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Baldor 1/3 hp bench grinder problem.

thopkins1124

Plastic
Joined
Mar 30, 2024
Location
North Carolina
Hello everyone, I acquired a Baldor bench grinder from a family member. I went through and cleaned it up and put a new power cord on it. I wired it up exactly how it was from factory. The other day I was deburring a pipe and the other end touched my drill press and arced and caused sparks. Would anyone have any idea why is may be doing that? When I had the green grounded to the bottom plate the grinder wouldn't run at all. Anyone have ideas what I've done wrong or didn't hook up correctly? Cause I really want to use the grinder. I've also included a pic of the inside below. Thanks in advance for any help.20230131_083852.jpg
 
Hello everyone, I acquired a Baldor bench grinder from a family member. I went through and cleaned it up and put a new power cord on it. I wired it up exactly how it was from factory. The other day I was deburring a pipe and the other end touched my drill press and arced and caused sparks. Would anyone have any idea why is may be doing that? When I had the green grounded to the bottom plate the grinder wouldn't run at all. Anyone have ideas what I've done wrong or didn't hook up correctly? Cause I really want to use the grinder. I've also included a pic of the inside below. Thanks in advance for any help.
I'm glad you're still alive and able to write this. I recommend you unplug it immediately.
 
Problem may not be at the grinder. If you have the polarity reversed at the new plug, that would cause this. Is it possible something is reversed at the drill press? Is the drill press and the grinder using he same power source? You need to be very careful with this situation, maybe call in an electrician at this time, before you get fried. Just because you wired it as it was before, the grinder may have been wired wrong to begin with.
JC
 
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I'm glad you're still alive and able to write this. I recommend you unplug it immediately.
Yea man it's unplugged ; however, I come here for help with it to correct the problem and get it running again. I didn't come here for smart a** comments!! It's comments like yours that I don't post on forums cause everyone is a keyboard genius!!
 
thopkins1124: I don't think that yan wo was being snarky. It certainly isn't necessary for you to be shatty with him. Smart alecks like you is what discourages people to try to help thos like you that are ignorant.
JC
 
I second what J Clark said. Nobody was being a smart ass, but someone was being a little sensitive and reading in what was not there. And nobody has any idea how much electrical wiring knowledge you have already.

If either machine has a polarized plug, make sure they both have the black wire going to the smaller of the two tangs. Or if un-polarized, try to plug in the side wired black into the smaller slot on both machines. Especially without the ground. The fact that the grinder wouldn't run with the ground I think says that the grinder has a problem. If you have a volt meter, you might touch it across the two machines and see what's up. Anything over a few milivolts spells a problem.

Try to google up a wiring diagram for your grinder and make sure it's done to match.
 
You were running an ungrounded tool that was not designed to be run ungrounded. Yan Wo was right to be concerned about your safety/life. You might choose to be thankful.
 
Until the sparks started to fly I thought this was some kind of AI or human troll. Do you know basic electriciy and how to use a volt/ohm meter? Green wire should always be attached to frame and checked for continuity through plug and to electrical system. Check the outlet first. 120 volts between the two flat plugs. Which side is hot(black) and which side is neutral (white)? Probe volts between each of the flat holes in the outlet and the round hole( ground). O volts reading is neutral to ground. They have the same potential and are usually connected together at the panel. 120 volts between flat blade and round hole identifies the flat hole as hot. If you checked ten outlets they would all have the same configuration if they are wired correctly. Easier yet get a plugin tester at the store that has lights on it to tell if the outlet is wired correctly. Now we go to your plug. Could you have switched the hot and neutral? Easy to check. It should match your outlet. Disconnect the motor wires and check each to the frame of the grinder with ohmmeter. You should read no continuity(infinity). Looking at your pic you have a number of black wires going to a frame screw. They should probably go to the white wire and not to the frame.
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As you have the motor wires disconnected( the 3 black wires on the right going into the motor) ohm them out to identify them. Highest resistance between any two wires will be from s through c and out to r. You have measured the start and run windings in series, but you don't know which is which. Take each in turn and measure to the third wire which is c or L2. The higher resistance is the start winding and by default the other is the run winding. Now wire it up as you see in the diagram putting the toggle switch in series with L1. Unless the capacitor is marked it does not make a difference which side you wire to. Sorry if I sound too simple. I do not know your knowledge level. Youtube vids are a big help to most folks.
 
Hello everyone, I acquired a Baldor bench grinder from a family member. I went through and cleaned it up and put a new power cord on it. I wired it up exactly how it was from factory. The other day I was deburring a pipe and the other end touched my drill press and arced and caused sparks. Would anyone have any idea why is may be doing that? When I had the green grounded to the bottom plate the grinder wouldn't run at all. Anyone have ideas what I've done wrong or didn't hook up correctly? Cause I really want to use the grinder. I've also included a pic of the inside below. Thanks in advance for any help.View attachment 434707
That green wire is supposed to be electrically attached to the cast iron frame, even if the grinder is older than when that was required, precisely to prevent such events.

I don't see the usual attachment point, but a ring terminal crimped onto the green wire and put under one of the four steel mounting screws will do the trick. The other end of the power cord needs to have a three-blade plug attached, the round blade being the ground pin attached to that green wire. I'd also replace the motor capacitor (that big aluminum can). If the breaker pops when plugged in, or when the motor is turned on, you'll need to figure out what's shorted in the motor, which is a more complicated process, so first let's sort the wiring and capacitor out.
 
I bought a 240 volt welder that I had a hard time using. Finally checked it out with a meter. The ground plug was backwards so the case was at 120 volts and the machine only saw 120 volts. Lucky me since it sat next to the laundry sink to plug into the dryer outlet. If I had touched. the case and the sink faucet I would be dead. I assume his old shop had the outlet wired wrong.
Yan Wo was giving you good advice.
I would check voltage and continuity between grounds on drill press and grinder outlets. It should be zero volts and almost zero ohms.
Don't flame me too, but make sure your meter is on ac volts not dc.
BilL D
 








 
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