Cura. Prepare and preview don't match

[kennycain 1]

Strange occurrence happening here in Cura. A simple feature in my project that I have done many times seems to work in design but does not slice properly. As you see here there are two holes (created with a simple boolean difference operation). I have done this many times but this time although it shows well in the "prepare" screen, these holes close up in the preview screen and consequently do not exist in the final print. The mesh looks perfect so there are no apparent flaws to confuse the slicer, so I am at an impasse. Please help. Note: there is a lateral hole through the front made with the same boolean operation that survives. BTW I am using Blender for design.

[GregValiant 1,330]

Under Mesh Fixes see if "Remove all Holes" is checked.  It has it's uses but it's for very specific cases so you need it unchecked for that model.  While you're there make sure "Make Overhangs Printable" is also unchecked or you will lose the horizontal hole as well.

Edited December 21, 2021 by GregValiant

[kennycain 1]

 

47 minutes ago, GregValiant said:

Under Mesh Fixes see if "Remove all Holes" is checked.  It has it's uses but it's for very specific cases so you need it unchecked for that model.  While you're there make sure "Make Overhangs Printable" is also unchecked or you will lose the horizontal hole as well.

It is not checked. I have uploaded the STL file for you to play with.

pick_base_V10-03.stl

[kennycain 1]

When I select the object 

I can see circles in blue where the holes ought to be. Does this shed any light?

[GregValiant 1,330]

When I opened the file I got the "Not Watertight" warning.  I uploaded the file to https://formware.co/OnlineStlRepair

Here is the report from the STL repair site:

--> 0 Naked edges (?)
--> 0 Planar holes (?)
--> 0 Non-planar holes (?)
--> 0 Non-manifold edges (?)
--> 11108 Inverted faces (?)
--> 2 Degenerate faces (?)
--> 0 Duplicate faces (?)
--> 0 Disjoint shells (?)
-> Repairing: 100.00%
----- Repair completed in 15324ms ------
-> Vertex count changed from 35183 to 38579 (+3396)
-> Triangle count changed from 70364 to 78876 (+8512)

 

I'm not sure how you got that view showing holes.  When I open the STL in Cura 4.12.1 there are no holes at all.  Same with MS 3D Builder and PrusaSlicer - no holes.  These screenshots are of the un-repaired model.

 

Here is my prepare screen in Cura

 

Here it is in PrusaSlicer

 

Either your conversion to STL was wonky or your modeling operation was.  The X-ray view in Cura doesn't show any holes or internal artifacts.

Edited December 22, 2021 by GregValiant

[kennycain 1]

Call off the dogs. Somebody in another group gave me the answer. Seems there was an error in the STL file I couldn't detect. Loaded it into 3D-Builder and it detected the problem and prompted me to have it automatically fixed. Thank you for your input. I learned a little more about Cura.