Noisy motor

Discussion in 'Cinestar 8' started by Cris Olariu, Apr 13, 2014.

  1. Cris Olariu

    Cris Olariu Member

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    Hey guys -

    One of my motors stated making a very strange noise. I changed the bearings on it, but it still does it. Please see the attached video and let me know your thoughts.

    Thank you.

     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Cris:
    I presume you are referring to the rattling noise?
    Can you check to see if there is vertical play -- that is, hold the boom and lift up and down on the outer bell of the motor. There may be some, but just barely detectable using your fingers. If there is a lot, that could be the cause of the rattling.

    Andy.
     
  3. Jason Smoker

    Jason Smoker Active Member

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    I would do a bearing change first and check inside bell housing sounds like something small inside
     
  4. Cris Olariu

    Cris Olariu Member

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    Andy - checked for vertical play. Outer bell moves up and down less than 1mm, but that is more than any of the other 7 motors. Do you think that's the issue? How does one fix that problem?

    Jason - I have just replaced the bearings, then did the motor test in MKTools, and that's the rattle I got. I will open up the motor next to check for anything that could've gotten stuck in there.
     
  5. Jason Smoker

    Jason Smoker Active Member

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    Chris I had one motor that had a loose bearing insert overtime i guess heat warped the housing for it. That motor at the time was giving me weird temp too. Sometimes it would be ok and sometimes it would almost overheat. So i took the motor off and then i realised i could push the bearing in with my finger without any tools. something to check maybe??
     
  6. Cris Olariu

    Cris Olariu Member

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    Jason -
    Thank you for your suggestion. I'll check on that. I used Bart's tool to change the bearings (never had trouble before).
     
  7. Jason Smoker

    Jason Smoker Active Member

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    Yeah I always used it to then i tried it with my finger and it slipped in way to easy. Then i thought if it spun up that bearing could easy be loose in the housing causing troubles!! Just a thought!
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Cris: I've noticed increased vertical play on one motor after I used Bart's bearing change tool -- I wondered whether I had overtightened the tool and the bearings were now in a different relative position that allowed that "slop" to occur.

    But check -- some motors have two set-screws (aka grub screws) that hold the motor bell on to the shaft, others seem to use the technique of heating the bell (or cooling the shaft) to allow the shaft to slide through the bell (they may use both technique)....so I'm not sure if you can slide the bell further down the shaft to eliminate the slop.

    Andy.
     
  9. Cris Olariu

    Cris Olariu Member

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    Alright, just pulled the motor apart again. Bearings seem nice and tight. I gave the inside of the bell a nice clean with a toothbrush. Once I've put it back together, I tried it again. Same noise. Then I thought maybe something else may be loose on the same boom. I checked but nothing was loose (GPS board, Nav board, OSD board and FPV camera are all on that boom).
    I'm attaching another video I took with the motor in hand, to try to hear the noise without any resonance from the boom.

     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Yeah, it's that same sort of "ticking" sound. I've only ever been able to associate with vertical play in the motors....actually, overall, as motors go, that one sounds pretty smooth....no screeching/whining....

    And.
     
  11. Cris Olariu

    Cris Olariu Member

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    Thank you Andy. I'm afraid however I don't really understand what I should do next... Do I keep using the motor despite the sound, is there a fix, or do I need a new motor?
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I would do some test flights with the motor and look at the GPX files and also see how it handles.
    I'm not convinced you need a new motor, but flight testing will suggest an answer.

    Andy.
     
  13. MIke Magee

    MIke Magee Active Member

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    Chris, when you held the motor in your hand, did you "feel" the vibration? Is it possible that a stator or magnet is loose? It's an interesting problem.
     
  14. Cris Olariu

    Cris Olariu Member

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    Mike -
    I did not feel the vibration, no. The magnets inside the bell didn't seem to move when I cleaned them. Didn't get a chance yet to do a test flight. I think I need to replace bearings on 2 other motors but I had to order them, so I figured I'd wait.
     
  15. MIke Magee

    MIke Magee Active Member

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    If you did not feel it (you should have given the sound) is it possible that the noise is some type of arcing? Do you smell anything?

    -m
     
  16. Cris Olariu

    Cris Olariu Member

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    No smell either. Nothing out of the ordinary other than the small vertical play that Andy is talking about.
     
  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    If you grab the base of the motor in one hand (no -- not while it's running! :) ) and pull up and push down on the bell of the motor does it make any kind of clunking/clicking sound?

    Andy.
     
  18. Cris Olariu

    Cris Olariu Member

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    No noise either. Not even a simple click. That's what makes it so annoying. LOL
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hmm. Well, I've measured the accelerations on a motor like this and I've seen values like 30 meters/second/second -- so the forces on the motor are a lot greater than you may be able to generate by hand.

    I think you're probably back to test flying (as you doubtless have figured out). :)

    Andy.
     
  20. Cris Olariu

    Cris Olariu Member

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    Yup, that's what I'll do, hopefully over the weekend, if my bearings show up by then.
     

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