DXF export loses correct layer names and sub layers

DXF export messes up layer names, everything now is 26 chars or less with a $ sign thrown in where the layer name ends and the sublayer name begins.
They were all sublayers and now have a prefix of the parent folders name, so the actual layer names they need is 6 chars long and meaningless.

I see no options to retain layer names, but it goes without saying that the recipient needs to see the original layer names.

How do I resolve this at Rhino’s end and retain long file names and sublayers ?

is it that Autocad cannot have sublayers and/or names longer than 26 chars or both ?

I chose R12 Natural and went with the default settings assuming all ok, nothing there anyway for layer name retention.


Try one of the newer DXF file formats and open the results back in Rhino and see if you get the same layer name limitations.
I suspect this limitation is because of the DXF file version you selected.

here are the file formats I see with DXF in V5.

not sure which is the newer one, I chose R12 natural
DXF file formats V5

would dwg or iges be suitable and better, its for a company laser cutting sheet steel.
I asked if they had Rhino but they hadnt heard of it.


2004 is newer.
R12 was released in 1992

If you are exporting to another program, I would probably not use sublayers. Depending on the export format and the receiving program, they may not transfer correctly.

I’m pretty sure we support Sub layers in the newer AutoCAD versions, but they would be in V6

I see four options for 2004, nothing is simple !

Just which one is best for small holes and curves, this is for laser cutting ACCURATELY, after all my work I dont wish to see classic autocad turn my curvaceous S bends and small holes into straight lines and anything else I didnt see or expect.

This will be the third email sent them, so I want to get this right.

I have now ‘de subbed’ my layers, whilst exporting.


Since the LASER probably uses G-Code for cutter control, and you’re using a brain dead file format that does not handle NURBS curves, you either need to use a different export file format, IGES is preferred. Check with the LASER guys to see if they can handle IGES files.
If so, that’s the easy fix.

If not, if you must you DXF, then you will need to convert all your curves that are not already straight lines, circles, and arcs, to chains of arcs using the Convert command.

You’ll need to convert your Degree=3 (and higher), curves in Rhino before exporting them as DXF/DWG.

Your Mill/Router/WaterJet follows G-code instructions. G-code supports three movements:
1 - Straight lines
2 - Clockwise arcs
3 - Anticlockwise arc
It’s your job to make sure you’re only send supported curves to the machine.

Lines, arcs and circles in Rhino are good to go.
Twisty Rhino NURBS curves need to be converted to arc chains. If you don’t convert them, they will be approximated by hundreds of short straight lines.

Since you need more efficient Arc objects in your DXF/DWG file, you’ll need to convert your wiggly Rhino curves to arc segments before exporting.

Use the Rhino Convert command.
Use these command option settings:
Tolerance=0.01mm or 0.002"

The tolerance controls how far the arcs will pull away from your NURBS curves. Your machining process and project will determine how much is OK. The distance is in current model units.

Then when you Export to DXF, use the “CAM Imperial” export scheme for inches and “CAM Metric” for millimeters. Both of these export simple geometry as lines and circles.

Always check your DXF file by opening it in Rhino before you send it for cutting to make sure it looks good.


I hope they use IGES, I will find out, if not I will get my client to sue someone that does !
yet again this job rolls on for another week.

DXF is truly brain dead for this modern day.


I’ve never run a LASER myself, but from what I understand from talking with people that do, using IGES files is fairly universal, particularly for commercial services. The people that insist on DXF are either “cut-rate garage” operators, using hobby level CAM tools, or are too busy with orders to bother learning how to efficiently use their tools.

These guys have just invested in a million pound laser cutting system they tell me, so I hope they wish to be up to date on files as well.


The other issue is dealing with users that don’t know any better. While “brain dead” DXF is fairly universal and does work, it’s just a hassle to deal with it’s limitations.
If your service insisted on IGES files, then they would be forced to teach their customers about it.
Tech support is like being stuck between a rock and a hard place, while being blasted with a 4" fire hose.
I can see all sides of this issue.

