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  1. #1
    Registered
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    Dec 2017
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    24

    Servo is randomly changing direction

    I'm just setting this up. Everything seemed to be working fine. Until it wasn't.
    When I jog either up or down, I don't know which direction the motor is going to turn.
    This is a Nema 34 with 8 wires. I'm using the Probotix Unity M Box with UCNCC software and a UC100 controller.
    I got the Probotix for $200 off over christmas.
    I've been scouring the forums, and can't find anything about this.

    Bruce

  2. #2
    Moderator
    Join Date
    Dec 2005
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    513

    Re: Servo is randomly changing direction

    A servo or a stepper motor?

  3. #3
    Junior Member
    Join Date
    Jun 2010
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    3699

    Re: Servo is randomly changing direction

    a Nema 34 with 8 wires
    Sounds like a stepper to me!

    If it was a servo it would sound as though you have a loose connection somewhere on the Dir line. I am not sure whether that is even possible with your stepper controller, but it might be.
    Failing the Dir line, you might, possibly, have a loose connection on one of the motor windings.

    In any event, it does sound like a loose connection somewhere.

    Cheers
    Roger

  4. #4
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    Jan 2005
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    1796

    Re: Servo is randomly changing direction

    Many drivers require a delay between setting the direction pin and the step pulses otherwise the motor could move in the wrong direction. This should be set in the control software.

  5. #5
    Community Moderator ger21's Avatar
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    Mar 2003
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    33422

    Re: Servo is randomly changing direction

    Could also be a loose dir in connection, or a bad cable.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  6. #6
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    Dec 2017
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    24

    Re: Servo is randomly changing direction

    Thanks for the replies to my misquote. It is a stepper motor.
    And the whole cable was bad, which is why I couldn't find it.
    ger21, thanks for making the light bulb go off, that was about the only thing I hadn't checked.
    A wire was broken in their somewhere when I put the meter on it.

  7. #7
    Registered
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    Jun 2015
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    724

    Re: Servo is randomly changing direction

    This is why I always advice to MEASURE. But of course first you have to know what to measure.

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