# Help me Make my GCFI Stop Tripping



## Chips O'Toole (Feb 4, 2020)

My Gorton 375 grinder arrived. Unfortunately, I can't use it. The outlets in my workshop are on a GFCI circuit, and every time I turn the motor on, it trips the GFCI instantly. I have connected the motor power leads directly to the hot and neutral lines, and the GFCI still trips, so it has to be a motor issue. The motor starts and runs fine on a normal circuit. The resistance between the hot and neutral motor leads, when disconnected from the switch, is 2 ohms.

I figured I would change the motor's capacitors and see if it helped, because that's all I can do short of taking it to a shop. I got the motor out of the grinder, and now I'm stumped. It has some kind of fancy vibration-isolation hubs on it, and I can't figure out how to get them off. Also, I don't see the capacitors. I assume that if I get the end of the motor casing off, I will eventually find a capacitor in there somewhere. 

I thought I knew a few things about AC motors, and one of the things I thought I knew was that they used start capacitors. Now I'm reading that this is not always the case. Not sure what to think about the motor I'm working on now.

I would like to find out a) why the motor is tripping the GFCI, b) how to open it up, and c) whether it has capacitors in it. It's a 1725-RPM 1/4-HP 110V motor. Tips appreciated.


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## kb58 (Feb 4, 2020)

I seem to semi-regularly replace GFI outlets for false trips. I know that's the case because I replace them and the tripping stops. Sometimes I find them full of fried black ants, no kidding. As a test, try plugging it into a different GFI outlet. 

On the other hand, it could be trying to save your life. The resistance you saw between the black and white wires is about right, so that alone isn't the issue. What's important is the resistance from the white and black wires to the ground wire; it had better be near infinite resistance. I doubt it's the caps, if they exist. Also inspect the wiring closely, you never know what you get when you buy someone's "surprise package", and electricity is something to respect.


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## Karl_T (Feb 4, 2020)

Not sayin' its right, but I had to give up on ground fault for my shop machines.


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## Cadillac (Feb 4, 2020)

Ive had to replace gfi outlets on the outside of my house which had outlet covers on them. Rarely used and one day I couldnt plug anything in them without tripping. Replaced outlet with a new gfi and haven’t had a problem since. Any problem on the nuetral side will cause it also they are sensitive.


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## Chips O'Toole (Feb 4, 2020)

I think I'm going to get a blow gun and knock the dust out of the motor before I do anything else.


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## kb58 (Feb 4, 2020)

Good idea. It takes veeery little leakage to trip those things. Even slightly conductive dust touching the right points will do it.


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## RYAN S (Feb 4, 2020)

While working on a remodel last year, I ran into a new  style breaker that was code for new electric installs. It basically would trip if there was any spark whatsoever detected.  It was impossible to run almost any power tool. I don’t remember all of the specifics, other than it was a pita and we just ran extension cords from the garage!


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## silence dogood (Feb 4, 2020)

I suggest that you take your motor to a electric motor place and ask them to test the motor with a megger(AKA as megohmmeter) . The insulation on your motor may not be up to snuff or there may be some contaminates causing a high resistance short.  The GFI could be at fault, too. Try the motor on a different GFI.  Also, you may have a split phase motor which does not use capacitors.


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## MontanaLon (Feb 4, 2020)

RYAN S said:


> While working on a remodel last year, I ran into a new  style breaker that was code for new electric installs. It basically would trip if there was any spark whatsoever detected.  It was impossible to run almost any power tool. I don’t remember all of the specifics, other than it was a pita and we just ran extension cords from the garage!


Arc fault interrupters, a good idea which in practice isn't so hot. A friend of mine had them in his breaker box in a new home. Any lightning strike within a mile or so would shut off circuits at random. He ended up yanking the ones that powered the sump pumps in his basement when they went out during a torrential downpour during a thunderstorm and got him 6 inches of water in the basement.

GFCI breakers can be a pain and where GFCI is required, kitchen and bathroom, it is better to use GFCI outlets.


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## tjb (Feb 4, 2020)

I'd be inclined to think your problem is a faulty GFCI.  Here on the farm, we have several GFCI outlets outdoors, and fairly often they need to be replaced.  Like kb58 mentioned, it's not uncommon for ants to get up in them and short them out.  An electrician once told me that apparently, they produce some sort of imperceptible hum that attracts insects.  Also, there is an issue with humidity where you and I live.  Around here, these outlets are notorious for short life span, and that's definitely been my experience.

