Help rigging a compound bow

This is the result I want:
This is how the bones are arranged:

The particular part that I can’t figure out is the string rolling OFF the wheel.
The bow bending etc. is all done and working with bone constraints.

I animated this frame by frame which is why it’s not fluid and looks jarring.
I’ve searched for weeks but I just can’t find a way to achieve this result without frame by frame animation.

Thanks in advance for the help.

That is a very nicely designed rig! I only see very small glitches in the string rolling off the wheel/cam as is, are you looking to polish this to perfection?

The uh string rolling off is in all likeliness a rigid body with constraints.

cgMasters tutorial <-- could give some additional ideas

I definitely do, I’d prefer it to be automated with constraints but if I can’t make it work I’ll do ~180 frames by hand.

That’s what I started with but rigging a compound bow is way more complex. The string on a regular bow has only 3 points that need to be accounted for. The string on the compound bow has about a hundred, the more bones the more accurate the string will be.

OK, I see now. Any chance you can make the .blend available to work on?

Yes, a blend would help a lot. You don’t need to share the whole model. The armature should be enough. Also the string mesh and at least the cam would help. (Or suitable stand ins.)

I recently “fixed” a bow from the cgmaster’s course. The limit distance constraint used in that rig will not allow proper main/root bone scaling. I replaced that constraint with a couple transformation constraints. The thread is here:

Good luck!