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Old Jul 06, 2011, 08:53 PM
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EightOhMike's Avatar
United States, NC, Greensboro
Joined May 2011
39 Posts
Help!
Help me ID a component found loose in my brushless outrunner, please

Greetings all--

I'm still brand new to the hobby, and have only about five flights on my E-Flite Apprentice. On my only two serious crashes, I've lost perception of depth and flown the plane totally controlled into obstacles. The second obstacle was power lines, and after the plane dangled there for a second threatening to seriously embarrass me by not coming down, it augered nearly straight down onto firm soil.

The motor, a brushless outrunner, was pulled in two with the rotor and stator pulled away from the backplate. Turning the shaft caused a clicking noise that was nearly ratcheting, that is, sometimes preventing backwards rotation. After much exploring with an eye loupe, I found a small cylindrical piece of metal, slightly magnetized, rolling around between the windings and magnets on the bell.

After removing the piece, the motor seems to run correctly again, and I'm at a loss as to what function the piece served... speed signal for the ESC, perhaps? So, here's a picture of the piece next to my knife for scale.

Anybody able to say with reasonable certainty what my motor's now missing?
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Old Jul 06, 2011, 09:45 PM
OFF TOPIC POSTER
Des Moines IA
Joined Dec 2005
4,811 Posts
Was it on the outsideof the motor?
Might have nothing to do with the motor as the mags might have picked it up.
Just a guess or part of the shaft.
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Old Jul 06, 2011, 10:04 PM
Reduce the drama...
rick.benjamin's Avatar
USA, OR, Damascus
Joined Apr 2004
4,044 Posts
Hi Mike,
Looks like a roller bearing.
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Old Jul 06, 2011, 10:20 PM
just look at it smokin'
z-matrix's Avatar
Joined Dec 2005
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That can be debris, or a balancing weight got loose in the bell.
The outrunners usually use ball bearings...

Z
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Old Jul 06, 2011, 11:08 PM
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EightOhMike's Avatar
United States, NC, Greensboro
Joined May 2011
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It was quite inside the motor, but as you point out, it might have come from somewhere else on the installation, though I'm still stumped. It's slightly magnetized, but that could have come from being rubbed against the magnets in the motor.

I'm encouraged that nobody immediately said that it was something critical to the motor, and again it seems to run fine now after the reconstruction. I'm learning that the reconstruction is nearly as much fun as the flying.

Thanks, guys.

Mike
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Old Jul 07, 2011, 02:43 AM
just look at it smokin'
z-matrix's Avatar
Joined Dec 2005
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hmm one more thing i can think about is if the shaft and the bell has a hole, that steel rod can be used to stop the relative rotation.
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Old Jul 07, 2011, 06:23 AM
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Austin,TX
Joined Jul 2009
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Perhaps it is the pin that some outrunner manufacturers use to help lock the stator to the stator tube? Follow the red arrow! That would be my guess, and if so, you should be able to notice a half circle void somewhere on the inside diameter of the stator and another on the od of the stator tube. When you repaired the motor the two may have been offset (stator rotated on tube) so that you didnt easily notice.

regards
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Old Jul 07, 2011, 06:27 AM
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Austin,TX
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Oh and...........had a foamy well attached by the gear to some power lines myself once, took several minutes before a breeze finally dislodged it. Never did find the motor that ripped away due to the sudden impact.

quite embarrassing as there were many spectators
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Old Jul 09, 2011, 11:22 AM
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United States, NC, Greensboro
Joined May 2011
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@billcat: quite embarassing, indeed, to watch it just hanging there in front of God and everybody. I need to get a good 1.5 mm allen driver to loosen the shaft to inspect more thoroughly.

In typical (I think... I hope) noob style, I wrecked her again, flying inverted... COMPLETELY getting ahead of myself, after some touch and go practice. I figured since the loops and rolls were going well enough, I'd practice some inverted flying. Worked JUST well enough to tempt me to fly lower...

Live, repair, and learn, I suppose. Thanks for the support.

Mike
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Old Jul 09, 2011, 12:49 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,000 Posts
Quote:
Originally Posted by EightOhMike View Post
@billcat: quite embarassing, indeed, to watch it just hanging there in front of God and everybody. I need to get a good 1.5 mm allen driver to loosen the shaft to inspect more thoroughly. <snip>
Mike,

Give a 1/16" straight shanked (not ball ended) hex wrench into that 1.5mm socket. There is only about 0.003" difference in a 1.5mm and a 1/16". If the Chinamen missed the tolerances on the right side you're in business.

I keep a short piece cut off of a 1/16" handy and tap it into 1.5mm sockets when I have one that is stripped and won't respond to 1.5mm.

Ball ended hex wrenches are a curse, they are OK for advancing screws but if you have one that is Loctited (blue or red) it turns the ball end into a hex socket reamer...

Jack
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