Looking for a math whiz

[Skinny Shooter]

Originally posted by gumpokc
easiest way i know of....
you need a protractor, ruler, and something to mark with.
measure top/bottem, left/right to find center point from inside of circle.
lets say your staring with 0 degrees.
place far left end of proteactor at 0, use ruler to run out from center at 120 degrees, mark spot, relocate protector, remark at 120 again, the repeat for third spot. wala all done.
or you can eyeball it, just depends how accurate you want it, but for three points, each mark is 120 degrees from the other two.
so one mark at 120, 240 and 360/0 degrees.

I understand marking a point every 120 degrees.
So no matter what size protracter I use, the ruler should be laid across the top of it and just follow the ruler out to where it intersects the material?
I want to do this fast with minimal movement.
I'll look for a 360 degree protractor and then make a "jig" or pattern with a known center and 3 lines running out at 120 degree intervals. It can be printed on heavy paper.The ring would get laid on top of the paper and then make my marks that way.
I also make three-legged candlestands that can have a spread of 24" or so.
Once I get the correct dimensions for that, I'll make a metal jig for the feet to lay on and will use that for the correct adjustment.

Most of my blacksmithing is done by eyeballing the work but this part needs to be a bit more precise.
thanks for all your help,
Allen