Smoothing lines


I am hoping you might be able to help me with this drawing, I have used it to make the former with a CNC machine but the machine is a bit jittery so i am hoping there is a way to smooth these lines out. Could it be an export issue with resolution perhaps? Any thought hugely appreciated.Rear former pair…3dm-James…3dm (102.3 KB)

Here is the file.

Many thanks,


You didn’t mention what intermediate file format you used - and that is probably where the issue arises. The curves are degree 3 and as such ‘smooth’ (*) in Rhino.

(*) everything is relative - If you look at the curvature graph in Rhino you will see that the curves are not necessarily very smooth but I don’t think that is what you are talking about here…

Thanks Wim, just the standard rhino file, should i try exporting in say, STL. What would be considered the best way of preserving the smoothness from my drawing to the CNC company?

The STL format doesn’t carry curves - only meshes. Preferably you’d use a format that carries splines / NURBS.
You should check with the CNC company what file formats are used - that will give you a good start (but perhaps not the final answer).

i have quite a few components CNC cut or laser cut from outside companies, if it is just flat 2d profiles being machined I always export to DXF format, never had any issues to date, I always supply them with a PDF document of the drawing too, with all the basic dimensions so they can quickly check no scaling problems

Thanks for your replies, the forms will be made “solid” as these will be formers so 3d carved objects, the machine is jittery around the curves.

might be a good idea to just ask your CNC company what file formats open best in their CAM software, I’ve also had a few things done on 5 axis CNC, if I remember correctly IGES and STEP files seem quite versatile