On Tue, 29 Mar 2005 19:59:42 -0800, JR North
wrote:

In reverse engineering my radar scanner for mods, I am in the process of
machining an adapter, and I have run into a conundrum.
I need to very accurately plot a bolt circle radius consisting of 4
evenly spaced 3mm screws, about 1/2" radius. The screws rock slightly in
the threads, so I can't just mike the screw shafts and extrapolate.There
is an open center, so I can't easily locate x0y0. The hole centers must
be plotted very accurately for alignment of the vaveguide. Help?
JR
Dweller in the cellar

If you can't easily locate x0y0 in an open center , you're in a world
of hurt. Consult Lautard's "Machinist's Bedside Reader" for how to
do this quickly and easily. I don't recall which volume, others may
help here.