GB2117317A - Sawing apparatus - Google Patents

Abstract

A saw blade 23 is pivotally mounted on a work top 20 eccentrically of an arcuate sawing edge 52 such that the blade cuts into a workpiece on movement about the pivot. <IMAGE>

Description

SPECIFICATION Sawing apparatus This invention relates to sawing apparatus.

It is an object of the present invention to provide a sawing device which is accurate in operation, is simple to operate, is usable indoors without the need of a vice, is readily portable and which preferably has a facility for accurately cutting a workpiece at a desired angle, for example in making mitred joints.

According to the present invention there is provided sawing apparatus comprising a curved saw blade eccentrically mounted on a pivot in such a way that it can cut into a workpiece as it is turned about the pivot.

Preferably the degree of eccentricity of the saw blade is variable.

Preferably, the sawing apparatus comprises a worktop provided with a slot within which the saw blade can pivot.

Preferably, the sawing apparatus comprises a slotted saw blade guide adapted to fit into the slot in the worktop to secure the saw blade in position on the worktop without impeding its pivotal movement.

Preferably, the sawing apparatus comprises a workpiece locating device comprising a worktop engaging member and a main body adapted to be locked to the latter and capable of being movable longitudinally and rotationally of the latter.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is an exploded perspective view of the sawing apparatus with ancillary detail views; Fig. 2 is an exploded perspective view of the workpiece locating device; Fig. 3 is an underneath plan view of the workpiece locating device illustrating the possible adjustments thereof; and Fig. 4 is a perspective view of the assembled sawing apparatus.

The sawing apparatus comprises a worktop 20, a saw blade guide 21 which engages in a slot 22 provided therefor in the worktop 20, a saw blade 23 adapted to be eccentrically and pivotally mounted in the guide 21, a handle 24 for attachment to the saw blade 23 to operate same and a workpiece locating device 25 adapted for adjustable location on the worktop 20 to present a workpiece (not shown) squarely or at an angle to the saw blade 23.

The worktop 20 is formed of a plastics material by an injection moulded process for example. The worktop 20 is of open-bottomed box configuration and its upper surface is divided into two unequal areas by the slot 22. The two opposed edges of the worktop 20 are delinated by upstanding walls 26. Between each wall 26 and the slot 22 the top surface of the worktop 20 is constituted by alternate rows of uninterrupted recesses 27 and castellated formations 28 both parallel with the slot 22.

The recesses 27 are deeper than the lower level of the castellated formations 28 so that the top surface of the worktop 20 has a three level A, B and C configuration. The recesses 27 and castellated formations 28 are of the same width.

The slot 22 which is wide when compared with the rows of recesses 27 and castellated formations 28 is also bounded along each long side by an upstanding wall 29 parallel with the walls 26 and the walls 26 and 29 are the same - hight as the upper level A of the castellated formations 28.

The short end walls 30 defining the slot 22 with the walls 29 terminate below the level of the walls 29 and each of these walls 30 has a vertical cut-out 31 extending down from its top edge.

The slot 22 is closed at its bottom and is of the same depth as the worktop 20.

Inwardly of each end wall 30 and lying midway of the cut-out 31 is a bridge member 32 screwed into two shoulders 33 defining between them a narrow slot 34.

These shoulders 33 inwardly of the bridge members 32 increase in height to just below the level of the walls 29 as indicated at 35 and are recessed as indicated at 36 to define cradles for mounting the saw blade 23 as later described.

A deep recess 37 between the pairs of shoulders 33, 35 serves as a sawdust receptacle.

It is to be noted that each wall 26 or 29 has immediately adjacent to it one of the uninterrupted recesses 27.

It will be manifest that the slot 22 can be arranged to divide the worktop 20 into two equal areas.

The worktop 20 can simply be laid flat on a workbench or table and rubber feet 38 are provided at the worktop corners to provide a non slip grip. If it is disposed adjacent an edge of the latter then locator bars 29 are provided on the worktop 20 positively to position the worktop 20 at said edge. At each corner of the worktop 20 underneath its top surface is pivoted as indicated at 40 one of these locator bars 39. It will be manifest that any appropriate two can be pivoted down into a vertical attitude abut against the edge of the workbench or table to position the worktop 20 at the edge.

The saw blade guide 21 is made, for example, of aluminium and is of T-configuration. It is constituted by two spaced inverted L-shaped members 41 fastened together with a distance piece 42 therebetween and extending from one end to just under one half the length of the guide 21.

At one end the stem 43 of the T is formed from its edge with an inwardly-directed cut-out 44, the stem 43 below this cut-out being shortened as indicated at 45.

Inwardly of the other end of the stem 43, the latter is cut away to define an inverted L-shaped cut-out 46 open at the bottom edge of the stem 43 and directed towards the adjacent end of the support 21. This cut-out 46 permits a bayonet connection of the blade guide 21 in the slot 22 of the worktop 20 as will be described later.

The cross-bar 47 of the T is provided with a rectangular cut-out 48 merging with the unfilled slot 49 between the inverted L-members 41. The corners of this cut-out 48 at the slot 49 are cutaway as indicated at 50 for a purpose to be described later.

