A PIVOT ASSEMBLY

Abstract: A pivot assembly for a guide or marking tool (10) comprising a first member (12) with a reference edge (31) alignable with a desired datum (36), a second member (13) with a sighting, guiding or marking edge (16) and a semi-circular quadrant (18) provided with angle indicia (19). The first member (12) is pivotally connected to the second member (13) so that the angle between the reference edge (31) and the sighting edge (16) may be adjusted to a predetermined setting and the pivot axis (9) of the first member (12) related to the second member (13) is located at the intersection between the reference edge (31) and the sighting edge (16) at all relative angular settings between the first and second members (12, 13). Pivoting of the two members is provided by arcuate guide tracks on the first member (12) mating with corresponding depending flanges on the undersurface of the quadrant (18). A slot (22) concentric with the guide tracks is provided in the quadrant (18). Tightening of the tumb wheel (24) clamps the quadrant (18) firmly against the upper surface (28) of the first member (12). The pivot assembly may be used in surveying, angle sighting and drafting instruments.

Description: A PIVOT ASSEMBLY This invention relates to a pivot assembly particularly though not solely suited or use in tools such as guide tools or marking tools for woodworking or metalworking and to tools incorporating such pivot assemblies. " Many instruments or tools have been proposed in the past to enable guide lines or marking lines to be marked on a workpiece at a predetermined angle to another line or edge. It is a general disadvantage of such tools that the point of intersection between the reference line or edge and the guiding or marking edge changes when the tool is adjusted for different angles. This necessitates in use a repositioning of the tool on the workpiece. It is a further disadvantage of such tools tha it is difficult to in¬ corporate a length marking scale on the guiding or marking edge as the zero or reference point of the scale shifts relative to the reference line or edge as the angle of the tool is adjusted. Accordingly in use, the angle is marked and then a tape measure is used to measure along the marked line. This can lead to inaccurate marking. Similar dis- advantages are also found in other devices that are used for marking or measuring various angles such as in various types of drafting or surveying equipment. Furthermore many cutting tools such as bench mounted abrasive saws and circular saws provide a pivotable guide or location means for angularly positioning the workpiece to be cut relative to the cutting blade. Generally the pivot connection for the guide is constituted by a pivot pin and as a result the guide can be deflected from its set reference position when the cutting blade is cutting at a position spaced from the pivot pin, placing a load on the pivot connection which increases as the leverage increases and causing inaccuracies in use. It is an object of this invention to provide a pivot assembly for guide and/or locating means and tools utilizing same which will alleviate the abovementio ed disadvantages and which will be reliable and efficient in use. Other objects a d advantages of this invention will hereinafter become apparent OMPI With the foregoing and other objects in view this invention in one aspect resides broadly in a pivot assembly for adjustably connecting a pair of members together for relative pivotal movement, said pivot assembly including an arcuate guide face on one said member; locating means on the other said member adapted to abut said guide face so as to locate said other member relative to said one member and retaining means for securing tήe members together. If desired there may be provided a plurality of guide faces on said one member and in the preferred form the guide face or faces are sectorial and are arranged concentrically with, one another. The guide face or faces may be formed by providing sectorial slot or slcfcs or grooves in said one member. The locating means may be in the form of a com— plementary abutment face on said other member adapted to abut said guide face or it may be constituted by a pair of spaced pins or the like fixed to said other member and adapted to abut said guide face at spaced locations there- along. The pins may be fixed or rotatable if desired. Pre erably the retaining means is in the form of a threaded stem fixed to one said member and passing through a slot in the other said member, said slot being disposed concentrically with said guide face and there being provided a nut on said threaded stem rotatable to secure the members together. Alternatively the retaining means may include or be constituted by a captive arcuate slot or groove in one said member concentric with or constituting said guide face and complementary locating means in the other