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Unanswered Y Axis can't get to home position after long print. Grinds Belt

Discussion in 'Troubleshooting' started by David Sparrow, Jul 1, 2015.

  1. David Sparrow

    David Sparrow Member

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    After each long print, if I don't grab the Y Axis and yank it on it to get the bed to touch the Y axis stop sensor, the printer would grind the Y axis belt when travelling to home position. It appears to have gradually over a long print forgotten where the end of the bed is. However it prints fine the first time, it just grinds the belt when travelling to home position the second time. Short prints don't do it, just long ones. I'm in the habit now of grabbing the bed and yanking but I was wondering whats wrong in the software or maybe the firmware?
     
    #1 David Sparrow, Jul 1, 2015
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Neither.
    Probably your Y belt is binding against something under the bed.
    Raise the bed plate (from the magnets) and move it back and forth while watching it.
    (I assume an R1 here, you did not say)
     
    #2 mark tomlinson, Jul 1, 2015
    Mike Kelly likes this.
  3. David Sparrow

    David Sparrow Member

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    It's the KS version. It's not hanging on anything. I'll try to think of a better discription.
     
    #3 David Sparrow, Jul 7, 2015
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The other thing the Y belt can bind on is the center set of capstans and this will happen if the drive cog on the motor shaft slips.
    That will cause the belt to ride up/down on the capstans and bind at the edges of the travel.

    It is more of a pain to troubleshoot and work on with the original beta since removing the bed is non-trivial. However you can verify that by watching the center capstans and belt while moving the bed. You can just see them with a flashlight.

    It could also be a loose Y belt. If it gets loose enough it will skip teeth. Tightening that on the beta also means removing the bed.
     
    #4 mark tomlinson, Jul 8, 2015
  5. Mike Kelly

    Mike Kelly Volunteer

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    If you can't figure out what's causing it just remove the G28 at the ending g-code
     
    #5 Mike Kelly, Jul 8, 2015
  6. David Sparrow

    David Sparrow Member

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    I may have to try the G28 suggestion. I'm not sure what that is supposed to do but whatever is going on with it, it's likely a settings or firmware issue. There is nothing blocking/shifting etc. When it tries to home it gets too much resistance from the motor, it's like the motor is fighting itself. It's the motor I'm working against when I yank it'.
     
    #6 David Sparrow, Jul 8, 2015
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The motor will run until the endstop switch is contacted and it changes from open to closed (or closed to open).
    When you tell it to home it will home each axis (drive the motors until the endstop switch is contacted for each axis).

    It may be remotely possible that the belt is too tight, but that would cause it to happen during prints as well.
     
    #7 mark tomlinson, Jul 8, 2015
  8. Mike Kelly

    Mike Kelly Volunteer

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    Yeah the fact that it happens after a print finishes is weird.

    Kickstarter printers didn't have a fan on the ramps board. It's possible it's getting too hot.

    Maybe try adding a cooling fan with a Mother of all Fan Bracket http://www.thingiverse.com/thing:166045
     
    #8 Mike Kelly, Jul 8, 2015

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