If you have a 'good' GFCI' outlet, you might try replacing it with the one that shorts out.  If it works, you know it's the outlet.  If it doesn't, then you know you need to go to Plan B.

Regards,
Terry


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## tjb (Feb 4, 2020)

P.S.:  Is the outlet on a circuit that has a ground-fault 'breaker'?  Those have a tendency to go bad as well.


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## stupoty (Feb 4, 2020)

Have you tried a HV insulation test ?

If the outlet isn't tripping for other devices I would suspect some leakage from worn or failed insulation.

Good idea as you said to thoroughly clean out any duct and recheck

Stu


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## Diecutter (Feb 4, 2020)

Don't know much about residential wiring, but learned three things while dealing with tripping gfi's.  I had to replace the gfi outside TWICE due to ants building nests and frying themselves.  Also, there  are weather-resistant rated gfci's available which is what I now have outside. Lastly, it turns out that if you have a gfi in your main panel or in a circuit before the gfi causing problems, the two gfi's  will not play nice together.  Hope this helps.


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## ub27Rocks (Feb 4, 2020)

It is a ground fault circuit, so check between hot and ground, and neutral and ground. One of those is where the fault is in the motor. Unless it is the outlet of course. You check between hot and neutral only means your windings are ok. Lastly, make sure that the ground/frame is also connected to the power connector. GFCI's need all 3 wires, e.g. did someone cut the ground prong off?

And of course try running something else on that circuit to see if it blows as well.


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## Chips O'Toole (Feb 4, 2020)

It turns out the bearing in the grinder spindle is fried. When I take the belt off the motor, it does not trip the GFCI.


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## ub27Rocks (Feb 4, 2020)

Ok, but did you ohm out the others as well? And check that ground is passed through to the outlet? Load on the motor can make the ground fault worse.

When you say fried do you mean seized?


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## Chips O'Toole (Feb 4, 2020)

The bearings are not completely seized, but they are very hard to turn. I'm not concerned about the GFCI now. It looks like the problem was the excessive starting load.


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## ub27Rocks (Feb 4, 2020)

To me it would seem prudent to finish checking out the electrical before moving to the next item. A basic tenet of troubleshooting is to change one thing at a time. If you now fix the bearings, you could very well be hiding an electrical problem that will eventually show up again.


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## Chips O'Toole (Feb 4, 2020)

I don't know if I was clear. I believe the friction from the bearings caused the GFCI to trip.


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## middle.road (Feb 4, 2020)

Chips O'Toole said:


> I don't know if I was clear. I believe the friction from the bearings caused the GFCI to trip.


minuscule drop or increase in voltage causes a GFCI to trip doesn't it?


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## MontanaLon (Feb 4, 2020)

middle.road said:


> minuscule drop or increase in voltage causes a GFCI to trip doesn't it?


Only if the voltage is leaking to ground. It is possible though that rough bearings increased the current draw of the motor beyond what the circuit breaker is rated for.


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## stupoty (Feb 4, 2020)

Some GFI are combination circuit breaker also.


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## middle.road (Feb 4, 2020)

MontanaLon said:


> Only if the voltage is leaking to ground. It is possible though that rough bearings increased the current draw of the motor beyond what the circuit breaker is rated for.


I thought it was if there was fluctuation between the Hot and Neutral? I'm thinking two prong plug equipment...
But then I'm not very good at electricity at times.


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## stupoty (Feb 4, 2020)

middle.road said:


> I thought it was if there was fluctuation between the Hot and Neutral? I'm thinking two prong plug equipment...
> But then I'm not very good at electricity at times.



I think your correct they check for differential between the two lines as if there was a dangerous fault condition it might be leaking through a human being to ground not down the earth wire.


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## hman (Feb 4, 2020)

I'm not an electonicker, but here's my understanding of how a GFCI works.  Think of wiring two transformers in series with the load - one on the "hot" side and one on the "neutral" side.  Then connect the secondaries of the transformers in series, with one of them reversed.  As long as the amount of current coming in on the "hot" side is exactly the same as the amount of current leaving on the "neutral" side, the two secondary voltages will be exactly the same.  So they'll cancel each other out and the series voltage will be zero.  Now introduce a little bit of leakage to ground somewhere in the load.  When this happens, the outgoing current will be different from the incoming ... part of it is taking a different path.   So the voltages of the two secondaries will differ and they won't cancel exactly.  A circuit in the GFCI detects this small voltage, and if present, it will trip the switch.

