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P1 v1.1.1 grounded due to progressing vibration

Discussion in 'Phantom 1 Discussion' started by JKDSensei, Sep 24, 2015.

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  1. JKDSensei

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    My 1.1.1 has about 50 flights on it give or take. Maybe a little less.

    About 10 flights ago I started noticing what I call a resonation vibration in flight only.
    It started out small and barely noticeable and has progressed to a startling, jello producing vibration.
    Up front, I will say I'm kind of a fanatic about things like this. Some would surely ignore what I consider a serious vibration.

    I took the propellers off and CAREFULLY examined them one by one for cracks, nicks, warping, threaded collar damage etc and can find absolutely nothing. They look brand new. No crashes ever. Prop guards have been installed since the first flight.

    The vibration is so bad now (IMO) that after the last flight, I've decided to ground it until I find a cause.
    On the ground if I hold the Phantom down and run it up full throttle I cannot detect a "serious" vibration.
    In fact, the only evidence I have is from my camera video. I can hear the resonance in the props when watching the video and I started getting Jello in my videos about 10 flights ago. Also, when hovering around a low altitude it seems ok. It only does it after it's been up like 50 feet or more for several minutes...worse if there's some wind. The vibration seems to be worse towards the end of the flights. Not so much at first.

    This is leaning towards a motor(s) heat issue. As if a motor is getting hot and the bearings are acting up once hot. Maybe from a lack of lubrication. The motors are relatively new (young) so you wouldn't expect the motors to be failing...but new Chinese parts are not immune to failure.

    I removed the props and ran the motors up full speed...one feels very smooth, the other three have a very slight vibration. Nothing bad and possibly normal UNLESS the motors should be "sewing machine" smooth.
    Not sure about that.

    3 of them have VERY slight vibration but the shafts have no play in them left, right, up or down and spinning them by hand revels no rough spots or any other noticeable problems that might indicate a magnet coming loose etc. I would kinda relate this to front wheel bearing vibration on a car. If you've ever changed front wheel bearings on a car you can probably appreciate what I'm talking about. It seems to be that kind of a vibration / resonance.

    All motors are securely fastened and there is no movement whatsoever. There is absolutely no melting or distortion of the shell and no cracks are present anywhere.

    I have ordered a precision balancing rod to check the balance of the propellers but the props all look perfect and they are clean. For all intents and purposes, they look "out of the package" new. So to be honest, I'm expecting to find them all well balanced.

    If they are, I think I'll go ahead and replace the motors. For $40, it's probably not worth waiting for one to fail. Since I may be replacing them anyway, I did order some of that teflon lubricant to try. Nothing to lose and if it resolves the issue even temporarily, I'll know for sure it's the bearings.

    Could an ESC controller board cause his? I don't see how.
     
  2. cheebs

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    Just for the hell of it, have you tried a different set of props? That's an easy way to eliminate them as a possible suspect, and the least expensive to replace.
    Next would be the motors, as you say the bearings could be the culprits there, some lube can't hurt. The good thing is that motors for the Phantom are plentiful and cheap. Lots of options for a little extra grunt too. May I suggest you connectorize them if replacing. Saves a great deal of time for other replacements down the line.
     
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  3. N017RW

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    The bearings are sealed. Lube will only retain foreign materials.

    There will always be some vibrations. If it's only evident in the video then you may just have a damping issue.
     
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  4. cheebs

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    Noted. No K-Y for the P1.
     
  5. JKDSensei

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    Just because it's a caged internal roller bearing does not guarantee it's sealed. In fact, I'd be a bit surprised if these tiny inexpensive bearings in THIS application are sealed. Shielded but not necessarily sealed. Looking at many of them, some seem not to be sealed. Can you point me to definitive info that shows they are in fact always sealed?

    This P1 was smooth as silk for the first 40 flights or so. Absolutely smooth. The vibration has developed lately. My camera has no dampers. It is directly connected to the frame. P1. AFAIK, there are no dampers.

    The lube is a shot in the dark. However, I'm probably going to replace the motors anyway and dispose of them. Nothing to lose. Some have reported success with the teflon lube. . If it quiets them even for ONE flight, that's well worth it as I will then know then that they were the cause of the vibration. I do suspect dry bearings.
     
  6. syotr

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    I would download one of the vibration apps for your phone, Hold the phone against each arm while revving the motors (no props) and see if you can isolate the problem.
     
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  7. N017RW

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    You're right.

    But it has been determined and discussed here many times.

    Be prepared to be surprised.
     
  8. JKDSensei

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    I would say it has been discussed yes, but It has not been "determined". Quite different.
    Forum discussion does not necessarily conclude with the correct or only answer.
     
    #8 JKDSensei, Sep 24, 2015
    Last edited: Oct 14, 2015
  9. N017RW

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    Good bye Censay!
     
