I was trying to make this cvt belt animation but can't figure it out how to make increase or decrease belt size animation I have tried curves but doesn't work.

Any body can recommend how I can I do a belt animation like this

  • $\begingroup$ You might need to activate the Animall addon, (I think that's what it's called) it lets you animate curves which should let you do this. $\endgroup$ Mar 10, 2021 at 1:00
  • $\begingroup$ Instead of having users go through links and external sites please use the builtin tools to embed images in your post. See How to upload an image to a post? $\endgroup$ Mar 10, 2021 at 1:04

1 Answer 1


The changes in a CVT belt ratio can be simulated using softbodies in Blender.

enter image description here


  1. Create a new blend file.
  2. Add geometry for the pulleys and belt as shown in the animation.
  3. Set the pulleys physics to act as collision.
  4. Set the belt as a softbody.
  5. Turn off gravity to prevent the belt from slipping.

It take 2 steps to animate the belt size change. First the belt needs to be fit to the pulleys. Then the pulley size can be animated with the belt keeping fit.

  1. Animate the pulleys moving apart to the final location. The belt will stretch to fit the pulleys as they pull apart.
  2. Animate the change in pulley size. The tension on the belt will ensure it stays close the pulleys as they change size.

The blend file is available here -


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