BB seems to try to print below the glass

Discussion in 'Calibration, Help, and Troubleshooting' started by Tetrikus, Apr 3, 2016.

  1. Tetrikus

    Tetrikus Well-Known Member

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    I'm driving crazy. I'm trying to print an object, but the big box does always try to print below the glass and scratches on the glass withouth beeing able to extrude any filament on the glass since it is to tight.

    I prepared the print with autohome, autolevel and autohome again and I don't see where the issue is. Did anyone else had this problem as well? What am I supposed to do in this case?

    I had this problem once before and donig about 17 autolevels and 63 autohomes did eventually "fix" the issue. But this time, nothing seems to work. Shouldn't the bigbox be clever enough to handle that? As far as I know, I did a proper setup of the axis and as mentioned before - for the most prints it's just working fine.

    I'm trying to start this print since 2 hours now, and it's quite annoying! :mad:
     
  2. Kick2box

    Kick2box Well-Known Member

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    Perhaps you do G28 again after G29 in some start script. Look into the gcode!
     
  3. Tetrikus

    Tetrikus Well-Known Member

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    eeehmmm... I do not really understand gcode, honestly. This is the starting process until the skirt begins:

    Code:
    G90
    M83
    M106 S0
    M140 S60
    M190 S60
    M104 S200 T0
    M109 S200 T0
    ;BigBox Printer Start Script Begin
    M117 Print Starting.
    ;Dock
    G1 X70 Y200 F3000
    G1 X70 Y240 F3000
    ;Prime Extruder
    T0     ;Select Extruder 0
    G92 E0     ;Reset E
    G1 E10 F200     ;Extruder 10mm
    G92 E0     ;Reset E
    ;Undock
    G1 X80 Y240 F3000
    G1 X80 Y200 F3000
    ;BigBox Printer Start Script End
    G1 E-1.5000 F4500
    G1 Z0.188 F180
    M117 Layer 1, Z = 0.1875
    T0
    ; tool H0.250 W0.600
    ; skirt
    G1 X109.930 Y39.233 F5000
    G1 E1.5000 F1350
    G1 X109.931 Y39.229 E0.0002 F1950
    G1 X110.404 Y37.916 E0.0870
    ...
    I do not see any G28 nor G29 in the whole gcode file.
     
  4. Rob Heinzonly

    Rob Heinzonly Well-Known Member

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    I just compared your gcodes with one of mine, and it looks like your first layer is too low.
    In this line the head is moved 0.188mm above the bed, in my gcode it is 0.380mm. I think you should change this.
     
  5. Kick2box

    Kick2box Well-Known Member

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    I agree to Rob Heinzonly. As it seems that you don't do it in the start code, you possibly pressed Autohome after doing Autolevel.
     
  6. Tetrikus

    Tetrikus Well-Known Member

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    Yes, I mostly (every time) press autohome after autolevel again, since otherwise, the printhead is banging to the back, when the print starts directly after autolevel. After autolevel, the head is stopping somewhere in the right back corner.

    To clarify again: What is your workflow when starting a print? Something like this?
    1. autohome
    2. autolevel
    3. start print
    I did change the z value for the first layer. Even when i set it to 0.6, the nozzle is directly on the glass. When I manually pull down the bed, the filamet gets extruded, but this does not really help of course, since layer 2 is at 0.4 and this does completely destroy the first layer. I think, there is something completely wrong on my z-axis. I just wonder, why it sometimes works quite okay and sometimes not. :confused:
     
  7. Kick2box

    Kick2box Well-Known Member

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    Yes, that's the correct workflow. Don't do autohome after autolevel. Also heat up the bed before levelling. Go into octoprint terminal and send a G28 (autohome) and after that a G29 and look for the response. Maybe there is something wrong with your print bed or distance of sensor.
     
  8. R Design

    R Design Well-Known Member

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    Autohome ERASES the autolevel settings. Must only be done before!
     
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  9. Spoon Unit

    Spoon Unit Well-Known Member

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    Autohome
    Auto level (or better still manual level using firmware change)
    Store Memory
    Start Print
     
  10. Tetrikus

    Tetrikus Well-Known Member

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    Thanks guys! You solved one more of a few problems I have/had with the BigBox. Looks like the machine is only as smart as the user who is using it. :rolleyes: I tried again a few times with the described process. And it's like magic. Whenever the autohome does work correctly (some of the autohomes do fail and place the printhead at a wrong y-position), an autolevel and a following print does work just fine, including correct Z-height. That's awesome. :) I did quite a few prints since saturday and all of them went extremely smooth. :) Thank you so much for your support!

    EDIT: There is one more question though. Could I add 'autohome' and 'autolevel' to the start script so that I don't have to do them manually before every print? When I add them to the gcode, does the printer wait with the following steps until it has completed? Or is there any benefit if I do it manually before every print?
     
  11. Spoon Unit

    Spoon Unit Well-Known Member

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    In theory, once you've done your levelling once, it should be good until you next do something which might unlevel it. I've learned to become quite careful about taking stuff off the bed, opting now to wait until it's cooled and easily removed rather than being impatient and trying to pry it off early. Anytime my print doesn't start well, that the time for another re-level. Seems crazy running it repeatedly unless you live in an earthquake zone.

    Autohome is G28
    Autolevel : not sure - nothing obvious here - http://reprap.org/wiki/G-code
     
  12. Kick2box

    Kick2box Well-Known Member

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    Add to your start code before docking. Autolevel is G29.
     

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