Went out to the garage, located some EMT pieces and tried fitting it
to the tail stock pieces of the clamps.

It was not snug enough to allow the clamp to bite into the EMT. It
would slip. Now if you took a hammer and oval'd the EMT, perfectly,
you could get it to bite but you would need a machine to make
consistent oval and then you would have to keep the oval vertical to
the wood. So it is just not worth the effort for consistent operation.

While messing around I did come up with a tip to keep black or galv
pipe from messing with your wood surfaces. That would be to use
unistrut clamp rubber insulators on the pipe by themselves. Easy to
use. Very efficient.

Was going to post a link to a picture for the rubber insulators, WOW!

I didn't remember the "for ea." price being do high, its ridiculous
and to think I had boxes of these things at one time.