Autosmooth issues: sample file attached. Mesh not reacting to Autosmooth at all --?

No imported objects, so that stumbling block is absent.

Here’s a sample file with 2 objects: one is a test cylinder, and it works fine w/Autosmooth. The other ( “Turret” ) are are samples. For some reason Autosmooth does not seem to have any effect on the Turret object. Why might that be?

AutoSmooth issue.blend (2.5 MB)

The ‘Turret’ object has a custom normal data in it. If you want to use Autosmooth instead of Custom Data, you need to clear the Custom Data (Mesh Properties > Geometry Data > Clear Custom Split Normals Data).

That was it. Thanks. Now, how did that happen??? I don’t even know what “custom normal data” IS, let alone how to apply it.

It might be that you imported the mesh from another software, or you edited the Normals Data by any means (modifiers, addons, python, accidently pressed ‘Add Custom Data’, etc).

About ‘Custom Split Normals Data’, it allows you to specify which edges should be smooth, or what should be the Vertex normals for each loop (a bit as ‘smoothing groups’ in other packages).

This is a purely Blender project - ie, no import. No python intentionally applied. So, modifiers might do this? Hmmm, for this bit of mesh even that seems unlikely. That seems a nasty little land-mine.

Thanks for the info.

Applied modifiers such as Weighted Normal (to flatten faces after beveling adds strange geometry) or just the Bevel modifier with harden normals, will/can add custom normal data. Not nasty, it’s what they’re supposed to do.

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Neither of which I used in this case. Nor was it imported, just to get that off the table.

The thing is that there’re plenty of functions that create mesh custom data…

For knowing exactly what was in this case, you need to go step be step and replicate exactly everything (and allways check if the custom data was created).

Something in that path is the cause… What exactly, it’s a bit impossible to say, because we can only see the end object (who knows if you started with a Suzanne, and with extreme mesh editing, you got to that point???).