How to lock a line so it doesnʼt move while drawing in Autodesk Fusion?
Short Answer
Yes — in Autodesk Fusion, the most common way to lock a line so it does not move while drawing is to apply a Fix/UnFix constraint inside an active sketch. This pins the selected line’s position in the sketch. Limitation: it locks current geometry, but it does not replace proper dimensional constraints.
What You Need to Know Before
Warning: A fixed line can over-constrain your sketch if you also add dimensions or geometric constraints that try to control the same endpoints. This often causes sketch solve errors and makes later edits harder than necessary.
How to Lock a Line So It Doesn’t Move in Autodesk Fusion
Command: Fix/UnFix
Shortcut: None by default
Quick Steps:
- Edit or create a sketch, then draw the line in the Sketch workspace.
- In the Sketch Palette or Sketch toolbar, choose Constraints > Fix/UnFix.
- Click the line to lock it; Fusion will mark it as fixed so it stays in place while you continue sketching.
Use the fastest professional method: apply the constraint directly after creating the line.
Real option: make sure Show Constraints is enabled in the Sketch Palette so you can confirm the fixed constraint icon appears.
Variables & Settings
Key Setting: Show Constraints
Expert Setting: When Show Constraints is turned on in the Sketch Palette, you can immediately verify whether the line is actually fixed. If this display is off, users often think the line is locked when the constraint was not applied correctly.
Why it Fails
- Cause 1 (Geometry): The line endpoints are still being driven by other sketch constraints or dimensions, creating an over-constrained condition.
- Cause 2 (layers/Locks): The geometry is in a projected or linked sketch reference, so it may behave differently from normal editable sketch geometry.
- Cause 3 (Command/Logic): The line was not fixed at the sketch level, or the user expected body/component grounding to control sketch entities.
Quick Fix & Best Practice
- Quick Fix: Delete conflicting dimensions or constraints, then reapply Fix/UnFix only to the line or point that must stay stationary.
- Manager’s Verdict: Use Fix/UnFix sparingly for anchor geometry, layout references, or imported sketch cleanup. For production sketches, prefer dimensions and geometric constraints because they are easier to edit and more robust.
FAQ
Can I lock just one endpoint of a line in Fusion?
Yes — apply Fix/UnFix to the endpoint instead of the whole line.
Is Fix/UnFix better than dimensions?
No — dimensions are usually better for controlled, editable design intent.
Why is my fixed line still changing shape?
Because connected geometry, constraints, or sketch edits may still affect related elements around it.
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