said member adapted to engage and be held captive in said slot. The captive slot may be in the form of a T-slot or a re-entrant recess of any desired configuration. It is also preferred that the guide face is formed as a sector of a cylinder or truncated cone disposed such that its axis is coincident with a straight guide or marking edge of one said member and that abutment means having an abutment plane coincident with said axis is provided on the other said member. In a further aspect this invention resides broadly in a guide or marking tool having a first member incorporating a reference edge or plane alignable with a desired datum, a second member incorporating a sighting, guidirtg or marking edge, said second member being pivotally attached to said first member so that the angle between said reference edge or plane and said sighting, guiding or marking edge may be adjusted to a predetermined setting and wherein the pivot axis of said first member relative to said second member is located at the intersection between said reference edge or plane and said sighting, guiding or marking edge at all relative angular settings between said first and second parts. Preferably the first and second members are pivotally attached to one another by a pivot assembly as defined above. Preferably said first part is provided with a reference line or plane adapted to be aligned, for example, with the edge of a workpiece. The reference plane may be in the form of a protrusion or protrusions from the body of the first member. Preferably the protrusions comprise a con¬ tinuous flange. Preferably said second member is pivotally attached to said first member by a quadrant incorporating grooves or tracks arrayed in an arc or arcs about said pivot axis. Preferably said quadrant comprises a semi-circular quadrant protruding from one side of said second member and having said pivot axis located on the edge of the opposite side of said second member. Notwithstanding any other forms that may fall within its scope one preferred form of the invention will now be described by way of example only with reference to the accompanying drawings, wherein:- Pig 1 is a perspective view of an adjustable circular saw guide/angle marking tool and illustrating a typical application; Fig 2 is an underside perspective view of the tool illustrated in Fig 1; OMPI Fig 3 is a cross-sectional view taken along the line 3 - 3 of Fig 2; Fig is a view similar to Fig 3 but illustrating an alternate form of pivotal connection, and Fig 5 is a plan view of a further embodiment of a tool made in accordance with the invention. In the preferred form of the invention a tool par¬ ticularly suitable for marking out a metal or timber work¬ piece or for guiding a power tool along that workpiece is constructed as described below although it will be appre¬ ciated that the basic invention has many other different forms and applications. The tool 10 according to the invention when adapted for use as a tool or marking guide on a workpiece 11 comprises a first member 12 and a second member 13 both of which are elongate members and formed for example from aluminium extrusions or castings. The first member 12 incorporates a reference abutment face 1 formed by one face of a downwardly depending continuous flange 15 extend- ing along the underside of the first member 12. The second member 13 incorporates a straight edge 16 which forms a sighting, guiding or marking edge which may be used to guide a marking pencil or a tool such as the base plate of a power saw. When used in the latter application the shape of the edge portion 16 " is such that its overall height is sufficiently low to clear any overhanging portions of a power saw. The surface 17 adjacent the guiding edge 2.6 is bevelled to clear any protrusions and to assist in sight¬ ing the edge 16. A semi-circular quadrant 18 is screwed to the second member 13 so as to protrude therefrom on the opposite side from the sighting, guiding or marking edge 16 and indicia 19 marked in degrees is provided around the outer periphery thereof. The undersurface of the quadrant 18 is provided with two guide grooves or tracks 20 arranged concentrically with the quadrant 18 and with their axis 9 coincident with the sighting, guiding or marking edge 16. OMPI The point of coincidence is designated 21 and it will be seen that this point 21 is in alignment with the abutment face 14. Complementary arcuate flanges 20A on the first memb ' er 12 engage neatly within these slots 20 whereby the members 12 and 13 are guided for relative pivotal motion with respect to one another about the common axis 9 of the tracks 20 and the flanges 20A. The quadrant 18 is also provided with an arcuate locking slot 22 extending through the quadrant and concen- trie with the guide tracks 20. A stud 23 is fixed to the first member 12 to extend through this slot 22 and a knurled thumb wheel 24 threadedly