Converting Mesh to NURBS process?

Hello, I just started my Rhino trial in effort to convert my Mesh based object into a Nurbs kind of object. For some reason, guy who works in 3D printing shop asked for .stp/.igs file type. So I ended up trying to convert this in Rhino.

Can somebody help me with this process? Right now what I did was to go to the Mesh Tools > Convert Objects to Nurbs. This indeed converted my mesh into the polysurface the way I need, but since my mesh object was lower in resolution, the polysurface creation is now quite jagged and rough all around. My question is how to make this smoother if possible? Or, if you have any other ideas about how to do this process properly, please let me know.

Than you so much!~

Edit: There is a video on YT ( where someone uses command: MeshtoNurbs , and also uses T-Splines. I couldn’t find any of those two.

T-Splines does not exist anymore for Rhino, it was bought by Autodesk and is now a part of Fusion 360. T-Splines would in fact be the way to go. Rhino 6 has some sub-D tools but they are beta and hidden (search subD on this forum). There are also some plug-ins like Mesh2Nurbs and Clayoo

That doesn’t make any sense - 3D printers almost always run off of mesh-based files such as .stl…

Ah, there is a Rhino built-in command “MeshToNurbs”. This command simply converts quad faces to 4-point quad surfaces and tri faces to 3-point tri surfaces. So basically what it does is to just mess things up, but sometimes it works in some cases that only accepts NURBS surfaces. Again, this command is not an option in most cases, but it’s up to you if you want to give it a try.

Details on MeshToNurb:

It it typically much easier to modify CAD surfaces for print issues, wall thickness, shelling, etc or just to save the STL model with a different resolution.

I use the new quad mesher > to SubD > to NURBS. Quite and interesting reverse engineering process.

For mesh to nurbs conversion you can find this step by step tutorial helpful:

Or as a video screencast: