hi, thanks for everyone's help so far. i'm trying to calculate what size pulley i'll need and what should be the speeds at the chuck. i visited several "star" brand lathe websites, found one with an old catalog. the entry in the catalog for the jackshaft they sold for this lathe to convert it from treadle power to steam power said "...speeded up to200 rpm." i figure that must mean the maximum recommended speed for the jackshaft (and hence the input speed for the lathe) would be 200 rpm. so i've been trying to come up with a pully combination that'll supply the lathe with (as close as possible) a 200 rpm input speed.
what i've come up with so far... motor 1725 > motor pulley 2" > reduction drive v belt pulley 14" (largest i can find in die cast (=inexpensive), the cast iron pulleys go for between sixtysomeodd bucks ~ $140 (w/o collar!)) > with formulas i found on the web that makes 244 rpm for the input to the cone pulley reduction. the reduction cone pulleys are 4.5"/5.625"/6.5625" the cone pulleys on the lathe are 5.4375"/4.3125"/3.1875" that, according to my calculations, with a 244 rpm input, will produce, at the chuck, 20.17/318.25/502.34 rpms. it seems unbelievable there's such a huge difference in the speeds between #1 and #2. is 20 rpm (and that's even w/o back gears) too slow?! i don't even KNOW what it'll be in back gears. is 502 rpm on the highest speed too slow too? i'm a little concerned about speeding this lathe up too much, it has bronze bearings (and they don't look perfect, there is some scoring.)