If you need to fix any parts of your assembly in place (or just lock certain translation or rotation axes), you can use the
The only required input for this component is the Frame identifying the rigid body you want to anchor.
You have the option of setting a Target frame, for if you want to lock it somewhere different to its original location, but if you leave this input blank it locks it in place.
With the target frame you can also move it during simulation from Grasshopper, with a slider for example.
Here’s a simple example definition:
assembly_support.gh (19.4 KB)