I'm new to Blender. I apologize in advance if the question is not clear, I will try to explain the problem as best as I can.

I have a mesh that represents a knocked-down box (think rigid, hard material) ans I'm trying to animate it into a folded box container. To do that I rigged my mesh as follow:

enter image description here

From a high-level overview, everything works fine. However, I notice that the stretch at the junction of the bone when folding 90 degree is too large.

enter image description here

This behavior causes undesirable hole in corner of the folded box because the stretching of the joint was too large.

enter image description here

How do I reduce this stretching.

File for reference:


  • $\begingroup$ Heads/tails of the bone should be at the exact location where the box is to be bent. Additionally vertex weights will matter, so please edit your question to see how are the weights or upload your file. $\endgroup$ – lemon Mar 4 '17 at 17:22
  • $\begingroup$ @lemon thanks for the tip, i will go investigate the weight - i think they are uniform. Additionally I updated the question with the file link. $\endgroup$ – taiduckman Mar 4 '17 at 17:32
  • $\begingroup$ In this case nearly all vertices (if not all) need to be linked to only one bone. So remove all weights, then assign the wanted vertices to the wanted corresponding group. Also, some of the bones articulations are misplaced. And probably, you have too much bones here each face which has 4 bones could have only one $\endgroup$ – lemon Mar 4 '17 at 17:43
  • 1
    $\begingroup$ And important too: when flat, bones and box are not on the same plane (did not saw it first, but maybe the main point here) $\endgroup$ – lemon Mar 4 '17 at 17:58

Bones heads here need to be placed on the exact place of the folding.

Here the bones and the box are not on the same plane. So when the bone rotates it stretches the box:

enter image description here

This is the main problem.

Make so all bones are well aligned with the wanted folds, in all directions.

When the bone is aligned:

enter image description here

| improve this answer | |
  • $\begingroup$ hmm ok. good point thanks. bone pivot location seems to be very important $\endgroup$ – taiduckman Mar 4 '17 at 18:42

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