I have a scene that I need to run simulations on, and quite a few of the collision shapes need to be set to mesh. This works fine for most objects but there are some that are acting weird, basically falling through each other.

Following the tips here and here, I have tried to solve this by:

  • Increasing the number of steps per second
  • Applying the object's scale
  • Tweaking the boundary margin
  • Subdividing the meshes
  • Flipping Normals

Further, the masses are similar and the dimensions are reasonable.

None of these tweaks have helped. Though the simulation runs fine if one of the objects collision bounds is set to convex hull. Is there something I can do to the meshes to make this work?

Example file:

  • $\begingroup$ Have you checked your normals? Flipped normals can cause issues in Soft Body and Cloth collisions - not sure if same could apply with Rigid set the Meah collosion. $\endgroup$ Commented Nov 1, 2018 at 10:18
  • $\begingroup$ Yep I've also tried flipping normals $\endgroup$
    – A. Bollans
    Commented Nov 1, 2018 at 11:07
  • 1
    $\begingroup$ You need to remove double geometry. Select objects in edit mode, press W then "remove doubles". Then, lower "sensitivity margin" for both table and lamp. Even zero works. $\endgroup$
    – m.ardito
    Commented Nov 1, 2018 at 14:02
  • $\begingroup$ This doesn't seem to work. 'Remove Doubles' returns 'Removed 0 vertices' and the collision is still weird $\endgroup$
    – A. Bollans
    Commented Nov 1, 2018 at 14:43
  • 1
    $\begingroup$ As @m.ardito says, you need to remove doubles - select the table, go into Edit mode, select all, Remove Doubles - you have overlapping faces. It also appears that you haven't Applied Scale to either your table or your lamp - that will affect the simulation. $\endgroup$ Commented Nov 1, 2018 at 16:58

1 Answer 1


As @m.ardito and @Rich Sedman pointed out, the solution is to remove doubles: Edit mode, select all, Remove Doubles.

The simulation now runs fine


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