I read somewhere that a GFCI will trip if the imbalance between gazinta current and gazata current is as low as 5 milliamps.  That's below the threshold of harmful current for a human being.  So a GFCI is designed to save your life.

Two failure modes are possible - either the GFCI will fail to trip at 5 milliamps or higher, or else it might trip at a much lower threshold.  I'm pretty confident that the GFCI circuitry is well designed to be fail-safe, so the former scenario won't happen.  But the latter scenario remains possible and would result in nuisance tripping.


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## stupoty (Feb 4, 2020)

hman said:


> I'm not an electonicker, but here's my understanding of how a GFCI works.  Think of wiring two transformers in series with the load - one on the "hot" side and one on the "neutral" side.  Then connect the secondaries of the transformers in series, with one of them reversed.  As long as the amount of current coming in on the "hot" side is exactly the same as the amount of current leaving on the "neutral" side, the two secondary voltages will be exactly the same.  So they'll cancel each other out and the series voltage will be zero.  Now introduce a little bit of leakage to ground somewhere in the load.  When this happens, the outgoing current will be different from the incoming ... part of it is taking a different path.   So the voltages of the two secondaries will differ and they won't cancel exactly.  A circuit in the GFCI detects this small voltage, and if present, it will trip the switch.
> 
> I read somewhere that a GFCI will trip if the imbalance between gazinta current and gazata current is as low as 5 milliamps.  That's below the threshold of harmful current for a human being.  So a GFCI is designed to save your life.
> 
> Two failure modes are possible - either the GFCI will fail to trip at 5 milliamps or higher, or else it might trip at a much lower threshold.  I'm pretty confident that the GFCI circuitry is well designed to be fail-safe, so the former scenario won't happen.  But the latter scenario remains possible and would result in nuisance tripping.



The GFI (RCD) should be rated , mostly in europe they are 30mA or 50mA 

30mA is considered good for life protection ,


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## Flyinfool (Feb 4, 2020)

A high load on the motor will NOT trip a GFCI. It does not even look at the load. With the motor disconected from the house wiring, take your ohm meter and check the motor leads, check from black to green, and from white to green. They must both read infinity. If they do not, you have an electrical issue with the motor. The bearing will have no effect on the GFCI.


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## stupoty (Feb 4, 2020)

Flyinfool said:


> A high load on the motor will NOT trip a GFCI. It does not even look at the load. With the motor disconected from the house wiring, take your ohm meter and check the motor leads, check from black to green, and from white to green. They must both read infinity. If they do not, you have an electrical issue with the motor. The bearing will have no effect on the GFCI.



They do make combined breakers and GFI devices.  since the OP hasn't said what make and model he has it's difficult to know.


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## Flyinfool (Feb 4, 2020)

The circuit breaker will respond to load of course, but the GFIC will not. Some of those just trip and you can not tell why it tripped, others have a seperate trip for GF vs over current. Yes it will help if we know what type of protection the OP has.


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## ub27Rocks (Feb 4, 2020)

Flyinfool, thank you for voicing sanity and clarity on what a Ground Fault circuit does. I would have hoped from the name itself its function would have been clear, but apparently I was wrong.
Personally I would be going through the electrics very thoroughly at this point before doing anything else on this machine.


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## ub27Rocks (Feb 4, 2020)

Chips O'Toole said:


> I don't know if I was clear. I believe the friction from the bearings caused the GFCI to trip.


Yes, I understood what you believe. However you do have a meter so it seems best to just check for total isolation of hot and neutral from ground/frame? And that the cable from machine to wall is actually wired correctly.


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## Chips O'Toole (Feb 4, 2020)

Why would removing the belt prevent the GFCI from tripping, if the motor is the problem?

I will go back over the wiring, but the bearings are the big problem right now.


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## ub27Rocks (Feb 4, 2020)

Chips O'Toole said:


> Why would removing the belt prevent the GFCI from tripping, if the motor is the problem?


The load/overload could be causing enough increase in leakage from hot to neutral/ground to trip the GFCI.


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## GL (Feb 4, 2020)

I had random trips on a GFCI outlet in the basement.  It had a refrigerator and a deep freeze plugged into it.  The research I did at the time indicated that GFCI outlets like resistive loads but not inductive loads (like motors starting).  Since these appliances were in the basement, and you don't look at them often, a trip can be a major expense.  So, while not to code probably, the outlet was pretty high on the wall and I have a gravity drain to let any water out, I changed to a standard plug and got on with it.  

I suspect the "belt off doesn't trip the outlet" is the difference in induced load when the rest of the machine has to spin up.


