I use a compass myself. Measure the diameter of the circle set the compass
to the radius put one leg of the compass on several points around the edge
and the other leg will cross on the center.


"Spehro Pefhany" wrote in message
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Sorry for the metal content, but there might be someone here who knows
the answer!

I would like to find the center of a 6" metal disk (center the mill
spindle precisely over it).

Here is my plan...

Use an edge finder and find 3 points at roughly 45 degrees to the
center by moving only the X axis, then only the Y axis (forming
a right triangle) with the hypoteneuse over the disk. Go halfway on
both X and Y between those pairs of X and Y numbers.

Does this sound like a reasonable plan?