delete default cube, add a cylinder with 32 vertices
Blow up an object until you can see each of the 30 lines along the cylinder.
Go into object mode (or edit mode, neither works), and turn on AutoSmooth from the mesh menu. (Default degrees is 30).
The object remains EXACTLY the same.
I boost the degrees to 80
Nothing is changed
I take degrees to 10
As far as I understand, it round part of the cylinder should become smooth because the angle is like 10 degrees or so, and the edges of the two circle faces at the top and bottom of the cylinder should remain sharp because the angle is more than autosmooth (90 degrees).
A bug in blender?
If anyone can help me or confirm it’s a bug, I would appreciate it.
As Musk said, you must first indicate to blender that you want the object to be smothed (‘Set Smooth’ button) before trying to set up where and how it is going to be smoothed.
The edge split modifier is quite a neat alternative. Be aware that its effect will differ greatly accordingly to its position in the modifier stack though.