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Continuous Servo Shaft Weight Limit — Parallax Forums

Continuous Servo Shaft Weight Limit

ajwoodajwood Posts: 3
edited 2010-02-08 22:33 in Robotics
Want to use a Parallax Continuous Servo shaft horizontally which in-turn would hold another Continuous Servo. Two lightweight plastic arms would attach to each.
All in all, the first servo would be supporting about 9-14 ounces of weight.
Neither servo would need to use much force and the plastic arms would be balanced.

Can the Parallax Continuous Servo do this without a support bearing?

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-02-07 23:08
    A continuous-rotation servo, by definition, rotates continuously without end stops. If you attach another servo to one of these, what is to keep the wire leads to the second one from becoming twisted, tangled, or wrapped around the one supporting it?

    -Phil
  • ajwoodajwood Posts: 3
    edited 2010-02-08 01:21
    My software and sensors will prevent tangles.
    I want to make sure that in a few months or years the rotating drive shaft doesn't bend or break due to the 9 to 14 ounces of weight held horizontally.
    If anyone has loaded up their servo in a similar fashion, I'd like to hear about it.
  • ercoerco Posts: 20,256
    edited 2010-02-08 02:29
    14 ounces inline with the servo axis is probably pushing it. If you're going to put that at the end of an arm attached to the servo, it will exert a moment (weight times distance) and bend/break your axle for sure.

    And most hobby-grade servos are designed for VERY light, intermittent use. Reliable continuous duty for months or years (depending on the load and how often it moves) is fairly unlikely.

    Sorry to be the bearer of bad news!

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    ·"If you build it, they will come."
  • ajwoodajwood Posts: 3
    edited 2010-02-08 03:20
    tis' better to bear the bad
    than be the bad.

    thanx
  • ScopeScope Posts: 417
    edited 2010-02-08 03:27
    Have you considered getting a high torque, all metal gear, ball bearing drive servo and then converting it to constant rotation?

    Would that work?

    You can get really large, powerful servos - I have one of these:

    www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.2546/.f
  • ercoerco Posts: 20,256
    edited 2010-02-08 05:14
    Or, go from big to ridiculous:
    https://www.servocity.com/html/spg785a-4_5_servo_gearbox.html

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·"If you build it, they will come."
  • FranklinFranklin Posts: 4,747
    edited 2010-02-08 19:02
    NICE!

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    - Stephen
  • Spiral_72Spiral_72 Posts: 791
    edited 2010-02-08 22:33
    erco said...
    Or, go from big to ridiculous:
    https://www.servocity.com/html/spg785a-4_5_servo_gearbox.html


    I could arm wrestle that dude!
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