Thx mptak! Yes, I have download some and reversed engineering. It really helped. I find a lot of this is trial and error. Love puzzles. : ) This really helped: https://sites.google.com/site/sketchyphysicstutorial/ The car tutorial, put things into perspective. Once you know how it's easy. I just figured out how to make a table turn that supports a controlled seesaw. Huge personal satisfaction!