3d view cannot detrmine board outline when it is a DXF import

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I imported a dxf file as an irregular outline for the board.
The DXF is at the board outline layer
When I try to view it in the 3d viewer I get a message that the board outline cannot be determined and it displays a rectangle that roughly encloses the components.

Is it a limitation of the viewer or did I do something wrong during import?
I do notice that the imported outline is drawn much thicker than when you manually draw it inside Pcbnew

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Is it a limitation of the viewer or did I do something wrong during import?

It’s (most probably) a general limitation of the dxf-import and the requirements for board-outlines:

  • there are restrictions / requirements to the board-outline. These have to be respected.
  • The FAQ-article shows the important things: (How to define the board outline, PCB edge)
  • The DXF-shape must fulfill all the points regarding the board-outline
  • some pitfalls from dxf-import-issues from the last month in the forum:
    • the lines/arcs/segments forming the outline are not exactly forming a closed shape (it’s not enough that it looks visually closed - the coordinates of succesive line-segments have to be exactly the same)
    • double outline - the DXF consists of a doubled contour-line instead of one line.
    • using to new-fashioned features of the DXF-file-format. The dxf-importer only supports a small subset of dxf-features. So it’s sometimes a good idea to save the dxf-file as “old”-dxf-format. If possible try DXF-R12. This has a reduced feature-set, but the chance of correctly importing this is higher.

I do notice that the imported outline is drawn much thicker than when you manually draw it inside Pcbnew

Two possibilities for this:

  • the line-width is already defined in the DXF-file (this depends on the CAD-software used to create the dxf-drawing). Than Kicad respects that setting and imports the lines with exactly that linewidth. So you should set the linewidth correctly in the CAD-program prior to saving the DXF-file.
  • If the CAD-software has not defined a linewidth in the dxf-file, than Kicad uses the “default linewidth”-parameter in the import-dialog. So you can change this value during the import-step.
  • For the real board-outline the line-width on edge.cuts is not important, the outline is calculated on the drawed middle of the line.
  • you can also select the imported shapes after the import-action and change the linewidth with the line/polygon-tool-dialogs.

If you can’t resolve the dxf-import-problems: attach the demonic dxf-file and we can also look at it.

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Thanks
I will take a closer look at the dxf and see what has to be changed

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OK - Solved.

Indeed, for each line and arc in the DXF there were 4 overlapping instances in Pcbnew, so after I removed the 3 extra everything works OK.

I used Freecad, and did there the export quite some time ago so I do not remember exactly how. However now I tried again and this time exported it through the TechDraw workbench and the imported DXF has only one instance for each feature (It is also a newer version of Freecad so maybe something changed).

It could be an issue of layers - in the old dxf file I see two layers and in the file I exported today only 1.

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