Brian wrote:

A follow up question from my request for trig. help. For a person with a
fully manual bridgeport and a rotary table, what's the method most likely to
be successful and efficient to drill hole circles, up to say 6 holes.

For up to 8 holes:
If you have n bolts evenly spaced around a circle of radius R,
the holes are R times h apart. If you know the holes are H apart,
the radius of the bolt circle is H times r.

n h r
2 2.0000 0.5000
3 1.7321 0.5774
4 1.4142 0.7071
5 1.1756 0.8507
6 1.0000 1.0000
7 0.8678 1.1524
8 0.7654 1.3066

For setting up on a manual mill, see
http://www.metalworking.com/DropBox/...ed_reducer.pdf

Ted