# Safety Concerns About Old Electric Motor.



## pgmrdan (Oct 15, 2015)

The motor was still in use when I bought the Craftsman lathe a couple of weeks ago.  It's a Delco Motor A3375, 1/4th hp, 40+ lbs.  It's a heavy beast.

I can't see anything wrong with it.  It does have the cloth insulated wires and the lathe is made to take a 1/3rd hp motor so this one might be a bit weak for it.  The cloth isn't dry and crumbly.

The pluses are that it's heavy and the base on it is nice.  The base is attached to the motor at an offset on pivot points and has a spring that pulls the motor back into position if the belt pulls it over a bit.  I sort of like the idea.

Should I continue using it or should I consider it unsafe?


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## JimDawson (Oct 15, 2015)

From your description it sounds safe.  Maybe a bit under powered for your machine, but I would would use it.

Just make sure you have a proper ground on it.


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## Ulma Doctor (Oct 15, 2015)

if the motor runs well and doesn't smell during operation, i'd consider running it to it's final demise. 
But i'm not like all the others 
Just because it's old , doesn't mean it's bad
you could (should) do a thorough inspection and testing, should you have a question  

if you need help in testing procedures, i'd be glad to lend a hand and walk you through the process


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## pgmrdan (Oct 15, 2015)

Thanks guys!

I'll open up the case and vacuum out the swarf and what-not then reassemble and make sure the outside is cleaned up.  I'm going to put a new cord on it with ground. 

I also need to wire up a switch.  Plugging and unplugging was the previous switch.

I just hope I don't release the magic smoke!


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## Ulma Doctor (Oct 15, 2015)

i like to see magic smoke, 
that usually means that either i'm going to make money OR get to play with a new motor or control system!!!


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## pgmrdan (Oct 15, 2015)

Since this is a 110/220 motor I know that there are two windings that run in series when running as 220 and in parallel when running as 110.  Is there a phasing concern when wiring up the motor for 110 (or 220 for that matter)?


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## Ulma Doctor (Oct 15, 2015)

if it has a start capacitor, the phase will determine rotation


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## Alan Douglas (Oct 15, 2015)

> Is there a phasing concern when wiring up the motor for 110 (or 220 for that matter)?


Yes, but if you keep each side of the AC line connected to one winding, the other end of each winding will come out right.


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## Bill C. (Oct 15, 2015)

There should be a rubber coating under the cloth.  If it is still soft then I would think it is safe.


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## Andre (Oct 15, 2015)

No motor expert here, but I've put to service a few motors into service with fabric insulation. Never had an issue thus far, it worked back then 

If you notice it's under powered, you could try a speed reduction countershaft for more torque.


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## Chipper5783 (Oct 15, 2015)

Yes, run the motor, but ensure you apply the usual safety instructions.

I just started up a great old motor:  1HP.  It had a promenent label stating it had sleeve bearings (and the flip top oil cups).  Must have weighed 50 pounds.
http://www.hobby-machinist.com/threads/carboloy-excello-tool-grinder.37715/#post-323170

It was wired for 440V (series windings).  When the went to reconnect it to 220V (parallel windings), I noted the insulation crumbling on the leads from the fuse, sort of a rubber material (yes fuses and a knife switch disconnect).  The leads inside the pecker head used small bolts and a rubber tape to make the connections (it was a very small connection box).  The woven insulation on the motor leads was very hard.  I carefully reconnected the motor per the lead numbering instructions (solder and heat shrink - the box had very little room).

The original set up was not grounded, was using #12 wiring and 30 Amp fuses at that 440V (nameplate draw of 1.4 amps).

I added a ground from my wall plug, to the fuse box, to the motor switch and the motor case (put new #14 wire through out - I had some nice 3C+G cab tire).  I changed the fuses to 5 Amp (motor name plate is 2.8A at 220V).  The motor starts well off my RPC (which is going to be somewhat unbalanced).  Granted if I switched the motor FWD to REV it would likely blow fuses (but it is a grinder, I can't think of a reason to be changing direction quickly).

Ensure the integrity of the wiring, use a ground (as you have already stated).  Another good strategy for small 120V loads is to run through a GFI (cheap, easy to install and gives very good protection against most electrical faults).


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## pgmrdan (Oct 27, 2015)

I opened it up.  Geez!  Looked like it was full of powdered graphite.  Like a pencil sharpener but no wood shavings.  I'm sure it was crumbly dry grease like the grease that had everything covered when I bought the lathe.  The thing is totally black inside and covered with the stuff.  If there were a way to dip it in kerosene and soak it clean it might just work but I doubt that would be safe on the motor.  There's no smell of overheating in the past.

I think I'll toss the motor and use a much more modern version with a full 1/3 rd hp for the lathe as Craftsman recommends.

Thanks for the information guys.


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## pgmrdan (Oct 27, 2015)

Lo and behold, motors can be dipped.  I'm seeing where people dip them in mineral spirits, spray them with pressure washers, etc.  I went ahead and put the pieces of mine in a 5 gallon bucket and poured 3 gallons of kerosene on top of it.  It's soaking now.  Seems to me mineral spirits might be too harsh.

