GB2264894A - Jig for cutting slabs of hard material - Google Patents

Abstract

The jig (10) is for use with a rotary disc-type cutter (48) and a slab (46) resting on a supporting surface. The jig (10) comprises a guide frame (12) defining a guide slot (24) for receiving the cutter (48) and is positioned in alignment with the line of cut. Clamps (36, 38) are then secured in an appropriate position along the guide frame (12) so that each jaw plate (40) engages a lateral face of the slab (46). With the jig (10) thus located thereover, the cutter (48) is passed backwards and forwards along the slot (24) until the cut is completed. Stabilizing plates (40) stabilize the jig (10) in relation to the supporting surface. Each jaw plate (40) may be inclined to the line of the guide slot (24) to allow the line of cut to be inclined to the side faces of the slab (46). <IMAGE>

Description

APPARATUS FOR USE IN CUTTING SLABS OF CONCRETE OR SIMILAR HARD MATERIAL This invention relates to jigs for use in cutting a slab of concrete or similar hard material with a rotary disc-type cutter. The construction and building industries are among the most hazardous in which to work, as potentially dangerous machinery is used on a daily basis, often leading to complacency on the part of the operator.

The mandatory wearing of safety clothing minimises risk to a certain extent yet, due to its bulkiness, it can ironically increase the likelihood of injury to operators using certain types of equipment.

A disc blade cutter is, as its name suggests, essentially a circular saw, driven either by mains electricity or a petrol engine, andis used to cut all types of masonry, including concrete and brickwork. Hand-held, it is large and unwieldy, and tends to buck viciously, particularly when starting to cut.

For neat and tidy paving, slabs need to be cut cleanly and accurately - a difficult task for an operator wearing clumsy safety equipment and fighting against a heavily vibrating power saw amidst dust and flying concrete chips.

It is an aim of the present invention to make the cutting of all types of paving slabs as safe as possible for the disc cutter operator, whilst at the same time improving the accuracy and cleanness of the cut.

According to the present invention there is provided a jig for use when cutting with a rotary disc-type cutter a slab of concrete or other hard material resting on a supporting surface, the jig comprising guide frame defining a guide slot for receiving the cutter disc and positionable, in use, on the slab in alignment with the line of cut, first and second clamping means each releasably securable in a desired position along the guide frame and including a jaw for engaging a lateral face of the slab such as to locate the jig thereover, and stabilizing means for stabilizing the jig in relation to the supporting surface.

Preferably, the clamping means are positionable such that each jaw may be inclined to the direction of the guide slot, and the guide slot is formed with upstanding, outwardly inclined walls.

Desirably, the stabilizing means each comprise a member having a lower edge which is slightly spaced from the supporting surface.

Although the invention may be carried out in a variety of ways, one particular embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which Figure 1 is a side elevation of a jig according to the invention and showing the slab to be cut and cutter in chain dot; Figure 2 is an underside plan of the jig of Fig. 1 on the arrow II in Fig. 1; and, Figure 3 is a section on the line Ill-Ill in Fig. 1.

As shown in the drawings a jig 10 comprises a guide frame 12 formed of a pair of mild steel outer strips 14,16 and a pair of mild steel angle strips 18,20, the upstanding, outwardly splayed webs 22 of which together define a guide slot 24. The outer strips 14,16 and the horizontal webs 25 of angle strips 18,20 are welded at each end to the underside horizontal web 26 of a transverse L-section end-piece 28 having depending webs 30.The inner edge of each outer strip 14,16 is spaced from the outer edge of the respective web 25 of the neighbouring angles 18,20 to form an elongate aperture 32 for slidably receiving respective bolts 34 of two clamps 36,38, each comprising a vertical jaw plate 40 having the general shape of a letter 'U', the arms of which extend into horizontal flanges 42, each having a slot 43 for receiving a respective one of the bolts 34 with the interposition of a washer. The clamps are tightened by means of drilled and tapped arms 44 received on the upper end of each bolt 34, again with the interposition of a washer.

For use in cutting a concrete paving slab 46, the guide frame 12 is placed on the upper surface of the slab 46 which is positioned horizontally over a suitable flat support, with the guide slot 24 being carefully aligned over the desired line of cut and the clamps 36,38 being loosened, if necessary. The jaw plates 40 are then engaged against the opposed side faces of the sides of the slab 46 and the handles 44 of the clamps 36,38 firmly tightened.

The disc cutter 48 is then started and the blade 50 thereof placed in the cutting slot 24, the cutter subsequently being moved backwards and forwards along the slot until the cut is complete and the slab 46 is severed.

When the cut is complete the clamps 36,38 are loosened and the jig 10 removed.

If the desired line of cut is not perpendicular to one or both of the side faces of the slab 46, the consequent inclined orientation of the guide frame 12 can easily be accommodated because the slots 43 allow the clamps 36,38 to be secured at angles of from 900 down to, say, 300 to the line of the cutting slot 24.

Not only does the above-described jig 10 allow a cut to be made at any practicable inclination to the side of a slab, but it may be used to ensure quick and simple cutting of any size and type of paving slab.

Moreover, the jig ensures increased efficiency as, besides requiring no maintenance, it ensures that a clean, straight cut is made every time; minimizes chipped edges and corners on the cut slabs, reduces paving slab wastage; and reduces damage to the cutting blade.

Finally, the jig reduces the risk of injury to the operator by eliminating cutter bounce when the cut is being started, minimizing the risk from flying chips generated by the cutting; and, by means of the upstanding flanges, guiding the blade to prevent the danger of slipping and to reduce operator fatigue.

Claims (7)

1. A jig for use when cutting with a rotary disc-type cutter a slab of concrete or other hard material resting on a supporting surface, the jig comprising a guide frame defining a guide slot for receiving the cutter disc and positionable, in use, on the slab in alignment with the line of cut, first and second clamping means each releasably securable in a desired position along the guide frame and including a jaw for engaging a lateral face of the slab such as to locate the jig thereover, and stabilizing means for stabilizing the jig in relation to the supporting surface.

2. A jig as claimed in claim 1, in which each clamping means is arranged to be positionable such that the respective jaw is inclined to the direction of the guide slot to permit said direction to be inclined to at least one lateral face of the slab.

3. A jig as claimed in claim 1 or 2, in which the guide slot is defined by upstanding, outwardly-inclined walls.

4. A jig as claimed in claims 1, 2 or 3, in which the stabilizing means comprise a member depending from each end of the guide means such that its lower edge is just clear of a planar supporting surface.

5. A jig as claimed in claim 1 and substantially as hereinbefore described.

6. A jig substantially as hereinbefore described with reference to the accompanying drawings.

7. The features as herein described, or their equivalents, in any novel, patentable selection.