An arc defining apparatus

Abstract

An arc defining apparatus for defining a predetermined arcuate path on a workpiece, comprises a radius track having radius track pivot means providing a pivot point around which the radius track is rotatable and a radius tool carrier having a radius brake. The radius track brake is operable to fix the radius tool carrier to the radius track at a predetermined position. The predetermined position corresponds to the radius of the predetermined arcuate path. The arc defining apparatus further comprises a pivot support adapter having attachment means and adapter pivot means. The attachment means is operable to attach the pivot support adapter to a support and the adapter pivot means is disposed to co-operate with the radius track pivot means to provide the pivot point.

Description

AN ARC DEFINING APPARATUSTECHNICAL FIELD

[0001] The present invention relates to an arc defining assembly and particularly to an arc defining apparatus for marking or cutting an arc or circle at a predetermined radius on or in a workpiece.BACKGROUND

[0002] Professional trades people, craft people and hobbyists often need to define and mark or cut an arc or circle in a workpiece. Arcs and circles are usually defined and / or cut using an arm of known length which is anchored to the workpiece to provide a pivot point at one end such that the arm is rotatable around the pivot point. A marker or cutting tool can then be attached to the end of the arm and as the arm is rotated around the pivot point an arc or circle can be defined and the marker can mark, or the cutting tool can cut, an accurate arc.

[0003] There are known apparatus which define, mark or cut an arc or circle on a workpiece. For example, prior art Patent Document number US5,515,611A describes a guide for attaching to a router to form arcuate cuts in a workpiece. The router guide has a circular mounting plate which replaces a lower plate of a router. The guide has an elongated arm extending from the mounting plate with a slot extending along the longitudinal centre line of the guide arm. An anchoring mechanism slidably carried in the slot includes an anchor fastener such as a wood screw or nail to anchor the anchoring mechanism to the workpiece and define a pivot point for the router and guide. The anchoring mechanism further includes a locking mechanism to releasably lock the anchoring mechanism in place along the slot to define the radius of travel of the router and guide about the pivot point.

[0004] However, known apparatus are disadvantaged in that they are cumbersome to use, are restricted for use with a single type or manufacturer of cutting tool and not universally adaptable, do not provide means for easily attaching cutting tools, and they do not have an easy-to-use measurement system.

[0005] Moreover, known apparatus are particularly disadvantaged in that they require a pivot point to be anchored directly into the workpiece, which may be by screwing or nailing the apparatus through the workpiece. This is in many cases particularly undesirable as the workpiece may have a finished surface which has to be punctured and marked, such as, for example, when the workpiece is a kitchen worktop or other workpieces having a finished surface.

[0006] It is therefore desirable in the industry for there to be an arc defining apparatus for marking and / or cutting an arc or circle which is relatively simple and lightweight in design and use, which is adaptable for different types of markers and tools, and which does not need to be screwed, nailed or in any way directly anchored to the workpiece at the pivot point.

[0007] Accordingly, it is an object of the present invention to provide an arc defining apparatus which is relatively simple and lightweight in design and use, which is adaptable for different types of markers and tools, and which does not need to be screwed, nailed or in any way directly anchored to the workpiece at the pivot point.SUMMARY OF INVENTION

[0008] According to a first aspect of the present invention, there is provided an arc defining apparatus for defining a predetermined arcuate path on a workpiece, the apparatus comprising: a radius track having radius track pivot means providing a pivot point around which the radius track is rotatable; a radius tool carrier having a radius brake; wherein theradius track brake is operable to fix the radius tool carrier to the radius track at a predetermined position, the predetermined position corresponding to the radius of a said predetermined arcuate path; the arc defining apparatus further comprising a pivot support adapter having attachment means and adapter pivot means; wherein the attachment means is operable to attach the pivot support adapter to a support and the adapter pivot means is disposed to co-operate with the radius track pivot means to provide the pivot point.

[0009] The pivot support adapter advantageously comprises an adapter member and an attachment member, fixed relative to each other in a substantially perpendicular relationship, and wherein the attachment member advantageously comprises the attachment means operable to attach the pivot support adapter to a said support and the adapter member comprises the adapter pivot means.

[0010] The attachment means are advantageously operable to detachably attach the pivot support adapter to the said support.

[0011] The adapter member is advantageously extendible in length.

[0012] The adapter member advantageously comprises a fixed member and an extension member, wherein the fixed member is advantageously fixed relative to the attachment member and the extension member is advantageously displaceable to adjust the length of the adapter member.

[0013] The adapter pivot means is advantageously disposed on the extension member.

[0014] The extension member is advantageously fixable at a predetermined position relative to the fixed member.

