Peter Grey wrote:
Hello all,

I have a '33 11" SB lathe with a '31 Westinghouse 1/2 HP motor on it. The
motor started acting up so I took it to my local motor shop who got it
running decently, but told me that it would cost a mint to do what needs to
be done to make it right (70 years of oil soaking into the winding
insulation and all that). While the motor works, it doesn't work as well as
it should, and rather than spend more money than it's worth, I'd like to
replace it. The question is; with what?

I've been told that 1931 HP were bigger than 2006 HP and that I should go
with a 3/4 or 1 HP motor to get similar work capacity. That's fine, and my
shop is wired for 110, 220 and I have both a rotary and static phase
converter. My lathe has a screw-on chuck so I don't have a need for instant
reversing (although the lathe is currently wired for reversing and I'd like
to keep that capability). My question is, are there any advantages to 220
or 220 3-phase over 110 when choosing a motor without concern for instant
reversing.
Yes, a 3-phase motor also runs smoother than a single-phase plain
induction motor. Because of the power line cycles, the single-phase
motor is essentially shut off 120 times a second. Capacitor-run motors
are better in this regard, but a 3-phase motor is even smoother. Some
people have been troubled by bad surface finish and other vibration
problems and found DC or 3-phase motors solved the problem.

Later, you can always get a Variable Freq Drive for a 3-phase motor
and have variable speed, too.

Jon