engageable on the stud 23 is provided to lock the members 12 and 13 in any desired pivotal relationship. Tightening of the thumb wheel 24 clamps the quadrant 18 firmly against. the upper surface 28 of the first member 12. In the preferred form of the invention the thumb wheel 24 is of low profile as shown (i.e. of the same height as the upper surface of the second member 13) so that any over- hanging portion of a tool which is guided by the edge 16 will clear the thumb wheel 24. The quadrant 18 is also provided with a part frusto-conical downwardly depending flange 25 which extends inwardly at a re-entrant angle as illustrated in Fig 3» The arcuate end portion 26 of the first member 12 is shaped complementary to engage with the flange 25 whereby the first member 12 is held captive in the quadrant 18 so as to reduce the separation loads applied to the stud 23. In this manner the first member 12 is engaged with and may pivot relative to the second member 13 by sliding of the flanges 20A in the groove or tracks 20 and by the engagement of the end 26 with the similarly shaped and bevelled part circular flange 25 so that the first member 12 can pivot relative to the second member 13 about the pivot axis 9 which lies on the sighting, guiding or marking edge 5. The edge 16 ±3 provided with length measuring indicia 30 having their zero or reference point at the pivot axis 9. The inner edge 31 of the first member 12 is also provided with length measuring indicia 32 having a zero or reference point at the edge 16 when the latter is atright angles to the .inner edge 31« In. this position the angular indicia 19 on the quadrant 18 indicates 90". In use of the tool 10 for example for marking or guiding relative to the edge 35 of a workpiece 11 the tool 10 is placed face down on the workpiece 11 so that the lower faces of the first and second members sit on the surface of the workpiece. The flange 14 is then drawn towards the reference face 36 " of the workpiece 11 where it is held in abutment therewith. The angle of the second member relative to the reference face 36 of the workpiece 11 may then be adjusted by loosening the thumb wheel 24, moving the second member 13 to the desired angle which may be measured by sighting a reference mark or arrow 37 against the angular indicia 19 and locking the desired angle on the tool by tightening the thumb wheel 24. The pivot axis 9 may then be moved to the desired position of the mark or cut by sliding the flange 15 along the reference face 3 of the workpiece 11 whereupon the desired marking may be made along the guiding edge 16 and a measurement back from the edge of the workpiece may also be made directly using the indicia 30. It is a particular feature of the illustrated tool that the reference point for the indicia 30 is located at the pivot axis 9 between the first and second members whereby it will remain in alignment with the reference face 36 regard¬ less of the angle set between the first and second members and whereby the indicia 30 may be used at all angles to measure the distance back from the reference edge of the workpiece. Where desired the tool may be held fixedly in place and the angle adjusted without altering the zero point of the indicia 30 relative to the edge of the workpiece. A further advantage of the pivot assembly described is that it provides large bearing areas for accurate control of pivotal movement between the members and for maintaining selected alignment therebetween even when heavy loads are applied. O P As such the pivot assembly will be useful in bench mounted equipment or the like for selectively positioning a work¬ piece for retention in the selected position during cutting or machining operations. The large bearing areas also ensure the retention of precision throughout the working life of the pivot assembly. Fig 4 illustrates an alternate form of connection which is formed as an arcuate dovetail joint 39. In this embodiment any form of clamping or indexing means could be used to control the relative pivotal movement between the first member 12B and the second member 13B. In the embodiment illustrated in Fig 5 level vials 40 are provided to allow measuring of the angular position of a given item in relation to the perpendicular or horizontal plane. For this purpose the inclination of a face is measured by holding the edge 16A on or parallel to the face and by moving the first member 12A until the appropriate vial 40 indicates level. The angle reading is then read directly from the angular indicia 19A. It will also be noted that in this embodiment the elongate edge portion of the second member 13A is connected pivotally to the quadrant 18A at 4l whereby when not in use the second member 13A may be pivoted relative to the quadrant 18A to a position subs- stantially co-extensive with the first member 12A. A releasable spring loaded catch assembly 42 is provided to secure the second member 