Joseph Gwinn fired this volley in news:joegwinn-
:

This is how most wire tensioners used in coil winders work.

yep. Thanks, Joe.

I have that series of patents.

The main problem here is that there is a substantial amount of stretch in
the roving I'm spooling, and it is in its fully elastic domain, so that
any hysteresis in the tensioning clutch will cause (first) excess
stretch, followed (second) by sudden recovery when the clutch slips.

The use of a magnetic hysteresis clutch obviates the mechanical problems,
since they are continuous-slip devices. But clutches in the 20 ft-lb
torque range cost thousands of dollars.

I'm going to employ a dumbed-down electro-mechanical servo system. A
tensioning arm that can swing a fairly long arc over a small tension
differential, limit switches to sense "spool on/spool off" limits, and a
slow gear motor that has torque in excess of that required to maintain
the limit tension.

Including the metal work to remove the existing clutch system and replace
it with this, the solution comes in at about 1/6 the price of a magnetic
hysteresis or magnetic particle slip clutch of that required torque.

LLoyd