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DJI Phantom Balance Rod for Balancing Self-Tightening Props

Discussion in 'Phantom FC40 Discussion' started by 2014fc40, Feb 6, 2015.

  1. 2014fc40

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    Here's a question that concerns Phantom and FC40 prop balancing.
    I was using the balancing rod that came with my DuBro balancer. The rod had a short peice of flexible tubing so I could squish the props onto it and proceed to balance. Seemed to work well and I thought I got some really balanced props out ot this setup.

    So....I started thinking maybe one of the threaded balance rods would be a more accurate way to go. I ordered the one below from Ebay and tried some pre-balanced props. They all seemd to be a bit heavy one one end of the prop. OK, that could be becuase this rod is more accuratly balanced than the other I was using....it got me to thinking:

    If the threads are reversred on both ends, and if the thread cutting isnt done just right, the shaft wouldn't be balanced. They would have to be perfect mirror images of each other and stop exactly in the same spot or else the rod would have a heavy side (rotationaly). After all, the rod I had been using was perfectly straight and had no threads...it would (should) be perfectly balanced or very close to it.

    Its a minor amount of balance difference, but still now I dont know which to trust....

    Also, any idea why the one end has the 1/4" or so milled off of it?
    http://www.ebay.com/itm/191368829908
     
  2. 2014fc40

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    Re: DJI Phantom Balance Rod for Balancing Self-Tightening Pr

    Wow, two weeks and no reply. Guess no one knows.... :cry: :cry:
     
  3. tcope

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    Re: DJI Phantom Balance Rod for Balancing Self-Tightening Pr

    IMHO the threads would not matter that much as they are in the center or focal point. While it would influence the result slightly, I don't think enough to cause a big concern with the prop.
     
  4. J.James

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    Re: DJI Phantom Balance Rod for Balancing Self-Tightening Pr

    Ya the threads will not make any difference being you need the rod to be balanced rotationally not end to end like a seesaw.
     
  5. 2014fc40

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    Re: DJI Phantom Balance Rod for Balancing Self-Tightening Pr

    Yes I meant balanced rotationally.

    Another thing I'm finding I dont like is the larger mass of the rod itself. The smaller rod is more reactive to tiny differences.
    I wish there were some small ends I could find to stick on the rod that comes with the balancer...
     
  6. rexster314

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    Re: DJI Phantom Balance Rod for Balancing Self-Tightening Pr

    One end is milled off so you can tell the difference between righty tighty and lefty loosy
     
  7. kengineer

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    PROP ARBOR 1.JPG
    My guess is that the reduced area on one end has to do with the manufacturing process. It may be that the left hand die that these were made with needed to have a smaller major diameter and the right hand threads could have been formed a different way.

    One reason that you see threaded rods is because it would take a larger piece of stock to make on with a flange. Without the flange it is as simple as a 6mm rod with right and left threads formed on it.

    I have always been concerned about using a rod that did not match the same mounting scheme as the intended use. In other words, the face that stops the prop on the vision that I fly is on the flange of the motor. It is what squares the prop to the axis and that is how it should be balanced.

    There is clearance between the prop threads and the spindle threads, it is toleranced by the class of thread fit.

    Without the prop being firmly drawn into a face that is perpendicular to the axis, I would be concerned about balancing the prop the way it is used. If the balancing spindle locates the prop in any way other than how it is mounted in use, there will be variation. If there is any possibility of the mounting scheme having variation, the result may not be desired.

    The engraving on the model would also throw the balance of the rig off, but do it anyway! PROP ARBOR 1.JPG
     
  8. IflyinWY

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    I don't know what the rest of the folks think of the dubro, but, why don't you just start from scratch and finish with your threaded stainless rods? ;)
     
  9. sohail99

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