Rigging telescope with pistion

Tried to do some rigging for a new crane.
I have made a simple setup to test the rigging see attachment.
When I grab the ending to stretch the telescope I don’t want to stretch the piston _up2 bone.
How do I prevent that.
piston_telescope.blend (688.4 KB)

I’m not completely sure that I understand what you need, but this might help you: https://m.youtube.com/watch?v=yxQlIbFdKU0

Sorry thats not giving me the answer.
I have to connect the piston to the first arm. But that one is stretching which is good for telescope but not for the piston.

I think I have to make the telescope rig part again only now with a transformation constraint. That might work.

If you don’t want piston_up2 to inherit the scale of its parent, Bone, disable “inherit scale” in properties/bone/relations.

If, at that point, you want piston_up2 to scale in its local Y to reach piston_bottom_2, give piston_up2 a stretch to constraint. This will be easier to do if you reposition piston_up2’s tail to lie on either the head or tail of piston_bottom2.

You have some dependency loops btw. You should take care of those before you get deeper. Check out the console.

Thanks this is just a sample model for testing.
I have already made a handler piston bones against dependency cycle.