How to spot it
- Blender 3D Print ToolboxIntersections: “some slicer applications can deal with this, so it’s not always required to resolve this issue”3D Print Toolbox wiki
- UltiMaker CuraUnion Overlapping Volumes is on by default and merges crossing volumesCura 5.13 definitions
Why it happens
- A surface folded through itself by an edit or a sculpt
- Boolean operations that left crossing faces behind
In our tests
22/ 87
87 of the 198 public test files had crossing faces. After FixSTL’s repair, 22 were free of them.
The hardest problem in the test: no tool repaired more than a quarter of these files.
Public Thingi10K test set, FixSTL engine 0.6.0 (a7ea280), default repair. How we test
How to fix it
What FixSTL does
- Cuts out the crossing faces with a ring around them and fills the opening, if the patch spans under 15% of the model and the surface moves less than 1%
What it leaves
- Separate parts pushed into each other, and boolean leftovers
- The basic check, used when your browser cannot run the full one, does not look for crossings
Elsewhere
- Blender Boolean modifier, Union, for parts that should be one
- Source model Undo the edit that folded the surface and export again