Difference Boolean acting like Union Boolean

So, I’m trying to boolean out a pattern on a hollowed out cylinder. I’ve checked the normals (edit mode->select all vertices -> Ctrl N) on both the beginning object and the end object. I even made sure the two objects aren’t completely aligned (that seems to confuse some programs if vertices are in alignment -I don’t know why), and when I apply the Modifier I have either the “cutout” by itself (Intersection), the cutout added to the cylinder (Union), or the cutout added to the cylinder (Difference)… I can’t seem to get the cutout to make a hole in the cylinder…

When I set it for “Difference”, the normals flip, but the cutout doesn’t actually vanish. If I apply the Boolean, they are merged together, like a Union has occured… The copy of the cutout is there, but now the cylinder has the cutout hanging out on the side.

If I go in reverse (applying the modifier to the cutout and “Intersecting” to the cylinder) then the cutout just disappears form the stage altogether.

Any ideas on what is causing this? I’d really hate to have to manually model a cylinder just so I could get this cut in it…

I’ve checked the normals (edit mode->select all vertices -> Ctrl N) on both the beginning object and the end object.
This is not sufficient to ensure the normals are correct. Have you actually turned on the normal display in the properties panel (N) ?

Upload a blend file that shows this behaviour to http://www.pasteall.org/blend/ and tell us the download link

Thank you! Okay, I did that! It’s called: “BASE PRINT-Converter” I’m unsure how to get a link here?

No, I’m still a little new to Blender and I’m still trying to adjust to the interface. I’m old school at 3D modelling, but very new to Blender.

So, I did as you recommended, hit “N”, I have Transform, Grease Pencil, View, 3D Cursor, Display, Motion Tracking, Background images and Transform Orientations… but I’m not seeing anything (I presume it would be in “View”) that would let me view Normals (I am sort of hoping for the little lines that pop out of the faces to tell me which way they are going)… I can guess that something is wrong because the shading is weird on one of the two objects that we are involved with…

Anyway, thank you for the assist… this is very frustrating that it took me one hour to get here and 4 hours to do this one boolean operation… o.O

You will find what Richard mentioned about the Normals by first going into Edit mode and scrolling down to mesh display. The 2 little boxes give you options for Face or Vertex Normals, or both.



Awright! That was the trick (For seeing Normals)! Thank you! Okay, now I know all of my normals are going the correct direction (out), but I’m still getting the boolean issue. I kinda need this to head to a printer relatively soon (It’s a work thing), so I may have to simply model the cylinder with the notch by hand, but for future projects, I’d love to know if anyone has a solution for this!

Thank you!

For your boolean testing, set Object panel > Display > Maximum draw type: Bounds
Then you can easily see the real effects.
Here is boolean with Union.