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## hman (Feb 5, 2020)

stupoty said:


> The GFI (RCD) should be rated , mostly in europe they are 30mA or 50mA
> 30mA is considered good for life protection ,


THANKS, stupoty!  That video does a MUCH better job at explaining a GFCI/RCD than I did.


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## hman (Feb 5, 2020)

Chips O'Toole said:


> Why would removing the belt prevent the GFCI from tripping, if the motor is the problem?


Admittedly a wild theory:  It might be that there's some kind of high resistance "short" to the rotor somewhere inside the motor.  Belts, though they are rubber, are loaded with carbon, and may well be slightly conductive.  Installing the belt would allow the leakage to get to the frame of the machine.  Removing the belt gives the leakage nowhere to go.  This assumes that your motor is mounted with rubber isolators at each end, and is not otherwise grounded.  If the motor frame is hard mounted to the machine it will provide a leakage path to ground, and my scenario would be invalid.

I suppose you could test this theory by removing the belt, turning on the motor, connecting  test lead to the machine's frame, and briefly touching it to the motor shaft.  If this pops the GFCI, look for an internal current leak to the rotor.


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## stupoty (Feb 5, 2020)

hman said:


> Admittedly a wild theory:  It might be that there's some kind of high resistance "short" to the rotor somewhere inside the motor.  Belts, though they are rubber, are loaded with carbon, and may well be slightly conductive.  Installing the belt would allow the leakage to get to the frame of the machine.  Removing the belt gives the leakage nowhere to go.  This assumes that your motor is mounted with rubber isolators at each end, and is not otherwise grounded.  If the motor frame is hard mounted to the machine it will provide a leakage path to ground, and my scenario would be invalid.
> 
> I suppose you could test this theory by removing the belt, turning on the motor, connecting  test lead to the machine's frame, and briefly touching it to the motor shaft.  If this pops the GFCI, look for an internal current leak to the rotor.



Thats a good thought , also could possibly be some issue with the centrifugal switch perhaps when the motor is stalled at start.  I had one motor that was a little susceptible to swarf and this being a grinder there is high likelihood of a little dust being inside and it's probably quite conductive.

(some single phase motors use a seperate starting relay to switch it but i'm less familure with this kind)


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## Flyinfool (Feb 6, 2020)

It takes 10 minutes and no cash to test the electrical. (You already have a meter) I do not understand the reluctace to eliminate the easy stuff before spending a lot of time energy and money replacing parts?


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## stupoty (Feb 6, 2020)

Flyinfool said:


> It takes 10 minutes and no cash to test the electrical. (You already have a meter) I do not understand the reluctace to eliminate the easy stuff before spending a lot of time energy and money replacing parts?



I think he (OP) said there was a separate issue with stuck bearings in the spindle which he found when he took the belts off.  

He did mention he was going to check the motor out a bit.

It's all a todo list with things to check off 

Stu


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## Chips O'Toole (Feb 6, 2020)

I can give you several reasons why I'm not looking at the electrics closely.

1. I have a virus, and I don't feel like doing too much right now. This is the primary explanation. I somehow managed to get pink eye at my advanced age. I started having symptoms on the same day I finished welding my arbor press stand, so I thought I had a flash burn. That was an interesting experience.

2. The behavior of the grinder suggests that fixing the bearings may end the GFCI problem.

3. No new bearings, no grinder. If I can't fix the bearings, it doesn't matter whether the motor works.

4. No one has given me any information that would help me open the motor up, so even if there is something wrong with it, I can't get inside it yet. No one has even told me whether it has capacitors.

5. I'm also trying to get air lines installed in the shop.

I have read that the only way to test a motor's windings correctly is to use an expensive megohmmeter I don't have. If that's wrong, feel free to let me know.

I'll post a photo of the motor. I don't have a shot of the nameplate right now. It's a 1/4-HP GE. I believe it says "Type M" on it. I haven't made any effort to find out what that means. In the photo, you can see the rubber mounts which I don't know how to remove.


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## middle.road (Feb 6, 2020)

That looks, at least from the rear to be a standard GE motor type. I've got a few 1/4 & 1/3HP floating around here.
Once you get a picture of the tag we can roll from there.
They're not real 'industrial' grade motors IIRC.


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## Chips O'Toole (Feb 6, 2020)

I'll try to take a photo tomorrow if there isn't too much pus oozing out of me.


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## middle.road (Feb 6, 2020)

Chips O'Toole said:


> I'll try to take a photo tomorrow if there isn't too much pus oozing out of me.