The stem 43 under the rectangular cut-out 48 is cut away to provide a substantially oval-shaped opening 51.

To mount the blade guide 21 in the slot 22, the stem 43 is inserted into the slot 34 with the opening to cut-out 46 aligned with one of the bridge members 32 and the rectangular cut-out 48 aligned with the cradle recesses 36.

The blade guide 21 is then pushed firmly down into the slot 34 and then longitudinally to engage cut-out 44 on the other bridge member 32, the first-mentioned bridge member 32 fully into the inverted L-cut-out 46, and the rectangular cut-out 48 away from the cradle recesses 36 which now lie under the cross-bar 47.

It will be manifest that the blade guide 21 can be fitted in either direction into the slot 22 to cater for right hand or left hand usage.

The saw blade 23 has an arcuate serrated peripheral portion defining a sawing edge 52 merging with a non-serrated peripheral portion 53. It has a somewhat acimitar shape with a narrow handle end 54 which fits into a slot 55 of a handle-receiving member 56, the blade 23 being screwed to the latter, The handle-receiving member 56 has at its free end a male screw 57.

The saw blade 23 is formed with a fourposition eccentrically-located slot 58 (or possibly four separate holes) for receiving into any one position a pivot pin 59. The latter has a flat surface 60 for engaging flats 61 in the slot 58 to prevent relative rotation between the pivot pin 59 and the saw blade 23. A pair of plastics hubs 62 provided with flanges 63 are also provided.

To fit the saw blade 23 in position on the worktop 20, the blade guide 21 is in the position with the rectangular cut-out 48 aligned with one set of cradle recesses 36 depending on right or left hand usage.

The pivot pin 59 is insereted in the slot 58 in the desired position of eccentricity so that it projects from each side of the saw blade 23 and then the hubs 62 are slid onto the pivot pin ends with the flanges 63 abutting the saw blade 23.

The saw blade 23 is then located in the slot 49 of the blade guide 21 with the hubs 62 resting in the cradle recesses 36 below the rectangular cutout 48 and with the hub flanges 63 engaging in the cut-outs 50. The saw blade handle end 54 is uppermost.

The blade guide 21 is then slid longitudinally as described aforesaid and the cross-bar 47 due to the provision of the opening 51 slides over the hubs 62 to secure the saw blade 23 in position on the worktop 20 without impeding its eccentric pivotal movement through the slot 49 of the blade guide 21.

The handle 24 is a lever 64 which has at one end a female screwthread 65 which permits it to be secured to the saw blade 23 by engagement with the screw 57 and a sawing action can thus be imparted to the saw blade 23 by the user gripping the handle 24 and pivotting or levering the saw blade 23 to-and-fro against a workpiece.

The workpiece locating device 25 is formed of plastics material and is used, as aforesaid, to hold a workpiece square or at an angle against the saw blade 23.

The device 25 comprises a main substantially flat body 66 with an integral workpiece abutment bar 67 at one end and with the other end of semi circular configuration marked off with a scale 68 into 1 80C or thereabouts. The main body 66 has an elongate slot 69 directed towards the mid point of the scale 68 and lying midway between the latter and the abutment bar 67.

The underside of the main body 66 is cut away to define an elongate recess 70 aligned with the slot 69 and extending between the scale 68 and the abutment bar 67, the main body 66 at the mid-point of the scale 68 between cut away to provide an opening 71. The recess 70 runs diametral of a circular recess 72 which is interrupted by two quadrants 73 which assist in defining the recess 70 and which are disposed at the scale-adjacent end of the slot 69.

The device 25 also includes a worktopengagement member 74 comprising a circular disc 75 of a diameter conforming to the internal diameter of semi-circular end of the main body 66.

This disc 75 has a screw 76 at its centre, which screw 76 passes through the slot 69. Extending diametrically from the screw 76 and integral with the disc 75 is an elongate projection 77 engagable in the recess 70 and of a length equal to the radius of the circular recess 72. A short projection 78 aligned with the projection 77 and equal in length to the difference between the radius of the circular recess 72 and the radius of the disc 75 is disposed at the circumference of the latter remote from the projection 77.

On the other side of the disc 75 (the lower side in use) along the same diameter as the projections 77 and 78 are two bars 79, 80 engaging the head 81 of the screw 76. The bar 79 has a depending foot 82 at the disc circumference. This bar 79 and foot 82 lie within the disc circumference. The other bar 80 has an identical depending foot 82 at its end which, however, projects beyond the circumference of the disc 75 and at this end there is an upstanding lip 83 marked with an indicator arrow or mark for cooperating with the scale 68.

The spacing between the feet 82 is equal to the width of three castelled formations 28 and two intervening recesses 27.

Finally, the device 25 has a circular handle 84 with a central blind screw bore (not shown) for engaging the screw 76 adjustably to secure the disc 75 to the underside of the main body 66 with the indicator lip 83 at the scale end of the latter.

