I'm trying to model for my school a very specific arch, and I have to do an animation to explain how it works. As you can see in this picture : enter image description here

Here's what the arch looks like. Modeling it separately is easy but I want to be able to join those individual arches into one and be able to select each face. Here is an example :enter image description here

I would like to cut the face selected into two and cut where the other arch come through. I want to delete what is below because I don't need it. I tried to boolean each of them but it's junky and doesn't work.

Do you have a solution? Thank you!

Léo Thiery


1 Answer 1


You should better use the Mirror modifier with the Bisect option enabled (here on Y) and an empty as Mirror Object:

enter image description here

Now if you rotate the empty on Z (RZ30 for example) and move it, you can achieve what you're trying to:

enter image description here

But you can also select one of your meshes, go into the Face panel > Intersect (Knife):

enter image description here

It will create an edge all along the intersection, now you can select the faces and remove them:

enter image description here

  • $\begingroup$ Wow ! I'm surprised of how fast you answered, with such an easy and well explained solution. Thank you very much it will for sure help me ! $\endgroup$
    – leo thiery
    Apr 21, 2022 at 10:02
  • $\begingroup$ you are welcome, maybe choose the second solution as your meshes are ready $\endgroup$
    – moonboots
    Apr 21, 2022 at 10:04
  • 2
    $\begingroup$ Snuck in before me again! :) I know you get this, but just for OP... 3 consecutive bisecting Mirrors, the first 2 through origin Empties rotated by 30 and 60, will take you all the way from 1 arch to a 6-way vault. The internal math for bisecting mirrors is much cleaner and simpler (therefore more accurate?) than 'Intersect > Knife', so personally I would prefer that? $\endgroup$
    – Robin Betts
    Apr 21, 2022 at 11:07
  • $\begingroup$ I agree, it would be much cleaner, but for the animation I sadly have to keep what is under the arch, to show their intersection. With the mirror workflow I dont have those intersections. $\endgroup$
    – leo thiery
    Apr 25, 2022 at 8:02

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