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Unresolved Z axis keeps getting out of wack during printing.

Discussion in 'Troubleshooting' started by gunsmoke132, Jun 3, 2019.

  1. gunsmoke132

    gunsmoke132 Member

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    during long prints it seems the right side will move to a higher relative spot then the one on the left causing it to get slanted. it doesn't matter if I fix it before a print it always ends up messed up
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    So one of the steppers is missing steps. That can be a bad stepper motor, but usually it is the stepper driver for that motor getting weak.
     
  3. gunsmoke132

    gunsmoke132 Member

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    Aren’t they driven off the same stepper
     
  4. BrooklynBay

    BrooklynBay Active Member

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    Each motor has its own driver. This issue once happened to me. The thick wire loom cable needed to be adjusted. The right limit switch was seated but the left one was not making contact.
     
  5. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    On the A4988 steppers, which Robo used 2 for Z there is a little potentiometer on one end. There are a bunch of YT videos that explain how to adjust them, you can even with the cheapest Harbor Freight voltage meter. Just make sure they are similar in output That is the best way to make sure it isn't the driver causing the missing steps.
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Or just replace the silly thing :) (or both of them) the driver chips/cards are less than a couple of bucks each (usually 5 for $10 or something close). Yes you can adjust the current output, but my experience has been that once it starts needing to be adjusted then the driver card is headed south and you will sooner than late need to replace it. So save the effort and replace it. If you want to know how I can link you to various videos on how to set/adjust the current output (or you can google for "pololu stepper driver current adjustment" and see them yourself.
     
  7. gunsmoke132

    gunsmoke132 Member

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    i know they are in the factory bord but as seen here ( https://images.app.goo.gl/Da2P9jhQN9bgatrN7 ) on ramps 1.4 thery are wired to the same driver. i forgot im using a ramps 1.4 my bad :oops:
     
  8. gunsmoke132

    gunsmoke132 Member

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    i forgot to mention im using a ramps 1.4 board. as seen here ( https://images.app.goo.gl/Da2P9jhQN9bgatrN7 ) on ramps 1.4 thery are wired to the same driver. because on that board you only use 4 i had an extra that was not used im going to plug it in and send it.
     
  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yep, the standard RAMPS 1.4 can easily support both Z on the same stepper driver AND -- you do not have to worry about them being out of sync. If the stepper driver gets weak you may have them lose steps, but BOTH will :)
     
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The reason both work on a single stepper driver is that the stepper drivers are good to about 1.5amp and on the X and Y axis the steppers make fast moves with sudden changes in direction and that means they draw a lot more current. The Z does not move that quickly nor does it make sudden direction changes.
     
  11. gunsmoke132

    gunsmoke132 Member

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    that's what i was thinking... so the motor is bad or is it something else? i did the "led test" and it seemed fine...
     
  12. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yes, if both are attached to the same stepper driver and one steps and the other does not... you have eliminated everything else except the motor. Good news is that those are cheap too.

    I used this style (step angle of 1.8 degrees or 200 steps/rev which is what the stock ones are) but shop around there are many out there. Plus I bought the 5 pack since they were cheaper and you might only want 1 :) Those have more torque than the stock ones too which is a win.

    https://smile.amazon.com/gp/product/B00QEXSCE8
     
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    pay attention since these are 4-wire steppers and 6-wire ones are not uncommon (but will not work without some tweaking).
     
  14. gunsmoke132

    gunsmoke132 Member

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    what specs am i lookinf for.
    40mm
    torque?
    4wire
    amps?
     
  15. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    1.5 AMPS max, 4 wire and at least 32 nm of torque (although more is always better).
    Check the physical sizes as well -- measure yours and make sure the ones you buy are close to that same size.
     
  16. gunsmoke132

    gunsmoke132 Member

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  17. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    64 oz-in of torque (like the ones I linked) converts to 0.4519 nm* :)
    Those are listed as 0.4 nm (or 400 mnm**) so probably fine.

    Engineering is all about unit conversions ;)



    *Newton-Meters

    **milli-Newton-Meters
     
    #17 mark tomlinson, Jun 4, 2019
    Last edited: Jun 4, 2019
  18. gunsmoke132

    gunsmoke132 Member

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    thanks! do you know what pitch the lead screw is on the r1+ ? i found out the hard way its not 8*8
     
  19. albert3d

    albert3d Member

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    I believe they are TR8*4 looking back at the original thread on the upgrade lot for R1 users to R1+
     
  20. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I'd have to go to the shop and disassemble and measure an R1+ threads ... the 8*4 sounds spot-on.
     

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