Valid Polysurface becoming Invalid after export?


I’ve a valid closed polysurface. No naked edges. No non-manifold edges. No bad surfaces.

I uploaded the model (in .stl) to a 3D printing website and it says that the object is incorrect, contains errors and can’t be printed…
I did export before from Rhino to .stl file and uploaded to the same website and my objects were accepted without error. The object is in fact the same object which I made some changes.

Here two screenshots of the check in Rhino before export to .stl and the check result from the .stl file from the website.

Is the problem before the export or is it the export itself. How do I fix it? Thank you for your help.



I fixed it.

I opened the .stl file in Rhino and checked bad naked edges. Found some. Went back and open the original 3dm file, zoomed at the same spot and could see some bad surfaces. Deleted them, rebuild new clean ones and exported again to .stl. That time it was accepted.

Why Rhino was not finding the naked/bad edges on the 3dm file. This I do not know.

Sometimes it depends on mesh export settings, I always check STL files with netfabb Studio, which is pretty nice, and has a free version. Another great alternative is MeshLab