Thanks guys, good info.
I get the physics of what causes spin but my body just doesn't comply for some reason
I have no trouble serving with slice and can put a sick amount of backspin on a ball but topspin is very hit/miss for me. I'm sure my technique sucks and the best luck I've had was to envision "pulling" the racquet up on an angle as opposed to swinging it...if that makes any sense????
Anyway, thanks again.