DXF issue (Onshape -> Estlcam)

I’m trying to make some gears with ma MPCNC. But I can’t make a correct dxf to do that.
Look at the pictures, I often have this problem each time I try to have some ‘curves’ in my sketch. I don’t know if the problem comes from Onshape or Estlcam.
In Onshape, I tried all types of DXF (Release 14, 13, 12, 2000, 2004, etc…).
If I import back the exported DXF in Onshape, I’ve no error.
If I import the same DXF in Freecad, I’ve got something even stranger.

Has someone an idea about the problem I have? Is it Onshape or Estlcam which is the problem?
I searched several hours on internet to find an answer, but it doesn’t seem to be a famous problem.

Any idea is welcome, because I 'm stuck in the early beginning of a project…

I tried another way to make Gear in Onshape. The result is “artistic”…Pictures below…

I find a way (a real boring way…):
-Rotate the part in Onshape to be in the ‘Top Plane’.
-Export the part in IGES format
-Open the IGES in Freecad
-Export as DXF with Freecad
-Open it in Estlcam, it works now

So, the problem seems to come from Onshape. That’s sad, because I only use that now…
At least I can work again, but if somebody have another easier way, you’re welcome.

I’ve got a response from Onshape Team:
Today we do not export spline data as splines but as poly lines in the DXF/DWG format. I have added you to the request for this type of support. ~Lou

Your support ticket:

“DXF export issues”

has been marked as an improvement request. Onshape development will evaluate the request and we will notify you if/when this has been implemented. Thank you for helping us make Onshape awesome!

If some people have the same problem, now you know there is a boring way to do it ;=)

Please include me in this issue. I have the same desire and need to export spline data as splines. My primary use of Onshape was to model and work with gears.

You have to do it from your Onshape account (even if it’s a free plan). More people ask for it, faster they will work on it.


can you send me the .dxf file so I can have a look at it?


I send you a gear, but it’s the same with an half circle: if I draw my half circle clockwise it will work on estlcam, but anti-clowwise it’s not a the good place (or the opposite, I don’t remember). No problem with circles.

Copy-2-of-Part-Studio-4-Face.zip (14.3 KB)


I’ve just opened the file with LibreCAD and it shows the same issue.


Has this been resolved yet? I just exported a dxf from Onshape to go to Estlecam and it is stepped instead of curved…

Have attached the Onshape sketch and the Estlecam output.

Screenshot 2022-08-14 122654
Screenshot 2022-08-14 121705

Found the solution… smooth fillet corners need to be ticked