[0015] The radius track pivot means advantageously comprises a pivot aperture and the adapter pivot means advantageously comprises a pivot pin suitably disposed anddimensioned to extend through the pivot aperture to provide the pivot point around which the radius track is rotatable.

[0016] The radius track advantageously comprises one or more track members and the radius tool carrier advantageously comprises corresponding one, or more, track receivers disposed and dimensioned to receive the, or each, respective track members and allow the radius tool carrier to travel along a length of the radius track in a slidable relationship.

[0017] The, or each, track receiver is advantageously an aperture.

[0018] The radius tool carrier advantageously comprises one or more brake apertures corresponding to the one, or more, track receivers, respectively, and the respective one or more brake apertures advantageously extend in a direction substantially perpendicular to the direction of the respective track receiver, to intersect therewith.

[0019] The radius tool carrier advantageously comprises a brake actuator associated with each of the one or more radius brakes, and wherein the brake actuator is advantageously operable to cause the associated radius brake to travel through the associated brake aperture and clamp the radius tool carrier onto the associated radius track at a predetermined radius position corresponding to a predetermined radius of desired arc to be defined.

[0020] The radius tool carrier advantageously comprises a tool mount for mounting a tool onto the radius tool carrier.

[0021] The arc defining apparatus advantageously further comprises a trammel coupler having trammel coupler attachment means for attaching the trammel to the tool mount, and a pair of trammel rods, wherein the space between the pair of trammel rods is adjustable.

[0022] The tool mount is advantageously operable to mount a tool onto the radius tool carrier. The tool may be a manual tool or a power tool, such as, for example, a power cutting tool, such as, for example, a router or jigsaw.

[0023] The arc defining apparatus advantageously further comprises a marker coupler having marker coupler attachment means for attaching the marker coupler to the tool mount and a marker holder for holding a marker.

[0024] The arc defining advantageously further comprises a jigsaw adapter having tool mount attachment means for attaching the jigsaw adapter to the tool mount and jigsaw attachment means configured to attach the jigsaw adapter to a jigsaw power tool.

[0025] According to a second aspect of the present invention there is provided a trammel coupler for use with an arc defining apparatus according to the first aspect of the present invention. The trammel coupler advantageously comprises trammel coupler attachment means for attaching the trammel coupler to a tool mount, a pair of trammel rods, and trammel rod adjustment means operable to adjust the space between the pair of trammel rods.

[0026] The trammel rod adjustment means advantageously comprises an adjusting rod comprising a first threaded portion and a second threaded portion, and wherein the first and second threaded portions advantageously have an opposing thread direction relative to each other. Additionally, or alternatively, the trammel rod adjustment means may comprise an opposing rack and pinion arrangement operable to adjust space between the pair of trammel rods. The rack and pinion arrangement may comprise two racks and a pinion cog disposed between the two racks.

[0027] The first and second threaded positions are advantageously separated by a non-threaded portion.

[0028] The trammel rod adjustment means advantageously comprises a first trammel rod traveller ring and a second trammel rod traveller ring, wherein each of the first and second traveller rings comprises an internal thread for cooperating with the first and second threaded positions, respectively, and rotation of the adjusting rod causes the first and second traveller rings to travel along the first and second threaded positions, respectively, to adjust the space between the pair of trammel rods.

[0029] According to a third aspect of the present invention there is provided a pivot support adapter for use with an arc defining apparatus according to the first aspect of the present invention. The pivot support adaptor comprises attachment means and adapter pivot means, wherein the attachment means is operable to attach the pivot support adapter to a support and the adapter pivot means is operable to provide a floating pivot support.

[0030] The pivot support adapter advantageously comprises an adapter member and an attachment member, fixed relative to each other in a substantially perpendicular relationship, and wherein the attachment member comprises the attachment means operable to attach the pivot support adapter to a said support and the adapter member comprises the adapter pivot means.

[0031] The attachment means is advantageously operable to detachably attach the pivot support adapter to the said support.

[0032] The adapter member is advantageously extendible in length.

[0033] The adapter member advantageously comprises a fixed member and an extension member, and wherein the fixed member is advantageously fixed relative tothe attachment member and the extension member is displaceable to adjust the length of the adapter member.

