I found this post, which suggests it's not just me but this is a little old and hopefully they're working by now... http://forum.unity3d.com/threads/joints-in-unity-5-are-very-unstable-and-its-not-just-me.319084/ I'm testing out using physics and forces to control my characters. Ultimately it looks like the Final-IK plugin is what I want to use for procedural walking animations and character animation control, but I want to start by prototyping my game using very basic things. So I created a simple 6-legged robot model out of a rectangular prism for a body and 6 sets of legs of 3 segments each. I made an empty object and added them to it and then made a box collider and a rigidbody for it, and then for each leg segment I made a rigidbody and on the 'foot' segment I also added a box collider. I used a chain of fixed joints to link the leg segments up to the body rigidbody.... And when I press play it drops a couple inches to the ground and then the legs start freaking out and wiggling all over the place and the whole thing and the whole thing bounces around. Are there any tutorials out there on how to set up a multi-piece fixed jointed object? Most of the physics tutorials out there are too simple and just apply forces to spheres and stuff.