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Unresolved Z-Axis not moving suddenly

Discussion in 'Troubleshooting' started by TheRealDarthGuy, Feb 14, 2021.

  1. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Also, is this an R1 or an R1+ (or worse yet -- a Beta)?
    If it is an R1 (not a beta, not a +) then it likely has a single Z stepper driver.
    Not a problem since the RAMPS is designed to use a single stepper driver for two Z steppers -- mostly because speed, acceleration and jerk are very low numbers for the Z. In that case it could be a failing stepper driver and I'd swap it out.
     
  2. TheRealDarthGuy

    TheRealDarthGuy New Member

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    It's an R1 (original).

    Gave Repetier a go and same result. In Cura the settings must be messed up because it's way too far off the bed. It makes layers but they are far too thick/large.

    Just weirds me out to be able to print 5 or so things fine then try again and get none to print properly.

    Excuse my ignorance here but isn't the stepper motor the very motor that moves the z-axis? ...and we're able to manually send G-Code to move that freely without problem?

    Edit: I guess the question is... How can it move all over completely fine manually but require a motor replacement to raise while printing?
     
    #22 TheRealDarthGuy, Feb 16, 2021
    Last edited: Feb 16, 2021
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The stepper motor is indeed the motor, but the stepper driver is like this and it is what converts the signal from the Arduino into current steps for the motor. If this part (one for each stepper motor) on the RAMPS fails or gets weak then steps will be dropped and the stepper won't (step) correctly.

    612wiH-VKGL._SL1000_.jpg
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It may work when manually driven because you are not driving it the way the slicer will (speed, acceleration and jerk are going to be higher when driven by the sliced GCode). The driver boards are cheap and easy to swap -- if it is the RAMPS board or Arduino Mega board those are a bit more work to replace (there is one for each stepper motor except the Z which uses one for both).

    And again we are not talking about replacing the stepper motor at this point, but the wee electronics board that makes it go :)
     
  5. TheRealDarthGuy

    TheRealDarthGuy New Member

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  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    That is indeed the part. Just make sure that the heat sink is installed when you replace it :)

    Here is the diagram showing where each one goes:

    RAMPS Wiring Robo.jpg
     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The above picture is only for the Beta and R1 -- it is not correct for the R1+
     
  8. TheRealDarthGuy

    TheRealDarthGuy New Member

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    Am I crazy of are the stepper drivers not in that image?

    Also, how many of these things are inside the printer total?
     
  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    4 total, one for X, Y, Z and Extruder

    The above diagram is a connection diagram (where things connect) this is physically where they mount:

    Ramps with stepper.jpg


    But you only have 4, not 5 because the E0 is the only extruder one used, not E1

    The R1+ uses E1 as a second Z drive (which is not needed -- you can see that the Z connector has a spot for TWO stepper connections to drive the Z.
     
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    another pic -- the green shaded area in the middle are the stepper driver cards and the Robo uses a single extruder (E0 or extruder motor 1 in the graphic)

    RAMPS.png
     
  11. TheRealDarthGuy

    TheRealDarthGuy New Member

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    Would there be any use to swap them with each other before ordering to see if a different axis fails?
     
  12. mark tomlinson

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    Perfectly fine test, but... if it fails on the Z axis it may well work on another one with a single stepper (the Z has two)
    Just FYI :)
     
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It could be that the Z axis driver has had the heatsink fall off -- make sure it still has one installed when you look into it.

    That would make it act odd and sometimes work and other times fail
     
  14. TheRealDarthGuy

    TheRealDarthGuy New Member

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    Ok, whelp... cheers to another disassembly. I'll report back results once I have some.

    Seriously though... Thanks for all the help.
     
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  15. mark tomlinson

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  16. TheRealDarthGuy

    TheRealDarthGuy New Member

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    New update... After swapping out all of the stepper drivers I now have this result...

    it sounds like the motor is "tightening" then it ultimately stops. If I spin it manually it will raise again and repeat. Suggestions on next steps?
     
  17. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    So, is yours wired the way the diagram in http://community.robo3d.com/index.php?threads/z-axis-not-moving-suddenly.24226/page-2#post-142166 shows?

    If so then you may need to bump up the current on the Z axis stepper driver (or just swap it for another one). I would suspect it is just not quite giving it enough current for the two of them to spin. If you remove the top cover you can try lifting the crossbar off and just making sure that both are spinning at the same speed when they do work. If one stepper is dropping steps the crossbar would bind them pretty quickly. With the crossbar removed they can't bind (but you can be certain that is the problem then). If you can identify that without removing the crossbar -- even better :) Maybe measure the travel on both sides to make sure it is the same.
     
  18. TheRealDarthGuy

    TheRealDarthGuy New Member

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    Got it resolved by reinstalling firmware. BUT... another failed print where it fails to raise up. I printed the "configuration circle" fine and then moved to another STL and it did the same old don't raise up again. I'm trying another STL now and seeing what happens. I'm at a complete loss as to what do do now.
     
  19. mark tomlinson

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    Well, you have a few options.

    1) The Z driver -- swap it out.
    2) It is possible that it is the RAMPS board itself
    3) It is remotely possible that it is the Arduino Mega

    I'd try those in that order from cheapest to least cheap :) Not that any of that is rude prices. You can get a kit from Amazon that has ALL of the electronics the Robo uses for about $35 (includes Arduino Mega 2560, RAMPS 1.4, Stepper drivers, and even an LCD)
     

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