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Solved Z-Axis Doesn't always work

Discussion in 'Troubleshooting' started by Travis Deel, Jul 29, 2015.

  1. Travis Deel

    Travis Deel New Member

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    I have been having issues lately with what I think is my z-axis not connecting. When I first connect my Macbook pro to my ROBO (Using MatterControl 1.2), sometimes the x and y axis will move properly, but the z-axis will not move up or down. It makes a humming sound, but does not move (see video below).

    So far I have been able to get it to work by unplugging the usb cable, plugging it back in, flipping the machine off and on over and over till it works after some unknown sequence of flipping and reconnecting...

    Once I get the z-axis to connect (Or whatever changes its mind) it seems to stay connected and prints great. I accidentally bumped the power cable loose while printing once and didn't notice until the computer went to sleep which paused the printer, when I turned it back on it continued to print where it left off, but the z-axis didn't reconnect leaving it printing layers at the same height...

    One theory I have is maybe the usb ports are not supplying enough power to the Arduino? Also, I tried to connect my laptop with less than 50% charge and the z-axis wouldn't work, and I tried again after it had charged to around 60% and it connected! Should I be using a powered USB Hub?

    I have also read that the steppers could be in an under or over-powered state and need to be calibrated with the potentiometers on the driver, but I don't want to mess around with it unless I'm sure that is what it could be...

    Has anyone had this issue before?

    Here is the video of the sound the system makes when it won't respond to the up or down commands.
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I would suggest tuning the stepper driver for the Z if you are up to it. The alternative might be to just replace the stepper driver.

    The general instructions are here:

    https://bootsindustries.com/portfolio-item/pots-adjustments/

    The only one you are going to want to adjust is the one for the Z axis since the others are working.
     
  3. Travis Deel

    Travis Deel New Member

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    I will give it a whirl when I get a chance and let you know how it goes! Hopefully it just needs a bit of a tweak...
     
  4. KTMDirtFace

    KTMDirtFace Well-Known Member

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    I had that issue, z was intermittent.

    Mine was a wire was not screwed into the power supply. it was just sitting on top of the screw head.

    ( Mine from factory.. that wire was just sitting on the screw head and my Z axis would stop working )



    [​IMG]

    Additionally this plug was not plugged in all the way from the factory for me either.

    Open the bottom and take a peek :)

    [​IMG]
     
  5. Frankn

    Frankn Member

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    First off, flash in Matter 1.2.3. Frank
     
  6. Travis Deel

    Travis Deel New Member

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    Ok... I tried all three suggestions. I Updated Matter control, checked the wires, and Adjusted the pot (both higher and lower than what it was when I started).

    It still just makes a humming noise when I tell it to go up or down... when I turned the voltage up higher on the pot, it seemed like the humming sound got louder. when I turned the voltage down (from where I started) on the pot, the steppers didn't work at all and there was no noise....

    I'm still tying to figure out whether this is a hardware or software issue... Could it be the pulse rate or signal being sent to the stepper?
     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    That sounds like a bad stepper.
    If you were not able to get it moving with adjustments to the StepperDriver.

    You could do purely a test by moving the connection for one of the other steppers to that one and see if the problem moves. Just as a test mind you. If the problem moves with the motor... it is a bad motor.
     
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  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    P.S. the 'update' matter control needs is to be moved to the recycle bin. However that is not likely a contributing factor in this case.
     
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  9. Travis Deel

    Travis Deel New Member

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    I tried adjusting the z stepper driver pot again today, and was able to get it to work. Then I tried again later in the day, and it was doing that same buzzing sound...

    Its becoming very difficult to diagnose because it works at sometimes and other times not. It seems like it is getting worse. At first it was just an inconvenience, but now it is rarely works...

    Is it possible that both z-axis steppers are bad? The left and the right side are both completely still when the commands are sent to them. Could it be I need a new driver?
     
  10. Frankn

    Frankn Member

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    You know, It's starting to sound like a bad connection in the stepper wiring if it comes and goes. Loose pin connector most likely by board. Just a guess. Frank
     
  11. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    @Frankn has a good idea -- check the wiring first.
    Then I would suspect the stepper driver... not two bad steppers.
     
  12. Mike Kelly

    Mike Kelly Volunteer

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    Also verify that your ramps cooling fan is running
     
  13. bamhm182

    bamhm182 Active Member

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    Were you able to try plugging the Z steppers into another working stepper's place? If you plug the Z steppers into the spots for the X/Y steppers and then try to move the X/Y steppers and the Z steppers move, it would suggest that the steppers themselves are fine. If not, then it may be the steppers or wiring on the steppers. Since they both do it, I feel like this isn't the issue.

    You could also try swapping the stepper driver with X or Y and seeing if the problem moves. Before you start screwing around with the stepper drivers' pots, I would strongly suggest writing down their default values. Anyone active in the shoutbox could tell you I'd wish I'd done that before I started breaking my printer, haha.
     
  14. Travis Deel

    Travis Deel New Member

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    I got it working!
    I swapped the y and the z-axis drivers, and the y-axis worked with the z-axis board, and the z-axis moved but stopped half way and twitched back and forth. I swapped the boards back and used my handy volt meter to check the voltages.

    The x, y, and extruder voltage on the potentiometer were all around 0.43V while the z voltage was only 2.something.

    I adjusted the z pot to read 0.43V and tested the controls again. It moved about half way again before the twitching... then I adjusted it to 0.53V (they are super sensitive! Just a little nudge is a tenth of a volt!) and it worked perfectly going up, but skipped a bit on the way back down. I finally adjusted it up to 0.59V and it works great!

    I didn't have my voltmeter when I adjusted it the first time and was just kind of guessing where it should be. I recommend a volt meter before attempting to adjust the pots...

    Thanks for all the help!

    I also found some other really helpful videos on tuning stepper drivers and how steppers work for future reference...



     
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  15. bamhm182

    bamhm182 Active Member

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    Glad to hear you got it working. If you think that the A4988's are sensitive, try upgrading to DRV8825. I have to hold my breath when calibrating those, haha. I also highly recommend that you have a volt meter on you and take your readings before and after, or even during depending on how you're doing it. Makes things a LOT easier. I could have avoided so much headache if I had done it this way.
     

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