Another SB9a rotary wiring question

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mzvarner

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In another thread I documented a new to me model 9a. Some wire photos are there that i dont have on my phone at the moment. Transportation issues lead to a missing countershaft pulley. When the replacement arrived, and I fired her up the motor sounded like it needed bearings badly. So after a quick function test seeing everything worked, and learning how amazing back gearing is, I took the motor apart, cleaned the case and replaced the bearings. I rewired it the same way it came apart and she runs so quiet and smooth now. I was able to verify correct rotation (CW vs CCW) by swapping leads per the motor diagram.

But now when I try to wire it to the switch, it runs for a few seconds, then blows the breaker switch. Reset the breaker, verify tight connections, turn on, motor sparks, breaker trips.....and here we are.


20240612_063331.jpg
Previous owner appeared to have motor setup for "high voltage" as all wires primarily come off the 3 terminal. There is nothing but an empty square at terminal 2 as seen in the "no therm prot" diagram.

He claims never had reverse from the switch and was wired for 110 as I need to. I thought "high voltage" was 220?

20240616_190535.jpg
Pic of wiring before removing everything to replace bearings. For reference the 3 terminal is where the spaghetti starts

13934.jpeg
Photo the previous owner supplied of how to wore the switch. Notice no grounding, and the thick gauge wire jumper for the middle and right terminals.
 
If you can wire it with a pigtail and run it off a wall receptacle than look into your switch wiring.
An ohm meter is a great help here.
Without power and with a sketch pad, note the positions and readings on the ohm meter as you change switch positions.
 
You currently are running on 115 volts? You do know that the amp requirement at that voltage exceeds the capacity of
most 115 volt outlets? (15 amp)
A motor that large should be run on 230 volts. However, you might can get by on 115 providing you don't put a large load on the motor.
1.5 HP is really oversized for a 9a

A 115 volt reversing connection should have 4 wires from switch to motor- show me a top view of your switch so I can ID it
It looks like a "chopstick" style or 3-phase switch
 
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The poster says he ran the motor after rebuild quiet and smooth, it wasn't until he tried wiring the switch in that the problem started
 
markba633csi said:
You currently are running on 115 volts? You do know that the amp requirement at that voltage exceeds the capacity of
most 115 volt outlets? (15 amp)
A motor that large should be run on 230 volts. However, you might can get by on 115 providing you don't put a large load on the motor.
1.5 HP is really oversized for a 9a

A 115 volt reversing connection should have 4 wires from switch to motor- show me a top view of your switch so I can ID it
It looks like a "chopstick" style or 3-phase switch
Click to expand...


Electricity is not my forte. I did think it was odd when the original owner said he upgraded to a 1.5hp. He "owns a fab shop" so me being ignorant about Electricity and "real" lathe, I made a few assumptions.

To clarify the OP, I took the machine apart including the motor. I used some of what I learned on these forums to test the motor phasing. I used a new, longer 3 prong cord to test with. These were brief function test, not under load or attached to the lathe. When I attempted to rewire and it ran briefly before tripping the breaker, I did notice the insulation in the cord was warm. So it has sat unplugged until I can figure this out.

I believe the switch is a hockey stick style. Attached is the inly Pic I have at the moment.

Reverse.jpg

Sounds like I need to purchase an appropriate sized motor.
 
This should work if the switch is a 3-phase type: (ground not shown)
Bring out the red and black wires from the motor separately and connect as shown:
1.5hp115vrev.jpeg
 
Wow, thanks!

I live in a rental, so my major concern is safety. Is this motor safe to run or should I purchase a new one?
 
I highly advise getting a smaller motor if you don't want to or can't run 230 volts
the switch contacts will burn up very quickly on 115 volts with a motor this large, and you won't be able to load the motor much
before the house breaker trips.

You can run the 1.5 HP motor for a while anyhow on 115v
It should be safe enough provided the switch and motor cases are both grounded
 
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No problem. Keep in mind that the current rating of the motor is for full load- you won't be pulling that much using it with
a South Bend 9" lathe. So you could use the 1.5 hp motor for a while just to get up and running.
A 3/4 HP to 1 HP would be a good size motor for that lathe- up to 1 HP is comfortable for a standard residential power outlet
 
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