Importing splines from DXF file to kicad from Fusion 360


So basically I’m trying to import this outline that I made in fusion 360 to kicad that contains spline lines and when I import it to kicad it the splines simply don’t show up as shown:

Original Fusion 360 file:

KiCad import:

at the manual
you need to Explode splines and save dxf as R12

6.1.2. Using a DXF drawing for the board outline
As a first step, any POLYLINES need to be split (Exploded) into their original simpler shapes. In LibreCAD use the following steps:

  • Open a copy of the DXF file.
  • Select the board shape (selected shapes are shown with dashed lines).
  • In the Modify menu, select Explode.
  • Press ENTER.

but recently a new option is available, if you dare to use FreeCAD

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Well thanks but I’ve tried the simpler looking LibreCad method (Sins I didn’t quite get what you have to do in FreeCad) and when I import my shape it kind of misses the fillets in the edges making it an open vector sketch.

so sometimes it could be easier to learn the new way :wink:

Yeah so I’m stuck here after not understanding the interface of free cad at all and imported the step file.

How can I extract a sketch of this face and import it to kicad? also when I import the DXF file it doesn’t show me an ability to choose “sketch”.

and here I am with the DXF:

ok, so it comes the tricky part, only because your file is not natively done in FC, and so you need to convert your design to FC sketch.

  1. is it fine to convert what you get from the STEP import in FC (I’m referring to the first image) to a pcb edge?
    EDITED for a faster way
    The following process is intended to convert your STEP model in a Sketch in FC
    A) import your STEP model
    B) go to ‘Draft WorkBench’ and after selecting the STEP model, go to Menu ‘Draft’ and select ‘Shape 2D View’
    C) select the ‘Shape2DView’ object and export it as ‘Autodesk DXF’
    D) import back the DXF in FC using legacy importer and set the importer to treat spline as polylines
    E) then install the Macro ‘DXF to Face and Sketch’ through ‘Tools’, ‘addons installer’ and open the file Macro_DXF_to_Face_and_Sketch.FCMacro in FC
    F) select the ‘SHAPE2DVIEW001’ imported object and switch back to the ‘Macro_DXF_to_Face_and_Sketch.FCMacro’ and run the macro (Ctrl+F6’)
    G) then you should have your Sketch
    N.B. all this steps are not required if you design your pcb edge directly in FC

Now the StepUp part:

  1. select the Sketch and click on the ‘push PCB edge to Kicad’ button and select your kicad_pcb board
    (it is assumed in that procedure that your kicad_pcb file exists and it is empty)

That should be enough for your conversion.
I admit it is not straight full, but this is because your spline comes from an external sw that needs to be converted to a different sw. Starting from FC everything would be just one click ahead.


Lost you at D and when I export and import the thing it does actually show the sketch.

that’s fine … probably you have an import setting that simplify the Sketch creation…
could you please post your DXF import options?

so from your sketch you should be able to push the pcb edge in kicad

Not sure how it but this is what I got.

use these settings:

then follow steps from E)
(the macro could takes long to finish the job)

ok, sometimes a picture speaks a thousand words
NB this is working only with FC0.17

and here the Macro
Macro_DXF_to_Face_and_Sketch.FCMacro (9.2 KB)

this new macro is approximating bsplines to arcs
dxf2shape.FCMacro (11.7 KB)


Short story: use “polylines” rather than splines. Splines are not supported in KiCad and after much deliberation on a number of occasions the unanimous consensus is that splines will never be supported as an entity within kicad. That doesn’t mean that the DXF importer will never support it, but if anyone adds that feature they will need to approximate splines using a series of arcs (this would be much better than the alternative which is approximating splines with a ridiculous number of straight segments). Anyone want to volunteer to write spline code?

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FC can do it; I updated the macro to convert bsplines to arcs…

but in general I would suggest to use FreeCAD to design the Edge to have a simpler integration with KiCad
All those steps are required just to convert an external design to a sketch in FC instead of just designing the sketch itself in FC and pushing it to kicad with a single click
Ellipses and BSplines are allowed


Yeah well thanks I’ll try that later but even just importing and exporting the DXF file from FreeCad does the job thanks!

I included the macro in StepUp workbench, so now the process to convert a DXF or even a SVG with bsplines to KiCad it is much easier.

The conversion will approximate bsplines with arcs, to have a gerber generation even better than a fine discretization of the curves.


Hi I actually just walked around it by importing it to FreeCad and just export it then kicad can read it somehow.

But I’ve came across anther thing I want to be doing which is importing a dxf file in a thicker(or just different) line width(did the width change or weight in AutoCad) and the shape remains but the width also stays the same.

Maybe I’m doing something wrong? if so how would you do that?

I’m not sure if line width is supported in KiCad dxf import…
A workaround is through the scripting code you have already reached in another post…