[David G4EBT]

In the 'MFJ' (made from junk) coil winder I designed using a sewing machine motor and foot controller, the feed spool was only 0.5KG so I mounted it horizontally and designed an adjustable tensioning drive to keep the wire taut as the coil was wound, and to stop the feed spool from 'free-wheeling' and loosing tension if I slowed or stopped the motor. I mounted the feed spool at the rear of the winder to lessen the angle of the wire at the front pulleys as they traversed back and forth to guide the wire onto the inboard coil former.

But that was for winding a field coil with 20,000 turns (2.2km) of fine wire from a small spool. Had it been a large spool it couldn't possibly have been mounted in that way or the kinetic energy required to turn the spool would have been too great and would I think have snapped the wire. Likewise, the stored kinetic energy in a large spool rotating at any speed would have caused it to 'run on' when the motor was slowed down or stopped. Hence, the feed reel would have had to be on the floor, end-on for the wire to have been spooled off the end cheek.

Hope that's of interest, but it's a bit off topic really, because the coil that's the subject of this thread consists of only 337 turns, and only 13.5 Metres of wire, for which either the manual sewing machine bobbin winder or lathe will be fine and most likely only a small spool of wire is involved.