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Forgive me, I'm a Blender Noob, but I can't for the life of me figure out what I'm doing wrong. Can anyone please either reproduce this bug, or explain what I'm doing wrong?

  1. Start with a short cube wide enough x/y to cut an array of holes
  2. Create a thin, tall (>cube height) cylinder that extends above & below cube
  3. Move that cylinder from 0,0--away from the center and toward the edge of the cube
  4. You should now have a thin cylinder sitting off-center within a cube
  5. In Edit mode, use the Spin tool to "extrude" multiple copies of the cylinder 360° around z-axis with a count of 4 (or any #)
  6. You now have 4 tall cylinders equally spaced within the cube
  7. Using Boolean tool or Modifier on the cube (both result in same for me), subtract/Difference the cylinders from the cube.

I don't get any result whatsoever. Both objects remain independent, unaffected by the operation. HOWEVER, if you switch to Union, they join just fine and become a single object. Also, if you switch the operands and subtract the cube from the cylinders, you get a proper gap in your cylinders. Why can't I subtract the cylinders from the cube?

Thanks in advance!

Removing cylinders from cube with Difference to make holes in the cube fails: enter image description here

Adding cylinders to cube with Join correctly creates new merged object: enter image description here

Removing cube from cylinders to create a gap in cylinders works: enter image description here

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  • $\begingroup$ I'm having trouble following your steps. Maybe you could link a file showing the boolean failure? $\endgroup$
    – Nathan
    Commented Feb 4, 2022 at 23:57
  • $\begingroup$ @Nathan, I added pics. Also this is really simple to reproduce, but I wasn't clear in step 5 that "Spin 360" means use the Spin tool to "extrude" multiple copies of it in a circular pattern, not simply rotate the cylinder. Hope that helps! $\endgroup$
    – Spacefuzz
    Commented Feb 5, 2022 at 1:54

1 Answer 1

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I figured it out. Maybe not a bug, but understandable odd behavior in Blender. 1st part of solution is the checkbox "Use Duplicates." This makes duplicate meshes that properly make holes with Boolean Difference. The 2nd part of solution is fixing the degrees rotation in the Spin 360°. The 360 means my original cylinder starting at 0° gets confused/clobbered with the last of 4 copies at the 360° position, causing the Boolean to not function properly. The fix is to only Spin 3 Duplicates over 270°. Now works perfectly as expected.

enter image description here

Success! enter image description here

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