How can I make curve segments into a single curve such as a radius or circle

When I unbend a 3D STEP model into a 2D blank with another software (Varicad) and import the resulting 2D DWG into rhino, I have a bunch of curve segments that should be fillet radii or circles, I know you can join these segments into a single curve, but when I Import the DWG into my laser cutting program, it only sees the curve segments & ocasionally it will see these as point to point lines. Any Ideas?

Any help? Ive tried SMOOTH, but its not what I want.

Can you post a small sample of the unbent curves to test? --Mitch

examples.rar (283.7 KB)

Here you go…The one titled “before saving to dwg” is how it comes from my unbending software. The one called after saving to dwg is nothing more than me taking the file & saving it to a dwg in rhino. It seems to break the curves up even more when I do this & it drives my laser software crazy.

If I could just get it to fit the closest arc in each radii & ciecle, I would be happy.

Thanks again.

So it’s obvious that the main problem is your “unbending” software. In your file “before”, note that one small segment - which looks like it should be an arc - as actually a polyline with 120 points. And everything else in the file is like that except for the long straight sections…

What I did was this:

  • Lowered the file tolerances temporarily to 0.1 (temporarily!!!)
  • SelLine to select all the long lines and Lock
  • Select all and Join (will join as much as can be joined)
  • Select the result and use FitCrv to convert the polylines into NURBS curves (DeleteInput=Yes)
  • Select the result and call SimplifyCrv. All the arcs should now be arcs. Unlock all.
  • Reset the file tolerances to .001!
  • Either Join or not the outer border (depends on your fabricator)
  • Then export DWG with the correct scheme - I used “2004 Natural”

The result in Rhino V5 format and dwg below…

Simplified.dwg (16.8 KB)
Simplified.3dm (47.0 KB)

HTH, --Mitch


Thank you Mitch! I will give it a try. It looks like something I can make a macro out of.