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Rotor gets tight when the front is put on. Emerson 1510


Tim Babcock

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I have the Emerson fan tack together for the most part. It runs without the front cover on but when I put on the cover and it goes over the bolts a bit tight but not horrible the rotor gets stiff. Not sure if I need to drill out the holes on the front cover just a bit to take the stress off or what. I tried tightening the bolts down so the cover is on tight but that does not seem to do it. Thanks for any helpDSC00270.thumb.JPG.32331c4ccf3cee062181ed0ceefd9ab5.JPGDSC00271.thumb.JPG.409c0846cb0ccc4a0e8cf03d61ccb619.JPG

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Did you put the nuts on the stator when you put it back in? There's no front bearing so cover shouldn't make a difference, it sounds like the stator is shifting?

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Yes the nuts and washers were put on the stater. Then the nuts on the cover. I may try slightly drilling out the cover so its does not move the bolts at all. This is the only thing I can think of.

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I'd wait for advice from some experience Emerson guys. That's a step you can't come back from. I've had the covers tight against the screws but it never affected the rotor movement.

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Not sure what that is. Nothing is there so it must be part of the Rotor. It look like something is there but there is not. I will take a shot of the motor with cover off morrow.

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Did you re-install the brass wedge as I mentioned in your other post on this fan?

If you did not, you may want to try that. If you did, the wedge may need to be moved, or even left out.

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They make something called pin gages. They’re used to check thread pitches. I have a set that I use to determine stator centering on those Emersons with the brass centering wedges. You insert the pin at various points between the rotor and stator like a spark plug feeler gauge. 
 

is it possible that the stator is not fully seated into the housing? 

Edited by Lane Shirey
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The advice above is spot on to check first.  Regarding the stud / cover hole alignment I wouldn't recommend drilling the casting holes.  Easiest way to remedy is to slip a 5/16" nut driver over the stud and use that as a handle to slightly bend the studs so they align with the holes.  Often those studs are bent to begin with and you do not even notice.  

The cover should ideally slip right over those studs or at most have a mild interference that's overcome with a slight push on the cover casting to get it seated against the motor housing.

 

..........Dan H.

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2 hours ago, Mark Olson said:

Did you re-install the brass wedge as I mentioned in your other post on this fan?

If you did not, you may want to try that. If you did, the wedge may need to be moved, or even left out.

Yes I did. Although I did not pound it in fully. I used half the wedge. I did not want to risk cracking the head. But with the wedge in, the motor runs free with the cover off.

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2 hours ago, Lane Shirey said:

They make something called pin gages. They’re used to check thread pitches. I have a set that I use to determine stator centering on those Emersons with the brass centering wedges. You insert the pin at various points between the rotor and stator like a spark plug feeler gauge. 
 

is it possible that the stator is not fully seated into the housing? 

The Stater is flush with the main body of the head unit. I tightened the nuts under the cover as far as I can go. Anyone know if the stater on these go beyond flush?

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It's hard to tell from the photo, but the gap between the rotor and stator may be a little bit close along the bottom. You are looking for the rotor to be as perfectly concentric with the stator as you are able to accomplish.

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It seems all in is order on your stator install and rotor as well.  No idea of how the cover fitment to the housing is causing the rotor to get bound.  There simply is no contact points of the cover to the rotor, by design.

........Dan H.

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1 hour ago, Tim Babcock said:

Here is the motor with the cover off.

DSC00272.JPG

It appears there is nothing involved with the cover itself to in some fashion compress on or bind the rotor when you tighten it down on the housing. If your rotor is free to spin with the cover off.... yet binds when you try to snug the cover down, your rotor must not be centered in the stator.  Do not drill your stator bolt holes on the cover. 

Keep in mind the fan was operational before your restoration.

Edited by Russ Huber
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One thing the motor will run with the cover off but only if I start it by turning it when its plugged in

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1 hour ago, Russ Huber said:

Did it start on its own and run before restoration? 

The owner said it did. But I am not sure about that. The cord was in a state that I would not test it. It was in very bad condition. Some one had put a new lamp type cord on it. The cord was bad up to the stater. So I had to remove it to put the new cord on. Only thing I did was to test the two lines to see if it was showing an Ohms reading. I polished up the two centrifugal contacts and put a bit of Dielectric grease on the hub after polishing out the copper to give it a good contact.  The other thing I noticed is that when it is running it seems to not change speed on either of the contacts. Could be no fan blade on it can make it seem like that. My first order of business is to get it running without the cover. Than I can work on the cover. Maybe it will be fine once I get it running right. The amp draw is .85 when running.

 

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9 hours ago, Dan Hilton said:

The advice above is spot on to check first.  Regarding the stud / cover hole alignment I wouldn't recommend drilling the casting holes.  Easiest way to remedy is to slip a 5/16" nut driver over the stud and use that as a handle to slightly bend the studs so they align with the holes.  Often those studs are bent to begin with and you do not even notice.  

The cover should ideally slip right over those studs or at most have a mild interference that's overcome with a slight push on the cover casting to get it seated against the motor housing.

 

..........Dan H.

I think Dan is on to it.The studs are not straight and when you put the case on it’s binding the stator against the rotor.

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5 minutes ago, Paul Carmody said:

I think Dan is on to it.The studs are not straight and when you put the case on it’s binding the stator against the rotor.

I get that but first I need to get it running minus the cover. I will work on the cover fit later. I do detect a bit of motor slowing on the second speed. But without the fan blade its going to be hard to tell right now. I just want to know what could be causing the motor to not start up by itself .

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I would add a shim or two to back of rotor, move the centrifugal forward, see if it goes. You may be moving it just enough by hand when you spin it to get it to fire...

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1 minute ago, Michael Rathberger said:

I would add a shim or two to back of rotor, move the centrifugal forward, see if it goes. You may be moving it just enough by hand when you spin it to get it to fire...

I put two fiber washers behind it, but I will try a few more.

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3 hours ago, Tim Babcock said:

I polished up the two centrifugal contacts and put a bit of Dielectric grease on the hub after polishing out the copper to give it a good contact. 

This is a mistake. Dielectric grease is an insulator. I am not saying that this is causing your motor not to start, but it is definitely the wrong thing to do.

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Dielectric grease is specifically made to insulate against electricity!

In regards to your motor binding, it sounds like there may be a hairline fracture somewhere that you aren't aware of. Presence or absence of the front motor cover should NEVER affect a single bearing Emerson. 

Use the soda can trick or find a similarly thin metal or paper shim to check the rotor gap. Use a metal brace or plate over the studs to check the rotor gap with a load on the studs/housing. 

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1 hour ago, Mark Olson said:

This is a mistake. Dielectric grease is an insulator. I am not saying that this is causing your motor not to start, but it is definitely the wrong thing to do.

Yes, if you want to use something, there is contact enhancing grease used on radio tuners. But not dielectric grease. 
 

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