Making the mould

I’ve started work on Geoff’s OO shape guitar. One thing that I’ve had to do, is make a new mould for this shape. The mould is used to construct the rim of the instrument- the assembly of the sides, linings, end blocks. I don’t like making moulds (chipboard kills your tools!) and I’ve got far too many, but I do like the OO shape, it’s a lovely little 14 fret guitar. Fortunately, I did some repair work on a Martin OO a few years ago and at the time a made some drawings of it.

The first step in making a mould is gluing up some sheets of chipboard to make up a thickness of about 45 to 50mm.

Once this lump has been made, the shape of the guitar is cut out on the bandsaw. As you can see, I’ve got a fairly small bandsaw, which is good for most of my needs, but 50mm of chipboard pushes it to the limit.

Once the shape has been cut out, I glue a plywood plate on to each end to join the two halves together.

I then use a sanding drum on my pillar drill to get rid of the saw marks.

Once the inside shape is smooth and accurate to the shape, I give the mould a coat of sealer: it needs to be water proof as the damp guitar sides (after bending) are clamped in to place and also when doing any gluing up, you reduce the chance of gluing your sides to the mould!

The mould is then cut into two again and another two plywood plates are used to join the two halves using screws so the mould can taken apart and re-assembled as required.

Next step, bend the sides!