> > A servo-controlled winch?  :-)
> 
> Maybe instead simply a small DC motor. Should give me
> an adjustable force; at least at the stall point, and since the
> force decreases with increasing speed, that's probably not
> a practical problem

I recall a post from a looong time ago from someone who wanted
(I think) to make a monitor appear from out of a false ceiling. The
query ISTR was more about the s/w (end-stops etc) rather than
the mechanics. I believe he was using Archimedes screws (ie like
the square-cut drive screws on a lathe bed)

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