[0034] The adapter pivot means is advantageously disposed on the extension member.BRIEF DESCRIPTION OF DRAWINGS

[0035] Various embodiments of the invention will be described with reference to the following drawings, in which:

[0036] Figure 1 is a drawing showing an arc defining apparatus according to a first embodiment of the present invention;

[0037] Figures 2 to 4 are drawings showing different aspects of the radius track of the arc defining apparatus of the present invention;

[0038] Figures 5 to 7 are drawings showing different view of a radius brake of the arc defining apparatus of the present invention;

[0039] Figures 8 to 12 are drawings showing different views of a pivot support adapter of the arc defining apparatus of Figure 1 ;

[0040] Figure 13 is a drawing showing an arc defining apparatus according to a second embodiment of the present invention;

[0041] Figures 14 to 17 are drawings showing different views of a pivot support adapter of the arc defining apparatus of Figure 13;

[0042] Figures 18 to 22 are drawings showing different views of a trammel coupler according to the present invention;

[0043] Figure 23 shows different views of a jig saw adapter according to the present invention.

[0044] The present invention will be described more fully hereinafter with reference to the accompanying drawings. The arc defining apparatus and components and parts thereof, are not necessarily to scale and the parts may just be representative of components or other described entities.

[0045] While this present disclosure is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail specific embodiments, with the understanding that the present disclosure is to be considered as an example of the principles of the present disclosure and not intended to limit the present disclosure to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings.

[0046] In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by "comprises ... a" doesnot, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0047] Reference throughout this document to "one embodiment", "certain embodiments", "an embodiment" or similar terms means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments without limitation.

[0048] The term "or" as used herein is to be interpreted as an inclusive or meaning any one or any combination. Therefore, "A, B or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.

[0049] For simplicity and clarity of illustration, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Numerous details are set forth to provide an understanding of the embodiments described herein. The embodiments may be practiced without these details. In other instances, well-known methods, procedures, and components have not been described in detail to avoid obscuring the embodiments described. The description is not to be considered as limited to the embodiments described herein.

[0050] The exemplary embodiments of the present invention, and parts thereof, are not necessarily to scale and the parts may be merely representative of components or other described entities.DESCRIPTION OF EMBODIMENTS

[0051] Referring to Figure 1 , a first embodiment of an arc defining apparatus 10, according to the present invention, comprises a radius track 12 and a radius tool carrier 14. The radius track 12 is formed from a transverse pivot end member 16, a first track member 18A and a second track member 18B, which extend longitudinally and at least substantially perpendicularly from the transverse pivot end member 16. The first and second track members 18A and 18B extend from the pivot end member 16 in a parallel spaced apart relationship to provide a slot 20 disposed therebetween, as shown in Figure 3. In an alternative embodiment, the radius track may comprise a single track member (not shown).

[0052] Referring to Figures 1 and 4, the radius track 12 further comprises radius track pivot means in the form of a pivot aperture 22, which functions to define a pivot point 23. In an alternative embodiment the radius track pivot means may be in the form of a pivot pin (not shown). Also, referring to Figure 4, at least one of the first and second track members 18A and 18B comprise a radius dimension rule, 24A and 24B, which has zero dimension extending through the centre of the pivot aperture 22.

[0053] Referring also to Figure 2, the tool carrier 14 comprises a tool mount 26 for mounting a tool 28 on the tool carrier 14. The tool mount 26 is positioned on the tool carrier 14 such that a mounted tool 28 can be easily set to cut a desired arc or circleat a predetermined radius, measurable from the pivot point 23, using the radius dimension rules, 24A and 24B.

[0054] The tool carrier 14 comprises a pair of radius brakes, 30A and 30B, operable to fix the radius tool carrier 14 to the radius track 12 at a predetermined position corresponding to the radius of a predetermined arcuate path, measured using the radius dimension rules, 24A and 24B.

[0055] Referring also to Figures 5, 6 and 7, the tool carrier 14 comprises a base 32 which is of a cuboid-type external shape. The tool carrier 14 has a first track receiver 34A and a second track receiver 34B. The first and second track receivers, 34A and 34B, are formed as a first slotted aperture, 36A and a second slotted aperture 36B, respectively, which extend through the base 32 of the tool carrier 14. The first and second slotted apertures, 36A and 36B, are suitably disposed and dimensioned to receive the first and second track members, 18A and 18B, respectively, in a slidable relationship, wherein first and second track members, 18A and 18B extend through the first and second slotted apertures, 36A and 36B, and wherein the tool carrier 14 is slidable along the length of the radius track 12 (Figures 1 and 2).

[0056] The top surface of the base 32, comprises a first brake aperture 38A and a second brake aperture 38B. The first and second brake apertures, 38A and 38B extend downwards in a direction substantially perpendicular to the first and second slotted apertures, 36A and 36B, and intersect to open into the first and second brake apertures, 38 and 38B.

[0057] The radius brakes, 30A and 30B, comprise a first radius brake pad 40A and a second radius brake pad 40B. The first and second radius brake pads, 40A and 40B,are dimensioned to be able to pass through the first and second brake apertures, 38A and 38B, respectively.