It will be manifest that if the feet 82 and associated bars 79,80 are engaged in one of the recesses 27 then the workpiece locating device 25 can freely be moved along this recess 27 the device 25 sliding bodily or "floating" across the tops of the castellated formations 28. This allows a user to push or urge the workpiece against the saw blade 23.

If, however, the device 25 is laid at 900 to the recesses 27 the feet 82 engage opposite sides of two castellated formations 28 spaced apart as aforesaid with the bars 79, 80 lying along level B of the latter. In this disposition it will be clear that the device 25 is bodily locked in position.

When securing a workpiece, the latter is held between the abutment bar 67 and the saw blade 23 to which a to-and-fro sawing action is imparted by the user pulling on the handle 24.

The workpiece locating device 25 is capable of adjustment in order to present the workpiece correctly to the saw blade 23 irrespective of whether the device 25 is supported freely (recesses 27) on the worktop 20 or in locked position (castellated formations 28) on the worktop 20 (see Fig. 3).

Let us assume that the device 25 is in one of its extreme conditions, i.e. the screw 76 is at the end of the slot 69 nearer the abutment bar 67 which means that the projections 77 lie within the diametral recess 70. In this condition there can be no relative rotation between the disc 75 and the main body 66 and hence no angular adjustment.

Release of the circular handle 84 permits, for example when the device 25 is in its locked position, longitudinal movement of the main body 66 and hence the abutment bar 67 relative to the locked disc 75 thus giving a fine longitudinal adjustment facility to the device 25 (see dot-dash lines Fig. 3). This facility will be of little, if any, use when the device 25 is in its "floating" position. It will be manifest, however, that when the device 25 is in its locked position it can only bodily be moved in fixed steps and consequently this movement of the main body 66 relative to the disc 75 permits the fine adjustment between these fixed steps.

When the screw 76 is at the other end of the slot 69 it is in its other extreme condition with the indicator lip 83 projecting beyond the main body 66 and with the projections 77, 78 within the circular recess 72 thus permitting the abutment bar 67 to be set at any angle through 1800 (see dot-dash lines Fig. 3). This angular adjustment facility is useful whether the device 25 is "floating" or locked and can be used, for example, in making mitred joints.

If necessary, an outrigger support may be fitted to the worktop 20 to provide sufficient support for longer pieces of wood. Such a support may consist of a pair of rods engageable in a side wall of the worktop 20 with a support member of appropriate height at the other ends of the rods.

Alternatively, the worktop may be capable of being separated into two parts, if necessary, being temporarily tied together by connecting rods or the equivalent.

Claims (16)

1. Sawing apparatus comprising a curved saw blade eccentrically mounted on a pivot in such a way that it can cut into a workpiece as it is turned about the pivot.

2. Sawing apparatus as claimed in claim 1 in which the degree of eccentricity of the saw blade is variable.

3. Sawing apparatus as claimed in claim 2 in which the saw blade has an arcuate sawing edge and a slot eccentric to said edge and adapted nonrotatably to receive a pivot pin in any one of a plurality of positions along the slot.

4. Sawing apparatus as claimed in any one of claims 1 to 3 comprising a worktop provided with a slot within which the saw blade can pivot.

5. Sawing apparatus as claimed in claim 4 in which a plurality of pivot locations for the saw blade are spaced along the length of the slot.

6. Sawing apparatus as claimed in claim 4 or 5 comprising a slotted saw blade guide adapted to fit into the slot in the worktop to secure the saw blade in position on the worktop without impeding its pivotal movement.

7. Sawing apparatus as claimed in claim 6 in which the saw blade guide is secured to the worktop by a bayonet connection.

8. Sawing apparatus as claimed in any one of claims 4 to 7 in which the worktop slot is of closec bottom construction and serves as a sawdust receptacle.

9. Sawing apparatus as claimed in any one of claims 4 to 8 in which the worktop is of openbottomed box construction with at each corner an anti-slip foot and a pivotal locator bar which can be extended out of the bottom to bear against a vertical surface.

10. Sawing apparatus as claimed in any one of claims 4 to 9 in which the upper surface of the worktop save for the saw blade guide slot is divided into alternate rows of uninterrupted recesses and castellated formations parallel with the slot.

11. Sawing apparatus as claimed in claim 10 in which a recess is provided at two opposed sides of the worktop and at each side of the slot, such recess being disposed between a castellated formation and a boundary wall.

12. Sawing apparatus as claimed in claim 10 or 11 comprising a workpiece locating device adapted to be movable along a recess or to be locked across and within a plurality of the castellated formations.

13. Sawing apparatus as claimed in claim 12 in which the workpiece locating device has a worktop engaging member and a main body adapted to be locked to the latter and capable of being movable longitudinally and rotationally of the latter.

14. Sawing apparatus as claimed in claim 13 in which the worktop engaging member has spaced feet adapted to abut spaced castellated formations to lock the workpiece locating device relative to the worktop.

15. Sawing apparatus as claimed in claim 13 or 14 in which the main top comprises, at one end, a workpiece locator bar and, at the opposed end, a scale whereby accurate rotational adjustment can be made.

16. Sawing apparatus, substantially as hereinbefore described with reference to the accompanying drawings.