Arch Intersection


I am working on an arch design and I have an issue I am struggling to fix; so the arch is made from a triangle, which has been mirrored to create an intersection. However, I want the two arch to be flat at the top so when they intersect, I only have a flat top. Can someone help me with this please.

Screenshot and the script has been attached.

Cheers all!

Arch (29.5 KB)


You are using a sweep along an arc, so the profile is oriented perpendicular to this arc. If you want both arches to meet “flat”, they would need to be part of a common surface, which has to contain the two rails. This means that the section would be flat along the average vectors, and not along each rail. Therefore you have to build this surface and trim it, which means the section won’t be a real triangle.

Two more details :

  • The Sort List is useless, you already provided the points in the correct order. More importantly, you shouldn’t put Points in the Keys input, it’s meant to receive numbers. If you enter points, Grasshopper will convert them to numbers by computing their distance to the origin.
  • You used Interpolate, is it really needed, you can build a real arc with Arc 3 Pt.

Arch (39.9 KB)

Thanks a lot for solving that and also providing the explanation.