"Dave Hinz" wrote in message
...
OK, I now know several ways not to do this. Sounds simple - 4 holes,
evenly spaced, around a circle 0.600" in diameter.

The center of the circle, I can find easily (lathe & center drill). The
edges are concentric to the center, by definition, because I turned it
on that lathe.

I marked the 0.600" circle on the face of the disk by lightly touching
it with a cutting tool on the lathe & turning the work around, scribing
a circle at the right diameter.

Now, how do I get the 4 points layed out properly from there? I can use
a center finder to get two of 'em, but how do I get the other two evenly
spaced from those points? Or, worse yet, what if I wanted 3, or 5 holes
on that circle, rather than 4?

Dave Hinz


Do you have a mill?

If so, trig the dimensions and do it by starting with the centerline of the
part, established by dialing it concentric with the spindle. That way you
can drill any conceivable hole pattern without any special tooling.
Needless to say, you must be able to hold your part vertically. If it's
too long to get under the spindle, this method may not work. Be sure to
keep backlash always in the right direction if you don't use a DRO.

Harold