What is a ʼRigid Groupʼ in Autodesk Fusion?
Short Answer
A Rigid Group in Autodesk Fusion is a joint relationship created with the As-Built Joint command that locks selected components together so they move as one solid unit without relative motion. It is the fastest professional way to define fixed behavior in an assembled position. Limitation: it does not allow any mechanical movement between grouped parts.
What You Need to Know Before
Warning: A Rigid Group only works correctly when components are already in the right position before you apply it. If parts are misaligned, Fusion will lock the wrong assembly state and can break downstream motion studies or joint logic.
How to Create a Rigid Group
Command: As-Built Joint
Shortcut: None by default
Quick Steps:
- In the Design workspace, go to the Solid tab > Assemble panel > As-Built Joint.
- Select the two or more components that are already positioned correctly in the assembly.
- In the dialog, set Type to Rigid, optionally enable the Flip option only if needed for orientation review, then click OK.
Variables & Settings
Key Setting: Type = Rigid in the As-Built Joint dialog
Expert Setting: This option removes all relative degrees of freedom between the selected components while preserving their current placed position. It is the standard choice when hardware, welded parts, or purchased subassemblies should behave as one unit.
Why it Fails
- Cause 1 (Geometry): Components are not already positioned correctly, so the rigid relationship locks an incorrect placement.
- Cause 2 (layers/Locks): One or more components are grounded or linked in a way that conflicts with the intended assembly behavior.
- Cause 3 (Command/Logic): Users apply a Rigid Group where actual motion is needed, causing joint conflicts or preventing mechanism simulation.
Quick Fix & Best Practice
- Quick Fix: First use Move/Copy to place components correctly, then reapply As-Built Joint with Type = Rigid.
- Manager’s Verdict: Use Rigid Groups for fixed subassemblies, fasteners, and non-moving part sets. Avoid them in mechanisms that will later need revolute, slider, or other motion joints.
FAQ
Is a Rigid Group the same as grounding a component?
No, grounding fixes a component to world space, while a Rigid Group fixes components relative to each other.
Can a Rigid Group include more than two components?
Yes, you can rigidly relate multiple components so they behave as one unit.
Can I edit a Rigid Group later?
Yes, you can edit or delete the As-Built Joint from the timeline or browser.
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