View Full Version : repeatable circle cutting jig

10-20-2015, 03:57 PM
I wanted a circle cutting jig for my dremel router base (Stew-Mac) that would provide absolute repeatability so that I could always cut the same size rosette and sound holes. That way I could have corresponding patterns for the rosette material (pearl), pre-defined for various width purfling around the edges of the pearl.

Because I wanted absolute repeatability I did not want any sort of 'adjustable' circle cutter. There would always be a little variation whenever the adjustment was made. So ... my local community college offered a 2 evening course in using their laser cutter at the "Fab Lab" where they are moving into all sorts of new manufacturing techniques. The laser cutter will cut 1/4" acrylic, with accuracy of .001". It will cut precise 1/8" holes.

I made up a router base, with 1/8" holes spaced so that the difference in diameter when any 2 successive holes are used as the pivot points around a 1/8" pin is .1" With this router base I never have to adjust anything, and can repeatedly cut holes from 2" in diameter to 6" in diameter, in increments of .1" I can write in my log book that this rosette was cut with #4 inner and #9 outer. I have not done it yet, but this would also proved a repeatable way of doing 'offset' rosettes, where one side was thicker than the other, just by having two pivot points.

The laser cutter is just a "printer" of a Corel Draw graphic document. If anyone wants the Corel Draw file to try just let me know.

The router base:

Beau Hannam Ukuleles
10-21-2015, 04:53 AM
You got the smarts- you'll make good ukes :)