Why does Cura fill empty space?

[tomofo 0]

I'm new to 3D printing and Cura.

I have designed a Mobius strip shape in Blender, as in attached "Mobius_blender.PNG" screenshot and STL file.

Obviously there is a hole through the middle of this shape.

When I slice the model in Cura, the hole through the middle is filled in. See the yellow part in the middle of the attached "Cura_slice.PNG" and "Cura_slice2.PNG".

This happens with default settings and preferences, supports on or off, and several other variations in attempting to fix it.

I know I will need supports to make this print properly, but why does Cura fill in the middle section?

Thanks in advance for any help or advice.

Mobius.stl

[ingo46 5]

Bei mir sieht "Mobius.stl" so aus (Cura 5.7.1):

[Slashee_the_Cow 409]

Your model is bad.

 

It has no faces on the inside:

 

Also it looks like the normals are flipped where it joins:

 

If you're on Windows then Microsoft's 3D Builder app is actually pretty good at fixing broken models. On other platforms you could try something like FreeCAD or MeshLab, but they're a lot more complex. There's also online tools that can fix models. I've attached a fixed version (from 3D Builder) because I can't help but help 🙂

 

Blender isn't always the best at exporting STL models (CAD software is) so sometimes it works fine, sometimes you have problems. Sorry but I don't know enough about Blender to help try and avoid his happening 😞

Mobius-fixed.stl

[tomofo 0]

Thank you for the tips and fixed model. I did not imagine the source STL could be wrong.