Extruder motors stopped during print

Discussion in 'Calibration, Help, and Troubleshooting' started by Karel, Aug 7, 2018.

  1. Karel

    Karel Member

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    Hi all,
    I have a problem with my BigBox dual, where both extruders stopped during a print.
    There was no clogging or related problem, just both stepper motors halted.

    Restarted my BigBox and all is operational, except.... both motors.
    Checked wiring -> OK
    Heaters -> OK
    Axis motors -> OK
    Extruders -> Nope

    Any ideas what is the problem and which steps tot take to solve it?

    Thanks, Karel
     
  2. Ephemeris

    Ephemeris Well-Known Member

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    Are you saying both extruders will go to normal operating temperature but neither will extrude? Are the steppers turning? Are the steppers making any noise? Are the steppers hot?
     
  3. Karel

    Karel Member

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    Thanks for chiming in.
    Yes, both extruders are heating as supposed, but the steppers are not turning.
    They are not getting hot and are completely dead and silent

    Karel
     
  4. Ephemeris

    Ephemeris Well-Known Member

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    I am assuming there is no error message about the temperature being too cold for extrusion.

    I would suspect that the stepper drivers died but losing two at the same time would be unusual. You can test the stepper drivers but it will take several minutes.

    ***ALL THE USUAL ANTISTATIC WARNINGS APPLY***

    1) Turn printer off
    2) Keeping track which is which, carefully remove the two extruder and the X and Y A4988 stepper drivers
    3) Insert the Left Extruder driver in the X driver socket and the Right Extruder in the Y driver socket
    4) MAKE SURE YOU ORIENTED THEM THE CORRECT WAY!!!! Compare to the Z driver that you did not remove
    5) Power up
    6) Through the control panel see if you can move the carriage in X and Y
    7) If the carriage moves in X & Y the drivers likely are not the problem
    8) Turn printer off
    9) Put all four stepper driver boards back to their original positions
    10) MAKE SURE YOU ORIENTED THEM THE CORRECT WAY!!!! Compare to the Z driver that you did not remove
     
  5. Karel

    Karel Member

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    Great tip, thnx. (Should have thought of that myself...)
    So the steppers are ok, but it seems that the drivers are the culprit.

    Does that mean that the Ruma board needs replacement?
    Weird that both died during printing with the left extruded only...

    Any idea of the cause?

    Karel
     
  6. Ephemeris

    Ephemeris Well-Known Member

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    So you did the test and you believe the drivers are dead? :(

    Supposedly, under some circumstances, the belts can build up a significant static charge which can charge up the XY carriage. If the voltage gets high enough it can dissipate through the steppers and potentially destroy the drivers. This is why DC42 recommends grounding all stepper motors. If that's what happened to you, you're the first BigBox owner to fall victim of it that I know of.
     
    Old_Tafr likes this.
  7. Karel

    Karel Member

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    So I hit the jackpot... :mad:
    I might as well replace it with a Duet WiFi then.

    One other question: there is this print that I need finishing.
    Is there an easy way to connect the left extruded to the third driver?
    Wiring is no problem, but what has to be changed in the firmware?

    Thanks for all your help

    Karel
     
  8. Ephemeris

    Ephemeris Well-Known Member

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    The little A4988 driver boards are readily available and cheap. If that's all that's damaged it would be a simple one for one swap and you'd just have to adjust the reference voltage on the board the same way as when you built the BigBox.
     
  9. Old_Tafr

    Old_Tafr Well-Known Member

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    Fascinating info on static. I tried to point out some time ago that the MOSFET components used for the driver board are particularly susceptible to static (high resistance component plus high voltage static = big whack of heat = big failure) only to be told that the anti-static bag it came in did the job :confused:. I'm not happy to be proved right, but the possibility of two drivers getting whacked at exactly the same time is difficult to explain otherwise.

    The all wood or acrylic frame does not help with static build up at all, acrylic possibly being worse in building up static. I can sort of see the belts being a problem but another possibility is if the wiring to heaters, sensors etc. rubs on the smooth rods as the X-Carriage moves back and forth. Normally you would expect metal (the rods) to conduct static away but they are at all points insulated by the plastic printed components that they are located in. There is no path to ground as the frame does not have a ground.

    Interested to know what route adding the grounding wires would take, maybe following the existing wiring looped up from the X-Carriage? The X motor would still be a problem as you would need to run a wire to another moving part.

    Doesn't the PT100 wiring have an external braid? which may or may not be grounded. This would certainly help for the X-Carriage if it was.

    This braid maybe cut to add connectors and not then have continuity to ground.
     
  10. Ephemeris

    Ephemeris Well-Known Member

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    I've thought about running a ground wire through the Y-cable chain and using that to ground the X-stepper. One could run another ground up the extruder umbilical and ground the extruder steppers to that. Maybe someone else has a better idea?
     
  11. Karel

    Karel Member

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    Well, it is odd, but it seems that de A4988 boards are OK. I swapped the extruder1 driver board with the X-asis board to check.
    So the damage appears to be in the Rumba board itself ... ?
     
  12. Old_Tafr

    Old_Tafr Well-Known Member

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    If everything else works? and the driver boards are both ok, and there was no corruption of the firmware (very unlikely) then a closer look at how the Rumba is designed.

    When trying to understand if all Rumba boards available are the same, I'm sure I came across a WiKi page with a circuit diagram. This may give a clue but the chances of repairing one are slim. If you can get a replacement Rumba then I assume it would have to be flashed with the firmware from E3D.
     
  13. Karel

    Karel Member

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    Yes, I saw the schematics, did some test and came to the conclusion that the rumba is beyond repair.
    So I will replace it with a Duet WiFi.
    Furthermore I will look into some ways to ground the x-y system.

    Looking back at the weather data, it appears that the relatively humidity on that particular day was < 30%, which in my opinion contributed to the event.

    Thanks for all your help.

    Karel
     

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