Mechanical Animation Help

Hey Guys,

I’ve been working on a simple stirling engine that im trying to animate the piston movement with constraints. Basically i want to be able to move the big flywheel and have everything else move in sinc so i only have to animate one thing. Im just a little stuck on how to do it, i figured constraints were the way to go. I’d appreciate any help or if there’s an easier way let me know.

As it happens, I posted a short article on the topic of rigging a piston and crank system to the ‘Tutorials’ forum exactly two weeks ago. It hasn’t appeared yet, but so far I’m guessing that’s just because whichever moderator is responsible for approving new tutorial threads is on holiday, since no new tutorials at all have appeared in that time.

I’d really prefer not to have to upload it all again …

Best wishes,

Thats Great! I’ll keep and eye out for it, and check it out as soon as its up. Thanks a bunch!

This is my stirling engine model. Probably not the best way to control using constraints but seemed to work.

Stirling Engine1.blend (449 KB)


Like every other example of Blender piston rigging I have seen, Richard’s model has circular constraints between the rod and piston: ‘piston’ copies the location of ‘empty2’; ‘empty2’ is a child of ‘pistonrod1’; ‘pistonrod1’ tracks to ‘piston’. It works (and indeed this particular one seems to work more smoothly than most), but the way Blender breaks the circularity means that there is inevitably some jiggling of the joint between rod and piston.

You can avoid the circularity by using an armature with constrained IK. In the continued absence of my tutorial post, here is a sample:

pistonIKdemo.blend (261 KB)

Best wishes,