Hi - without a specific file, this is a rather general question. The general answer is that the reason is that either the object type is not supported by the DXF file format / export scheme OR the object is bad in some way.
For the specific case of your example, I will answer that in your other thread.
I’ve just found this solution (and that in the other thread). Can you offer a guesstimate on when the patch would be ready to fix this issue?
If it’s more than 6 months away then I’m going to need to come up with a workaround in the meantime. If it’s close, then I can probably put up with it for the meantime.
Sorry for the delay in the answer.
At this point, I’m not sure what the fix will be. Also, it’s not a regression from Rhino 5, nor a crash bug, and so this is on the table for Rhino 7.
That said, I’m not sure what the problem is that you are looking at. In the case of the OP, there was a short curve segment in a profile that was 1000 times shorter than the document tolerance. Somehow, this short segment was used in the creation of a solid. That solid was then dropped when exported to DWG/DXF.
So, as long as you have clean geometry, you should be able to export to DWG/DXF.
Thanks for the reply.
As far as I could tell, I’m having the same issue. The report that I get from hitting F2 tells me one of the resulting lines is length = 0. I’ll keep testing it, but for now, it appears random, though I suspect it might have to do with crossing a curve (giving a ‘point’ rather than a line?). Most of the surfaces I’m working with are develop-able surfaces for boats, so modeled cleanly and properly. That being said, the model is made in an older version (Rhino 4 I believe).
Try _SelSmall or _SelShortCrv to find tiny objects/curves. Also _SelBadObjects to see if there any invalid objects - they will not be exported.
The problem in the case that I filed is that _SelBadObjects doesn’t select the profile curve with the short segment nor the resulting polysurface. I don’t know how the curve was made but exploding it and, with all segments selected, joining it again excluded the short segment from the result.
Yep, that’s usually the case… there is an automatic function built-in. And yes, the curve should be flagged as bad, and the best case would be that Rhino should refuse to create surfaces from it before it is fixed - as nothing useful that I know of can be gained from keeping it that way.