Tilt axis slipping

Discussion in '3 Axis Gimbal' started by Justin John, Jun 29, 2012.

  1. Justin John

    Justin John Member

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    When lifting heavy weight (red epic) the lock screw will not tighten enough due to the plastic thread on the wheel thus causing slip. Is there an alternative to this ? Something with a tougher thread?

    Thanks
    Justin
     
  2. Jon Fredericks

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    Justin - we use all metal hardware and works great, just tighten nut w/ a little wrench. Way more secure than finger-tightened plastic.
    Hope this helps...
     
  3. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Justin, Are you sure the set screw is slipping? Or is the carbon clamp on the other side of the aluminum shaft slipping? I have had the clamp slip when it was not tight enough but have never had the setscrew slip. The set screw takes a pretty strong bite into the aluminum so it should be difficult for it to slip. If it is indeed slipping (after checking the clamp)
     

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  4. Justin John

    Justin John Member

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    Its the set screw forsure. It seems that it cant bite hard enough because of the plastic threads. I was thinking about trying to cut an indent in the rod so that it could lock in there.
     
  5. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Justin, Sorry about that. Seems like you might need a new pulley if the threads are toast. When you re-install the new pulley you can certainly file a small flat where the set screw will bite on the aluminum shaft...this will ensure that you need a very minimal amount of torque on the set screw to get a very firm bite.
    -Tabb
     
  6. kimkonan

    kimkonan New Member

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    hmm.
    good information!
     
  7. Justin John

    Justin John Member

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    A quick update. For a temporary fix we drilled a small divot for the set screw to lock into. Ordered a new pulley from quadrocopter, got here in 4 days and we are back up and running. Just beware not to tighten set screw too hard, once that thread start to strip the pulley the tilt axis slips easily with the red epic weight.

    Cheers
    - Justin
     
  8. Berndt Frogner

    Berndt Frogner New Member

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    I have an issue with the carbon clamp(s) slipping on the pulley/poti shaft, it's not the clamps themselves, I swapped between two gimbals and problem remains, is there a reason why the poti shaft is so short, it doesn't reach thru the carbon clamp on any of my gimbals ?

    Dirty fix is to just put some friction tape on the shafts but appreciate any thoughts/fixes to this ?

    Thx
    -Berndt
     
  9. Berndt Frogner

    Berndt Frogner New Member

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    Please discard earlier post, after a bit more checking indeed it's the pulley lock screw that needed to be tightened, no more slipping of the tilt axes.

    -Berndt
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Tabb:
    How easily should you be able to rotate the lower transverse boom assembly with the camera plate on it in the tilt axis without the servo pulley moving, please? On my 3-Axis, it requires little more than fingertip pressure. I'm concerned that the slight offset weight of the camera (the CX760's tripod mount wants to be right above the transverse boom) will cause the boom/camera plate to sag without the servo moving. I've tightened up the M3 bolts that run fore/after on the clamp assembly that holds the transverse boom onto the pulley shaft that doesn't alter the amount of force that the two semicircular friction plates apply to the pulley axle.

    I'm wondering whether I should use Berndt "dirty fix" and use some tape to bulk up the diameter of the shaft -- the downside with that is that I suspect the slippage is designed to happen to prevent burning out a servo if the motion is blocked.

    Also, see the attached image -- just curious why the bolts on the two semi-circular friction plates have their hex heads pointing outwards where you cannot reach them?

    Regards
    Andy
     

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  11. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Andy, I hope this will help explain. Crank down on the 2 bolts in called out in the photo and make sure the set screw on the pulley is snug. These 2 things should make sure nothing will slip in flight. Yes you are correct the system is designed to slip if needed (impact, obstruction, etc.)

    Best,

    Tabb Transverse Boom Mount.jpg
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Tabb:
    Correct -- those were the two fore/aft bolts I tightened (well, actually, I tightened all of them on the front and back dogbone pieces to avoid asymmetrical stresses).

    Tightening the set screw did the trick. I didn't realize it was the shaft turning in the pulley. Duh.

    Andy.
     
  13. Brad Meier

    Brad Meier Active Member
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    Guys.. Ive also had the plastic pulley slipping on tilt. The set screw through the plastic threads is probably not enough to hold over a long period of time. This is probably the weakest part of the mount. With the weight of the camera that point takes the most stress when the servo is in motion. If the rod the pulley is mounted to were threaded it would be easy to clamp it between a few nuts for more rigidity.
     
  14. Morgan Friedland

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    My tilt axis has about a 20 degree arc where it barely gips at all. Then, beyond the 20 degree arc, it grips normally. It has always been like this. Does anyone else's have this problem? (it is a problem yes?)

     
  15. Howard Dapp

    Howard Dapp Active Member

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    Can you film it from the opposite side to show the pulley and shaft while you finger tilt.
     
  16. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    That suggests that there's a "flat" on the axle shaft, doesn't it Morgan? I suspect you may need to take the gimbal apart so you can see the contact point where the grub screw on the pulley makes contact with the shaft.

    Alternatively, view this as a mechanical implementation of ramping in the tilt axis and sell it as a "feechur"... :D

    Andy.
     
  17. Howard Dapp

    Howard Dapp Active Member

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    That solves tilt now what about pan;) are there any set screws to loosen there:)
     
  18. Tabb Firchau

    Tabb Firchau Administrator
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    Hi Morgan, this not normal. Please check that both the set screw and the clamp on the Aluminum shaft are tight. See my photo above for reference.

    Tabb
     
  19. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I'm workin' that problem, Howard. No set screws (sorry I used the English term "grub screw") on those other big pulleys, but I figure if we loosen the boom clamps'n'servo mounts just enough.....or perhaps slacken off the servo pulleys... ;)

    Andy.
     
  20. Morgan Friedland

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