I'm trying to use rigid body physics on a Lego model that was built inside of Mecabricks and exported into Blender. My hope is that the model will stand in place until I animate a sphere to go crashing through one of the walls. That is the point that I want the rigid body physics to kick in and destroy the wall. However, instead of waiting on the sphere to cause the destruction, the model begins to explode on its own as soon as the timeline hits the first frame, thus never allowing the sphere to be the catalyst for causing the destruction. For the sake of my animation, I need the sphere to centrally cause the damage and not just have the entire model self-destruct.

I tried multiple different collision shapes (convex hull, box, mesh, etc) but I never seemed to get the desired effect.

Just to make sure that I was setting everything up correctly, I created a new Blender scene and used cubes to build a wall. When done with cubes (and not a Lego model from Mecabricks) the cubes sat patiently waiting until the sphere crashed through and caused the destruction. So, that verified for me that I was setting up the rigid body physics okay.

Has anyone else ever experienced this problem? If so, is there a way to fix this?

Thanks so much.

Here is my blend file I made for testing....

  • $\begingroup$ Since most folks here will probably have never heard of 'Mecabricks' let alone know how the object (s) it produces are constructed, it's impossible to answer that question without more details. At least add an image of Blender's window which you can save via the Window > Save Screenshot menu in Blender and add to your question, and if possible your Blend file too via blend-exchange.com following the instructions there. $\endgroup$
    – John Eason
    May 19, 2023 at 15:15
  • $\begingroup$ Thanks for the reply @johneason . Allow me to back up a bit and give some more info: Mecabricks is a free, online site that allows users to build with 3D Lego bricks. You can create anything out of Lego that you wish, or even select from models that other people in the community have created. Then, there is an add-on for Blender that allows you to export your creations from Mecabricks into Blender. I will attach a blend file so you can see a model that I have added rigid body physics to. However, the model explodes and does not wait for me to trigger it with a sphere. $\endgroup$ May 30, 2023 at 12:33
  • $\begingroup$ Here is my blend file I made for testing.... <img src="https://blend-exchange.com/embedImage.png?bid=rNZ33Qqg" /> $\endgroup$ May 30, 2023 at 12:58
  • $\begingroup$ I've added the link to your Blend file into your question which should re-submit it and allow other folks to see it and hopefully give you an answer. $\endgroup$
    – John Eason
    May 30, 2023 at 14:27
  • $\begingroup$ Thanks again @JohnEason . I'm new to this forum and am not sure the best practices just yet. But I'll get there. LOL $\endgroup$ May 30, 2023 at 14:52

1 Answer 1


If you enable Split Impulse on Scene Settings, it will be better, but not perfect. It does not explode but jump up every brick

enter image description here


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