Cutting the sound hole with a circle cutter
Cutting the sound hole with a circle cutter is easy make your self one or modify one. The blade on the ones commonly sold must be ground as in the image to work well, set the blade to cut a 85mm hole. Make a laminated workboard with a ¼ inch hole to receive the shaft of the circle cutter. This board is also usefull for thinning and other things. Cut the sound hole one half way only. Finish the surface of the hole after the finger board is on.