I'm trying to extrude an indent into an object, but for some reason whenever I apply the Subdivision Modifier, it gives the indent an overhang partially covering the indent. I have used loop cut and slide where I can, but some surfaces near the indent will not loop cut. What am I doing wrong?

Cut out test

enter image description here

  • $\begingroup$ That's probably because you have two meshes or not connected vertices in the mesh if only one mesh. Subdivision will round/average the hole of the horizontal part, but if connected with the below surface, that won't be the case. $\endgroup$
    – lemon
    Commented Mar 17, 2017 at 12:52
  • 2
    $\begingroup$ Please post a picture of the mesh in edit mode so we can see the topology. $\endgroup$
    – David
    Commented Mar 17, 2017 at 12:55
  • $\begingroup$ I hope this is what you wanted, David. Cheers Dave $\endgroup$
    – Dave
    Commented Mar 17, 2017 at 14:45
  • $\begingroup$ Lemon, the mesh is connected. I have just pulled and pushed the verticies around to see if there are any gaps and there are none that I can find. $\endgroup$
    – Dave
    Commented Mar 17, 2017 at 14:49
  • $\begingroup$ OK... I don't know what you wanted to do, but you have a lot of duplicated vertices at the hole's corners... what is that for? But the problem is due to the pie ngons around the hole $\endgroup$
    – lemon
    Commented Mar 17, 2017 at 15:13

1 Answer 1


The problem is due to ngons (again), probably because of the use of a boolean modifier (again).

The faces which overlap the hole are these one, two ngons around the hole:

enter image description here

The aim will be to organize quad around the hole. That could be done all over the discus, but, as the other part may stay flat this is not absolutely mandatory.

These quad will be "subdivision surface" modifier resistant!

You have also added many loops around the hole, I remove it for now.

So first cleanup:

  • Opening the ngons
  • Remake the border (which is not the same as the others)
  • Removing the doubled vertices

enter image description here

Creating vertices to obtain quad in the wanted part. I only do it here in the hole concerned part... So that will create ngons around, and that's not visible so long these faces stay flat and convex.

  • Subdividing the edges around
  • Grabbing vertices along the edges to the wanted location
  • Connecting quads

enter image description here

Now when we show the modifier:

enter image description here

As you want it squared, we'll add some bevel in order to maintain the subdivision effect. Use CtrlB to bevel and Numpad + and Numpad - to set the amount of edges.

enter image description here

  • $\begingroup$ Lemon, I have only had chance to have a quick look at your answer, but thank you very much for your help. Cheers $\endgroup$
    – Dave
    Commented Mar 17, 2017 at 16:48

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