FreeCAD/FreeCAD

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

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#14,447 opened on Jun 2, 2024

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 (5 comments) (0 reactions) (0 assignees)C++ (5,550 forks)batch import
File format: STEPHelp wantedMod: PartMod: Part DesignStatus: ConfirmedType: Bug

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Description

Is there an existing issue for this?

  • 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

[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

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