what's wrong with normals?

I loaded Blender and pushed space>add>mesh>tube, i made it tall as i needed in edit mode, then selected the upper vertex>extrude>clic>scale to make the thickness, then extrude until down, and connected all the vertex to make the faces, obtaining a tube. Then when i tried to render I get this. Why?? I recalculated the normals and everything but nothing works.

Also, why sometimes, making similar objects with same procedure, one is rendered good and one is like that?

Thank you

PS: This happens only when I use “set smooth”, if i put “set solid” it renders good but, of course, with faces, which I don’t want.


  1. Vertex normals may be distorted by the scaling. Try Ctrl-A in object mode to fix them.

  2. Turn on Autosmooth in the F9->Mesh panel. 2.4x seems to have issues with the smoothing algorithm.

Thanks! With Autosmooth now is perfect! I pressed everything but that while trying to fix :slight_smile:

But why that happens? Is it a bug that will be fixed or everytime you put “set smooth” to an object you also have to turn on autosmooth?

This is not a bug. It happened because when you turn on ‘set smooth’, Blender tries to smooth EVERYTHING, including the 90 degree edge of your tube. By default, when you turn on ‘auto smooth’ it makes the ‘set smooth’ function ignore all angles greater than 30 degrees.

Thank you for clearing that up LOTRJ.