Well the straight spring wire acting as a finger joint spring idea was a bust. Turned out when it bent to 90 degrees it would not return to straight again. I thought spring wire would but this stuff didn't. This is not what chatgpt said would happen so chatgpt failed me this time. Anyways, still glad for its help when its right which is most of the time I think.

That said, I fell back to my original spring solution which was to use a 3mm diameter tension spring as the return spring. I experimented with different lengths till I got one as short as possible that would stretch out the necessary .75" roughly to accomodate the finger joint's reverse direction counter tension needs. The shorter the spring the more it resists being pulled and also the thicker the spring the more it resists being pulled. I used default thickness from my premade tension spring order and it seemed fine and the length of the spring I cut and tested trial and error till I found a good length for my need. For my .75" draw length I went with one 1cm long spring which stretches itself out to .75" + 1cm in total without ruining itself. It seems like it pulls around 2lb of pulling force but I haven't measured it with a scale. I fed it through bowden tubing from the place I mounted it on the motor all the way to the joint being actuated - the backside of the index finger. It's job is to keep the archimedes pulley system and winch in place pulley taught at all times and to return the finger to full extension when the motor is not actively pulling it into a grasp position. I have not yet tested if it is strong enough to do this job but assume I'll need two of them to be strong enough. I'll test with just one for now and add another spring to double it's strength if needed later.

I deliberated alot on where to mount this spring and last minute decided to just mount it on the motor it is counter tensioning since I have enough space for it there and I can just follow the same bowden tube routing the motor is using generally. This seemed easiest for me given my massive space constraints and the need for a ton of these springs to handle all the finger joints. Seems like it should work well so far.