JR North wrote:
Your motor needs to be at least 1HP (2 Sears HP) and about 3-500RPM on
the spindle. If you have one of the wimpy 1/3HP jobs-forget it. It's not
gonna fly. Your clamp scheme needs to be Very rigid- a bit that size
will grab big time- the hoist support idea has no lateral rigidity. If
the hole size is not that critical, a better scheme might be to flame
cut them, and clean up with a die grinder. You really need to determine
what material you are working with. Especially for the tap job. Mebbe
someone can post a link to a spark analysis page that shows how to
determine flavor by grinding a spot and evaluating the spark color and
branching. You don't really want to be knocking yourself out drilling
and tapping some armor plate.
JR
Dweller in the cellar

I'm pretty sure the material I'm tapping isn't that hard. I cut it on the
big saw at work, and it didn't have any problem cutting it. I'll be
grinding a chamfer on one end before drilling it, so I'll have a chance to
confirm that impression.

I understand about the lack of lateral rigidity. I was planning on having
it setup where the 500# anvil I have will help in that regard.