CHEAP or EASY String Pots (source, or fabbed)

[kmcclary]

Originally Posted by IKE

Can you attach a chain to a structural member and then use a sprocket as a cheap rack and pinion system? If this doesn't make sense, I can try to re-explain it.

Yea, we thought of that, but now you're likely to require an additional drawer slide to assist alignment (for the chain with a fixed pot, or for the pot with a fixed chain), which is makes the total device heavy when compared to a cable pot or string pot.

We also looked at beaded chains wrapped around a drum with a spiral track groove and dimples. THAT looked promising, but it's still a complex fab for the drum. (Hmmm.. a weird thought. A wrapped ROLLER CHAIN on a "helical sprocket" that was clamped onto the pot shaft??? <shudder> Whoof... THAT would not only be heavy, it'd be a horrible thing to try to fab! <chuckle>)

Now a non-FIRST friend offered the pretty cool idea of coupling a cheap motor's shaft onto the pot end from a facing motor, and driving it with a tiny current limited supply. This makes it a "virtual spring". (In essence, stall the motor, but with a small enough current that it won't fry...) Now THAT was interesting!

A few problems with using that one in a FIRST contest: A) We're severely motor limited in this contest. We often only get ONE raw motor and even if we gut other assemblies we're losing useful motors for a trivial application that could probably be better done another way with some thought. B) The "motor-spring" -must- be driven by a Spike, Victor, or Jaguar without stuff between the motor and driver. If we drive it with one of the speed controllers at the lowest setting, it might not be so bad for ONE widget, EXECPT for -> C) The real killer with this method is the fact that all of the above drivers are disabled except when the round is active, creating a HUGE chance of it unwinding, and tangling. (DARN...)

So... back to researching a true "spring based method"...

More design thoughts? Comments? Experience?

- Keith