Smoothing complicated geometry


I need to smooth round edges while keeping corners sharp (.stl file made in CAD).

Tried tris-quads, edge split, subsurf mod, auto-smoothing, and manual smoothing. No luck :no:

Is there any hope?

Is there a reason why you export from your CAD application as .stl? Better export as .obj, which should maintain the custom vertex normal information your CAD software (hopefully) saves with the file.

Quick example:
Straight out of CAD (MoI 3D) as .obj, shading in Blender is pretty much perfect - not because the geometry is perfect (it never is and can’t be with CAD files), but because the smoothing information is imported with the .obj file and ensures correct shading however messy the underlying geometry.

And btw, make sure you’re using Blender >= 2.74. Older versions did not support custom vertex normals on import and recalculated (averaged) normals on every hit of the Tab key.

That was it! Obj looks great. Thank you so much for the thoughtful reply!!!:D:D:D