Is a sketch ʼclosedʼ when it turns light blue in Autodesk Fusion?
Short Answer
Yes. In Autodesk Fusion, a sketch profile is generally considered closed when the area turns light blue, which indicates Fusion detects a valid enclosed profile for features like Extrude. The most common professional check is to start Extrude and verify the profile highlights correctly. However, appearance alone can still be misleading with overlapping or projected geometry.
What You Need to Know Before
Warning: A light blue region usually means Fusion sees a closed profile, but tiny gaps, duplicate lines, or construction geometry can still prevent the result you expect in downstream features. A profile may also look closed visually while producing multiple regions or selecting the wrong contour.
How to Check if a Sketch Is Closed
Command: Extrude
Shortcut: E
Quick Steps:
- Finish or stay in the sketch, then go to the Solid tab > Create panel > Extrude.
- Click inside the light blue sketch area and confirm Fusion selects the profile as a closed region.
- In the Extrude dialog, verify the Profile selection and check the Operation option is set correctly, such as New Body or Cut.
Variables & Settings
Key Setting: Show Profile in the Sketch Palette
Expert Setting: When Show Profile is enabled, Fusion shades enclosed sketch regions in light blue. If this toggle is off, a closed sketch may not display shaded at all, making visual verification less reliable.
Why it Fails
- Cause 1 (Geometry): Small gaps, overlapping segments, or endpoints that are not coincident prevent Fusion from recognizing a single closed profile.
- Cause 2 (layers/Locks): Construction geometry or projected geometry may appear to complete the shape visually but does not behave as regular profile-defining geometry in the expected way.
- Cause 3 (Command/Logic): The sketch can contain multiple enclosed regions, so Fusion highlights a light blue area, but Extrude may select a different profile than the one you intended.
Quick Fix & Best Practice
- Quick Fix: Turn on Show Profile in the Sketch Palette, then apply Coincident constraints to all intended endpoints and remove any duplicate sketch entities.
- Manager’s Verdict: Use the light blue fill as a fast visual check, but always confirm with Extrude before modeling production geometry, especially on imported or heavily edited sketches.
FAQ
Why is my sketch not turning light blue in Fusion?
Usually because the profile is open, or Show Profile is turned off.
Can a light blue sketch still fail to extrude?
Yes, if you select the wrong region or the profile contains problematic geometry.
Does construction geometry make a sketch closed?
No, construction lines do not normally create a usable closed profile for solid features.
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