Looks older judging by the oil cups...
I thought that maybe 1/4HP seemed smallish for a grinder, then I went digging around on gorton-machine.org and found that the 375 uses 
a 1/4HP - 1725RPM motor. Shows ya what I know.


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## ub27Rocks (Feb 6, 2020)

> I have read that the only way to test a motor's windings correctly is to use an expensive megohmmeter I don't have. If that's wrong, feel free to let me know.
> 
> I'll post a photo of the motor. I don't have a shot of the nameplate right now. It's a 1/4-HP GE. I believe it says "Type M" on it. I haven't made any effort to find out what that means. In the photo, you can see the rubber mounts which I don't know how to remove.


1. You don't need a megohmeter, you only need a regular one which you already have. Check from hot to ground, check from neutral to ground. (you already know from checking hot to neutral that the windings are ok at 2 ohm). You are looking for ground faults, not high voltage insulation failures. You should see infinity readings, anything else is a problem. Also check the wiring from plug to motor etc. is correct and not hot/neutral swapped or ground missing.
2. Unless you find something wrong with the motor, don't take it apart. And so removing those isolation mounts is of zero relevance to any issues that there might be, unless they are trash (which they don't appear to be). At worst once you get the spindle sorted out you can put a similar 1/4hp motor on it to test.

This will sound harsh, rude or impolite but you need to a) slow down, b) pick whose advice you are going to follow, c) get methodical on how you approach this refurb/re-awakening of this machine. There are a lot of opinions already in this thread. Some are on target, some are noise.

Start a check list of things to check so you don't forget them along the way. And take photos of every step as you disassemble (notice that I repeated that  Ask me how I know. 

And most importantly get a manual and parts breakdown before taking anything apart. Take lots of photos before you and during disassembly. As far as I can tell there is none available for free online as a .pdf other than a catalog. The link I provided is the only source I found.

While you are not well enough to focus on working, take a bunch of photos so we can see what all you got with the machine, and what the spindle looks like from both ends.


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## Bi11Hudson (Feb 7, 2020)

ub27Rocks said:


> Yes, I understood what you believe. However you do have a meter so it seems best to just check for total isolation of hot and neutral from ground/frame? And that the cable from machine to wall is actually wired correctly.





GL said:


> I had random trips on a GFCI outlet in the basement.  It had a refrigerator and a deep freeze plugged into it.  The research I did at the time indicated that GFCI outlets like resistive loads but not inductive loads (like motors starting).  Since these appliances were in the basement, and you don't look at them often, a trip can be a major expense.  So, while not to code probably, the outlet was pretty high on the wall and I have a gravity drain to let any water out, I changed to a standard plug and got on with it.
> 
> I suspect the "belt off doesn't trip the outlet" is the difference in induced load when the rest of the machine has to spin up.





Seems to be a lot of "foo-fah-rah" over the question of motor vs GFCI. Now there's a lot of "possibilities" here. A GFCI circuit looks at the difference of current between line and neutral. *I don't use GFCIs on motor circuits*. Against code authorities sure, but I prefer to do things right rather than "to code". Codes are just minimum acceptable. A political statement here, possibly deletable.

The OP mentions motor bearings. The motor bearings may be worn enough to allow the rotor to rub against an internal wire. Without the side pressure of the belt, this is a very plausable cause. 

Belt off could well be static build up some where if the machine frame isn't properly grounded. Without a GFCI, you'd know as soon as you touched it when running. If you survived~~~

Remote troubleshooting is *at best* a troublesome project. There are any number of causes, most of which are plausable. The GFCI itself might be at fault. They degrade a little every time they trip. I could go on for hours on this subject. But I find myself forgetting where I was headed on a subject.

.


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## Chips O'Toole (Feb 7, 2020)

The bearings I'm concerned about are on the spindle, not the motor. Once I saw the oil cups, though, I wondered if they had ever been used.


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## Chips O'Toole (Feb 7, 2020)

The suggestion that I don't have a plan it's not really correct. my plan is to fix the bearings, and then if the motor stops tripping the GFCI, I plan to put the grinder back together and use it. If not, I plan to investigate other causes. Obviously, this is the logical way to go about things.

The grinder will not work with bad bearings. They have to be fixed. I'm fixing what I know has to be fixed before moving into other areas.

If it works well with new bearings, there is no reason to do anything else to it.


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## Flyinfool (Feb 7, 2020)

I missed that it is the spindle bearings thsat are bad, I (and I think a few others) thought you were referring to replacing the motor bearings before anything else. It is certainly a reasonable course of action to be working on needed machine repairs while working on the motor issues.

