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My basket case rotor  Rate Topic 
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 Posted: Fri Feb 19th, 2021 03:18 pm
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Jack Colley
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I have attached a photo of the rear of the rotor from the Emerson 77648 that I acquired as a basket of parts.  There were three copper-colored indentations in the metal, I presume when the blades were removed someone missed the indentation with a bolt to hold the rotor in place as the blades were unscrewed from the front.  I noticed too that the holes going through the rotor appear slightly offset.  There was some "proud" metal above the surface so I sanded it flat.  I was thinking the rotor would be copper-colored beneath the old dark grease but no, it is silver-colored.  was the underlying copper plated with some other metal?  Is there any way of making these blemishes disappear is there?  I know no one will see it and "the perfect is the enemy of the good", but still.....

Attached Image (viewed 287 times):

Rotor.jpg

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 Posted: Fri Feb 19th, 2021 06:27 pm
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Matthew Albach
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Hi jack,
What I was told that metal you see is actually helps
To balance the rotor when it spins so it does wobble
However, sometimes it’s a blob of metal on the rotor
I have seen on some Emerson as well

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 Posted: Fri Feb 19th, 2021 06:55 pm
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Jack Colley
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It is difficult to see that these marks are actually crescent-shaped groves instead of bumps of metal.  The metal was  pushed up around these groves.  I used fine sandpaper to removes these and this exposed the copper color.  

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Rotor 2.jpg

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 Posted: Sat Feb 20th, 2021 06:03 am
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Alex Rushing
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Silver color sharpie should hide them. Or silver modeling paint for better longevity. Honestly, that is probably the cleanest Emmy rotor I've seen that hasn't had a lot of work done to it. As long as the edges aren't broken, blade threads are sharp, and new leather seal is in place, your probably good to go.

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 Posted: Sat Feb 20th, 2021 09:23 pm
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Jack Colley
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Thanks again Alex. 
After seeing the restorations that you guys have done.  I want it to be as near perfect as possible  lol.

Do you have any idea what that silver-colored metal is?  I was thinking that it may be a very thin layer of tin.  I didn't expect to see it once I removed the overlying black oil residue.  

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 Posted: Sat Feb 20th, 2021 10:20 pm
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Alex Rushing
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It is a protective layer of tim over the rods and solder.What is there will outlast any of us on this forum, so not a big worry.

Am very happy to read you want to do the resto as well as possible.
I definitely don't believe my restos to be perfect, but do know they will outlast me and probably another generation before needing the work done again. To prevent rust or corrosion from setting up on the rotor, I tend to use a light coat of clear enamel spray. Since nothing is (or shouldn't be) touching the rotor surface, this is a long term solution. I also paint inside the motor cases now, and coat the entire stator in dousings of electrical EL600 clear varnish. It penetrates the windings, even through the old tape and varnish there and adds another level of electrical isolation to the motor. Headwire replacements are now done in a way where the factory taps are immobile and can be tied into again one day through my replacement wire.

It is a lot of fun, and definitely does a good part in keeping these beautiful air movers out of the junkyard.

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 Posted: Sun Feb 21st, 2021 01:37 am
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Jack Colley
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Is this what you use on the stator?    
https://www.sprayon.com/product/el600-clear-insulating-varnish/

Last edited on Sun Feb 21st, 2021 01:38 am by Jack Colley

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 Posted: Sun Feb 21st, 2021 05:18 am
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Tom Lefaivre
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Jack Colley wrote: Is this what you use on the stator?    
https://www.sprayon.com/product/el600-clear-insulating-varnish/

That stuff is more used for re-insulating the stator windings if they should arc. A bit of paint should be ok to cover that copper up, just to keep it from oxidizing

Last edited on Sun Feb 21st, 2021 05:18 am by Tom Lefaivre

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 Posted: Sun Feb 21st, 2021 09:45 am
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Alex Rushing
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Jack Colley wrote: Is this what you use on the stator?    
https://www.sprayon.com/product/el600-clear-insulating-varnish/

Indeed that is it. The factory insulation on the windings is brittle and the stator has grease and oil deep in the windings sometimes. The EL600 serves to reinforce the brittle insulation, fill in gaps, seal anything deep inside to keep it from having contact with air. This solves the "old fan smell" problem of a faint old oil smell too. Personally I hate the smell and don't care to ever catch a whiff of it after disassembly. Also, if you've gone and taken the fan apart, it doesn't make any sense to put a stator back in with the factory windings going into use with brittle insulation. This leads to buzzing and eventual arcing (as Tom mentioned). However, I differ from Tom, in I am a "one ounce of prevention is worth two doses of cure" kind of longevity thinker. Many fan guys prefer to take care of issues as they occur, which is fine, as it can possibly save money and time if nothing ever has an issue. But, there again, it literally takes an extra hour to do preventive measures, which could save you a lot of headaches in the future when stators and chokes are hard to find, and would need rewinding if the old brittle factory insulation stresses and shorts out.Definitely a two camp deal. But, I've laid out why and how I approach it, and do not intend on saving a few bucks in the hopes the 70-110yo motor and switch windings stay in a functional state. And of course, in a bedroom in our house, with 40 restored and preserved fans, not a single one has a loose switch, old wire, brittle insulation, factory fiber washers, or OLD FAN SMELL.
I also always leave every fan plugged in, which means I've ensured electrical isolation to the best of my abilities. Brittle winding insulation can cause voltage "leaks" that can zap you. I find that unacceptable, but some people just say "turn the plug around to change the hot leg".
Of course, I've not been in the fan resto game all that long, and have only done about 70 restos and/or complete rebuild preservations. One can of that varnish is good for about 20 fan rebuilds(stator soaking and switch choke coils).

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 Posted: Sun Feb 21st, 2021 10:50 am
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Lane Shirey
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The rotor is made of copper bars that are soldered together on the ends. The silver is the solder.  It should not affect its performance at all. 

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 Posted: Fri Feb 26th, 2021 02:38 pm
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Jack Colley
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Thanks everyone!!!

Alex, do you just use compressed air to blow out as much dust as possible from the stator then spray in the varnish?  How do you know when there is enough in there?

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 Posted: Fri Feb 26th, 2021 04:19 pm
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Chris Krenke
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You can use compressed air but be careful. To much pressure too close can cause damage. Blow out the dust. Use CRC lectra clean to really get in there. Wear goggle the lectra comes out like a fire hose. Let dry a few days then varnish. 

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 Posted: Fri Feb 26th, 2021 07:34 pm
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Alex Rushing
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Jack Colley wrote: Thanks everyone!!!

Alex, do you just use compressed air to blow out as much dust as possible from the stator then spray in the varnish?  How do you know when there is enough in there?

I use a brush to get the worst off the outside, and a 90PSI regulator on my 160PSI compressor to blow most of the dry dirt out. Like Chris said, you can use Lectra to clean it further, but Emersons don't run hot enough to need this and is a pretty expensive step.
I reserve the electrical cleaner for earlier and less common fans. A 77648 won't likely need it at all.

Varnish wise, I spray around the outside(where windings are proud), inside, until it drips from the opposite side. Then wait an hour, flip over, and soak a bit on the drip side. You don't need to tape off the steel stator core. The EL600 makes a good rust preventive as well in the steel/iron stator core.

Last edited on Fri Feb 26th, 2021 07:37 pm by Alex Rushing

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