Yeah, EE Smith's "blinding flash and deafening report". (old SciFi) I just want my yard back and to get it done before nature overgrows stuff and makes it really hard. Not to mention...thermal security for next year.
I'm not sure the motor type in my lathe (240v) or the mill (120v), probably they have a capacitor in there (but in series with some winding) - both are reversible and ~ 5 Hp (Chinese rating). I know if you switch directions on the lathe while it's spinning at all, it just keeps going the same way.
Given the way I use either one, I've thought that if I get that round-tuit, I might adapt a DC treadmill motor to either one, which would make speed control a snap - those readily available boxes are killer-good. You can run a nominal 4k rpm motor at 100 rpm and have full torque and speed regulation vs load. The reduced available full load duty might not bother me, as it's rare that I use the full power or either one for any length of time.
It would take some machining to do...but hey. On the other hand, it might be like This Old Tony's cheap drill press refurb. An interesting detour (de force?) that wound up in nearly the same place anyway. I don't need to move belts that often. My shop is more to enable me to do things at all, vs a production or job shop, I'm usually not in a hurry. It's just a nice capability to have.
Seems like anything without some kind of feedback right at the "output" has backlash issues. My lathe, which I got new, has enough slop in the drives that threading fine threads takes some hand-pulling on things to force the backlash to always be in the same state at the start of thread, for example.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.