[0058] The first radius brake 30A has a first lever pivot pin support 42A. The first lever pivot pin support 42A has a pair of substantially upright members 44A and 46A. The upright members 44A and 46A extend upwardly from the top surface of the base 32. A first lever pivot pin support member 48A extends between the pair of upright members 44A and 46A such that the first lever pivot pin support member 48A is raised to overlie the top surface of the base 32 and extends in the direction and to overlie the first slotted aperture 36A.

[0059] The first lever pivot pin support member 48A supports a first brake pivot pin 50A which is fixed relative to the first lever pivot pin support member 48A and extends substantially perpendicular to the first lever pivot pin support member 48A.

[0060] The first radius brake 30A has an elongate lever 52A having a handle portion 54A on one end and an actuating end portion 56A on the opposing end. The handle portion 54A is ergonomically shaped to be easy and comfortable for a user to engage with the lever 52A and to reduce the force required to actuate the first radius brake 30A The actuating end portion 56A has a cam surface 58A, a locking ratchet 60A and a pivot pin aperture (not shown). In an alternative embodiment the radius brakes 30A and 30B may be a clamp, such as, for example, lever clamps or screw clamps.

[0061] The locking ratchet 60A comprises a locking catch 62A and a latch 64A. The locking catch 62A comprises a plurality of catches 66A and is fixed relative to the actuating end portion 56A. The latch 64A has a latch pivot pin 68A which enables the latch 64A to pivot relative to the catch 62A. On one end of the latch 64A is a releaseactuating portion 70A and on the opposing end is a catch engaging portion 72A. The latch 64A has a biasing spring (not shown) which biases the latch 64A about the latch pivot pin 68A such that, in normal use, the catch engaging portion 72A is biased onto catch 64A to engage the plurality of catches 66A and to engage adjacent catches of the plurality of plurality of catches 66A as the lever 52A is actuated.

[0062] The first radius brake pad 40A has a first pair of spaced-apart side lobes, 74A and 76A, extending upwards from the top surface of the brake pad 40A. Each of the side lobes, 74A and 76A, has a pivot aperture 78A. Although each of the side lobes, 74A and 76A, has a pivot aperture, only one can be seen in the drawings, in Figure 5. The pivot apertures 78A is of an oblong shape having two opposing longer sides and opposing semi-circular ends.

[0063] The lever 52A is disposed between the pair of spaced-apart side lobes, 74A and 76A. The first brake pivot pin 50A is fixed relative to the actuating end portion 56A of the lever 52A and the pivot pin 50A extends through each of the pivot apertures, 78A and (not shown), in the first and second side lobes, 74A and 76A.

[0064] Similarly, the second radius brake 30B is the same as the first radius brake 30A and operable in the same manner to engage the second brake pad 40B onto the second track member 18B and lock the tool carrier 14 to the radius track 12 at a predetermined desired radius.

[0065] In use, to define an arc on a workpiece, the radius track 12 is positioned on the workpiece on which an arc is to be marked or cut. The radius track 12 is anchored to the workpiece by temporarily attaching the radius track 12 to the workpiece throughthe pivot aperture 22 disposed in the transverse pivot end member 16, using, for example, a nail or screw.

[0066] The first and second radius brakes, 30A and 30B, are disengaged such that the tool carrier 14 can slide along the lengths of the first and second track members, 18A and 18B. The desired predetermined radius of the arc to be defined is set by sliding the tool carrier 14 to match the radius dimension of the radius marker or radius cutting tool 28, mounted on the tool carrier 14, with the dimension on the radius dimension rules, 24A and 24B.

[0067] With the tool carrier 14 set at the desired predetermined radius measurement on the radius track 12, the first and second radius brakes, 30A and 30B, are actuated such that the first and second brake pads, 40A and 40B, are clamped onto the first and second track members, 18A and 18B, to lock the tool carrier 14 in position corresponding to the desired predetermined radius.

[0068] With the marker or cutting tool 28 mounted on the tool mount 26, the radius track 12, tool carrier 14 and marker / cutting tool 28, are rotated around the pivot point 23 to define the arc at the desired predetermined radius. Defining the arc includes, for example, marking an arc on the surface of a workpiece or cutting an arc in the workpiece.

[0069] It can be undesirable to directly anchor the radius track 12 to the workpiece as it can cause damage to the workpiece especially if the workpiece has a finished surface.

[0070] Referring to Figure 1 and 8 to 12, the arc defining apparatus 10, according to the present, further comprises a pivot support adapter 80.

