Ali T. Borahan wrote: (clip) Does it really matter if the contact point is
the tangent line that's exactly perpendicular to the center of the arm?
(clip)
^^^^^^^^^^^^^^
It matters not at all! The design I described in an earlier post takes this
to an extreme. Instead of slots, I mount the arm through a drilled hole,
with a clamping bolt. I get the distance from the centerline by swinging
the arms away from center--the action the guides would prevent. I have
built two steadies this way, both used on large lathes, and they work just
fine.

Long before the work has a chance to start whipping, you would notice a
little looseness at the wheels, and correct it. If the bolts are tight, and
the work is round, that is sufficient.