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Atom 6HV and 6HVU Compass Atom 6HV and 6HVU Model Helicopter Discussion


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Old 07-16-2011, 11:52 PM   #1
Jason O'Connell
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Default Horrible screeching sound.

Hi guys.

I put a new motor in my 6hv last week. On the 4th flight the motor made a horrible screeching sound when I flipped out if TH, I Hit TH right away and let her spool down. looked it over and thought that maybe my gear mesh was too tight. I had to go home so I figured I would fix it later.

I went out to fly a few days later and had forgot all about the screeching sound, untill I went to spool up. SCREEEEEEEECHHHHHHH. I reset my gear mesh and flew 6 flights without the sound.

Yesterday I was flying to get ready for my local funfly and the sound happened on my second to last flight, I hit TH and waited for the blades to stop spinning then flipped TH off again and she spooled up like normal.

Today an my local fun-fly it happened three times, each time if I hit TH and let the blades stop then tried again it would work fine.

Do any of you know what is going on with my heli? Would it be the motor or the ESC? When I replaced the motor (I was trying to track down some vibes) I found a cold solder joint on one of its connectors which broke apart with little force. Could that have damaged my esc?

I await your replies!


Thanks in advance.
Jason
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Old 07-17-2011, 07:31 AM   #2
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Have you checked your pinion / counter bearing?
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Old 07-17-2011, 10:35 AM   #3
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I agree with Crawl,

I would look for a bearing problem-motor or something else that turns at high speed.
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Old 07-17-2011, 11:56 AM   #4
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You think a bearing is causing too much resistance for the soft start to overcome? That would make sense.
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Old 07-17-2011, 12:02 PM   #5
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I think that would be the first place that I would look, sir.
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Old 07-17-2011, 01:29 PM   #6
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If your pinion is slipping on the shaft, that will cause lots of screeching and very little spinning.

Could be lots of things but I would def take a look in that area .
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Old 07-17-2011, 03:30 PM   #7
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I have the motor out now and everything turns smoothly and the pinion is tight.

I only get the sound when I flip out of TH. I hear the screeching, the blades barely start to spin (like the soft start normaly is) but it is still screechng, so I flip TH again. I do not know what would happen if I tried to spool up , but I am not willing to find out.

Then I let the blades stop, flip off TH again, and it spools up fine, no odd noise at all. And it does not happen every time.

The sound is much too loud to be a bearing at no rpm's that sounds fine just a few seconds later. It sounds like the motor is trying to soft start but does not have enough power and is screaming trying. I used to work with large motors and the sound reminds me of a VFD (Variable-frequency drive) motor at the verry beginning of start up.

I know this is my motor or esc but have no idea how to find out which.
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Old 07-17-2011, 04:02 PM   #8
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Open up the motor and check the bearings. Opening the motor is not difficult; the worst part is getting the snap ring off the motor shaft. Once that's done, just pull the can off the motor. The magnets are strong, do you'll have to pull pretty hard.
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Old 07-17-2011, 04:43 PM   #9
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And be aware when you go to put it back in, that sucker gets yanked in . Pinched my finger last time because I wasn't thinking
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Old 07-17-2011, 07:52 PM   #10
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You will most likely find a bearing issue somewhere, just went through this myself although no noise but massive end play from nowhere last week... Pinion hood bearing adhesive had failed and it was just flopping around upper motor bearing had been carelessly installed by manufacturer and had visible damage.

Rebuilt and maybe 30 flights so far all is good.....
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Old 07-18-2011, 12:30 AM   #11
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ahhh , what timing in the esc? also , try this to see if it does anything , spin the blades with your hand get them moving , then spool , same issue? or no?

i had a little foamie motor that did that from a dead start, turned out being a timing issue. odd motor poles for the esc timing setup. if i spun teh prop with hand and had motor moving before throttling up , it didnt do it. a timing change in esc fixed the issue.
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Old 07-19-2011, 05:26 AM   #12
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This might sound VERY stupid, but make sure that the stickers on the motor is not loose.. cured MANY schreetches in my life.....the actually tip of sticker lifts and create wind noise, but at the rpm's our motor turn, its very much like bearing noises.
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Old 07-19-2011, 08:48 AM   #13
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Quote:
Originally Posted by liaan View Post
This might sound VERY stupid, but make sure that the stickers on the motor is not loose.. cured MANY schreetches in my life.....the actually tip of sticker lifts and create wind noise, but at the rpm's our motor turn, its very much like bearing noises.
What stickers? And if there were any they would melt the first flight that sucker hits like 160 half the time.....

Thank you Dr. Kevorkian.....


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Old 07-19-2011, 08:58 AM   #14
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Quote:
Originally Posted by sarpilot View Post
What stickers? And if there were any they would melt the first flight that sucker hits like 160 half the time.....

Thank you Dr. Kevorkian.....


The early Atom 500 motors had stickers on them instead of the branding being printed directly on the can as on my 6HV motor. I assume the 500 motors aren't using stickers anymore.
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Old 07-19-2011, 09:08 AM   #15
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Call me crazy but I still think "sticker flapping" is not his problem, although that does remain an old time favorite.....
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Old 07-19-2011, 09:12 AM   #16
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Quote:
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Call me crazy but I still think "sticker flapping" is not his problem, although that does remain an old time favorite.....
True. I would agree with the majority that it's probably a bearing issue. The sticker was always more of a buzzing noise, not screeching.
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Old 07-19-2011, 10:29 AM   #17
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Quote:
Originally Posted by TheBum View Post
True. I would agree with the majority that it's probably a bearing issue. The sticker was always more of a buzzing noise, not screeching.
No guys, there is no sticker on the motor.

If it was a bearing issue how would it screech before it starts to spin? Only to sound fine 5 seconds later? I have alot of experience with larger motors and bearings do not screech loudly only to stop a second later, and then repeat the process. Besides, I have my motor out now and all the bearing turn smooth and free.

I have been super busy and have not been able to fly but Airworks seems to have the best concept of whats going on. I set my esc at 15deg but have not double checked the timing yet. My motor is getting pretty hot at 15ged so I am reluctant to swich up to 18 or 22.

I know I get the problem from a dead stop. In hindsight I do not think I let the blade come to a complete stop befor starting up again, so the blades would have been moving a little when I fliped out of TH and spooled up without the noise. Once again verry close to the scenario Airworks described.

I will check my esc timing before I fly next and I will also try giving my blades a spin by hand before spoling up to see if it happens in that scenario.

Thanks for the input guys! I will keep you updated.

Jason
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Old 07-19-2011, 10:42 AM   #18
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Jason,

If it is screeching before it starts to turn, I agree, it could not be a bearing.

Try the timing at 12.5 degrees. This will de-tune things, so your motor performance will be degraded but, if it is a timing issue, the timing change should either cause the tone of the screeching to change or the issue to go away.

I am running 22.5 on mine right now. At some point, I will be trying 18. My motor gets very warm, but not what I would call hot.
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