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Solved Z axis hardware broken

Discussion in 'Troubleshooting' started by Heimdall, Jan 20, 2016.

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  1. Heimdall

    Heimdall New Member

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    Hello, just got my Robo r1+ today. Did a successful test print followed by a less successful one (but that's ok, no hardware was failing, just lack of cohesion to build plate). Then, all of a sudden, the Z axis hardware was uneven. It must have happened after the second build but I don't know why. Basically, when I adjust the Z axis via the software to move the extruder up and down, both threaded rods are supposed to rotate. Currently, only the left one is rotating, while the right isn't. I can manually turn the rod to get it to raise/lower, so it's not jammed, but the electronics are messed up or something. I don't do a lot of tinkering with mechanics so I'm not even sure where to begin. Or is this something I have to go to tech support with? Thank you!
     
    #1 Heimdall, Jan 20, 2016
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Tech support might not be a bad idea in case there is a part that needs replacement.

    The two Z stepper motors are both driven in parallel off of the same electronics so if one works and the other does not then you either have a mechanical issue (which it sounds like you checked) or perhaps the connection for the stepper motor to the RAMPS board is loose or knocked off. You would need to trace the wires back to the RAMPS board (under the printer) to make sure the wires are connected correctly.
     
    #2 mark tomlinson, Jan 21, 2016
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Here is a pictorial layout so you can see where the two Z motors connect on the RAMPS.
    The connector could just be knocked loose...
    RAMPS.png
     
    #3 mark tomlinson, Jan 21, 2016
    Heimdall likes this.
  4. Heimdall

    Heimdall New Member

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    Thank you! I'll poke around with that. Now, newb question because I'm really paranoid around electronics--is it alright to turn the printer on its side to get at the RAMPS board? Or should I go at it by removing the bed somehow, and if so, how? I really don't have a lot of confidence with circuitry but I'm not a total imbecile--I built my desktop for instance, but that's basically just LEGOs for grown-ups. Thanks again!
     
    #4 Heimdall, Jan 21, 2016
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    With it off and unplugged you can turn it over however you like :)

    Just be careful since the X crossbar will come off the nuts when you turn it over.
     
    #5 mark tomlinson, Jan 21, 2016
  6. Heimdall

    Heimdall New Member

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    Fortunately/Unfortunately I turned it on just to check its status before poking at its guts... and it works again. Not sure why. If it happens again though I'll keep this thread in mind. Thanks again!
     
    #6 Heimdall, Jan 21, 2016
  7. Mike Kelly

    Mike Kelly Volunteer

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    Yeah either one of the Z axis wires are unplugged or jammed up causing it to not move correctly.
     
    #7 Mike Kelly, Jan 21, 2016
  8. Heimdall

    Heimdall New Member

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    Just started giving me trouble again mid-print so I'll have a look at it now!
     
    #8 Heimdall, Jan 21, 2016
  9. Heimdall

    Heimdall New Member

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    I had a peek at the undercarriage. I didn't notice any loose or unconnected wires, but I pressed them all in a little bit anyway just to be sure. There was one bundle that had a kink in it, though. I straightened that out too. So far it works. I'm beginning a 2~ hr print so we'll see what happens! Thanks again guys :)
     
    #9 Heimdall, Jan 21, 2016
  10. Kevin Alley

    Kevin Alley New Member

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    I have a R1+ and having the exact same issue. It is a very intermittent problem. Most of the time it works fine, but every now and then the right z-axis stops turning and stutters when trying to move it up or down. After tinkering with it for awhile it starts working again but no idea what it is that fixes it.

    I have greased the linear rods and the threads and can easily turn it manually by hand so does not appear to be a mechanical problem. It is if the stepper motor is either (1) not getting enough current or (2) is "off" by a step somehow. I have also lifted the printer and removed the bottom (but mounted the fan back to cool the rails) so it should not be a cooling issue.

    Finally I thought it may be an issue with the nut on the right side not being seated correctly (as seen in other posts) but I already fixed that.
     
    #10 Kevin Alley, Jan 22, 2016
    Last edited: Jan 22, 2016
  11. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The Stepper driver cards are what drive the current for the stepper motor.

    https://www.pololu.com/category/120/stepper-motor-drivers

    You can tune them (adjust the amount of current they supply). It is odd that one stepper will work and the other drop steps, but it could be set at a borderline I suppose.

    http://community.robo3d.com/index.p...iver-calibration-information.6466/#post-53721

    It is not super difficult to do the tuning. I always keep some spares on had in case one dies (they are cheap too -- if under warranty contact Robo if you can't tune it in).
     
    #11 mark tomlinson, Jan 22, 2016
  12. Kevin Alley

    Kevin Alley New Member

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    I thought about adjusting the pot. Happen to have a schematic of which card drives which motor? Otherwise I could just unplug one at a time to test.
     
    #12 Kevin Alley, Jan 22, 2016
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    ramps1-4connectors.png
     
    #13 mark tomlinson, Jan 22, 2016
  14. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Z is the one in the lower right :)
     
    #14 mark tomlinson, Jan 22, 2016
  15. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Nice thing about Robo is that it is based on all open source hardware.
    So parts (and documentation for the parts) are available everywhere and cheap.
     
    #15 mark tomlinson, Jan 22, 2016
  16. Kevin Alley

    Kevin Alley New Member

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    Mark, thanks for the info. I have an update:
    #1 is that my R1 plus has a slightly different layout - I only have 1 extrusion motor and instead have a Z0 and Z1 drivers for the Z-axis
    #2 I tried adjusting the current limit up from vref of .46 to .50 to no avail
    #3 I swapped the motor drivers and it is still the right hand z-axis that does not work
    #4 I swapped the plugs for Z0 and Z1 and still same motor that stutters
    #5 I swapped the cable (in case of loose or bad connection) and still the same motor stutters
    #6 finally I completely removed the X-axis such that there is no load at all on the z-axis and still only the left hand side spins while the right hand side stutters/vibrates

    At this point I think it must be a bad motor. Other thoughts?
     
    #16 Kevin Alley, Jan 24, 2016
  17. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You can try the same motor on another working axis to see that it fails, but I agree it seems to be a bad stepper.
    You can contact Robo directly for this to get a replacement.

    http://robo3d.com/contact-us/

    Good job proving it since the steppers themselves are usually not the problem :)
     
    #17 mark tomlinson, Jan 25, 2016
  18. Jtmon

    Jtmon New Member

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    same exact issue on my r1+ I got a week ago, same side etc. Intermittent.
     
    #18 Jtmon, Jan 31, 2016
  19. Jtmon

    Jtmon New Member

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    Found that on mine one pin in the plug on that runs from the motor to board is broken/blown out on the board side.
     

    Attached Files:

    #19 Jtmon, Feb 1, 2016
  20. Naor Biton

    Naor Biton New Member

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    I got my R1 +Plus just two days ago. Two sample prints were completed successfully, and this exact same problem started while I was printing the third.
    I called support which instructed me to realign the brackets on the brass nuts that go on the threaded rods, but that didn't help.

    So far one side is completely stuck.
     
    #20 Naor Biton, Feb 13, 2016
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