This is a roller drive I whipped up in literally one evening. I have a small lathe in my lab that allowed me to do this. There are only two bearings used, one in the center of the output shaft and and the other for the aluminum disk to press against along with the stepper motor output shaft.
Gravity does the rest.
This was really a quickie job, but it works quite well. When I make my permanent roller drives, I'm sure they'll give me no trouble at all. This page created on a Macintosh using PhotoPage by John A. Vink.