Filling in holes only when duplicating object

[JonathanFV 0]

I hate to only be posting when I think I found a bug, but here it is. I put a bunch of parts to print in Cura, and fortunately, I examined the layers before printing it, because on three objects out of eleven, it had filled very important screw holes. Puzzled, I remodelled my objects multiple times in Blender, reloaded them in Cura, to no avail. Earlier, I had printer multiple individual parts to test the fit, and it printed fine. So I tried loading just one model at a time, starting with one which hole had been mistakenly filled. When I spliced it again, suddenly, the hole was there. So I duplicated it, because I needed two, and then boom! Holes were gone again.

 

I think that there is really a bug this time, and it seems like when I duplicate objects with holes in them, Cura fills those holes.

 

Edit: I just tried duplicating the files instead of duplicating them in Cura, and adding them one by one. I add the first one: no problem. I add a second one: both objects end up with their holes plugged.

 

Edited April 8, 2020 by JonathanFV

[burtoogle 516]

Hello, could you please attach the model(s) that you are having problems with, thanks.

[JonathanFV 0]

Of course! Here's one example. Other objects in that same batch also have the issue, but for me, it can be replicated with just this one.

X-Center_Section__Left_2_5cm.stl

[burtoogle 516]

The problem is that the model's normals are wacky, install the cura mesh tools plugin and use it to fix the normals and then you should be OK...

 

[JonathanFV 0]

Thank you so much! And wow, this is crazy! Before exporting my STL file from Blender, my normals look fine! Then when I import my STL file again, the normals look all messed up. Guess I'll go ask if that's a Blender bug! Thanks a ton, again. Would you have an explanation as to why a single instance of the object sliced correctly, but two of them didn't? I'm just really curious.

[burtoogle 516]

Sorry, I don't know much about models, I expect someone else could answer your question.

[JonathanFV 0]

That's very fair, thank you so much again for your help!