Issue with Linear Pattern in the Part Design workbench when replicating an Additive Pipe based on an elliptical path.

[FreeCAD-Bug-Importer]

Issue imported from https://tracker.freecad.org/view.php?id=4781

• Reporter: @vectronic
• Date submitted: 11/8/2021
• FreeCAD version: 0.2
• Category: Bug
• Status: new
• Tags: Part Design

Original report text

I am trying to use Linear Pattern to duplicate a flange on a pin. The flange is created using an additive pipe which uses a path sketch involving an ellipse.

This doesn't work.

I have queried in the forum to see if this was:

• a known bug (doesn't seem to be)
• more experienced users can get it to work (they can't)
• more experienced users thought it might be a bug (they do)

Forum link: https://forum.freecadweb.org/viewtopic.php?f=3&t=63409

I have taken my sample from the forum, improved it based on their feedback and simplified it a lot more. I have also included a comparison of using a circle (instead of an ellipse) for the additive pipe path and this seems to work fine with the linear pattern feature.

In the linear-pattern-attempt-1.FCStd you will see:

• attempt-1-01.png : Linear pattern of a pin and a flange based on a circular path is rendered.
• attempt-1-02.png : Another flange based on an elliptical path is added to the first pin.
• attempt-1-03.png : When another linear pattern for the elliptical flange is added, the result is not as expected.

In the linear-pattern-attempt-2.FCStd you will see:

• attempt-2-01.png : A pin with a circular flange and elliptical flange is created first.
• attempt-2-02.png : If I try to create a linear pattern involving all of these at once (the pin, the circular flange and the elliptical flange) the linear pattern dialog displays an unexpected error.
• attempt-2-03.png : The final result is not as expected.

Additional information

Screenshots: https://f001.backblazeb2.com/file/vectronic-public/freecad/screenshots.zip attempt-1-01

attempt-1-02

attempt-1-03

attempt-2-01

attempt-2-02

attempt-2-03

Sample models: https://f001.backblazeb2.com/file/vectronic-public/freecad/models.zip models.zip

Steps to reproduce

Open the linear-pattern-attempt-1.FCStd file and observe that:

• the linear pattern using the feature of an additive pipe based on a circle path sketch IS rendered.
• the linear pattern using the feature of an additive pipe based on an ellipse path sketch IS NOT rendered.

OR

Open the linear-pattern-attempt-2.FCStd file and observe that the linear pattern including both additive pipes is rendered incorrectly.sketch is not rendered.

FreeCAD Info

OS: macOS 10.16
Word size of FreeCAD: 64-bit
Version: 0.20.Unknown
Build type: Release
Python version: 3.9.7
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.3
Locale: C/Default (C)

Other bug information

• Priority: normal
• Severity: major
• Category: Bug
• OS: MacOS 11.6
• Platform: Intel
• Updated: 11/8/2021

[luzpaz]

Renamed forum thread

[DrD4ffy]

Hi,

I am not sure if it is directly related to this issue, because it does not involve an additive pipe, but I think only the devs can say if the additive pipe or the linear pattern is the root cause.

It is definitely another example of "shapes created by linear pattern" are not correct. I came across this issue while following some Fusion 360 tutorials using FreeCAD. FreeCAD is not Fusion360, thats perfectly OK. But I could reduce the issue to a very simple example file, where I think you can expect the linear pattern to work.

I modelled a short pipe and wanted to create some sort of lamellas on the outside. So I created one at the bottom and used linear pattern to reproduce it ~30 times along the pipe. It looks good on the outside, but if you look on the inside you see some strange shapes:

I attatched the FreeCAD file: LinearPatternIssue.zip

I found it first in the latest dev version but also in the current release.

OS: Windows 10 build 19045
Word size of FreeCAD: 64-bit
Version: 0.21.2.33771 (Git)
Build type: Release
Branch: releases/FreeCAD-0-21
Hash: b9bfa5c5507506e4515816414cd27f4851d00489
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.3
Locale: German/Germany (de_DE)
Installed mods: 
  * Curves 0.6.21
  * fasteners 0.5.0
  * IconThemes
  * OpenDark 2023.12.17
  * OpenDark.backup1704310892.017628 2023.10.30 (Disabled)
  * PieMenu1291 1.2.7
  * Pyramids-and-Polyhedrons
  * QuickMeasure 2022.10.28
  * Render 2023.12.28
  * sheetmetal 0.3.15
  * ThreadProfile 1.89.0

OS: Windows 10 build 19045
Word size of FreeCAD: 64-bit
Version: 0.22.0dev.35570 (Git)
Build type: Release
Branch: main
Hash: 3ba0c3d7958dad891e125e065a41d95faac47c6e
Python 3.10.13, Qt 5.15.8, Coin 4.0.2, Vtk 9.2.6, OCC 7.6.3
Locale: German/Germany (de_DE)
Installed mods: 
  * Curves 0.6.21
  * fasteners 0.5.0
  * IconThemes
  * OpenDark 2023.12.17
  * OpenDark.backup1704310892.017628 2023.10.30 (Disabled)
  * PieMenu1291 1.2.7
  * Pyramids-and-Polyhedrons
  * QuickMeasure 2022.10.28
  * Render 2023.12.28
  * sheetmetal 0.3.15
  * ThreadProfile 1.89.0

[DrD4ffy]

I talked about the linear pattern with a more experienced colleague who is using 0.19. Interestingly, he pointed out to me that the example I posted shows no errors in 0.19. Attached is a screenshot of the same file with 0.19. ''' OS: Windows 10 Version 2009 Word size of OS: 64-bit Word size of FreeCAD: 64-bit Version: 0.19.24267 +148 (Git) Build type: Release Branch: Branch_0.19.4 Hash: 476ecf091941bead59b14e44afa6064d5a66afa3 Python version: 3.8.6+ Qt version: 5.15.2 Coin version: 4.0.1 OCC version: 7.5.3 Locale: German/Germany (de_DE) '''