VFD

Well that’s bad news because I need a bunch more RPM to make using different tooling easier. I need more SFM for most everything I do.
Exactly... Older machines don't spin fast enough for carbide insert tooling... Might consider a motor pulley change, you lose torque but gain SFM & as long as you don't take huge cuts it works pretty well... My small lathe can still take .120 cuts without showing any sign of being overloaded..

The big lathe will take .400 without much trouble... I rarely take more than .125 in a single pass...