Never too old to be stupid

I needed a new motor for my roof fan, ordered it on Thursday, and picked it up 40 miles from here on the same day. Friday, I went to the motor store in town to retrieve the old motor.
Same model number, on the box and on the name plate. I compared them and they seemed the same.
Installed the new one this morning at 9. Attic a little warm, but with my shirt off, not uncomfortable.
Always tricky but harder than I remember to get the blade and the motor past the 3 brackets, even though they are disconnected from each other and dangling. I wish I could put the blade on after putting the blade and motor in place separately, but that would not work. Not a lot of clearance. Motor has to be vertical, and if the blade were higher, would hit the cover of the fan. Which says Nautilus on it, btw. I pushed it and not brittle yet, afaict.
Get all three brackets bolted to each other, two of them tightened down, but the third is tight already and still 3/8" between the two brackets.
That's when it dawns on me that the new one has a layer of smooth black plastic around the top 3rd. Maybe 2 or 3/32th" thick. (The motor is about 3" high and 5.5" in diameter.)
Get out of the attic and check the old motor. No, it doesn't have that plastic. I wonder how hard it woudl have been to rip it off.
And now I wonder how long the bracket will hold with no lock washer (does that matter in this case?) and the two pieces of sheet metal not touching.
I'll call the fan company asaic.
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micky wrote:

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Well that's good.

Thanks for showing me the bright side of this
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So you've done this replacement at least once before?
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wrote:

Probably 4 or at least 3 times in the last 22 years (starting when the fan was 10 years old.) .
This is the first time the motor wasn't an exact match. The plastic layer looked like it would be very hard to get off, but I would have done it if it had only dawned on me that it cause the brackets not to fit right.
The motor also has 3 screws sticking out the back (that hold the thing together) and 4 sticking out the front (that have no other purpose) for mounting, so maybe they've forgotten that some mount the way mine does.
Except at www.emotorstore.com the motor is listed under Fasco and then under the category of "Roof Top Ventilator", and although it could be done another way, I'd bet most such fans mount the motor like mine. I still plan to call them when I get back from out of town, and it would be great if I found someone who actually knows why the plastic was added and if they considered people like me when they did so. They should have put a suffix on the model number and a note in the specs
http://www.emotorstore.com/productdetail.asp_Q_catID_E_3_A_subCatID_E_234_A_productID_E_389_A_skuID_E_25695
Another interesting thing is that the flat spot on the shaft, that the set screw tightens into, runs for almost 3 inches. I thought that might be enough to unbalance the motor. Do they make some other provision to make up for the shaft not being symmetric?
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On 5/17/15 8:25 AM, micky wrote:

Is it a 3/8" shaft? On a 1050 RPM motor, centrifugal force on the circumference of the shaft would be about equal to gravity. If it were a gram out of balance, that would be .001 newton.
If you'd popped the dome off, you would have had room to work. You should have left it off. An efficient fan works by imparting motion, not pressure. If a dome blocks the way, right above the blades, it turns the motion into pressure for the fan to fight.
What you need is an an electrical umbrella and a DPDT thermostat. An electrical umbrella will protect your vent from rain and snow. When the thermostat turns on the fan, the umbrella will collapse, leaving your fan free to do its job and not wear out the motor.
I happen to sell electrical umbrellas on ebay, but I don't want you to think this is a sales pitch. Check the electrical goods department at your Goodwill store. They may have one for 50% off. If you can't find it there, get back to me. I have a hundred-unit minimum, but when others see your electrical umbrella, you can charge what the market will bear.
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On 5/17/15 3:17 PM, J Burns wrote:

Uh-oh, it's a 1/2" shaft and 8 times gravity, or .08 newton.
This has shaken my confidence. I'd better double check the design of my electrical umbrella.
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Maybe you should consider one of these
http://www.homedepot.com/p/Master-Flow-12-in-Weatherwood-Galvanized-Internally-Braced-Dual-Bearing-Wind-Turbine-GIC12WW/100059101?N=5yc1vZc665
I have two on my roof that have been working without a problem for 30 years.
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