EM-56-P Motor?

[Graves]

Finally got out to the garage to spend some time on the lathe. To prepare for installing the spindle and new bearings I removed the intermediate shaft so I could change out the drive belts. The whole area under the head was a mess, 70 years of gunk I presume, I cleaned as well as I could without removing everything but I was concerned that some crud made its way into the needle bearings of the shaft, so I pulled the running gear out of the cabinet. While I had everything apart I wanted to extend the motor wires as they were too short to reach the VFD and figured that replacing the wires was better than just extending them. Well, that was a mistake, the insulation on the stator wires was like glass, disassembly of the motor and removal of the stator revealed more soft parts that had become super brittle, stuff was breaking everywhere. So now I’m looking at motors, any recommendations that won’t break the bank?

 

[Ulma Doctor]

56 frame motors are almost universal.
they have a 5/8" shaft and are generally come in 3 speeds- 1140,1740, and 3450 nominal RPM respectively
for your use a non inverter rated motor can be used in the 30Hz to 90Hz envelope for short periods of time (hours) and it can be used continuously between 50Hz and 70Hz.

conversely, an inverter rated motor can be used continuously at nearly any frequency.

where you'll never go wrong with a new motor, a used Baldor or WEG motor could efficiently do the job.
3 phase motors are generally trouble free for a long time, bearing changes often extend the life of old motors by many years

i found an inverter rated Marathon Black Max 5hp Motor (new) a few years ago for a couple hundred dollars, maybe you could do something similar

2 or 3 Hp would be sufficient for your needs, i would assume

 

[Graves]

56 frame motors are almost universal.
they have a 5/8" shaft and are generally come in 3 speeds- 1140,1740, and 3450 nominal RPM respectively
for your use a non inverter rated motor can be used in the 30Hz to 90Hz envelope for short periods of time (hours) and it can be used continuously between 50Hz and 70Hz.

conversely, an inverter rated motor can be used continuously at nearly any frequency.

where you'll never go wrong with a new motor, a used Baldor or WEG motor could efficiently do the job.
3 phase motors are generally trouble free for a long time, bearing changes often extend the life of old motors by many years

i found an inverter rated Marathon Black Max 5hp Motor (new) a few years ago for a couple hundred dollars, maybe you could do something similar

2 or 3 Hp would be sufficient for your needs, i would assume

It’s an old lathe so the motor standards hadn’t been cemented in yet. It’s a 184 frame motor, but with a 7/8 shaft, I figured that a 145T frame would be the easiest to convert to. I ended up buying a Teco 2 hp inverter rated motor, supposedly has additional mounting hole patterns in the frame, wasn’t too bad at just under $400 including shipping.

 

[Ulma Doctor]

If you are diligent, you can find a 56HZ frame, it has a 7/8” shaft