[0071] The pivot support adapter 80 has attachment means 82 and adapter pivot means 84. The attachment means 82 is operable to attach the pivot support adapter 80 to a support 86, which may be, for example, part of a work bench. The adapter pivot means 84 is operable to co-operate with the pivot aperture 22 and provide a pivot point 23.

[0072] The pivot support adapter 80 comprises an attachment member 88 and an adapter member 90. The attachment member 88 and the adapter member 90 are fixed relative to each other in a substantially perpendicular relationship.

[0073] The attachment member 88 is shaped and dimensioned to slide within an open squared C-shaped track 92, which is attached to, for example, a work bench. The C- shaped track 92 has an elongate top opening 94 extending along its longitudinal length.

[0074] The attachment member 88 has opposing fixing end potions, 96 and 98, and a central portion 100. The opposing fixing end portions, 96 and 98, each have threaded fixing bolts, 102 and 104, which are screwable through corresponding threaded apertures extending through the attachment member 88. The threaded fixing bolts, 102 and 104, screw down onto the base of the C-shaped track 92 to cause the attachment member 88 to abut and apply a force against the upper portions of the C- shaped track 92 and thereby clamping the attachment member 88 to the C-shaped track 88. That is to say, the threaded fixing bolts, 102 and 104, function as screws to screw down into the C-shaped track 92 to provide upward pressure by exploiting the technical effect of the C-shape of the C-shaped track 88 and clamping the pivot support adapter 80 in a desired position.

[0075] The adapter member 90 extends upwardly from the central portion 100, of the attachment member 88, to form a raised support portion 106. The raised support portion 106 extends into a lower cantilevered pivot support portion 108 which is formed to overlie the top surface plane of the workpiece in use. The raised support portion 106 provides additional support for the load on the lower cantilevered pivot support portion 108. The raised portion 106 also provides an ergonomic handle which facilitates use of the pivot support adapter 80 and apparatus 10.

[0076] The pivot support portion 108 has distal end portion 110 which has pivot means in the form of an upwardly extending pivot pin 112 for cooperating with the pivot aperture 22 on the radius track 12. The pivot support portion 108 has guidelines 114, which may be marked as crossed lines onto or into the top surface of the pivot support portion 108. The guidelines 114 intersect each other through the base of the pivot pin 112. The guidelines 114 are used to provide a visual indication of the pivot point, and thereby to facilitate positioning of the adaptor member 90 to dispose the pivot pin 112 in a position to correspond to the pivot point. That is to say, the guidelines 114, which may be an x-y cross marked groove, function to enable a user to position the pivot pin 112 accurately over a desired centre point, or centroid, for defining an arcuate path on a workpiece, at a desired or predetermined radius.

[0077] In use, the pivot support adapter 80 is attached to a support, such as, for example, a supporting work bench (not shown), which has, for example, an open squared C-shaped track 92 which is fixed to the supporting work bench. To attach the pivot support adapter 80, the attachment member 88, of the pivot support adapter 80, is inserted into the open squared C-shaped track 92 and slid along the open squared C-shaped track 92 to a suitable position. The attachment member 88 is then fixed inposition relative to the open squared C-shaped track 92 by screwing the threaded bolts, 102 and 104, through the top opening 94 onto the base of the squared C-shaped track 92 and thereby clamping the attachment member 88 onto the squared C-shaped track 92 in a fixed relationship thereto.

[0078] With the pivot support adapter 80 attached and fixed relative to the supporting work bench, the pivot aperture 22, of the radius track 12, is passed over the pivot pin 112, such that the pivot pin 112 extends through the pivot aperture 22. With the pivot pin 112 extending through the pivot aperture 22, the radius track 12 is supported by the pivot support portion 108 and the pivot point 23 is provided without the need to directly attach the radius track 12 to the workpiece. The pivot support adapter 80 therefore provides a contactless pivot point 23.

[0079] With the pivot support adapter 80 attached and fixed relative to the supporting work bench, and the radius track 12 supported by the pivot support adapter 80, the radius track 12, tool carrier 14 and marker / cutting tool 28, can be rotated around the contactless pivot point 23 to define the arc at the desired predetermined radius, without having to attach or fix, or in any way contact the workpiece to provide the pivot point 23.

[0080] Referring to Figures 13 to 17, an alternative second embodiment of an arc defining apparatus 200 comprises a radius track 12, as described in relation to the first embodiment and which functions in the same manner.

[0081] The arc defining apparatus 200 further comprises an alternative embodiment of a pivot support adapter 202. The pivot support adapter 202 has an attachment member 204 and an adapter member 206. The attachment member 204 and theadapter member 206 are fixed relative to each other in a substantially perpendicular relationship.

[0082] The attachment member 204 is detachably attachable to a support member (not shown) using a pair of clamps, 208 and 210. The clamps, 208 and 210, may be, for example, lever clamps or screw clamps. The support member (not shown) may be, for example, part of a support workbench or may be a sash clamp or even a length of timber which is clamped or attached to a workbench in another way. However, the support member must be able to provide support as an anchor to a stable workbench.

[0083] The adapter member 206 extends from an upper portion of the attachment member 204. The adapter member 206 comprises a fixed member 212 and an extension member 214. The fixed member 212 is fixed to and relative to the attachment member 204. The extension member 214 is slidable along and relative to the top surface of the fixed member 212, such that the extension member 214 cantilevers off the fixed member 212 and is slidable to extend the length of the adapter member 206.

[0084] The extension member 214 functions as a pivot support 216 of the adapter member 206, having a distal end portion 218 which has pivot means in the form of an upwardly extending pivot pin 220 for cooperating with the pivot aperture 22 on the radius track 12. The distal end portion 218 has guidelines 222, which may be marked as crossed lines onto or into the top surface of the distal end portion 218. The guidelines 222 intersect each other through the base of the pivot pin 220. The guidelines 222 are used to provide a visual indication of the pivot point, and thereby to facilitate positioning of the adaptor member 206 to dispose the pivot pin 220 in a position to correspond to the pivot point 23.

[0085] The adapter member 206 has an adapter member clamp 224 operable to clamp the extension member 214 and the fixed member 212 relative to each other, at a predetermined desirable length of adapter member 202. The predetermined desirable length of adapter member 202 is relative to the distance between the support member (not shown), to which the attachment member 204 is attached, and the predetermined desired position of the pivot point 23.

[0086] In use, the pivot support adapter 202 is attached to a support, such as, for example, a sash clamp clamped to a supporting work bench (not shown), using the clamps, 208 and 210.

[0087] With the pivot support adapter 202 attached and fixed relative to the supporting work bench, the extension member 214 can be adjusted relative to the fixed member 212 to the predetermined desired length of adapter member 206 and fixed at that length by clamping the extension member 214 and the fixed member 212 to each other using the adapter member clamp 224.

[0088] The pivot aperture 22, of the radius track 12, is passed over the pivot pin 220, such that the pivot pin 220 extends through the pivot aperture 22. With the pivot pin 220 extending through the pivot aperture 22, the radius track 12 is supported by the pivot support 216 and the pivot point 23 is provided without the need to directly attach the radius track 12 to the workpiece. The pivot support adapter 206 therefore provides an adjustable contactless pivot point 23.

[0089] With the pivot support adapter 206 attached and fixed relative to the supporting work bench, and the radius track 12 supported by the pivot support 216, the radiustrack 12, tool carrier 14 and marker / cutting tool 28, can be rotated around the contactless pivot point 23 to define the arc at the desired predetermined radius, without having to attach or fix, or in any way contact the workpiece to provide the pivot point 23.

[0090] Referring also to Figures 18 to 22, an arc defining apparatus 10 / 200, according to the first or second embodiment of the present invention, further comprises a trammel coupler 300. The trammel coupler 300 is operable to couple a tool 28 (Figure 2 and 22) to the tool mount 26, disposed on the tool carrier 14.

[0091] The trammel coupler 300 has a housing 302 of cuboid-type shape having a tool side 304, a mount side 306, opposing the tool side, a first short side 308 and a second short side 310, opposing the first short side.

[0092] The tool side 304 has a first trammel rod aperture 312 and a second trammel rod aperture 314. The mount side 306 has a threaded mounting shaft 316 for attaching the trammel coupler 300 to the tool mount 26, using, for example, a wing nut.

[0093] The trammel coupler 300 has an adjusting rod 318 having an adjusting rod end 320 and an adjusting rod head 322, wherein the adjusting rod head 322 is on the opposing end of the adjusting rod 318 relative to the adjusting rod end 320. The adjusting rod end 320 abuts the inside of the second short side 310 and the adjusting rod 318 extends through the inside and along the longitudinal length of the housing 302 and extends through the first short side 308 where the adjusting rod 318 terminates in a head 322.

[0094] The adjusting rod 318 has a first threaded portion 324 and a second threaded portion 326. The first and second threaded portions, 324 and 326, are separated by acentral washer 328 of the adjusting rod 318. The first threaded portion 324 has an opposing thread direction relative to the second threaded portion 326.

