I import a model from binary data and figure out that its normal vectors are in wrong direction. After flipping vectors, the faces do not look smooth like before although I try to use "Shading/Smooth faces" and "Clear sharps" feature. How could I do to make the face look smooth in this case? I attached the .blend file here. Thanks. Download sample
Your mesh has 211 double vertices that mess up the shading.
Select all vertices (Ctrl+A), disable Autosmooth and go:
- Mesh > Clean up > Merge by distance (this will merge 211 double vertices)
- Mesh > Normals > Recalculate outside
- RMB > Shade Smooth
This will ensure you have a clean mesh, normals pointing out and proper shading.