Definitely NOT a waste of time, especially in hand grinding. Breaking down grit does produce a finer surface, and cut succesive grit times, add a little water now and then, but don't push to far, as the discs will bottom out against each other = scrrrratches......, or stuck! At work we use a "30 stroke breakdown" on the overarm grinders, but it spins at 40-80 rpm, depending on job, but I'm not sure about manual times. ---Sorry, my po' ol back just can't handle hand grinding anymore---
Bill Marriott btk@ix.netcom.com