As mentioned above, a meger test is better but a standard ohm meter will still find most of the faults.


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## Chips O'Toole (Feb 8, 2020)

I think this thread may be annoying some people, and I'm afraid I'm here to make it worse. The motor has started working for no discernible reason. It starts with the belt attached, and I even started it while applying pressure to the pulley to make the motor work harder.

I have done nothing to the motor since the last time it popped the GFCI, except for adding oil to the cups. I don't see how this could matter.

The bearing on the wheel end is no good. I can confirm that. It gets too hot to hold onto after a few minutes. The other bearing stays cool. I don't know how bad things are. I have not measured the RPM's yet to see if the bearings are slowing the motor down.

I had never seen this type of motor before, so I thought it was pretty fancy. I have since learned that 1/4-HP 1725-RPM motors with rubber mounts are very common. TEFC jobs cost around twice as much, however, so I'm glad I don't have to buy one right now.

I have been trying to open the spindle with a pin wrench, but it's not going well. The slots are getting chewed up. I drilled two new holes for the pins. I could get a better grip on the nut if the inner spanner nut were out, so I'm going to see if I can remove it. I am hoping there is no shoulder trapping it under the big nut. I'm off to the auto parts store to  buy two 1/2-20 nuts so I can grind them down and turn them into jam nuts for immobilizing the spindle.


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## ub27Rocks (Feb 8, 2020)

Hi, can you post again a photo of where you are wrenching on? And don't forget, it might be LH thread. I assume you got the hub off (the thing with 1 1/4" diameter hub that looks as if it has a ground surface where the grinding wheel butts against?


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## Ulma Doctor (Feb 8, 2020)

i don't recommend this for the faint of heart...
i had a similar issue with machinery tripping the GFIC, so i removed the GFIC outlet, replaced it with a NON-GFIC outlet, and went back to work.
(some technology is worthless no matter how safe it is)


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## hman (Feb 9, 2020)

Intermittent/unreproducible problems are the ABSOLUTE WORST!!!!


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## ub27Rocks (Feb 9, 2020)

hman said:


> Intermittent/unreproducible problems are the ABSOLUTE WORST!!!!


Which is why some of us where strongly recommending checking the electrics now, before the next item on the list. Now that something has changed who knows when this will come back. I learned my lesson when working for Univac in the 60's- early 80's on mainframes spread across 3 floors. Change one thing at a time, if nothing changes put that back. Then on to next thing to try. Too often if nothing changed, you might have added a new problem masked by the original.


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## stupoty (Feb 9, 2020)

Chips O'Toole said:


> I think this thread may be annoying some people, and I'm afraid I'm here to make it worse. The motor has started working for no discernible reason. It starts with the belt attached, and I even started it while applying pressure to the pulley to make the motor work harder.
> 
> I have done nothing to the motor since the last time it popped the GFCI, except for adding oil to the cups. I don't see how this could matter.
> 
> ...



mostly everyone hear like a mystery 

The oil might have been all caked up and acting like glue , a little bit of warmth and manipulation might have loosened it up a bit.

With regard to the pin spanner ring, use a pick type implement and/or wooden sticks ,  to clear out all gunk you can and double check for set screws and such , I honestly haven't ever forced something open to find there was a set screw making a nice burr on some moderately important part, no no never happened (goes to corner from shame)



Stu


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## Chips O'Toole (Feb 9, 2020)

I got it apart. I had to make a tool. The bearings have something exactly like cosmoline on them. There are two bearings on the front end, mashed against each other. I haven't checked the rear bearing. The whole shaft assembly popped out in my hand unexpectedly, leaving the rear bearing in the machine. It appears to be a slip fit, which seems awfully odd to me.

There is no scoring or damage on anything, unless you count the marks I left on that infernal nut. I improved the design greatly. 

I'm surprised a slip-fit bearing can run without chewing up a shaft.

Now I have to identify the bearings.

Too tired to post photos right now.


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## Cadillac (Feb 9, 2020)

Without any pictures you not gonna get any definite answers. Having a double bearing in the front sounds like you have angular contact bearings in the front ,the rear bearing is gonna be a slip fit for expansion so the spindle doesn't bind up. I would doubt there is cosmoline in the spindle housing dried up grease or oil yes cosmoline no. The front bearing set is there a locknut holding the two bearings on the spindle? When you get some time take some detailed pictures and post it'll be the best way to get some accurate advice.


