[Hobbiest]

Here is an easy little tool that you can make in a few minutes to find the center of any circle that fits within it...Damn these infernal machines!!!! I can't save it as any type of file that can be posted here!! Drew it in turboCAD. Any way...cut a right angle out of mdf...just mimic a framing square. Cut an equalateral right triangle. Screw them together so that the hyptenus (don't know if that is spelled right...been years) sits at 45 deg to the right angle. Mark a line through the center of your circle. Move the jig any number of deg, 90 reads easiest, and mark again. Wher they intersect is the center. For some people this may be a no brainer, but some my have never known an easy way to do this.