Brain's40,
It would be nice if this could be done, but it can't. As gtow69 pointed out, gearing would be the only practical way to do this on your small drill press. The larger the drill bit, the slower you turn it...you must want to drill a large hole.
The AC motor will lose torque when you slow it using electrical means, while a sheave reduction will up the torque proportionately.
Small AC frequency drives are available that allow nice variable speed features, but sticking one of these on a small, cheap drill press might not be the best move.
Stuart