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## 7635tools (Feb 10, 2020)

ub27Rocks said:


> It is a ground fault circuit, so check between hot and ground, and neutral and ground. One of those is where the fault is in the motor. Unless it is the outlet of course. You check between hot and neutral only means your windings are ok. Lastly, make sure that the ground/frame is also connected to the power connector. GFCI's need all 3 wires, e.g. did someone cut the ground prong off?
> 
> And of course try running something else on that circuit to see if it blows as well.



GFCI’s do not need a ground wire hooked up to it to function properly. It senses the current imbalance between hot and neutral. 


Sent from my iPhone using Tapatalk


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## ub27Rocks (Feb 10, 2020)

Typically spindles retain only bearings on one end, the other is free to float to compensate for expansion due to heat build up.


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## ub27Rocks (Feb 10, 2020)

7635tools said:


> GFCI’s do not need a ground wire hooked up to it to function properly. It senses the current imbalance between hot and neutral.
> 
> 
> Sent from my iPhone using Tapatalk


Yes you are right, but given the other issues I would be checking the wiring. If the GFCI is tripping, then I would want a proper ground as well. Without verifying it might look like things are ok but they might not be.


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## Asm109 (Feb 10, 2020)

ub27Rocks said:


> Typically spindles retain only bearings on one end, the other is free to float to compensate for expansion due to heat build up.


This is  very true.  Bearing makers also want the rotating ring of the bearing to be a press fit. Avoids fretting corrosion that way.

So the upper bearing should be press fit to the shaft and floating on the OD in the housing.  That is bearing best practice, doesn't mean the designer of this machine followed them.


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## Chips O'Toole (Feb 10, 2020)

Cadillac said:


> Without any pictures you not gonna get any definite answers. Having a double bearing in the front sounds like you have angular contact bearings in the front ,the rear bearing is gonna be a slip fit for expansion so the spindle doesn't bind up. I would doubt there is cosmoline in the spindle housing dried up grease or oil yes cosmoline no. The front bearing set is there a locknut holding the two bearings on the spindle? When you get some time take some detailed pictures and post it'll be the best way to get some accurate advice.



I wasn't looking for answers. Just reporting on the situation.

I don't believe there is cosmoline in the bearings. I think the grease turned into something exactly like cosmoline because of the heat from the bad bearings. It's almost as if someone melted a brown crayon in there.

Someone suggested cleaning the old bearings out and re-greasing them, but I don't think the grease would have been corrupted had the bearings been sound. I don't know, though. They appear to be sealed, so I would have to pry the seals off and put them back on. They're supposed to be cheap, so I see no reason to struggle with the old ones.

Why would there be grease on the outside of sealed bearings? I haven't seen that before. Wondering if it migrated out from inside the bearings.

I'm trying to find out what kind of bearings I have. I'm contacting the manufacturer. We'll see how that works out. If I have any trouble with the removal or installation, I'll be back.

I'm trying to find a set of sockets for castellated round nuts. I know they exist, because the nuts exist. I'm finding all kinds of names. "Spanner sockets." "Spindle sockets." "Spindle locknut sockets." Making things more complicated, most are made for automotive use, so it's not like you can look for a set from 1/2" to 1-1/2" with a 1/2" drive. You have to look for Honda, Chevy, or whatever.  Also, they're extremely expensive, which makes no sense, because they're very simple to make. I would love to have a set, but it looks like it's easier to make them on demand than to find them ready to  buy.

For anyone else who makes a tool for these nuts, don't make the mistake I made. Do not make an 8-pin tool. You only need 4 pins. It's much easier to make on the mill.

A company called SKF makes a bunch of tools for this type of nut.



			https://www.skf.com/binary/98-81522/13074EN_Spanner_and_sockets.pdf


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## Chips O'Toole (Feb 10, 2020)

I have a couple of photos. Not the greatest, but they show the parts I'm talking about.


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## middle.road (Feb 10, 2020)

Looks like old grease to me. I'd think that if the bearings overheated the grease would have 'melted' out of them.


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## Cadillac (Feb 10, 2020)

So those are angular contact bearing on the wheel side. Those are not seals on the bearing that is the cage for the bearing angular contact have a different kind of cage to your typical sealed bearing. Keep track of the orientation of those bearings it matters. When you tighten the nut on the wheel side where that open  thread is it will preload the AC bearings. The only way to check condition of bearings is cleaned out completely and look at race and balls for fretting. Like said before the rear bearing should be a slip fit and there should be a wavy washer or bellevue washer to preload the rear bearing for expansion.


