I've got an old belt table sander. I rebuilt the top and just got a new belt it is 6" * 25" but found the motor is bad. The old one has no labels or markings to know what speed or brand it is. This sander was from a cabinet shop that was active in the 30's up until mid 70's.
I've got a couple newer ones but ? is what speed should th belt sander be run at. I can change the pulleys if needed but currently the motor I had in mind is a 1/3hp 1724 rpm.
-DDG