Mechanical rig setup problem

I’m having serious troubles setting up correctly a “simple” mechanical rig, after spending several hours i decided was time to ask here:


Basically i was trying to move the piston up/down by rotating the red lever. The arm is the link between the manually rotated lever and the automated piston up/down. I made a animation to explain better, is in the .blend .
The best thing is if the rig will work also when moving/rotating everything around the world.

Any help on how to setup this rig is really,really,really appreciated :slight_smile:

Although it looks a little different because the piston is folded around, this is basically just a standard piston and crank, and can be rigged in the same way as I describe in my piston tutorial.

The Stroke, Piston and Rod bones form an IK chain targeting the Crank bone. The Stroke bone is allowed to stretch but not rotate, the Rod to rotate but not stretch, and the Piston neither.

The piston object has a ‘Parent To’ constraint to the Piston bone, the arm object to the Rod bone, and, conversely, the Crank bone to the lever object. Rotating the lever makes the piston go up and down.

Best wishes,


mecrig_help.blend (561 KB)

Thank you! Your solution was really helpful and i understand a little more about ik rigs. It’s possible (i guess yes, but how?) to use only costrains instead of bones? I tried with them but the results where all “glitchy”…

Going off track a little. This special IK setting you get when IK is used under Bone property, what else can you use it for other than using it for a piston type of rigging? There are hardly any examples.

Ya, ok chipmasque, this IK property panel give you more control over how each bone segments reacts with IK target movement. Like with fishing rod, the tip is much more softer than the base. So with stiffness setting, you can control how rod, bones, bends from base to tip.