cutting a square / rectangle shaped hole in a cylinder cap?

What’s the best way to cut a square shaped hole in the cap of a cylinder? The resulting mesh should be work well with the subdivision surface modifier.
I’ve tried several approaches, but not matter what I do, I end up messing up the geometry of the cap so that there are odd bumps and creases after subsurf is applied.


sqHole.blend (408 KB)

I’d do it something like this:

sqHole.blend (455 KB)

If it doesn’t work for a Cylinder, start from a Plane.

that’s an interesting approach eppo…

@Kurtis, can you explain how you made that?

From left:

  • starting point, top faces selected
  • inset for outer edge support
  • inset for rectangle support, another before extruding
  • extrude down a few times.

Two other ways

A - Edge creases, sharp edges:

  • Rectangle in the middle
  • Extruded down, edge crease to 1 (shift+E, mouse drag and accept, or 3D view properties: mean crease), same edges marked as sharp (ctrl+E -> mark as sharp, or tool shelf)
  • Subdivision surface modifier added, autosmooth option on in object data properties. You can only do sharp edges with this method because creasing alone gives bad shading.

B - Bevel modifier:

  • Rectangle in the middle
  • inset outer
  • Edge bevel weight to 1 (ctrl+E -> edge bevel weight)
  • Bevel modifier: segments 2, profile 1, limit by weight. Subdivision surface modifier added. This gives rounded edges and shading is good, but bevel creates n-gons. It works because those n-gons get restricted on a flat surface and the edges have a continuous quad face loop around them.