Well, not to rain on your parade or anything, but I ran a small laser in a student model shop for more than 10 years before I left the school. As we had students using all kinds of software, DXF was the standard export format for student submitted files. We had very few problems cutting any kind of geometry, lines, circles, splines, dense polylines, whatever.

My opinion remains that DXF export can be fine for pretty much any 2D cutting operation, the main problem is either on the user end - they don’t know how to configure their export settings - or the receiving end - inadequate software, settings management, or training…

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In my experience, not all the programs our ‘clients’ were using could export IGES… Plus some of the programs we had to run things like our knife cutter couldn’t import it.

I was more going by what John had said,

While “brain dead” DXF is fairly universal and does work, it’s just a hassle to deal with it’s limitations.

and the list of things to do if using it.
If I can go export IGES and they get what I see, thats simpler for them and simpler for me, and that rhymes :slight_smile:

Yep. But if you have splines, hopefully their software can deal with them correctly.

Its drawn with standard Rhino vector tools and surfacing tools, sweep2 etc, extrusions, solids and surfaces, I have not chosen splines, unless normal Rhino commands such as these and extrude, split, boolean difference, trim, unrollSrf, DupBorder, ExtractSrf create splines.

is there a command to see if splines exist ?

Problem, warning message iges ( I chose default) does not support annotations.

What iges option do I need to just get this exported ?

Its got text block, leaders, dimensions, curves, green for dimensions, black all else, and light grey for grid.



Well, do you want to have dimensions laser cut?

I would send them just what you want to be cut

I wouldn’t do it that way. I would just send the file (iges, dxf) with the curves to be cut and nothing else. I would accompany that with a PDF exported from Rhino that has the curves plus all the rest - text, dimensions, etc. - any necessary explanations to make sure the design intention in the curves file is fully understood. This is also good if you have multiple pieces of the same part - just one part is sent in the curves file, and the quantity needed is designated in the PDF. This leaves the laser cutting company the freedom to lay out the sheets the way it works best for them.

They do/can. Unfortunately, Rhino has still not provided all the selection tools needed to easily find them - not even in the current WIP - so I have been using a number of scripts for years. My procedure is something like this:

  • Explode the entire 2D drawing
  • Select all the exploded parts and run SimplifyCrv
  • Now unselect everything, and run the following commands:
  • SelLine (native to Rhino) - Hide the selected objects
  • SelArc (script) - Hide the selected objects
  • SelCircle (script) - Hide the selected objects

Anything that is left visible is neither a line, nor an arc, nor a circle - hence it will be some kind of spline.

Mentally mark where those are and then Undo back to before the explode. Then go in and fix those curves that you found might be or contain splines segments.

I’ll post the selection scripts here in case they might be useful:
SelArc.py (466 Bytes)
SelCircle.py (498 Bytes)
SelEllipse.py (474 Bytes)

(note that most programs do not understand ellipses or ellipse segments, so they will most likely be interpreted as splines)


Martin, thanks
To explain, I asked them what they wanted me to send and they said dxf would be ok, with layers for dimensions they turn off, but gives them a check facility on setup and product.
If IGES doesnt support annotations then a pdf instead with such on would I presume be acceptable, I shall ask them.

I am still wondering which IGES option does support annotations and dimensions, even colour ?

Thanks for the steps to find splines, and therwas I thinking select items, export, choose IGES and job done.
I will work my way through this now and check.

Is this for DXF and IGES, and DWG and STL etc ?

Are those scripts ok for V5 ?

and as I say which IGES does support annotations etc as above ?

in fact which export options are best for accurate circles, elipses, retention of annotations & dimensions and full length layer names when sending to sheet metal laser cutters, and wood millers ?
Which of these does not need splines checking for and removing ?

on the user end - they don’t know how to configure their export settings

If I was to use DXF, just what are the best settings and which of the 2004 options to choose. I have done nothing fancy, just drawn and surfaced with the commands I mentioned. smallest radii is 0.035inch and smallest hole 0.1inch.