Connected Wheels animating

Hey all,
I am currently trying to rig a bell tower for an animator, trying to make it as easy as I can for them, and I have two wheels connected by a strap. I was wondering if it was possible to rig the wheels so that if you rotate one of them, they both rotate accurately. At the moment they rotate as if they are dancing with each other, I have scoured the internet, and cannot find anything. Help me blenderartists.org, you’re my only hope!

http://img529.imageshack.us/img529/8306/bellstrapsy3.png

One option is to use PyDrivers. See example: http://bebraw.googlepages.com/Drivenbell.blend . Tweak the parameters as desired. In this case it uses the object (“strap” or conveyor belt) as a driver. The rotation of the bell is animated by using this value and sine. Sine gives nice motion for the bell.

I like constraints. I’d put a “copy rotation” constraint on the two upper wheels, copying the rotation of the lower wheel. If the wheels are not the same size, you can adjust the “influence” (I think that’s what it’s called, going from memory) with the little slider thing in the constraint tab.

You can run into issues with constraint influence. It does not take amount of rotations in count due to the way it works. (Try to imagine a bunch of cogs rotating. This is where you would bump into the issue.) Constraint solution can work to certain extent though.

Very true! Especially if you get “feedback” (imagine an object constrained to Track To it’s own child… like a cat chasing it’s tail…).
In this case, though, I don’t think the bells will go all the way around, just back and forth, so constraints aren’t a problem.

Holy cow, BeBraw. In that one blendfile you have shown me things I hadn’t even thought possible with blender. I guess I am WAY more of a blendnoob than I thought… Thanks for all the input guys.