FreeCAD / FreeCAD/FreeCAD

Broken geometry exporting a solid derived from an arc of ellipse to a step file

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#14,447 5 comments 0 reactions 0 assignees View on GitHub
File format: STEP Help wanted Mod: Part Mod: Part Design Status: Confirmed Type: Bug
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Description

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Problem description

1. Create a sketch on the XZ plane.
2. Create an arc of ellipse centered on the origin. The exact dimensions don't seem to matter much, but place the major axis on the x axis.
3. I did 32 mm for the major and 12 for the minor axis. Draw the arc across the 1st quadrant from the Y axis to the X axis.
4. Close the sketch and revolve 360 degrees in the Part workbench creating a solid.
5. Export the revolve as a step file.
6. In a new document, import the step file from step 5.

It will take a long time to complete and the solid will look like a fusion of the dome and it's mirror over the XY plane.

When I create the arc with the major axis on the Y axis, it works normally. If I convert the arc to a B-spline, it works normally.
Creating a primitive ellipsoid and splitting it in half with a plane in the Part workbench also works.

### Full version info

```shell
[code]
OS: Ubuntu 18.04.6 LTS (XFCE/xfce)
Word size of FreeCAD: 64-bit
Version: 0.21.2.33771 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 0.21.2)
Hash: b9bfa5c5507506e4515816414cd27f4851d00489
Python 3.10.13, Qt 5.15.8, Coin 4.0.0, Vtk 9.2.6, OCC 7.6.3
Locale: English/United States (en_US)
Installed mods:
* fasteners 0.4.55
* ThreadProfile 1.89.0
* Curves 0.6.8
* 3D_Printing_Tools
* lattice2 1.0.0
* Silk 1.0.0
* Assembly4 0.50.6
* A2plus 0.4.61
* CfdOF 1.21.6
* fcgear.backup1677967119.4973533 1.0.0 (Disabled)
* fcgear 1.0.0
* sheetmetal 0.2.61
* Render 2023.8.18
* CurvedShapes 1.0.5
[/code]

Also tested with same version on MacOS and FreeCAD_weekly-builds-37464-conda-Linux-x86_64-py311.AppImage on the Ubuntu box.
```

### Subproject(s) affected?

None

### Anything else?

[Ellipse.zip](https://github.com/user-attachments/files/15524450/Ellipse.zip)

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

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Assessment

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