> If a leadscrew nut travels along activating microswitches as it passes 
> them, you will always know where the contraption is set to.  The only 
> hurdle is power up out in the middle somewhere and knowing where
> you are.  This could be handled by remembering the last place (nvram)
> or at power up, always travel a bit until a microswitch gets activated
> and then back up to where you just started from.

'last played' is already held in EEPROM, but this new system means
that if the crank is turned when the power is off, then the PIC will lose
its bearings unless individual positions are uniquely identifiable

> Plus requiring people to operate the hand-crank will slow their 
> enthusiasm for ripping back and forth on the system.

That is one concern, that some little wretch will spin the crank like
a foos ball game. And there is what to do at either end of the crank
travel so that the nut isn't jammed hard against the end stops. I've
suggested a felt or magnetic cluctch holding the crank to the screw so
that only a certain amount of force can be transmitted. Possibly the
thread could be tapered off so the nut is free-wheeling and re-threaded
by a spring but I imagine a cross-threading happening very easily
 
> It sounds like a fun project so if possible, let us know what you final 
> system solution is and perhaps photos?

Hopefully I'll be doing that quite soon

wbr
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