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Thread: Baldor bench grinder question

  1. #1
    Join Date
    Sep 2007
    Location
    St Louis, MO
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    Baldor bench grinder question

    Greetings to all:

    I got this bench grinder that is supposed to be a Baldor. It has no nameplate but it "looks" like a Baldor. It has 12" diameter wheel guards so I assume it is a 10" grinder. The arbor is 3/4" which is odd because newer models have heftier arbors. Anyhow, this unit had the bearings shot and was making a very big buzz with no movement in the shaft. I replaced the bearings and cleaned the unit inside (centrifugal contacts etc.) and the unit is running now. However, if plugged to a 115v receptacle & after 2-3 seconds the breaker trips.

    The guy I bought it from (I paid him $20 for it) did not know much about this unit but he guessed it was a 1 HP unit. It used to belong to a fabricating shop that had closed down. It had a 3 prong twist lock plug. From the NEMA chart pictures it could be a 115 or 230 volt plug. The motor does not have any wiring diagram or any other info on it. How do I tell if it is prewired for 230 v? It came with a 12AWG cord. Any leads will be appreciated.

    Sal.

  2. #2
    Join Date
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    Sal,

    Does the plug label start with L5- or L6-? Assuming the plug is correct for the internal wiring, an L5 is 120V and a L6 is 240V.

    L5-20 means 120V, 20A and L6-30 means 240V, 30 amp. Other numbers mean other things such as 3-phase power, which is not impossible either.

    Beyond that, without a motor nameplate any answer is at best a guess but...

    If you take the cover off of the motor termination box and get a picture of the internals we*may* be able to give some insight.

    Jim
    One can never have too many planes and chisels... or so I'm learning!!

  3. #3
    Join Date
    Sep 2007
    Location
    St Louis, MO
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    Thanks for the input. The wiring has no labels whatsoever. The motor spins fine (I measured the rpm, it is 1500-1600) with a loud buzz. I plugged it into a 20 amp outlet, it still tripped the breaker. I am thinkking perhaps it is prewired for 230V. If I plug it into a 230V would I risk burning the motor if indeed it is prewired for 115V?
    Sal.

  4. #4
    Join Date
    Dec 2007
    Location
    Kentucky
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    Look in the electrical connection box on the motor. See if there are wire numbers on the leads coming from the windings? Also how many wires are hooked to each power cord wires and if they are numbered what are they. If it is a baldor motor with the original windings the wires will be numbered.

  5. #5
    Join Date
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    "It had a 3 prong twist lock plug."

    Since this plug does not have a L-number, please compare it with this chart:

    http://www.repeater-builder.com/tech...ma-locking.pdf

    which will at least indicate what the motor should have been wired for, assuming it was working with the twist-lock plug. If you have questions, post where it is on the chart and we can go from there. Please note it's multiple pages.

    Jim
    One can never have too many planes and chisels... or so I'm learning!!

  6. #6
    Join Date
    Sep 2007
    Location
    St Louis, MO
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    Thanks again for the leads...
    Ken: The wires are indeed numbered. 1&2 are wired to one terminal on the switch (opposite the white wire in the second picture below), and 3&4 are wired to the other terminal switch opposite the black wire.100_4414.jpg100_4415.jpg I replaced the capacitor because the original one was wired incorrectly so it got too hot and was oozing some black stuff.

    Jim: I do not have the original plug but I will check into it. From what I remember it looks like L5 on the chart.

  7. #7
    Join Date
    Sep 2007
    Location
    St Louis, MO
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    I found Baldor 1022W to be the closest model in physical aspects to my grinder. The wiring diagram of 1022W is on p.9 of the following document:
    https://www.baldorvip.com/servlet/pr...cket/1022W.pdf
    I tried to wire 1&3 to neutral and 2&4 to hot wire (low voltage), the grinder did not spin at all.

  8. #8
    Join Date
    Dec 2007
    Location
    Kentucky
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    Sal the fact that the starting capacitor has been overheated means that it was either hooked up wrong or the starting switch inside is not working properly. The typical wiring for a baldor 1 phase dual voltage motor should be the following. One more thing I should have asked is how many wires come out of the motor and what are their numbers ?
    110 volts should be L1 with 1&3 L2 with 2&4. Now there are other wires that have to do with the start winding, centrifugal switch and capacitor. What are they on your motor?

    i just looked at the wiring sch. On your last post. That is for a run cap. 12mfd. That cap is meant to stay in the circuit along with the start winding. According to you original post you stated that there was a centrifugal switch in your motor. That is designed to drop the start winding and cap out of the circuit after it reaches a predetermined rpm. They are two entirely different motors and will hook differently. So which one do you have? Need to know for sure before hooking up and running!
    Last edited by Ken Lutes; 02-08-2013 at 1:02 PM.

  9. #9
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    There are 4 wires labeled 1,2,3,4 that go to the motor and the two wires (no numbers) that connect to the capacitor. The way it wired now is that 1&2 are wired to the neutral and 3&4 are wired to the black (hot) wire. When I connected 1&3 to neutral and 2&4 to hot wire (low voltage) per the Baldor wiring diagram, the grinder did not spin. Puzzling.

    When I took the motor apart to change the bearings and clean the contacts, I did see a centrifugal switch.

  10. #10
    Join Date
    Dec 2007
    Location
    Kentucky
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    This is puzzling what are the numbers on the capacitor and when you had it apart were there a switch with contacts that would open up by the centrifugal switch? A picture would be nice.

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