Kenneth Michael Guitars est.1978

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Building an arched/contoured top guitar in a mold with a "built-in" bottom seems to mystify some folks ---- this is the secret, if you could call it that. Simply put a perimeter spacer inside the mold. The reality is that most users of the body shaped molds end up screwing or clamping plywood to the mold at some point, so there is a bottom to work against. This spacer is made of ¼ inch plywood and it provides plenty on clearance for the arch of the top. You could do the same thing with pieces of cardboard. The instrument in the sequence has a 15’ radius back and 28’ radius top. Place the spacer in the mold, place the guitar body in the mold top down. I always glue the top on first – one of the main reasons is that I can tap tune after the top has been stiffened by the sides. On occasion I have shaved the braces. Makes sense doesn’t it?

Line up the centerline of the back with the centerlines on the neck and tail blocks, secure the back with a couple of rubber bands

Mark the location of the back braces on the rim.

Using a straight edge mark the top of the sides and kerfing.

To make sure the ends of the braces come through the rim and sit properly in the rim notches you need to taper the end to about .20” from the perimeter to the inside of the kerfing.

I found the best way to trim down ends was to  grind the tapered ends with a 60 grit flapper wheel  --- naturally chisels would also do the job.

Mark the depth of the notch with a square or compass to match the thickness of the braces. THIS MUST BE LESS THAN THE WIDTH OF THE BINDING MINUS THE BACK THICKNESS.

Use  a razor saw, sharp knife and a chisel to clean out the brace notches.

If the rim has been contoured correctly the back is now ready to glue in place.

It always intrigues me when I see photos of guitar tops and backs being glued in place.   There are usually twenty or so huge clamps or thirty spool clamps. It is not real clear, but the back in the last picture is being glued. Note how few rubber bands are used. This back is seated all the way around and there is glue squeeze out all the way around. This is a contoured back with a 15’ radius. I cannot repeat this enough  --- If it takes bone crushing force to bring your parts together something is wrong. Building stress into a musical instrument simply is not a good idea. I always glue the top on first – this makes the assembly very stiff. To complete the contour of the back it does have to be shaped over the waist to match the side taper. Again, if the back was braced properly there will be very little force required to get the longitudinal bend.

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