I have this part and it is symetrical (red axis). When I export the part as STL and open the STL anywhere, the "bumb" on the part gets skewed a bit to one side.

Any idea? Cause I have none.

STL here: lukasradek.cz/part.stl

side view side view with measurements enter image description here


1 Answer 1


Ok, got it.

It has to do with how Blender handles nonplanar faces. Inside blender, it can show a face that is bent (one face on each side of the bump). But for the STL export, it will break them down into 2 planar faces.

And it did not break them symetrically, but rather "in the same fashion". Meaning the newly created diagonal is (from this view) always from "top left" vertex to the "bottom right" vertex of the original 4-vertex shape. And since the original faces were mirrors of each other, they ended up split and creased differently.

I assume there is a better definition of the way, how non-planar face is broken down. 🙂

The two selected edges are the newly created ones.

enter image description here


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .