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REALLY Dusty Motors...

Discussion in 'Cinestar 8' started by Josh Lambeth, Oct 22, 2012.

  1. SteveWilson

    SteveWilson Member

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    A little trick I saw somewhere was to place a plastic baggie over your hand and the motor when you go to pop the clip off. 9/10 they do shoot off but the bag catches them.
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Nice trick, Steve. Thanks. Did you find some circlip pliers that will fit, by chance?

    Andy.
     
  3. SteveWilson

    SteveWilson Member

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    I've never changed a bearing on these motors. Changed many of the little Robbe motor bearings and small screwdriver worked well for me.
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    OK. I'm still waiting to hear back from Boca Bearings -- I tried their "live help" but got routed to leaving a message. I'll call on voice tomorrow.

    Andy.
     
  5. Ozkan Erden

    Ozkan Erden Distributor

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  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    One question regarding the bearing press: Bart (the guy who makes it) asked me: "Are those motors the same overall dimensions as the Tiger 2814's or are they more like the larger 3515's?"

    Anyone know the answer?

    Thanks
    Andy
     
  7. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I can tell you the MT3515's are a lot larger then the QC3328s...
     
  8. Ozkan Erden

    Ozkan Erden Distributor

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    QC3328 has 4x11x4 dimension, which is same with mt2814. You can use the tool without modification.
     
  9. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks, Ozkan. I've ordered up one from Bart. Looks much easier to use than an arbor press (and more portable!)

    Andy.
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Jose:
    I'm exchanging emails with Gareth Burrows at Boca Bearings.

    He is recommending a two ceramic bearing kit for the QC3328. The kit is #BMK-080C-OS Radial Bearings and consists of two SMR694C-2OS #7 AF2 bearings. There is a choice of bearings though: "Each size supplied in two different versions. One with Af2 oil for on road or clean environments and NB2 grease for off road or dirty environments."

    So the question remains: did you get the AF2 bearings or the NB2 bearings?

    It would seem to me that the NB2 "for off-road or dirty environments" might be the wiser choice considering this thread is "really dusty motors." Certainly I've experienced very dusting landing zones....

    Thanks
    Andy.
     
  11. Philip Ellerbroek

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    Hey Andy and Arthur - I'm following up to my post in this thread and your reply on the noise from one of my QC3328 ( Here : http://forum.freeflysystems.com/index.php?threads/really-dusty-motors.331/#post-4708 )

    After using compressed air per your instructions, it seemed to go away over the past few weeks, BUT, I unfortunately had a land-then-tip over on a landing at a golf course this weekend. Props on booms 2 and 3 took the brunt and the prop tips each buried about 3-4" into the softer grass (since these are brushless and there are no gears, there shouldn't be any major motor damage from the ground imposing the prop movement, right? I don't think it was violent enough to bend the prop shaft either).

    My concern now is that the flights immediately after I now notice on landing that props 2 and 3, particularly #3, are slower to stop spinning during power off when compared to the others, but only by 1-2 seconds. But I do hear an audible rpm sound now from 3. Its not grinding, but what sounds like what might be friction. When hand turning prop #3 I feel no restriction though. I haven't re-applied compressed air, but I'm wondering if some dirt may have gone into the motor/bearning or that their was damage done internally? The prop itself was not damaged. I also checked the mount and the screws are still tight, so it isn't the motor mount vibrating.

    At this point, besides your reply guidance and applicable instructions, I plan to blow it out with air again but I'd like to use some wd40 like Arthur previously suggested. Do I just shoot the wd40 onto the copper on the top of the motor and hand spin the prop, or in the 4 small slots at the base of the QC3329 motor casing? I know electronics can be very tempermental when it comes to wd40.

    Lastly, holy crap, replacing/removing the bearings seems like surgical work.

    SINCERELY :eek:

    Phil
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Phil:

    I've just started a thread under Cinestar Misc. With the right tool, changing the bearings takes less than five minutes. If you're hearing Bad Noises, I'd just swap out the motor with a spare if you have it.