After I get it cleaned up I'm going to soak it in distilled water with Dawn dish washing detergent and then I'll rinse it in plain distilled water.  Then you're supposed to bake them to dry them out or set them in the sun on a hot day.  I could just let it sit for several days to dry.  I might bake it if the little woman isn't around. 

Who would have thunk it?


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## 'Topcraft (Oct 27, 2015)

I think it would have been a better idea to buy a can of contact cleaner and flush it out with that. When it evaporates, it leaves no residue and you can even speed that up with a little air. Maybe a 15 min job.


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## pgmrdan (Oct 27, 2015)

I wish!!!  

It would take more than 25 cans of contact cleaner and many hours of scrubbing.  I would have pitched it before trying that.  I'm not joking when I say this thing is covered inside with black gunk.  The layer on the outside was probably close to 1/10th of an inch thick.

Some guys do this with a pressure washer or take them to a car wash and use the wand.


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## 4GSR (Oct 27, 2015)

The last couple of motors I cleaned, I used simple green mixed half and half water.  Put in a cheap spray bottle.  Sprayed on the winding's and used a soft bristle brush to work loose all of the grim, them rinse with the water hose with a gentle sprayer.  You don't want to it it with a pressure washer, could damage the insulation on the winding's.  I let the motor winding dry for a few days.  Then I took some red looking insulation spray and put a couple coats of this on the winding's.  Last I took a small portable electric heater and set it up blowing hot air on the inside of the winding's for a few days to dry out the insulation paint and any residual water.


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## pgmrdan (Oct 27, 2015)

Hey, good idea!  I have a couple of partially full large jugs of Simple Green.  I was wondering what to do about getting the kerosene out of the motor.  I was going to use water and Dawn but Simple Green will work as well and with that aroma!


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## 4GSR (Oct 31, 2015)

Kerosene or any other mineral spirits will leave some oil residue behind once dried.  Soap and water works fine, but you have to dry out the winding thoroughly before shooting electricity to the motor.  If money is in your budget, take winding to your local motor repair shop and let them go thru and tie in new leads if the old ones are frayed or bad.  Have them to meg the winding for shorts.  And last coat the winding with new varnish.  It would be worth it on a motor that is special made for given machine.  Much cheaper to replace standard frame motors up to around 10 HP than to have them rewound in my opinion.

Ulma Doctor would love to have your business if he was closer to you.


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## British Steel (Oct 31, 2015)

Just a quick tip, drying out motors - run a low-voltage supply through the windings (12v is more than enough, usually) to heat them from the inside, helps drive the moisture / solvents out much more quickly (but still give it a few days!) from the inside out - I've done this with motors, power transformers, big iron-core chokes etc. and it works a treat.

Dave H. (the other one)


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## JPMacG (Nov 1, 2015)

My Atlas mill came with a 60 or 70 year old motor.  Like you, I was worried about degradation of the insulation.  In order to reduce the possibility of an electrical shock hazard I replaced the old two-wire line cord with a three wire cord and made sure the ground wire was well connected to the motor case and to the body of the mill .   I also made sure to power the motor from a GFI protected branch circuit.   So far it is working great.   No problem at all.


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## Wobbles (Dec 8, 2015)

pgmrdan said:


> It would take more than 25 cans of contact cleaner and many hours of scrubbing.  I would have pitched it before trying that.  I'm not joking when I say this thing is covered inside with black gunk.  The layer on the outside was probably close to 1/10th of an inch thick.
> 
> Some guys do this with a pressure washer or take them to a car wash.




The "black gunk" is most probably old bearing grease.

• Do your bearings have zerk fittings? If so, then the motor probably received yearly applications of grease with the old grease being displaced onto the motor windings.

• If there are no grease fittings, then as older grease oxidizes it can sometimes work its way out of the bearing and (once again) work its way onto the armature. This means the bearings are now running dry.

I would highly suggest 2 courses of action...

1) Wash the beast. If the motor is to "burn up" it will more than likely be to an inability to cool itself rather than "old wiring". Note that solvents will merely move the "gunk" around. To remove grease one needs a detergent action, best found in hot soapy water. Obviously, all the water should be allowed to evaporate before placing the unit back in service.

2) Replace the older 'open' ball bearings with modern 'double sealed' bearings. Typically, modern bearings are loaded with a synthetic grease that will not oxidize and will therefore not require maintenance for many decades. The seals will also insure that the inside of the motor stays clean to promote cooling.


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## KBeitz (May 13, 2018)

Liquid electrical tape is great for fixing  old wiring in motors.


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## markba633csi (May 13, 2018)

Oh and another thing... 
Mark


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## CluelessNewB (May 13, 2018)

I like old motors. You can also cover old wires with heat shrink tubing if you are concerned about the insulation.


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## machinejack (May 14, 2018)

Used  brake cleaner to wash out the gunk before never noticed any deterioration of any windings. Use mean green and dry the motor in the wifes oven when she isn't looking.  Used red motor varnish that comes in a rattle can to dress up the windings. Customers though you had worked miracles refreshing there irreplaceable motors. Generally a good cleaning will do the trick. Just look for bad insulation like clueless says.


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## markba633csi (May 14, 2018)

Brake cleaner is strong, I would use something more mild like mineral spirits or white gas
You don't want to soften the insulation on the wire
Mark


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## KBeitz (May 21, 2018)

Liquid Electrical tape...


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