VPI SDS exact speed in .... 40 minutes?

Agree with pbnaudio - the actual frequency reading on the SDS is irrelevant; it's easy to prove that with different mass centerweights: lighter ones will need lower freq settings, while heavier ones will require higher. The good news is that you can get extremely accurate speeds with the SDS.

Thanks Ack. After emails exchanged with Peter, one of the couses would be the thickness of the small belts that goes from the motor to the flywheel so I bought new ones. As soon as I receive them will post the results. thanks to all for your input.

OK greak and sorry, I got the weight/frequency thing backwards