Mesh from Nurbs bug

I think I found a bug while trying to convert a polysurface to a mesh.

Running “check” on the mesh says:

This is a bad mesh.

Here is what is wrong with this mesh:
Mesh has 2 non manifold edges.
Skipping face direction check because of positive non manifold edge count.

The object was extruded from a planar surface. (I tried extruding from planar curves but the hollows would fill in–maybe a related bug?). The object has thin walls (0.4mm) with slightly rounded corners.

The attached screen capture shows the V5 version on the left (it converts correctly) and the V6 version on the right. The meshes are blue.

I can send the file if needed.

Thanks, John

Hi @ajohnblack, yes we’ll definitely need the 3DM file. Please post it here.

Hi Brian,

Here is the file.

thin_wall_test.3dm (532.2 KB)

Hi John - thanks, I’ll check it out.
@ajohnblack - for now, run DivideAlongCreases > SplitAttangents=Yes before meshing. You’ll see that the corner there where the mesh foes wonky changes from a single surface to having a separate corner surface .

That is usually better, if tangent surfaces are split out, for meshing and other operations as well. However, meshing should get this right…