13A fixedly to the quadrant 18A for normal use. Although the tool has been described in one particular application for use in marking or as a guiding edge for the cutting of a workpiece it will be appreciated that the principle used in the tool of placing the pivot point between two variable parts on the edge used as a sighting, guiding, marking or locating edge of one of those parts can also be employed in other types of tools or instruments such as surveying or angle sighting instruments and drafting instruments and the like. Of course all such modifications and variations as would be apparent to persons skilled in the art are deemed to fall within the broad scope IPO and ambit of the present invention as is defined in the appended claims. OMPI

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. A pivot assembly for adjustably connecting a pair of members together for relative pivotal movement, said pivot assembly including an arcuate guide face on one said member; locating means on the other said member adapted to abut said guide face so as to locate said other member relative to said one member and retaining means for securing the members together. 2. A pivot assembly according to claim 1, wherein said locating means is a complementary arcuate face on said other member. 3. A pivot assembly according to Claim 2, wherein one said member is formed with an arcuate groove or slot and the other said member is formed with an. arcuate flange adapted to be received slidably in said groove or slot, the latter and said flange forming said guide face and said complementary arcuate face. 4. A pivot assembly according to any one of the preceding claims, wherein said retaining means is constituted by a threaded stud fixed to one said member and passing through an arcuate slot in the other said member and arranged con¬ centrically with said guide face and a nut threadedly en¬ gaged on said stud and rotatable to clamp said members together. 5. A pivot assembly according to claim 4, wherein said retaining means further includes a part conical retaining face on said one member arranged concentrically with said guide face and having a radius less than said arcuate slot and adapted to retain the complementary shaped arcuate end portion of said other member. 6. A guide or marking tool having a first member incor¬ porating a reference edge or plane alignable with a desired OM datum; a second member incorporating a sighting, guiding or marking edge and said second member being pivotally attached to said first member by a pivot assembly as defined in any one of the preceding claims whereby the angle between said reference edge or plane and said sighting guiding or marking edge may be selectively adjusted to a predetermined setting. 7. A guide or marking tool according to claim 6, wherein the axis about which said guide face is generated is co¬ incident with said sighting, guiding or marking edge and said first member is provided with an abutment flange having a reference face contained in a plane containing said axis. 8. A guide or marking tool according to claim 7 » wherein length measuring indicia commencing at said axis extends along said sighting, guiding or marking edge. 9. A guide or marking tool according to claim 7 or claim 8, wherein said first member includes an angular scale concentric with said guide face. 10. A guide or marking tool according to any one of claims 6 to 9 > wherein said second member is provided with length measuring indicia disposed parallel to said reference face having a zero reference point coincident with said sighting, guiding or marking edge when the latter is disposed at right angles to said reference face. 11. A guide or marking tool according to any one of claims 6 to 10 wherein said second member is provided with a pair of level vials at right angles to one another. 12. A guide or marking tool having a first member incor¬ porating a reference edge or plane alignable with a desired datum, a second member incorporating a sighting, guiding or marking edge, said second member being pivotally attached to said first member so that the angle between said reference edge or plane and said sighting, guiding or marking edge may be adjusted to a predetermined setting and wherein the pivot axis of said first member relative to said second member is located at the intersection between said reference edge or plane and said sighting, guiding or marking edge at all relative angular settings between said first and second parts. 13. A guide or marking tool substantially as hereinbefore described with reference to the accompanying drawings. 14. A pivot assembly substantially as hereinbefore described with reference to the accompanying drawings. OMM

Inventors: VAN GORP KEITH NOEL, VAN GORP, KEITH, NOEL
Applicants: GORP KEITH NOEL VAN, VAN GORP, KEITH, NOEL
Application year: 1984
Main classification: F16C11
IPC codes: B23Q9, B43L7, F16C11, G01B3