On Sat, 17 Mar 2012 13:41:59 -0700, whit3rd wrote:

On Thursday, March 15, 2012 8:54:15 AM UTC-7, Tim Wescott wrote:
How would one make nice sharp-cornered, clean-sided (I'm not sure of
the surface finish, but mirror-bright would be nice) square holes,
about 0.1" on the sides, off center from the axis of the bar (so not
square to the bar surface), in a round steel bar about 0.75" in
diameter?

Why not mill a square slot in the end of the bar, then attach a cap?
It's certainly easy to do, and the bar is big enough to take a variety
of cap-fastening schemes (weld, rivet, bolt, pin, threaded section).

Because when I'm done making the holes, I'm going to bore the bar into a
tube with 50-mil thick walls.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com