From Blender Subdivision To N.U.R.B.S. (IGES) for free

Hi all, I have a little trick that I discovered just today and wanted to share it with you.
I found an easy way to convert the subdivision surfaces, in to nurbs surfaces.

To do this you need two free programs ’ FreeShip_Plus ’ and another to convert VRML format ’ 1 ’
First you need to export your files from Blender, eliminating the subdivision modifier and export to obj with the Z axis at the top, after using the program “meshconv” to convert from obj to wrl.

Open ’ FreeShip ’ and import the VRML format 1 of your object and go to export in IGES and you’re done you’ll have the nurbs surfaces generated from the cage of your mesh object.

Then import your IGES file with FreeCad and export it in STEP to others CAD

Object converter

Usage: meshconv -c wrl -vrmlver 1 blender-file.obj

Free!Ship Plus

and if this has problem use that for Win (2.1 MB)
I wonder how many people were expecting this XD, I have been trying a solution to this problem for many years.
Paolo F.


This is the BMW of Mike Pan converted to STEP, and imported into ‘MoI 3D’, the last six days of testing :frowning: this is a program that I have to buy as soon as possible.

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Is it possible to do the inverse process? (IGES->mesh)

You can convert IGES to mesh with just MOI itself Isscpp. Import NURBS object, export as either STL or OBJ. I usually push the number of faces to the max to keep the object as smooth as possible. Here’s a model of 1911 pistol grip I had in IGES format that I converted to STL, imported into Blender and then ran a Remesh Modifier on it to bump up the poly count for easy sculpting.

Thanks for this useful tip pafurijaz! I’ll give this a try here today and post some results.

I know. I was asking if it was possible to have good iges2obj in the freeware realm, all my efforts were unsuccesful

Hi with FreeCad you can export from iges to mesh but you don’t get a nice topology, Moi3D is the best for this task

silly question but how did you call the OBJ import and SUBD like smooth command in MOI?.
I was only able to access those commands after adding the icons in the toolbar.

MOI is a pretty good app also the ability to load obj mesh data and convert it into matching flat NURBS data or apply a catmul clark like smoothing onto the NURBS data.

Fusion 360 however delivers better face to face alignment. Hobby users can use it for free as well. Not trying to be an Autodesk seller but this currently
is one of the best and only professional solution and on top for 0 $ !

I think you have misunderstood, I did not use Moi3D to import but I used FreeShip to export in IGES format, the subdivision surfaces I had made with Blender.
Moi3d was only used for viewing surfaces Nurbs

Regarding Moi3d and execution of commands without the toolbar, just press the TAB key and enter the name of the command, or you can create a keyboard shortcut.

Moi3d also works with Linux and does not require a connection to the cloud of Autodesk, they has no cad for linux systems.

From Blender to freeCad

Some tests done yesterday. but not all surfaces are joined. All object done Blender with Subdivided surfaces

My Old Fiat500 in NURBS :slight_smile:

As regards the result of the conversion, there are several areas where surface remain divided, but for certain types of surfaces has no problems. I’ll do a quick tutorial about how to convert, but I must first prepare some objects for examples.

The steps to convert:

  1. Export from Blender in OBJ.
  2. Convert from OBJ to VRML1, with Meshconv. **
  3. Start FreeShip, and import the VRML1.
  4. Export the file to IGES (NURBS).
  5. Start gCAD and then open IGES file and export it, to IGES or other formats NURBS, Moi3d does not open the file exported by FreeShip.

** Meshconv usage: meshconv -c wrl -vrmlver 1 blender-file.obj


Weird. Looks like the Moi 3D website is down. Was going to check it out after reading this thread.

Hi, Thank you for sharing this- very interesting topic!
Did anyone find a little more streamlined workflow for this?
Maybe a way to export vrml 1 directly from blender?
Or any other news regarding sub d 7 NUrbs???

Hi! Sorry for bumping this old thread. This is a great topic.

If I may ask, how did you export the objects with subdivision data? Like sharp edges (shift E)?

Sorry but it is hard to keep track of old posts now with the new site is possible, In FreeShip, you can accentuate the edges as with Blender and after the program creates the IGES surfaces.

@pafurijaz, thanks for the tip! This looks wonderful.

Previously, I have only been able to get to good Nurbs by using T-Splines in Rhino. The team that developed T-Splines now develops Autodesk Fusion, hence @cekuhnen why it may work so well for mesh to nurbs.

Will try meshconvert and free!ship plus to see how well it works next time i need to go to nurbs.

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:wink: If you have difficulties I can give you some advice … you can also use gCAD3D to convert the files in vrml 1 format, just remember that depending on the orientation you will get different results.

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hi there,
is there any news or optimisation for this wokflow?
i tried it back then when you started this topic. workflow was a little “bumpy”, but still amazing that you figured that out. but i havent used it since then.
i might need to convert a model to cad soon,
so i woud like to try this again…
so any new tips?

Hi, not much more news but I just discoverd a way to export with opensource software the Blender’s basic mesh into STEP file using gCAD3d via DXF without projections. That is useful on redo a surface from Blender’s model. here below some image of various screenshots.

Blender mesh of an hull exported to DXF.
When you import a DXF file with gCAD3d it does automatically the conversion in triangulated surfaces and you can save easily the file into STEP and import it in other CAD to remake with using as reference a good Nurbs surface from it.

and here the mesh imported in Moi3d and if notice this is of course triangulated but is a regular solid.

And here some example of surfaces reconstractted inside moi from wire mesh of subdivision surface with NURBS CV curve and simple lofting…

The study and concept with Blender and below…

The hull rebuilding with NURBS surfaces…


thanks for reply and I’ll check out the moi…I also see other blender guys use fusion T-spline is any different? thanks for the informarion

it’s the same the conversion of moi3d is like Tspline, but the real difference was with FreeShip, that workflow with a bit of tweaking inside FreeShip you can have a very simple smooth surface with less control point, and with sharp edges.