I have read most of the messages about converting a (belt-driven) table
saw to a disc sander. I have an older saw collecting dust in the
corner (it's worthless as a table saw) and am considering one of the
sanding discs for infrequent use. I expect it to ruin the saw or arbor
bearing over time. I could care less.

The thing I am not clear on is RPM. My motor turns at 3450. The
grizzly disc sander says it turns at 3450.

What should the disc spin at? It's just a pulley choice. The messages
about the saw turning too fast and burning up wood don't seem clear. I
assume this is because people are using the same pulley ratio as they
were with the saw blade, which is faster than 3450?