Parenting a bone to another bone and keeping the other end locked in place

I tried to draw what i have in mind. The bone in the middle is the parent, the bones on each side should be parented to it and they should follow its location/rotation. I was able to achieve that with “child of” in the bone constraints tab. But i can’t figure out how to make the other end of these bones be locked in place. I hope what i’m saying makes sense. The points that i highlighted in blue should be immobile or preferably follow a different bone, and the points i highlighted in red should follow the bone in the middle


I think you should be looking at a damped track constraint, targeting the bone in the middle’s tail. (And the tracking bones should be unparented, or parented to the middle bone’s parent.)

But I’m not very clear on what you’re saying, that’s just my interpretation of what you want.

If you want the fixed bones to stretch, which it would have to if you moved your location, put another bone at the blue location on each and add a stretch to constraint to keep it there. Then you can just parent the side bones to the middle bone. Throw a root bone in for the whole mess and your good to go. But it really is not clear what you want to accomplish. What’s the rig for?

I’m trying to make a gimbaling engine. It would be controlled by the bone in the middle. The other two bones are supposed to be thrust vector control actuators. From the outside they should look like they’re attatched to the thrust puck above, but with some degree of movement at the bottom where they’re connected to the engine

Something like this should work for you. You will need to add and position your bone shapes so that they are easy to grab. Use root to move everything and use the nozzle mover to move your nozzle. Your actuators will need to be created and positioned so don’t be afraid to add a few bones to get a collapsible cylinder mesh to represent the actuators for them.rocketnozzle.blend (864.7 KB)

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Hey, Here are pics showing that set-up, its a little bit more than your drawing

So hopefully you see the parenting in the outliner, the TVCA_CTRL rotates only on the Z axis and all the other TVCA bones ‘Copy’ rotation in local/local space - note their names, that is their ‘bone roll’, that does the vectoring. The Nozzle bone rotates on the X and Z only to rotate all of it. Post back if you have any questions.

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@ajcdfin, @stilltrying this is exactly what i was looking for. thank you so much!