I have started my first 3d modelling project. After finishing the modelling process, I discovered the 3D Print Toolbox, which helped me to identify potential problems. However, after several hours of Googling, I'm still not able to resolve the last problem: Zero faces.

I used boolean modifiers to cut out a cylinder and a cube. I tried to use a solidifier before applying the boolean to avoid zero-faces but it didn't help. In addition, I tried to adapt the faces/edges at the cylinder but it didn't seem to have an effect on the zero faces. I deleted the cylinder that was originally used for the boolean, so technically there shouldn't be any interface between two objects. (I also tried to merge by distance, Mesh>Clean-up>Degenerage Dissolve, and more approaches - but seem to miss the right one.)

Zero faces due to boolean

My questions now:

  1. Will these zero faces have any impact on my 3d Print?
  2. How can I get rid of these zero faces?

Thank you very much for your thoughts!

Here is the blender file with the additional zero faces:

  • $\begingroup$ Hmm, it "causes zero faces"? What exactly do you mean? You're trying to cut a cylinder out of that rectangular prism, right? If that's your goal, you shouldn't solidify anything. The boolean modifier is finicky and sometimes it seems to break for no reason. I recommend that you instead cut a cylinder out of the box by following this process: Add a circle flush with the surface of the box at the location where you want the whole to be, delete that face of the box, and create new faces between the circle and the missing face of the box. Then, simply extrude the circle into the box :^) $\endgroup$
    – SilverRain
    Commented May 6, 2023 at 1:51
  • $\begingroup$ Explained here blender.stackexchange.com/q/245262/2214 there is also a link to a great video explaining it. So it can be your Threshold for Merge by distance was too small ... In case of cube cut out there can be a topology issue with bottom connection to the extended cube ... Also let display Face Orientation if those are not red which means they are pointing inside ... Or share your blend. $\endgroup$
    – vklidu
    Commented May 6, 2023 at 7:23
  • $\begingroup$ Thank you both very much for your comments! @SilverRain: Even without solidifying (which I used to address a previous issue), the boolean modifier results in zero faces. For the next project, I will use the approach you described – thank you! $\endgroup$
    – Nicolinna
    Commented May 6, 2023 at 19:55
  • $\begingroup$ @vklidu: Thanks! I’ve watched that video already a couple of times, I also think to understand what zero faces are (at least based on the example). However, in my file, I don’t understand where a zero face should exist if I use a Boolean modifier to subtract a cylinder. I tried the Merge by distance with a higher threshold but the zero faces still show. I have uploaded now my blend – (see post) of course, very grateful if you have time to have a look at it! Thanks again! $\endgroup$
    – Nicolinna
    Commented May 6, 2023 at 19:57

1 Answer 1


There are two things

  • Topology - If you move top face of lower cube you can see how badly it is connected between there two higher parts. You should avoid it.

enter image description here

Your topology should looks like this (see blend file for better understanding)... this lower Zero faces from few of them.

enter image description here

  • Second thing - change Degenerate threshold - add two more zeros
    (or you can upscale object by 10, but that is not what you probably want).

The threshold seems to represent kilometres ... so 0.000001 is 1 mm.
Since the tube side is 0.188 mm I would expect one more zero to get Zero Faces ... hm, but it works.

Anyway it just inform you a print will be simplified in print. Degenerate value should be adjust it for specific printer capabilities.

enter image description here

  • $\begingroup$ Thank you very, very much for taking the time and solving these issues! When joining the objects/unifying with the boolean modifier, it got somehow connected badly - now I know how I can check if the faces are connected well. And thank you for the explanation regarding the Degenerate threshold! Very much appreciated! $\endgroup$
    – Nicolinna
    Commented May 7, 2023 at 23:19
  • $\begingroup$ Great you found it useful :) $\endgroup$
    – vklidu
    Commented May 11, 2023 at 7:34

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