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I have created the beginnings of a marble run using blender 3.1 and rigid bodies. For the run, I extruded a circle along a path. For the marble, I am using a scaled icosphere. I can get the marble to roll down the run, but when it gets to a short loop I built into the run, it stalls and will not go all the way around the loop, falling back and rocking back and forth until it stops. No matter what parameters I try, it won't work. I don't think the loop is too big. I have a long steep slope leading into it. I am beginning to think it is a limitation of rigid bodies. Am I missing something? Any help would be appreciated.

Running blender 3.1 on a windows system with a graphics card.

Here is a copy of the blender file. \

https://www.dropbox.com/s/8k6v2nyy52wwmz5/marble_run.blend?dl=0

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  • $\begingroup$ It's possible the shape of the icosphere doesn't handle a loss in velocity and/or change in direction well. Maybe try using a "quad-sphere" for the marble instead - Start with a cube, then add a subdivision Surface Modifier level 3, and a Cast Modifier with the Factor set to 1. Apply them both. $\endgroup$ Commented Jul 12, 2022 at 22:21
  • $\begingroup$ i think there are two reasons why it won't work. First you have friction of ball and marble run set to 5. These should be as low as possible. Second the geometry of your marble run is ridiculous high which makes it hard for Blender physics to calculate. "normally" a density like this is more than enough for blender physics: [1]: i.sstatic.net/ci9yr.png if this isn't enough for your render, maybe make a second one with higher density for render and for the physics the low poly one invisible. $\endgroup$
    – Chris
    Commented Jul 13, 2022 at 2:37
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    $\begingroup$ @Chris blend-exchange.com/b/jX1pJ44A $\endgroup$
    – moonboots
    Commented Jul 13, 2022 at 13:36
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    $\begingroup$ @Chris Great, but I guess RAMickelsen wanted a trick to make it work as it is, that said, maybe write the answer ;) $\endgroup$
    – moonboots
    Commented Jul 14, 2022 at 7:06
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    $\begingroup$ There is not real world for „us“. We are living in a simulation (and we are doing bad…so I don’t think we are gonna make it). to your second question: so we ARE indeed living in a kind of blend file of the future which also can simulate smell, feelings, sounds and so on. I am probably made of 3 trillions peribets (which is the synonym of poligon in the future but which is too hard to explain to the human brain power💁🏻‍♂️). You wouldn’t believe: peribets can also be inverted: that’s known for you as disease. Of course you are confused: you are human. That’s your nature. $\endgroup$
    – Chris
    Commented Jul 14, 2022 at 7:45

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Thank you all for the excellent input. I messed around with the friction settings and that did not solve the problem. I guess the solution is a longer run into the loop. Like you said, physics. And you are right. Too many subdivisions. Live and learn.

You guys are awesome.

BTW, I love this program. It is my new hobby. I am 70 years old, retired, and love computer graphics. I have another blender marble run up and working so this project is kaput.

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  • $\begingroup$ Hi @RAMickelsen I'm in my 80's and came across Blender some 6 years ago and finished up ditching the commercial stuff, using Blender exclusively. I'd wager that dementia is kept at bay the more you use it! :) $\endgroup$
    – Edgel3D
    Commented Jul 18, 2022 at 7:16
  • $\begingroup$ Thanks Edgel3D! Guess Blender is not just for young folks! $\endgroup$ Commented Jul 19, 2022 at 21:35

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