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Unread 14-03-2014, 21:54
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DinerKid DinerKid is offline
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FRC #1768 (Nashoba Robotics)
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Re: Eliminating Arm Wobble

Quote:
Originally Posted by apalrd View Post
In the past, when we have been worried about lash on arms, we have intentionally increased the moving friction of the arm to keep it stable, and spring loaded the arm one way to force it to stay on the same side of the lash whenever possible.

For example, last year we pressed the arm axle into a block of delrin with an on-size hole to make our bearing. The delrin was slick enough for the axle to slide, but also had quite a bit of friction. We also sprung the arm up with surgical tubing to keep it on the same side of the lash in most cases.
Did the delrin hole wear over time or did it remain fairly constant for you?

https://www.youtube.com/watch?v=RqkAqpr-sHk

you can see the wobble at 3-5 seconds

I am working on pictures of the gearbox to the arm but it is just that, a drive-shaft (the output of the worm gear box) press-fit into a block of aluminum bolted to the arm.

The arm is currently back-heavy, however we have a mot of mass there and quite a bit of mass to stop rotating when we stop the tilt motor.

Edit: the talk of adding latex tubing to stay on one side of the lash, we are very unevenly weighted, the arm wants to fall back, I think just having so much moving mass is causing the arm to counteract this, the amount of latex we would need to add in order to completely stop this would likely just make the arm impossible to drive.

~DK
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Last edited by DinerKid : 14-03-2014 at 22:02.
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