SOLVED First layer does not stick together

Discussion in 'Calibration, Help, and Troubleshooting' started by Tetrikus, Jun 12, 2016.

  1. Tetrikus

    Tetrikus Well-Known Member

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    Hi all
    I'm having some issues again with the first layer. After I recalibrated the Z-axis (since the printer tried to print into the glass), I have now the issue, that the first layer does not really stick together. means, there seems to be a very slight gap between the filament "lanes". I feel like the printer is printing the first layer a little bit to high. I wonder now, how I should adapt the first layer height. I guess, this corresponds to the Z-offset, is this correct. I've got a Z-offset of -0.8. Should it help, when I cange it to -0.75 or -0.85? Which direction should I go?

    Thank you in advance for your help
    Markus
     
    #1 Tetrikus, Jun 12, 2016
    Last edited: Jun 12, 2016
  2. R Design

    R Design Well-Known Member

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    You are correct: your nozzle is too high!

    Haven't used Automatic bed levelling for a couple of months (now on mesh) and already have forgotten which direction was which for adjusting the Z-offset.

    In fact, sometimes when using it every week I'd get confused!

    My solution was to think back to what the Z-offset means: where it came from.

    During Z calibration the bed starts off "too low" and you slowly move it up until it touches the nozzle.

    The Z-offset is the difference between the original position (-5mm ??) and the amount that you moved it up (eg 4.5mm).

    So it's a number like 0.5mm (I forget whether + or minus).

    Now if you'd wanted the nozzle to be better adjusted (in your case closer to the bed) then during Z offset calibration you'd have moved it just a little bit further ... (eg 4.6mm instead of 4.5mm). So your Z offset would be a number like 0.4mm instead of 0.5mm (again I forget the +/- signs).

    Give it a go!
     
  3. Tetrikus

    Tetrikus Well-Known Member

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    Cheers! I'll give it a try after the current print has completed. I'll try to correct it from -0.8 to -0.7 and try again. Thanks so far for the explanation, I think this did help. :)
     
  4. R Design

    R Design Well-Known Member

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    Don't be afraid to stop the print half way through the first layer if you can see it's not right.

    When you use the LCD feature "stop print" the heaters stay on and the stepper motors are released. So you just push the print head back into the dock where it will ooze quietly whilst you make your adjustments (and scrape the bed clean). Then when you Start Print it gets going immediately. Very little time lost.
     
  5. PsyVision

    PsyVision Moderator
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    If you are on one of the newer firmwares, for example RC6, then you can additionally use babystepping to adjust the Z on the fly, such that if you note whilst doing a skirt that it is too low, you can raise it, or vice versa
     
  6. Alex9779

    Alex9779 Moderator
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    Must be active in the firmware, but still you can control Z in "Tune"->"Bed Z"
     
  7. R Design

    R Design Well-Known Member

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    I think you explained @Alex9779 that when you "tune" or "babystep" the Z it may take some time to take effect because of a backlog of commands / gcode that must be treated first...?

    That might confuse somebody if they didn't know...
     
  8. eli

    eli Member

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    so my first couple prints were good ...no problems now I am having the same problem the nozzle is not quite low enough...I changed the z offset from -1.2 to -1 and that put it in good posision but when I start a print is is messed up again...im using simplify 3d for a slicer
     
  9. Tetrikus

    Tetrikus Well-Known Member

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    I had this issue as well. After all that, I started over with the complete z-axis calibration, which helped to solve that. I don't know, whehter there would be an easier/faster way to fix this, but in my case it was worth the effort.

    Z-Offset calibration
     
  10. Stefan

    Stefan Well-Known Member

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    Not sure about Tune >Bed Z , but Babystepping applies on the fly, means no time between knob rotate and axis movement. So it is possible to move up and down on a currently printing straight line.
    (40 steps = 0.01 mm) here some more of my test results since Marlin has a big docu problem... and the Marlin Docu project... is kind of hard on you to contribute... its like 10 tools you have to install... before doing docu work, I think I got lost on the way.
     
  11. Alex9779

    Alex9779 Moderator
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    I just can tell you about babystepping from my UM2, there it is instant just like @Stefan describes...
    The Bed Z is not baby stepping. I played with that and my experience was, that it took its time before the change really happened...
     

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