Solid layers blocking a hole

[willeo 0]

I designed an object (adjustment screw) with a hole in the center and placed 8 copies of it onto the plate (figure 1).

 

Strange enough, 4 of them are sliced incorrectly, using 0.1mm layers. Others have solid layers blocking the hole:

- three are blocked in the first layer (figure 2)

- one is blocked between 1.7 and 2.0 mm and then again at 2.2 mm (figure 3 at 1.8 mm)

 

As said, the model (stl) is the same, just placed 8 times. Z is the same. What am I doing wrong?

[gr5 1,060]

My guess is you used sketchup.  This happens a lot with sketchup models.  If you are using sketchup:

 

Look at your model - especially inside that hole in the center.  Look for *any* walls that are gray instead of white.  Make them all white by right clicking and select "reverse faces".  Anything that shows as gray will confuse cura into thinking that's the "solid" side of a wall.  Most other CAD software doesn't have this issue - just sketchup.

[willeo 0]

Hi gr5! Thank you for the advise, but don't think this is the issue.

 

The model is exactly the same for all of these 8 adjustments screws, out of which 4 are sliced incorrectly. If the problem was in the model, I would suppose I had problems in all of them.

 

I printed similar batches (albeit with smaller diameter holes) with Cura v2, without any issues. The "CAD" is Microsoft 3D Builder, which sometimes make strange things, but here the hole looks perfectly clean (see Figure).

 

[willeo 0]

P.S. I exported the model as STL from 3D Builder, and opened that STL 8 times (instead of multiplying it). Now I tried importing 3MF directly from 3D Builder to Cura (and multiplied it there). That set is sliced OK, so I can continue my work now.

 

However,although the problem was apparently in the model, why were these 8 objects sliced so differently? I mean, especially, 0.4 mm thick solid block in only one adjustment screw is not a small glitch. Plus the three others with a single solid layer in the bottom.