading edge is shaped to provide a cutting edge, the leading surface is disposed on the side of the blade that faces a direction of rotation of the drill bit, and the longitudinal edge is distal the major axis.

20. An apparatus as claimed in claim 19, wherein the leading end of the shaft is provided with a spike, the spike lying along the major axis and protruding away from the drill bit, the longitudinal edge describing a substantially helical form, coaxial with said major axis.

21. An apparatus as claimed in claim 20, wherein the blades are provided with a plurality of teeth along said longitudinal edge.

22. An apparatus substantially as hereinbefore described with reference to the accompanying drawings.

22. An apparatus as claimed in claim 19, wherein the leading surface is generally planar, and the blades are 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 900.

23. An apparatus as claimed in claim 22, wherein the longitudinal edge is substantially parallel to the major axis and is provided with a cutting edge.

24. An apparatus as claimed in claim 19 or any claim depending therefrom, wherein the drill bit is provided with four blades.

25. An apparatus substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows

1. 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 normal to the elongate guide means; wherein the drill guide means comprises a bearing block including rotatable bearings, the bearing block having a hole therethrough adapted snugly to receive a drill shaft such that the drill shaft is supported, directly or indirectly, by the bearings of the bearing block and is rotatable therein.

2. 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 normal to the elongate guide means; wherein the drill guide means includes a cylindrical aperture configured rotatably to receive a bobbin, the bobbin having a through hole adapted to receive a drill shaft, and wherein the bobbin is made of or is coated with a low-friction material, or is provided with a collar made of a low- friction material.

3. An apparatus as claimed in claim 1 or 2, wherein there is further provided first and second adjustable stopping means on the elongate guide means so as to define limits of travel of the drill guide means.

4. An apparatus as claimed in any preceding claim, wherein a rack and pinion or worm screw mechanism is provided for moving the drill guide means along the elongate guide means.

5. An apparatus as claimed in any preceding claim, wherein a rack and pinion or worm screw mechanism is provided for translating the drill guide means in the direction having a resolved component normal to the elongate guide means.

6. An apparatus as claimed in any one of the preceding claims, wherein there is provided at least first and second elongate guide means.

7. An apparatus as claimed in claim 6, wherein the first elongate guide means comprises a rack of said rack and pinion mechanism or a worm screw of said worm screw mechanism.

8. An apparatus as claimed in claim 7, wherein the stopping means are mounted on the second elongate guide means.

9. An apparatus as claimed in any one of claims 1 to 4, wherein the means for translating the drill guide means in a lateral direction normal to the elongate guide means is provided by the clamping means.

10. An apparatus as claimed in claim 1 or any claim depending ultimately from claim 1, wherein the bearing block is releasably secured to the drill guide means.

11. An apparatus as claimed in claim 2 or any claim depending ultimately from claim 2, wherein the bobbin is made of an elastomeric material. Is-

12. An apparatus as claimed in any preceding claim, further comprising a drill shaft received in the drill guide means, the drill shaft being provided with a drill bit.

13. An apparatus as claimed in claim 12, wherein the drill shaft is adapted for connection to a power drill.

14. An apparatus as claimed in a claim 12 or claim 13, further comprising an integral motor for rotating the drill shaft.

15. An apparatus as claimed in claim 12, 13 or 14, wherein the drill bit is adapted to produce small swan.

16. An apparatus as claimed in any one of claims 12 to 15 wherein the shaft has a major axis along a length of the shaft about which the drill bit is rotated in normal operation, wherein a 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, a leading surface and a longitudinal edge, wherein the leading edge is shaped to provide a cutting edge, the leading surface is disposed on the side of the blade that faces a direction of rotation of the drill bit, and the longitudinal edge is distal the major axis.

17. An apparatus as claimed in claim 16, wherein the leading end of the shaft is provided with a spike, the spike lying along the major axis and protruding away from the drill bit, the longitudinal edge describing a substantially helical form, coaxial with said major axis.

18. An apparatus as claimed in claim 17, wherein the blades are provided with a plurality of teeth along said longitudinal edge.

19. An apparatus as claimed in claim 16, wherein the leading surface is generally planar, and the blades are 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 900.

20. An apparatus as claimed in claim 19, wherein the longitudinal edge is substantially parallel to the major axis and is provided with a cutting edge.

21. An apparatus as claimed in claim 16 or any claim depending therefrom, wherein the drill bit is provided with four blades.