DXF Polyline export format question

Hi there,

I have a question related to DXF export for a specific machine at one of our client’s production facilities. It is a machine that shoots little holes into wood using lasers, but that’s not really the issue here.

We export a large batch of DXF drawings from Rhino for them and this specific machine doesn’t accept them. What they tell me is that AutoCAD shows the polylines exported by us as either “3D-Polyline” or “2D-Polyline”, but what they need is just “Polyline”. When they explode the polylines in AutoCAD and weld them again, the machine accepts the file just fine.

Having done some research, it seems what the machine needs is the polylines being exported as what’s known as a “lightweight polyline” or “LWPOLYLINE” entity. This has replaced the previous “2d-Polyline” with AutoCad release 14 and has been the standard since 1997 (!).

I have now tinkered with the Rhino DXF settings for a day and for the life of me I can’t get it to export “Polyline”/LWPOLYLINE. Is there any way I can get Rhino to do this?

Any help is appreciated!


*This post was edited as I found out about the “LWPOLYLINE” definition.

@lowell, is this something you can help with?

I have been having sort of the same issues with my waterjet and cnc router. I think my fix was a bit easier. However both bits of kit also except dwg. Which for some reason (the reason being over my head) work better more often. Is dwg an option for your lazer?

Hi @doubleclick, thanks for your suggestion but DWG’s are not currently an option for me.

Hi @dale and @lowell,

do you see any chance to solve this within Rhino? Otherwise we might have to buy an AutoCAD license and either learn to script it very fast or do a lot of manual clicking in the next few days. But that would be a real setback to our approach of handling these types of data using Rhino.


@snabela: please keep watching this thread.

Hey @mathias , the developer who knows all about this is out on vacation. I’m sure he will chime in when he returns.

– Dale

Ok thanks @dale, can’t wait!

Mathias - Just confirming what you found - Rhino doesn’t export LWPolylines, but does export Polylnes.
It would be possible for us to write LWPolylines. It would require adding a switch in the options to select which type to write since I’m sure Id hear from people who can’t use LWPolys with their software.
That’s not likely to happen for v5, but I can add it for V6.

@lowell, thanks for the update. Well, we are currently working to solve our particular problem using AutoCAD, but judging from our experience it would definitely be a nice option to have for DXF export.

I added that option - a checkbox to use LWPolys when possible - to the V6 WIP.