Multipurposing a 1500w/4450rpm motor

I've been thinking of using an old Ryobi table saw motor (1500watt/~4450rpm) as an interchangeable drive source for a few shop made machines.



First off the line would be a 12" disc sander, then any of a thickness sander, spindle sander or multi-speed lathe as I get around to making them.



Obviously 4450rpm is way too fast for a disc sander so the simple solution, to me, is to rig up a pulley system for driving the disc while also catering for the speeds necessary for the other intended machines.



Using the pulley calculator at:

http://ift.tt/1mGdSKG

it seems like, for the disc sander at least, I'm looking at a 3" pulley on the motor driving a 9" pulley on the 12" disc to get it spin at about 1480rpm (close to Carba-tec's budget disc sander).



So I guess my questions are, "Torque? What's torque in relation to these machines and the motor?" and "what other speeds/pulleys should I be looking for to drive the other machines?"



From there I should able to decide what, if any, multi-size pulleys I should be looking for, or if I should just scrap the whole tight-wadded idea :)