Way to place a "hole" in footprint for reference only

After creating a pcb, I use the Export to step file option and then
import into FreeCAD for reference in making an enclosure.

The step file only has position information where there is a edge or hole. I would like to place
holes with the footprint editor that will not be in the gerbers but can be used
in FreeCAD.

In the footprint editor I have tried adding a NPTH hole, setting Copper:None, Technical layers:Dwgs.User and making the Hole size X match Size X:

But I get this message:

  • Error: the pad is not on a copper layer and has a hole
    For NPTH pad, set pad size value to pad drill value,
    if you do no want this pad plotted in gerber files.

If I set Copper:All with pad size and drill size the same, the gerber has the hole.

Maybe there is another way to put some type of reference on the footprint that can be
exported in the step file?


Application: Pcbnew
Version: 5.1.5+dfsg1-2~bpo10+1, release build
Libraries:
wxWidgets 3.0.4
libcurl/7.64.0 OpenSSL/1.1.1c zlib/1.2.11 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) libssh2/1.8.0 nghttp2/1.36.0 librtmp/2.3
Platform: Linux 4.19.0-6-amd64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
Boost: 1.67.0
OpenCASCADE Technology: 7.3.0
Curl: 7.64.0
Compiler: GCC 8.3.0 with C++ ABI 1013

Build settings:
USE_WX_GRAPHICS_CONTEXT=OFF
USE_WX_OVERLAY=ON
KICAD_SCRIPTING=ON
KICAD_SCRIPTING_MODULES=ON
KICAD_SCRIPTING_PYTHON3=ON
KICAD_SCRIPTING_WXPYTHON=ON
KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
KICAD_SCRIPTING_ACTION_MENU=ON
BUILD_GITHUB_PLUGIN=ON
KICAD_USE_OCE=OFF
KICAD_USE_OCC=ON
KICAD_SPICE=ON

You could place fiducials which exist for positioning purposes.
They don’t have holes. It’s like a specialized ‘smd pad’.

You just add them to your schematic in some out of the way place.
They will need a footprint to show up on the pcb.
Symbol and footprints are already part of the standard libraries.

Did not think of fiducials at all. That works very well, not in the gerbers but in the step file.
I did notice fill zones sees them and could find find a way to avoid.

But that is a small price to pay for the convenience.

Thanks a lot.

Do your footprints not have 3d models? Or does the step export not include them? Because i would really not add something to the design just to have a reference point for 3d modeling. This would be best done in the 3d models assigned to the footprints.

Oh and are you aware of the stepup extension for freecad? Kicad StepUp: a Seamless ECAD/MCAD PCB Data Integration

I have never used 3d models assigned to footprints so I added a 3d model to a switch footprint I need a center reference to which does not have a center pin and that worked very well.

I was not aware of the extension for FreeCAD and will give it a try.

I had always thought of the 3d models in Kicad as more for visual purposes but I see that is not so at all.

Thank you so much for suggesting them.

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