Exporting files as dwg or dxf?

Hi folks,
I finally bought Rhino. what a great program. I’ve been using it a bunch for ornamental iron designs.
Now I need to export my drawing so that I can send it to a steel supplier to cut out pieces from a plate.
When I do an export as a dwg or dxf file, the resulting file turns out blank. I don’t know anything about AutoCad so I don’t know how to edit any of the settings. I am probably missing something simple. Help?
What I’m doing is taking a 2D drawing from the top view and selecting the things I’ve drawn.

Can you post your 3dm file here?

When you select all those “things” that you have drawn, what does Rhino say you have selected?
The best way to get support here is by uploading your 3dm file! This is a helpful community :wink: but you might end up writing a book to convey the same message as a simple file…

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base-anvil-plates.3dm (28.4 KB)

I think I’ve attached the file. This is a very simple thing with a 2’x3’ rectangle and 9 25"x11.5" rectangles surrounded by a 4’x8’ rectangle. In the command it says to select the items and then press enter. I drag the cursor over all the rectangles so that they are high lighted, and press enter. Come to think of it I’ve never looked at the line where Rhino says what happened as a result.

When I open that file and export the curves to DXF, I get the following file - which imports fine back into Rhino…
base-anvil-plates.dxf (169.3 KB)

yes, when I took that file I could import it into Rhino. But my steel supplier is not using Rhino. He’s probably using AutoCad. When I import the file into a drawing package like DraftSight it is indeed blank.
I’ve got a friend who has AutoCad. I’ll send him the file and see what his reaction is.

The entities are black, which, won’t show up against the AutoCAD default Black background. Change the entity color, or have your customer do a “Select All” and change the entity color themselves.

Thanks for the hint about the entity color. That is very likely the problem I was having with DraftSight as it’s default background is black in “model” space, but I found I could see the things in “layout”. Never have understood the concepts of model vs layout.
But I did send the dxf file (which it turns out is what my steel supplier wants) to a friend with AutoCad and he was able to open it and see the thing properly scaled. He put a dimension on it and saved it as a pdf file and sent it back to me so I could verify that he saw it correctly. So I think I am okay at this point. But I will change the color of the entities which maybe will avoid future issues.
One other question though. I’ve used the default settings for exporting. Hopefully this should be okay? Again I don’t know about AutoCad and really don’t want to have to learn about it.
Many thanks, for the help.

If you work with curves/splines at some point you may need to convert them to arcs to be compatible with CNC cutting (ie plasma, laser, waterjet,)


Thanks for this suggestion. I am thinking that the best way to work with this is to work with my steel supplier if I can. I’ll try to develop a good working relationship with them so that they can flag me when they see issues. Sound right?

The supplier should tell you if they have to convert splines to arcs for their equipment. There are some tolerance settings in the conversion and its better to do it yourself so you can see how they convert.

However, I have seen cases where that doesn’t happen, and the spline gets converted to a polyline, with lots of little line segments, so you see a facetted edge on the part.

So it might be a good idea to clear that up before you send them a job cutting curves.

Thank you very much. I’ll keep that in mind as I have a project coming up where I’ll be using some free form curves. This current one is just straight lines.

Hey everyone, I have another question centered around this topic of exporting Rhino Nurbs into DWG or DXF file types for CNC processing.

So the CNC machine that I draw files for and operate the most is an Amada FOM2 3015 2500kw Co2 laser cutter. It runs with a Fanuc controller and utilizes G-code for all cutting movements. Its important to note that the machine is only capable of three different types of cutting motions 1) G01 or a strait line motion between two XY coordinates 2) G02 or a circular arc motion in the clockwise direction 3) G03 or a circular arc in the counter-clockwise direction. Both G02 and G03 movements are circular arcs with fixed radius meaning they are not allowed to have changing curvature.

So in order to cut out shapes that have complex varying radius curvature such as the file attached I must convert the native Rhino Nurbs geometry into lines and/or constant curvature arcs. Of course this “Arc fitting” process can cause part distortion and noticeable facets if the lines and arcs are allowed to be too long. Conversely if the lines and arcs are created too small the file becomes much to large in memory size and too cumbersome to efficiently work with. Also extremely small lines and arcs can cause other problems related to the absolute accuracy the CNC machine is capable of physically moving. An example would be trying to cut a line that has a length of .0005" if the laser beam has a diameter of .010".

So my question is this, I have great results using the Convert command in Rhino to carry out this “Arc Fitting” process by means of adjusting all the variables within the Convert command such as “Angle Tolerance” “Tolerance” and “Min Length” to get the desired lines and arcs that provide a reasonable depiction of the original nurbs geometry, but when I go to export this new converted geometry as a DXF or DWG I seem to lose my results. Why am I not seeing the results of the convert command in my newly made DXF or DWG file?

I have seen in the Rhino “export” dialog box after selecting the “save as type” to .dxf or .dwg that there are options for differing “export schemes” The schemes are labeled “Default”, “2007 Lines”, “2007 Natural”, “2007 Polylines” and so on. There are nine different schemes in total. From the “DWG/DXF Export Options” dialog box these existing schemes can be edited and there is even and option to create and save an entirely new scheme.

Do the schemes act similarly to the Convert command on any geometry that is exported from Rhino? If so how do I achieve the results I am after? Are there any resources to better understand how to control the export schemes?

Below is an example of a recent file file that has been causing me a big headache! Thanks for any info.

Quinn Bilodeau
19 0207 wyllacactus preped fourm.3dm (5.5 MB)

The export modules can automatically convert (tessellate) splines into line segments within a given tolerance, but not arcs. If you want arcs, you will need to use the Convert command as you are currently and then export the converted geometry.

I would prep the curves to export first with Convert as you now do, then I would start with something like 2007 Natural and modify it to not tessellate, split or explode anything on export.

I did a test on one of the curves in your file, exported as dxf and then re-imported it to compare. The result is almost a 100% exact duplicate, I do see that the “Polylines w/bulge arcs” setting in export converted a few nearly-flat arcs into line segments… You will find them if you explode everything, do a SelDupAll and then Hide. What will be left are 44 small bits, the original is an arc, the re-import is a line. The tolerance difference however is microscopic.

TestCurve.3dm (4.5 MB)

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OK great! This is really helpful Helvetosaur! Do you have any recommendations for resources or reading on the tessellate process? I would like to do more of a deep dive on all the settings and schemes to understand them more fully. Thanks, Quinn.