I am a beginner. I want to export a blender object to be cut on a CNC machine, the workshop ask me for a .stp file or a .igs file. My blender object has 250,000 tris, when I export to .stl the file size is 9mb but if I convert this file to .stp it becomes a huge 500mb file. Is there anything I can do within Blender before exporting the object to make this file size more reasonable?

  • $\begingroup$ By the way... in addition to the suggested answer below: Many CNC machines can be driven off Adobe Illustrator files, which are vector based. If your final object is a two-dimensional print on a cut-out, place your raster image inside an AI cut line.... We do this quite a bit.... But for machining a true 3D model, see answer below. $\endgroup$
    – rcgauer
    Mar 8, 2015 at 18:09
  • $\begingroup$ Another option is to export the G-Code straight from Blender using BlenderCAM $\endgroup$
    – user15824
    Jul 30, 2015 at 8:40

2 Answers 2


This is a good question, and the answer unfortunately is mostly "no". IGES and STEP files are (mostly) CAD/CAM files, and are not point- or polygonal-based. The file format itself is ASCII, and dates back into the 70s. It is great for driving CNC machines, since that's its history.

Some modeling programs (Rhino) can get you there from nurbs-based modeling. I am not aware of any option in Blender (or ZBrush, Maya) allowing you to get a clean IGES. You can get STL files, which are great for 3D printing and which some routers will accept.

There are a number of programs that will go back and forth between Nurbs, STEP and IGES... and some higher-end products (SolidWorks) will bring in an stl and generate an IGES or STEP.

If you finda better answer -- post here. We use Blender for a lot of 3D output, but when we need tooling, typically we need to have IGES... and this is the best info I have at the moment!

  • $\begingroup$ I used the affordable automapki autoconverter to convert my STL to STEP, it appears to my inexperienced eye to work fine for objects with a few thousand tris but anything bigger and the files get huge. The object will be a core for a lost wax bronze sculpture so detail is not so important, I will sculpt that back onto the wax before casting. I may have to cut it as a low poly object with the CNC machine and finish it off with sandpaper, not the ideal solution! $\endgroup$
    – user5049
    Mar 8, 2015 at 20:26

You could also potentially just convert your model to STL and then have your part 3D printed in PLA. There are some good videoes on youtube of people using 3D printed PLA parts over wax for casting. Check on 3D hubs for an affordable printer near your location. Also check out fusion 360. It is a free CAD program. You can export from blender to obj, and then import into fusion and convert the mesh into a BREP which you can export to step. Converting from mesh to BRep can be tricky if you don't have a clean mesh. You may need to use netfabb or meshlab to repair it.

  • $\begingroup$ please try to keep answers based around blender. $\endgroup$
    – David
    Jun 19, 2015 at 19:50
  • $\begingroup$ I don't think this is about blender, and I also don't think it answered the question. $\endgroup$ Jun 19, 2015 at 22:45

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