Z-axis right side "droops"

Discussion in 'Calibration, Help, and Troubleshooting' started by W1EBR.Gene, Dec 19, 2016.

  1. W1EBR.Gene

    W1EBR.Gene Well-Known Member

    Apr 10, 2016
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    Thanks, I will try that - I don't remember what it is set to. Someone else also had success at a lower voltage.

    I don't understand what is actually happening with the stepper motors... are they missing steps? I think it is time to read up on them so this makes more sense
  2. A Dragon In A Pie Costume

    A Dragon In A Pie Costume Well-Known Member

    Jul 6, 2016
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    not enough power, they're in parallel so the voltage(?) drops
  3. Jasons_BigBox

    Jasons_BigBox Well-Known Member

    Mar 25, 2016
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    I'm certainly not an expert in electrics but I fly electric powered R/C planes and the 'brushless' motors are similar in operation to our steppers. I'm told they work differently to 'normal' brushed motors. A brushless motor/driver works on a constant voltage, variable current basis so if the motor doesn't move to the required position then the current draw will increase to overcome the force stopping it. That's the reason why people get horrific injuries off electric powered propellers compared to internal combustion engines. IC engines tend to stop when something gets in the way, electrics draw more current and keep chewing....(sorry, a bit graphic there).

    Extrapolating that to our steppers, if there's a bit too much resistance to start the motion then the current increase can be above the limit on the driver board/chip so it stops or doesn't move. I assume that's why we see z-axis issues as it's two motors drawing the current off a single driver.

    It's also been argued that the power supply drops voltage under peak load so can't give the current required and again we get skipped steps or stuttering motors.

    It'd be nice to get something definitive on this from an expert. I found that dropping the z-driver voltage cured my problems. Others found increasing it fixed theirs. There doesn't seem to be a 'one size fits all' solution at the minute.

    One thing for certain though, there's no substitute for good rod/screw alignment, good bearings and good lubrication. These are low voltage motors and there's only so much they can do.

    Good luck all!


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