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Unresolved Z-axis stuttering

Discussion in 'Troubleshooting' started by Doug Gebhart, Mar 4, 2016.

  1. Doug Gebhart

    Doug Gebhart Member

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    I have a problem where whenever I try to move the z-axis, the stepper motors just seem to stutter. They stutter for about 2 seconds, then the lead screws stop moving and it seems like the stepper motor is whining. See the video below:



    I took off the lead screws and the behavior happens when they are off as well. However, it never gets to the point where the shafts stop moving, they just seem to stutter over and over.
     
    #1 Doug Gebhart, Mar 4, 2016
    Last edited: Mar 4, 2016
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Tune the stepper driver cards.

    This video shows over powered, underpowered and normal power (correctly tuned):



    Compare that to your symptoms,

    http://rigidtalk.com/wiki/index.php?title=Stepper_Driver_Adjustment

    There are two ways referenced in the link above for tuning them. One is to adjust the current until it moves correctly the other uses a meter an a reference voltage. You do not want to have the current too high or the steppers will run hot.
     
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Also, make sure the motors are mechanically free to turn (not binding).
    If you can't get it to tune in then you might have a faulty stepper driver.
    See what you get from tuning it.
     
  4. Doug Gebhart

    Doug Gebhart Member

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    Ok, I tried to calibrate the stepper drivers and had no luck. Either I don't have a fine enough touch to calibrate it exactly to where it needs to be, or there is some other problem. I will try it again when I have the chance, but for right now, I am stumped. Question: Could I use the voltage from one of my other Robos and tune this one to the same voltage, or is there a lot of variation?
     
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It is not that fine of a control. Sure, use the reference from another Robo.
    Essentially you either have too little (steppers skip steps) just enough (everything good) or too much (steppers step correctly, but run hot) current.
     

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