rpm plate is gone, I'm judging by the sound

logan 10. the plate that said the speeds is missing and the belt chart is a ghost. ive been picking the pulley that doesnt scream. mild steel, hss, about 1 inch. is there a sane way to know the rpm without a tach I dont own

Count motor rpm from the nameplate. Measure both pulleys. Ratio times motor rpm is spindle rpm, close enough. Or paint a mark and use a phone slow-motion if you must. 'Doesnt scream' is not a speed.

nameplate says 1725. big pulley on the spindle, small on the motor, i got something like 280. that was the quiet one. the scream one is closer to 900. ill write it on the headstock in pencil like a criminal

Pencil on the headstock is how every honest shop starts. 280 for an inch of mild with HSS is in the range. 900 is a polish speed you were using as a roughing speed.