John fired this volley in
news
A torque motor would do the job too.


But, John, it would have required "redesign" on a major basis. This
required only two things -- wrapping the takeup spool with bulking (vinyl
flooring sheet goods), and replacing ONE two-groove bearing with two
sprag clutch/bearings. Free for the sheet goods, and $50 for the two
bearings. No machine work -- none, period.

NO mechanical re-design of the machine, at all. Just re-fitting of
existing parts with new parts that fit in the same bores, same profiles.

I don't have a lot of experience re-working old machines to new specs (I
generally design to spec for new stuff), but it seems that replacing a
bearing is a LOT better than re-belting (or re-chaining) the whole
apparatus (along with building motor mounts, jackshafts, and power supply
for the motor).

All the constant-torque motors I've seen that would physically fit in
this space would require at a minimum 10:1 reduction to get to the 20ft-
lb torque I was looking for. That'd be two stages of belting or chaining
jackshafts in this case. And it wouldn't have gained me _any_ different
performance than I got with this method. Still, it would be constant
torque, not constant tension. ??? why would I want to DO that? To do it
in a "elegant" way? Elegance is in simplicity, I think.


LLoyd