False detection of top layers

[bkrahmer 0]

I've got an issue where Cura 4.0 wants to falsely create top layers part-way through my model.  I feel like it's a bug, but just wanted to see if anybody had seen this before, and could tell me that I just need to tweak some settings.  I know I can set top layers to 0, and for this particular model, this would probably work.  However, if it's a bug, it would be great to see it addressed.  I have linked to some screenshots, and can make the file available to anyone that would want to debug the issue.

 

thanks, brian

 

Edited May 2, 2019 by bkrahmer
added images

[burtoogle 508]

Hello @bkrahmer, that sounds like it is an issue with the model. Could you please attach it to this thread. Thanks.

[bkrahmer 0]

Ok, I've attached the model.  It is generated by software that I built.  Slightly different but similar models do not cause the issue.  Thanks for taking a look.

bowl.stl

[burtoogle 508]

FreeCAD says that it has "flipped normals". I un-flipped them and it now looks to slice OK. The Cura mesh tools didn't barf on the original file. Should it have done @ahoeben?

 

 

 

bowl-flipped.stl

[bkrahmer 0]

Ok, thanks for the information!  I've gotten conflicting information, because I have read that blender would show any faces with flipped normals in black.  I don't fully understand how normals work, so I've had to do some guesswork in my code.  If someone can tell me an algorithm for detecting if my normals are facing the right direction, or a further explanation of how Cura uses normals, it would be much appreciated.

 

thanks, brian

Edited May 2, 2019 by bkrahmer