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## pontiac428 (Feb 10, 2020)

When you identify your bearings, I recommend not bringing your coffee to the computer with you to look up the prices.  That's the spindle of a Gorton machine, possibly with a double-row cartridge on it.  If original, the bearings probably have a word like SKF or Timken or something similarly excellent etched on them.  I've been okay with sourcing new old stock bearings on eBay, but non-chinesium off-the-shelf bearings of the appropriate precision rating can be exorbitant in cost.  Only reason I am pointing that out is to make the idea of solvent washing and re-packing your existing bearings a little more palatable.  There is nothing wrong with re-packing a bearing unless it is brinelled or rusted from abuse or otherwise worn in a verifiable way.  High end bearings can go for an incredibly long time compared to the automotive grade stuff we are used to tearing into, so replacement may not be necessary in the broader scheme.


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## Chips O'Toole (Feb 10, 2020)

As noted previously, the guy who is advising me after his own rebuild says these are common bearings. I am hoping Gorton will get back to me so I will know exactly what to get.


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## Chips O'Toole (Feb 10, 2020)

They sent me some numbers. I am Googling this stuff to find out how bad the news is. Regardless, I do plan to see about fixing the old bearings.


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## Chips O'Toole (Feb 10, 2020)

Okay. The news from Gorton is not as wonderful as I had hoped, but it's not tragic. I see a range beginning at about $125 for two bearings. I was hoping for more like $20 for a pair, but $125 will not ruin me. 

This is the number for the forward bearings. The other one seems to be fine, so I don't see any reason to replace it.

If anyone has advice about opening these old ones up and putting them back together, I would appreciate it. In the meantime, I will be Googling.


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## pontiac428 (Feb 10, 2020)

That's not too costly, glad to hear it.  Some bearings cost their weight in gold (well, at least the weight of the balls).

Depends on the type of bearing, but most cartridge bearings stay together because they are swaged at the factory.  I use a fine dental pick and carefully pry the seals off, then wash in stoddard solvent to remove all the old grease.  Dry them with a rag (or compressed air if you dare) and inspect them carefully.  Look for axial play, radial play, and rotate them between your fingers to feel for bumps or brinelling.  If they have more than a very small amount of play (this is subjective, but common sense should apply) or if there are any tight/rough/bumpy spots, then they need to be replaced.  If they run smooth, congratulations!  Repack them with a grease selected for temperature and bearing speed, pop the seals back in, and enjoy grinding tool bits with your refreshed grinder.  Did I skip the part about preloading the spindle?  Yeah, I skipped that part... You'll need to glean any information you can about bearing/spindle preload from the manual or from the manufacturer's support line.  Every machine is different, and preload is a crucial tolerance based on loads and heat.  Considering it's a simple grinder, it may not be a huge deal, but the engineers planned for it by building adjustability into the spindle assembly, and probably wrote down the spec somewhere.  There are tricks to measuring preload, but it all depends on the form in which the spec is given.


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## Chips O'Toole (Feb 14, 2020)

I found some useful information for anyone else with these bearings. The grease you want is Mobil 28. Amazon has it. People will tell you to get nutty Euro grease, but Mobil 28 is fine. It's also supposedly the ultimate gun grease, and you can buy it in small syringes for gunsmithing. Should make filling the bearings easier.

Amazon sells the grease for $22 (big tube), and you can get 8 syringes for $9. I thought that was smarter than buying one syringe for $6. I may want to grease other stuff.


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## middle.road (Feb 14, 2020)

*Synthetic Aircraft Grease High-Temp, MilSpec-81322G*, interesting. . .
That should do the trick for spindle bearings.


Chips O'Toole said:


> I found some useful information for anyone else with these bearings. The grease you want is Mobil 28. Amazon has it. People will tell you to get nutty Euro grease, but Mobil 28 is fine. It's also supposedly the ultimate gun grease, and you can buy it in small syringes for gunsmithing. Should make filling the bearings easier.
> 
> Amazon sells the grease for $22 (big tube), and you can get 8 syringes for $9. I thought that was smarter than buying one syringe for $6. I may want to grease other stuff.


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## Chips O'Toole (Feb 15, 2020)

It tastes okay.


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## middle.road (Feb 15, 2020)

Chips O'Toole said:


> It tastes okay.


What type/brand of crackers?


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## Chips O'Toole (Feb 15, 2020)

You don't put grease on Florida crackers. They don't like it, and most of them are into concealed carry.


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