I have been doing a lot of design work for 3D Printing over the last year or so and this is the first time I’ve run into this issue. I have created a NURBS model, not even a very complex model, and exported it to STL to get the G-Code ready. When I opened it in NetFabb to check the model, make sure it’s water tight, I instead see this mess. There are two pictures, one of the nurbs model, one of the stl in NetFabb. You can see where the curves go straightened off. This time it wasn’t so bad, far less than normal, which is part of the problem, every time I export, it’s a little different. I even opened a new document and rebuilt one of the parts, same problem. I make a different test object using similar curves, no problem.
I finally thought, why not convert it to a mesh first then export it. That resolved, here is the results, the mesh model in Rhino v5 and the STL in NetFabb. I would still like to know what caused this and if i can avoid it in the future, Also, what’s so special about that shape?
Before the Mesh solution I had tried manually creating all of the surfaces, which allowed me to export part of it, but I could join the segments together because my surfaces where so non-uniform. it’s this that leads me to think it’s something with how the surfaces were generated when I extruded them or possible when I crated the initial flat surface of the base. Any ideas?