Pulling strings w/servos - check it out

[Eric Moon]

Here's a quick mockup of the kind of thing I'm thinking of...


changer fingers shown in full raise position...

[Eric Moon]

thanks, already great insights here. Thanks for the links. Good point about the G# string also.

I'm expecting to need a pretty strong spring to counter balance the string tension, as well as a way to adjust the spring...

pretty clear there will be a lot to experiment with. I haven't been able to find a more powerful servo yet, that can move that fast, but I'll keep looking. And maybe some clues in those links.

Thanks all!!

[Ian Worley]

...I'm expecting to need a pretty strong spring to counter balance the string tension, as well as a way to adjust the spring...

One big challenge to consider here is that the tension the springs are counteracting will vary as string pitch changes. On the smaller diameter strings that variability is more significant. Springs are also susceptible to changes in their mechanical properties with use and changes in temperature. I am skeptical that you'd be able to achieve a reliably stable and consistent neutral "open" position on a solid finger changer design with just springs and a lightweight servo.