Back To Pinshape   |   Blog   |   Contests

3D Printing Forum - Pinshape

How can I convert STL/OBJ to STP/STEP/IGS?

Hi Everyone,

This is my first post on the forum, so I’m looking forward to hearing what you all have to say.

I’m currently looking to mass produce plastic and rubber parts. I’ve been in contact with several facilities overseas who are all requesting that I send them my models as either STP/STEP or IGS files. Currently, the only versions I have are OBJ and STL.

I have two questions:

  1. As you can probably guess: Is there software that can help with such a conversion? As of right now, I’ve tried Fusion360 and FreeCAD. Neither seem to work. Could that have something to do with a high polygon model? I’m actually relatively new to 3D modeling and printing (I know more about printing than modeling), so I’m not sure.

  2. What exactly are STP/STEP and IGS models that seem to make them ideal for manufacturers? This is more just for my own knowledge and edification.

If anyone can offer ANY sort of help or advice, I’d be very grateful.

Very nice to meet all of you!


PS - I couldn’t upload images of some examples of the models I’m working with, so I put them in a folder, here:

Hi Matt;

I will try to give you some help.

I cannot answer the second question, because I don’t know the IGES or STEP file types very well, at least at their “DNA” level. In fact, I can’t say that about any software or file types that I use. I basically just use software and hardware, I don’t do any development.

I can say, about your first question, that what you are essentially talking about, whether you’ve thought of it this way or not, is reverse engineering. That’s what the procedure is called when you have an STL mesh, and want to end up with a hard CAD model. STL mesh is a large collection of triangles that create a 3D shape. You may have found this file on the web, or you could have 3D scanned your file, from a solid object. It looks like you have found your 3D file of a shirt and tie, am I correct? I say this because it’s perfect, and it looks like a modeled 3D item.

Now, the hard part. I hate to tell you this, and I have asked this many times, but creating a STEP or IGES is usually not simple from this point. You need the right software, such as Design X Geomagics (now sold by 3D Systems at $30,000) or SpaceClaim, sold by Ansys at around $5000. Massive prices aren’t they? I use both at times. I also have some luck using Rhino 3D, as I can import a mesh (STL) file, and build solid geometry in the same XYZ space. But, Rhino is not a true reverse-engineering software, and you can only build something that is sort of close to your original shape. In your case, the file appears to be very organic, with tons of challenging curves, so Rhino would not work well.

A real reverse engineering software does many things, including create complex, curved surfaces, that snap themselves to your STL geometry. That’s the real magic formula about rev-eng software packages.

If you are fairly gifted at 3D modeling, you might try Rhino, which is a free download (it only saves 25 times until you then buy it, at roughly $1000US).

I wish I could give you simpler news, but you have embarked on a challenging mission, and I don’t know of any free software that truly reverse engineers.

Good luck Matt.

Tom Kay, Ottawa.