[0095] The trammel coupler 300 has a first adjusting rod support 330, a second adjusting rod support 332, and an end adjusting rod support 334. The first and second adjusting rod supports, 330 and 332, are disposed inside the housing against a central washer 328 and the end adjusting rod support 334 is disposed inside the housing 302, adjacent the rod end 320. The central washer 328 is fixed to the adjusting rod 318 by, for example a weld. The first and second adjusting rod supports, 330 and 332, act to retain the central washer 328 in the central position as the adjusting rod 318 is rotated, thereby preventing lateral, i.e. sideways, displacement of the first and second threaded portions, 324 and 326.

[0096] The trammel coupler 300 has a first trammel rod traveller ring 336 and a second trammel rod traveller ring 338. The first and second trammel rod traveller rings, 336 and 338, are disposed on the first and second threaded portions, 324 and 326, respectively. Each of the first and second trammel rod traveller rings, 336 and 338, has an internal thread which engages and cooperates with the first and second threaded portions, 324 and 326, respectively, such that upon rotation of the adjusting rod 318, the first and second trammel rod traveller rings, 336 and 338, travel along the first and second threaded portions, 324 and 326, respectively. Because the first and second threaded portions, 324 and 326, opposing thread directions, rotation of the adjusting rod 318 in a first direction causes the first and second trammel rod traveller rings, 336 and 338, to travel towards the central washer 328 and rotation of the adjusting rod 318 in a second opposing direction causes the first and second trammel rod traveller rings, 336 and 338, to travel away from the central washer 328.

[0097] The trammel coupler 300 has a first trammel rod 340 and a second trammel rod 342. The first and second trammel rods, 340 and 342, extend from the first and second trammel rod traveller rings, 336 and 338, respectively, outwardly from the housing through the first and second trammel rod apertures 312 and 314, respectively.

[0098] In use, the spacing between the first and second trammel rods, 340 and 342, is adjusted by rotating the adjusting rod 318 causing the first and second trammel rod traveller rings, 336 and 338, to travel along the first and second threaded portions, 324 and 326, either towards or away from the central washer 328, depending on the direction of rotation. As the first and second trammel rod traveller rings, 336 and 338, travel along the first and second threaded portions, 324 and 326, the spacing between the first and second trammel rods, 340 and 342, is adjusted to match trammel rod receivers 344 and 346 of the tool 28. The opposing direction of the first and second threaded portions, 324 and 326, cause the first and second trammel rod traveller rings, 336 and 338, to travel along the adjusting rod 318 in opposite directions, thereby opening or closing, or increasing and decreasing, the space between the first and second trammel rods, 340 and 342 to enable different tools and / or the tools of different manufacturers having different trammel rods spacings to be attached to the trammel rod coupler 300. Because the central washer 328 is maintained in its central position and prevented from lateral displacement, the first and second trammel rods, 340 and 342, are always maintained at an equal distance from the centre relative to each other. Because the first and second trammel rods, 340 and 342, are always maintained at an equal distance from the centre, any tool attached to the first and second trammel rods, 340 and 342, is also centrally attached to the trammel coupler 300.

[0099] Referring to Figure 22, a power tool, such as a power drill 348, can be used to engage the adjusting rod head 322 to rotate the adjusting rod 318.

[0100] Referring also to Figure 23, an arc defining apparatus 10 / 200, according to the first or second embodiment of the present invention, further comprises a jig saw adapter 400. The jig saw adapter 400 is an elongate L shaped member 402 having a tool mount attachment portion 404 having attachment apertures 406 suitably disposed for attachment to the tool mount 26 on the tool carrier 14.

[0101] The jig saw adapter 400 further comprises a jigsaw engaging end portion 408, disposed on the opposing end of the elongate L shaped member 402, relative to the tool mount attachment portion 404. The jigsaw engaging end portion 408 inserts into an adapter receiver 410 disposed on a jig saw 412.

[0102] An arc defining apparatus 10 / 200, according to the first or second embodiment of the present invention, also comprises a marker adapter (not shown). The marker adapter may be, for example, an adapter for holding a pencil which is attachable to the tool mount 26, such that an arc can be drawn or marked on a workpiece at a predetermined desired radius as previously described.

[0103] Having described exemplary embodiments of the present invention, it should be noted by those skilled in the art that the within disclosures are exemplary only and that various other alternatives, adaptations and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited by the above-described embodiments but is only limited by the claims.* * *

Claims

CLAIMS1 . An arc defining apparatus for defining a predetermined arcuate path on a workpiece, the apparatus comprising: a radius track having radius track pivot means providing a pivot point around which the radius track is rotatable; a radius tool carrier having a radius brake; wherein the radius track brake is operable to fix the radius tool carrier to the radius track at a predetermined position, the predetermined position corresponding to the radius of a said predetermined arcuate path; the arc defining apparatus further comprising a pivot support adapter having attachment means and adapter pivot means; wherein the attachment means is operable to attach the pivot support adapter to a support and the adapter pivot means is disposed to co-operate with the radius track pivot means to provide the pivot point.