  10. JKDSensei

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    Grow up.

     
    #10 JKDSensei, Sep 24, 2015
    Last edited: Sep 30, 2015
  11. JKDSensei

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    Cool. Will try that.
     
  12. JKDSensei

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    Downloaded the Vibration meter app and used it. Vibrometer
    Acceleration Vector Sensitivity set at +30
    Baseline Cut set at -2.4
    (Are there better settings?)

    Here's what I got.....

    Motor 1 - 7.5, 10.0
    Motor 2 - 9.0, 10.6
    Motor 3 - 4.4, 7.0
    Motor 4 - 4.0, 6.2


    Just from this (and the way it feels, motor # 2 has the most vibration. It feels that way also when I grab the shell near it. And motor # 1 has a good bit of vibration.

    3 and 4 look good and feel good to the touch. Very smooth.
     
    #12 JKDSensei, Sep 24, 2015
    Last edited: Sep 24, 2015
  13. JKDSensei

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    So after being told in no uncertain terms that lubricating bearings was "Determined & Discussed" and found unnecessary...then told to basically get lost.....

    I did find a post by a ...uh..em....Phantom bearing manufacturer who said otherwise....

    Motor bearing upgrade | Page 2 | DJI Phantom Forum
     
  14. JKDSensei

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    Cheebs, after removing the props I ran a simple vibration test on all 4 motors. The vibration in 2 of them is significantly higher than the other two. One of those two is quite a but rougher than the other. So one appears to be going downhill. When my balance rod arrives I'll still check them all because that could have aggravated the sit U ation
     
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  15. Pilot_FML

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    A couple suggestions....

    Before buying new motors try some of these tips...
    http://www.rcgroups.com/forums/showpost.php?p=29062447&postcount=27340

    If you end up buying new motors keep track of which arms had the worst vibrations. If you still have vibrations after installing the new motors, you need to know this because your next step will be replacing the ESC(s) on the arm(s) having the bad vibrations.

    P.S. I assume you've already triple checked that the motor mounting screws are tight ... right? ....;)
     
  16. JKDSensei

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    Thanks Pilot_FML. Yes sir, the screws were all tight.

    Butt.....here's an interesting update. I received the Tri-Flow Teflon lubricant today and applied a bit to both the upper and lower bearings. After numerous tests and allowing the motors to heat up, I found the vibration was down significantly. Almost to the point that I'm wondering if my re test could be correct.

    Previously...motor 2 was 9.0, 10.6 (vs lower numbers for the others, see above)

    Today after lubricating, the highest vibration I could measure from that motor was 5.5, 7.0
    Much closer to the numbers on the two motors with least vibration.

    I don't want to completely claim the lubricating did the trick (or was even necessary) until I do more tests. But these the initial results "seem" promising. Remember, I was going to dispose of these motors anyway just to be super safe (and still probably will as I have a new set arriving later this week).
     
  17. Pilot_FML

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    I personally would not have lubed these motors because I think the verdict is still out on whether its a good idea or not....

    Be EXTRA careful when now flying with these motors...they're going to be much more susceptible to becoming contaminated with dirt or sand.

    You could just as easily have motor shaft(s) that are slightly bent, or just the beginning of slight motor imbalances occurring.
     
  18. JKDSensei

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    Pilot, I really believe these motors are toast....regardless. (Well, two of them)

    Took it for a test flight.

    It was definitely smoother......for about the first three minutes. Then most of the resonance came back right on schedule. So, I think the lubricant made it to the bearings...but didn't do a whole lot once there. Maybe not as much Teflon in the lubricant" as there was advertising.

    Or...(alternative thought)...the motors bearings had already run dry and the damage was done (wear) so lubricating the motors from day one probably would have helped (these motors anyway), but now it's too late.

    New motors should be here tomorrow.

    BTW, I do have a balancer and the props are as balanced as can be.
     
  19. JKDSensei

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    Here's a video where you can hear the "resonance?" Keep in mind I don't actually hear this with my own ears when it's flying. This is what I hear in my videos. It's usually too high up to hear it.
    This sound is NOT in my early videos.

    Password is Phantom1

     
  20. Pilot_FML

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    Not sure this on again off again vibration sound is motor related... the changing sound is low frequency (low pitch) and not a high frequency (high pitch) that I would normally associate with high speed motors. If motors were going bad, the vibration would probably be bad (constantly) and not waiver as much as I'm hearing.

    You could be picking up a vibration caused by something related to how your camera is mounted. If some attachment point loosened up, you could easily get this type of waivering sound as the P1 motors changed speed to maintain level flight.

    Double check how your camera is mounted and make sure there are no loose connections.
     
    JKDSensei likes this.