I am trying to create the motion of the inner parts of a simple engine. I made a simple crankshaft, piston, and connecting rod and am trying to get those 3 pieces to work as a unit. I want to somehow set up the kinematics so that I can just apply a spin to the crankkshaft and the other parts would move like they're susposed to. Can Carrara do this, or am I trying to make this more simple than it really is (as usual)? Suggestions would be highly appreciated.

I believe that can happen. I'll mess around with it in the next couple of days and see if I can offer any help. Mark

That can be done & yes, it sounds simple. You need to build child-parent links (in the properties window, links) and then constrain movement for each part by useing limits in each axis (behaviors, I believe)

I know I probably have the wrong settings. My attempts have all three pieces swinging around the crankshaft (like an arm sticking out from a spinning body).

I could be wrong but from what I found with IK you want your main motion piece to be last on the chain....Ie on an arm model you want the hand last on the chain..that way when you move the hand everything else moves with it. If you just move the shoulder everything else will still move but it wont move properly. So for an engine I would think you would want the chain to be piston > Rod > Crank. That way when you move the crank everything else should move. What I am curious about is how other objects can interact...IE can you hollow out a tube for the pistion and have the tube be solid enough to constrain the piston? This could be useful for my truck animation..right now I am just spinning the wheels myself. In the Carrara bible it showed how to use force to do it, but it still didnt do things properly from what I saw.