Quote from JorisCeoenOn 6/23/2020 at 9:41 PM, JorisCeoen said: You have unsmoothed parts of the collision mesh. Select ALL parts of the mesh, and assign them a single smoothing group (for instance, assign all parts with smoothing group 1 and it's fixed).
but where is that because I don't know much about blender and I mess up a lot with the program