How to do a 180° rotation

Hi, how can I do a smooth 180° degree rotation of “y” without having the mesh to break up. When I use tween or do anything, it looks like this and is not how the mesh looks like of course. Can anyone suggest a solution for this?

Thanks in advance

Hi @Oliver1470,

Do you have a sample project we could take a look at? With just the screenshot, I’m not quite sure what might be causing this behavior.

Or can you post the code for the tween. It looks like the transformation matrix is malformed.