here is the circle cutter I made based upon the LMI jig they had designed by Richard Schneider - his was made to use a blade to score the inner/outer edges, then remove the trough with a chisel. This one uses a PC 7310 lam trimmer instead, using downcut bits.
the orange piece is made to fit your trimmer or dremel if you wish. Simple enough it needs holes to mount the router. Then it needs two holes which are threaded, I used all 1/4 20 on this, easy to get knobs and such. In these holes mount the 2 rods. The two red pieces are your adjustment pieces. Each has two 1/4 holes for the rods to slide on, then drill holes into those holes, tap 1/4 20 for the lock knobs. Thru the centre of the 2 red pieces is another set of holes. The outer red piece gets tapped for the adjustment rod to turn. The inner piece gets a 1/4 inch hole, and two lock nuts secure the rod against either side of the hole. put in a 1/4 20 threaded rod and an adjustment knob, mines off a gretsch !!! I added the black piece in order to gethte pivot pin to slide under the lam trimmer, and enable smaller diameter circles. The pin is again 1/4 inch. I used all stainless rod here. You should be able to make this up in a couple hours max, and your rosettes and soundholes will love you for it !!
The only advice I can give, is drill all aligned holes together at once, and once one hole is drilled, put a rod into it to hold hte pieces together while you drill the next - helps keep it all aligned. Oh yeah, almost forgot, all pieces are UHMW plastic, Lee Valley, cheap.
