AddJunction: behaves wrong with inclined endges

[matwey]

Describe your issue

Using the Pad tool, I created a truncated pyramid with a square base and a 45-degree face angle.
Using the Thickness tool, I generated a shell from it.
Using the AddJunction tool, I want to split one corner so that I can later unfold the shell along the three remaining corners.

The AddJunction tool is not working correctly (see screenshot).

FreeCAD version info + SheetMetal WB version

OS: KDE Flatpak runtime (KDE/plasmawayland/wayland)
Architecture: x86_64
Version: 1.1.1.44874 (Git)
Build date: 2026/04/14 22:09:59
Build type: Release
Branch: (HEAD detached at 1.1.1)
Hash: 0108fd4b4850cc46e625b60e53cea7a7bbe69f8d
Python 3.13.13, Qt 6.10.3, Coin 4.0.8, Vtk 9.4.2, boost 1_86, Eigen3 3.4.1, PySide 6.10.3
shiboken 6.10.3, SMESH 7.7.1.0, xerces-c 3.3.0, IfcOpenShell 0.0.0, OCC 7.8.1
Locale: Russian/Russia (ru_RU)
Navigation Style/Orbit Style/Rotation Mode: CAD/Rounded Arcball/Window center
Stylesheet/Theme/QtStyle: FreeCAD.qss/FreeCAD Light/
Logical DPI/Physical DPI/Pixel Ratio: 96/102.299/1
Installed mods: 
  * sheetmetal 0.8.20

Put here any screenshots or videos (optional)

[shaise]

@matwey ,

It is always a good practice to add a sample file to help debug but anyways:
The junction tool is very limited and indeed not reliable. But this is not the recommended workflow for your purpose.
Here is what I recommend:
Create a truncated pyramid solid as before do not use the thickness too. Do not use the tapper angle of the pad tool. It created a body with curves as edges. I do not know why. Just use sketches/pad/pocket.

In sheetmetal WB, select the top and bottom face of the pyramid and select the edge to be opened as well.

Now select the "solid to sheet" tool. This will immediately create a sheet metal object with all the necessary bends. Set the desired thickness in the parameters.

click one of the faces and flatten the part:

sample file:

pyramid.zip

[matwey]

Attached here is my sample design. I hope this will help to improve the plugin.

sheet_metal.zip

Thank you for the advice. I would have never figured out about the taper angle on my own!