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How to cut out a large round hole

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What is the issue?
Cutting out a hole larger than the largest hole saw fitting can be daunting. It is very difficult to hand cut with a jig saw unless it is very large.

Why address this?
In time you will come across a piece of work that the aperture of a particular hole saw will not be able to cater for or it is a corner piece that the hole saw is not capable of achieving.

How to address this?
Make a jig as described in figure1. All that is required is a flat length of mild steel.
Drill two quarter inch holes next to each other, as close as possible, at one end of the rod, on either side of the axis of the rod. Measure the length of the desired radius from the intersection of the centre point of both holes and the steel bars axial line. Drill a hole at that point to provide fulcrum for the jig.
Drill a hole in centre of the area you wish to cut out and bolt the jig in place at the fulcrum. Run the drill through one of the quarter inch holes. Move the slot on one hole then peg it. Now run the drill through the other hole. Continue to rotate, peg and drill until a round hole is cut. Finish off with a coping saw and rasp if necessary.

With thanks to:
Michael Harpur, Yacht Obsession.

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