OM 01 Project - Making the Template and Body Mould

The book recommends building a clear template and a body mould to ensure accurate shaping and construction.

The template is made from clear polycarbonate and is just a "half" template, so you can flip it over for symetry. I simply traced the shape from the full size plan in the book and then cut it out using a fine-tooth metal blade in the bandsaw. Then sanded the edges to get nice smooth curves.

To make the body mould, I cut sheets of 18mm plywood into 4 - 600 x 300 panels and planed one edge flat. Then traced the outline of the body from the template onto each panel (2 for each side.

I put a narrow blade in the bandsaw, so it would cut tighter curves, and then cut the shapes out of the 4 blanks - 2 for each half.

Now I needed to sand smooth curves back to the traced shape. I bought a 2" drum sander that fits in the pillar drill, but needed to make a simple platform so that I could support the wood and sand something like a perpendicular face, right down to the face of the wood. 

I clamped the two pieces of each side together and sanded them back into the smooth outline. Because they were clamped together, I can be sure they are pretty much identical.

Next I cut 2 pieces of ply from the offcuts, that will form end plates allowing me to screw or bolt the two halves of the mould together. I also cut a load of 3" long "soldiers" out of some scrap softwood. They ended up being a bit less than 2" x 1" cross section after I'd planed them.

I glued and pinned the end plates and one of the soldiers at the waist, after ensuring that all was square etc., and left to dry. You can see here that I also cut waste away from around the body shape to take a bit of weight and bulk out of it. I actually took a bit too much off the lower part really - the instructions say to leave 2", but mine is a bit less than that - seems OK though.

After that had dried, I glued and pinned soldiers all around the edge, leaving them just slightly proud so I can sand back to the edge once dry. 

A day or two later, everything had dried solid and I used the drum sander again to sand back to a smooth curve. This photo shows it in the hand drill, but I actually found it easier to use the bench drill arrangement again. Once it was pretty much there, I finished off the last part with sandpaper by hand, ensuring that the faces were perpendicular to the top and bottom.

The finished product and the template still fits, which is pretty important! Now I just need to finish the other side.

With the other half of the mould now completed, I could finesse the joint so that everything sits nice and square when bolted together. I also sanded across the joins to make sure that there is a nice flat surface where the sides will be joined to the neck block and end block.

I used some scrap contiboard and ply to make this building board to clamp into an old Aldi Workmate. It will be perfect for working on once the build starts, and can be easily moved around the workshop.

There are two more parts I need to make for the body mould. The first is a clamping caul, which will be used to glue the top and bottom to the sides. I used a piece of scrap 12mm ply that was just big enough; drew around the template and then added 30mm around the edge and also marked a line about 10mm inside the edge. The idea is to rout out inside the inner line to leave about 3mm thickness, so that you end up with a solid perimeter and a hollow inner to allow the caul to flex and take up the shape of the back and front.

I cut the outline on the bandsaw. My routing out wasn't the greatest and I'd do it differently next time, but it does the job. The clamping caul is screwed down to the body mould in use and the screws adjusted to put the right amount of tension on the joint while it's being glued.

In place on the mould it looks like this.

The third part of the mould is a template for the shape of the sides. The front face of the guitar is flat but the back is flat from the bottom to the widest part and then follows a gentle curve to the neck end, which is about 15mm narrower then the bottom end. The template sits on the mould and is used to plane the sides to the right profile in the mould, after they have been bent.

I used 3.5mm ply and transferred the shape before cutting the inside out with a jigsaw and nice fine blade.

I didn't get any pictures of cutting out and glueing the curved battens but it's pretty straightforward and ends up looking like this (upside down to show the battens).

In place on the mould, you can see the curvature against a straight edge.

The last part is to make 10 stop blocks from some 1" square and 1/2" dowel. The protruding dowels fit into corresponding holes drilled into the sides of the mould. They are used to reduce the depth of the mould when it comes to gluing the top and bottom onto the sides. At this stage, I could only drill the holes in the mould for the top edge. Once the shape of the back is determined, I can drill the back set of holes.

So now I really have nothing else to procrasinate over - time to start doing some building! This mould has taken a lot of work to build but hopefully will be the basis of several future guitars, so worth spending the time on.