[sanddrag]

When it is so boring and slow on here in the summer it is funny how all of us just jump at something technical. I don't quite recall exactly what polyurethane is like (the only thing that comes to mind at the moment is the liqid stuff in a can that I applied to the top of my workbench to seal it) but are you sure it is going to spin well on the steel pins? Perhaps you would consider pressing a brass tube into the roller to let that ride on the pin. Also, there must be some sort of provision so the end of each roller doesn't rub on the plates.

Anyway, this wheel design isn't really that different from most I've seen, but it sure is welcome in these barren forums around this time of year.