Wiring a new drum switch to my original MW motor

[zayd]

Thanks, Robert. This could very well be the reason the lathe was retired in the first place. I am good opening the motor; I'll take a closer look to see if that's possible. Worst case scenario, I need a new motor. I do have a 3/4hp 3ph motor sitting idle and a VFD that I just pulled from another machine, so that may be a good match-up to give me some more finite speed control.

I measured again in the 200 ohm range. I checked and rechecked connections to ensure I had good contact. All the non-infinity numbers below are new:

Negative to 2, positive to:
Wire 6: 1.6
Wire 8: infinity
Wire C5: 0.8
Wire 7: infinity
Wire E: 1.6

Negative to C5, positive to:
Wire 6: 1.8
Wire 8: infinity
Wire 2: 0.7
Wire 7: infinity
Wire E: 1.8

Negative to 7, positive to:
Wire 6: inifinity
Wire E: infinity
Wire 2: infinity
Wire 8: this time, instantly down to 160 then immediately back to infinity
Wire C5: infinity

Negative to 8, positive to:
Wire 6: infinity
Wire E: infinity
Wire 2: infinity
Wire C5: infinity
Wire 7: this time, instantly down to 134 then immediately back to infinity

Negative to E, positive to:
Wire 6: 0.5
Wire 8: infinity
Wire 2: 1.6
Wire 7: infinity
Wire C5: 1.8

Negative to 6, positive to:
Wire E: 0.5
Wire 8: infinity
Wire 2: 1.6
Wire 7: infinity
Wire C5: 1.8

 

[wa5cab]

Either pull the end bell and see what is inside or take it to a shop.

I'm going to dinner.

 

[markba633csi]

My vote is to use the 3/4 hp motor and vfd, variable speed is a wonderful feature to have on a lathe
I think it's not really worth opening up the other motor, unless you are curious
Even if you were to power it up it may overheat and/or not deliver full power- sorry
-Mark

 

[wa5cab]

I looked back up the thread and don't see any mention of a 3.4 HP 3-phase motor and VFD drive. But if you do have one and have the proper AC supply to run it, that is certainly an option and probably your least expensive one.

 

[zayd]

My vote is to use the 3/4 hp motor and vfd, variable speed is a wonderful feature to have on a lathe
I think it's not really worth opening up the other motor, unless you are curious
Even if you were to power it up it may overheat and/or not deliver full power- sorry

I think you're right, Mark. The VFD is a little overkill at 3hp, but I can always get a smaller one in the future if I need to repurpose this one elsewhere. Better than just letting it sit.

I looked back up the thread and don't see any mention of a 3.4 HP 3-phase motor and VFD drive. But if you do have one and have the proper AC supply to run it, that is certainly an option and probably your least expensive one.

Robert, I just mentioned the VFD in my last post. It became available just yesterday, so it's now an option to run this lathe. I was hoping to get the original motor going, but it doesn't seem viable or cost-effective at this point.

This was my first time diagnosing a motor at this level and I learned quite a bit doing it. My gratitude to you and Mark for the guidance through the process! Tremendously helpful.