It doesn't always have to be difficult.
But you can still ask yourself whether you can make the swing run even better with a certain profile on the rotating shaft. I really don't know how you could calculate this for an optimal swing. The profile can then be printed in 3D.
HD: https://www.flickr.com/photos/fotoopa_hs/32039299867
Short video:
Update link youtube with new version better lighting:
https://youtu.be/eVIIrR1yCPk
Frans.