2. An arc defining apparatus as claimed in claim 1 , wherein the pivot support adapter comprises an adapter member and an attachment member, fixed relative to each other in a substantially perpendicular relationship, and wherein the attachment member comprises the attachment means operable to attach the pivot support adapter to a said support and the adapter member comprises the adapter pivot means.

3. An arc defining apparatus as claimed in claim 1 or 2, wherein the attachment means are operable to detachably attach the pivot support adapter to the said support.

4. An arc defining apparatus as claimed in claims 1 to 3, wherein the adapter member is extendible in length.

5. An arc defining apparatus as claimed in claim 4, wherein the adapter member comprises a fixed member and an extension member, wherein the fixed member is fixed relative to the attachment member and the extension member is displaceable to adjust the length of the adapter member.

6. An arc defining apparatus as claimed in claim 5, wherein the adapter pivot means is disposed on the extension member.

7. An arc defining apparatus as claimed in claims 5 or 6, wherein the extension member is fixable at a predetermined position relative to the fixed member.

8. An arc defining apparatus as claimed in claims 2 to 7, wherein the radius track pivot means comprises a pivot aperture and the adapter pivot means comprises a pivot pin suitably disposed and dimensioned to extend through the pivot aperture to provide the pivot point around which the radius track is rotatable.

9. An arc defining apparatus as claimed in any of the preceding claims, wherein the radius track comprises one or more track members and the radius tool carrier comprises corresponding one or more track receivers disposed and dimensioned to receive the, or each, respective track members and allow the radius tool carrier to travel along a length of the radius track in a slidable relationship.

10. An arc defining apparatus as claimed in claim 9, wherein the, or each, track receiver is an aperture.11 .An arc defining apparatus as claimed in claim 9 or 10, wherein the radius tool carrier comprises one or more brake apertures corresponding to the one or more track receivers, respectively, and the respective one or more brake apertures extend in a direction substantially perpendicular to the direction of the respective track receiver, to intersect therewith.

12. An arc defining apparatus as claimed in claim 11 , wherein the radius tool carrier comprises a brake actuator associated with each of the one or more radius brakes, and wherein the brake actuator is operable to cause the associated radius brake to travel through the associated brake aperture and clamp the radius tool carrier onto the associated radius track at a predetermined radius position corresponding to a predetermined radius of desired arc to be defined.

13. An arc defining apparatus as claimed in any preceding claims, wherein the radius tool carrier comprises a tool mount for mounting a tool onto the radius tool carrier.

14. An arc defining apparatus as claimed in claim 13, comprising a trammel coupler having trammel coupler attachment means for attaching the trammel coupler to the tool mount, and a pair of trammel rods, wherein the space between the pair of trammel rods is adjustable.

15. An arc defining apparatus as claimed in claim 13, wherein the tool mount is operable to mount a tool onto the radius tool carrier.

16. An arc defining apparatus as claimed in claim 13, comprising a marker coupler having marker coupler attachment means for attaching the marker coupler to the tool mount and a marker holder for holding a marker.

17. An arc defining apparatus as claimed in claim 13, further comprising a jigsaw adapter having tool mount attachment means for attaching the jigsaw adapter to the tool mount and jigsaw attachment means configured to attach the jigsaw adapter to a jigsaw power tool.

18. A trammel coupler comprising trammel coupler attachment means for attaching the trammel coupler to a tool mount, a pair of trammel rods, and trammel rod adjustment means operable to adjust the space between the pair of trammel rods.

19. A trammel coupler as claimed in claim 18, wherein the trammel rod adjustment means comprises an adjusting rod comprising a first threaded portion and a second threaded portion, and wherein the first and second threaded portions have an opposing thread direction relative to each other.

20. A trammel coupler as claimed in claim 19, wherein the first and second threaded positions are separated by a non-threaded portion.21 .A trammel coupler as claimed in claim 18 or 19, wherein the trammel rod adjustment means comprises a first trammel rod traveller ring and a second trammel rod traveller ring, wherein each of the first and second traveller rings comprises an internal thread for cooperating with the first and second threaded positions, respectively, and rotation of the adjusting rod causes thefirst and second traveller rings to travel along the first and second threaded positions, respectively, to adjust the space between the pair of trammel rods.

22. A pivot support adapter for use with an arc defining apparatus as claimed in claims 1 to 17, the pivot support adaptor.

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