    I would not hose it down with WD40 -- if there is grease on the bearings you could well wash it all off and having the bearings seize up. Note: I don't know affirmatively there is grease on the bearings -- I'm speculating.

    Andy.
     
  13. Philip Ellerbroek

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    Andy,

    I ran the motor minus the prop last night. I recorded audio but could not upload here. At 10-15% power, there is a growling and vibration. I'm guessing that either the motor shaft bent or made an indentation into one of the bearings, thus putting an elliptical shape to the bearing or a bend in the shaft? Either way, the sound and vibration pattern match the rpm, so this isn't dirt or debris. I'm guessing there is now a high/low spot on the bearing that is causing a tapping/bumping. I'm going to order a new QC3228 motor, but I will likely follow your new thread and see if I can find the issue and salvage the motor as it is only 4 months old. If curious, message me your email and I'll send you the audio of the motor to see if it cooresponds with your previous recordings after your close encounter of the tree kind. Had my tip over occured on cement the prop would have likely and preferably broke instead of the damage internally to the motor.

    Phil
     
  14. Philip Ellerbroek

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    Spoke to Riley - he thinks this is bent. http://www.quadrocopter.com/Propeller-Mount-for-QC3328_p_510.html

    Ordered one and we will see. If not that, then I'l move onto the bearings. I spoke with Boca this morning and he said its pretty much impossible to dent/bend the bearing casing walls, and suggested I try the shaft replacement first, particularly because it is $11 from QC.

    I did notice on Boca's page that they claim:
    RC Brushless Motor Orange Seal Ceramic bearing kits are the true secret weapon for serious RC racers. ABEC #7 tolerances makes the Orange Seal line the closest precision tolerance that Boca Bearings has to offer. The removable, non-contact rubber seals results in a bearing with less drag and that requires less maintenance than a typical shielded bearing. The Grade 5 ceramic Si3N4 balls will allow the bearing to be lighter and spin 50% faster than a traditional steel bearing. Free seal replacements are supplied upon request

    Link: http://www.bocabearings.com/bearing-inventory/Radial-Bearings/21490/xx-BMK080COS

    I'd be curious to see if this translated into better flight response, less cleaning maintenance, longer flight times, and most importantly for me being in the desert - lower BL temps. However, at $30/motor kit x's 8 motors, the hard ROI would need to be proven.

    Keep ya posted in 5 days....

    Phil
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    If you rename the file type to be, say, .png, you can then upload it unless it exceeds the 2MB limit. Just make a note in the posting as to what the file type should be so folks interested in listening to it can change it back to the correct file type.

    It's still not clear to me why a propeller mount would cause that growling sound. Vibration, yeah, I could see that if there's run-out on the top of the shaft and the prop blades are not transcribing a flat plane.

    Well, not so sure about that -- cement isn't exactly soft and the motor going at several hundred rpm probably experiences several tens of G-forces coming to a stop in less than a millisecond....William might be able to tell us more as I know he's measured motor RPM under prop load.

    Andy.
     
  16. Philip Ellerbroek

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    Attached is the audio, now in a .png file form. Download and then manually change it to a .wav --- The "sweet spot" for hearing the issue is at 10 seconds in, when the rpms are low. This sounds like a gorgeous Ducati GT1000, but unfortunately, it is not.

    I spoke to Riley at QC and he suggested starting with a replacement prop mount and prop shaft. Here's the link:
    http://www.quadrocopter.com/Propeller-Mount-for-QC3328_p_510.html

    If that doesn't work, then I'll crack the motor all the way open and double check for deep debris and inspect the bearings for replacement. I may pass on replacing the bearings at $30 total (plus $25 bearing replacement tool via Boca as well) and opt for a whole new motor for just $50 more for peace of mind.

    Phil

     

    Attached Files:

  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    If it makes that noise without a prop on it, it's definitely bearings. The prop shaft/prop cannot make that kind of noise, IMHO.
    I could be wrong, but I'm not uncertain!

    I you decide not to replace the bearings, I'd love to do some more recordings of that motor to help folks diagnose motor problems. Are you based in the North America? I happily cover the cost of shipping.

    Andy.
     

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