Dual hybrid started air printing

Discussion in 'Calibration, Help, and Troubleshooting' started by Proto_BB, Mar 4, 2017.

  1. Proto_BB

    Proto_BB Well-Known Member

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    For some reason my BigBox dual hybrid has started air printing. I run mesh levelling and level over 9 points on the bed. When that's done it goes through the auto-home procedure and I save to memory. Yet when I print via OctoPrint it is like it's totally forgotten the MBL settings and it's running the IR probe settings. After having weirdness with the MBL I upgraded to RC8 in the hope it would magically resolve. All upgraded fine but now it's printing a good 30mm higher than the glass bed.

    Any ideas on what's happening here? I have run MBL at least 10 times. I always save to memory after the tedious 9 measurements with paper between the nozzle and glass. The bed itself is reasonably level. Restarted the box a few times. Yet still the same result.

    It's strange to me that at the end of the MBL it homes and does the Z home with the IR. Why is this so when I just levelled with the MBL? I get the X and Y, but the Z by IR seems like it's unnecessary? Could that be replacing my fresh MBL settings?
     
  2. Spoon Unit

    Spoon Unit Well-Known Member

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    I got tired of the system forgetting my MBL settings long ago and moved to a more recent firmware. Currently on RC8. Oh pardon me, just read your post more carefully and see you're already on that.

    The process for MBL, where at the end it re-homes is exactly what mine does. MBL essentially is recording offsets from IR at the first position and then offsets from offsets for the remainder, so Z homing with IR is normal.

    I wonder if perhaps your gcode is embedding any GCODE which is altering MBL settings? If you've recently upgraded to RC8 are you sure you've retained all important settings?

    Finally, as a (complete pain in the ass) workaround, you might be able to at least get something up and printing by using the control > motion > z bed, or tune > zbed setting, by injecting a massive minus number in there until you're back on the bed.
     
    #2 Spoon Unit, Mar 4, 2017
    Last edited: Mar 4, 2017
  3. Proto_BB

    Proto_BB Well-Known Member

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    Thanks for the help Spoon Unit. It would be really good to know what your Start and End GCode scripts look like?
     
  4. Spoon Unit

    Spoon Unit Well-Known Member

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    My start script, mostly unchanged but with added lighting and prime-line


    ;BigBox Printer Start Script Begin



    ;Lights on

    M42 P6 S255





    ;Home

    M117 Homing.

    G28

    G1 Z5 F360

    ;M218 T1 X35.45 Y-0.60

    ;M301 P186.6 I36.5 D238.47

    ;M304 P204.84 I38.59 D271.82



    ;T0 Dock

    ;G1 X70 Y200 F3000

    ;G1 X70 Y240 F3000



    ;T1 Dock

    G1 X105 Y200 F3000

    G1 X105 Y240 F3000



    ;Select Tool

    ;T0

    T1



    ;Prime Extruder 0

    M117 Prime Extruder 0

    G92 E0 ;Reset E

    G1 E5 F50 ;Extruder 10mm



    ;T0 Undock

    ;G1 X80 Y240 F3000

    ;G1 X80 Y200 F3000



    ;T1 Undock

    G1 X115 Y240 F3000

    G1 X115 Y200 F3000



    ;Prime Line

    M117 Prime

    G1 X1 Y150 Z0.3

    G1 X1 Y50 E5.9868 F600



    M117 Print Starting.



    ;BigBox Printer Start Script End
     
  5. Proto_BB

    Proto_BB Well-Known Member

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    Thanks Spoon Unit. I will give this a try tomorrow. At the moment it's a bit of a dead loss. So much wasted time hunting the issue. It could be another half dead driver. I have already had to replace at least 3 over the last few months. I will be moving to Duet this week so this is my last Rumba hurrah!
     
  6. Proto_BB

    Proto_BB Well-Known Member

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    One thing I should mention is that when I do an auto-home the hot end stops a good 5mm above the bed. If I do a "move axis" and move the X (or any other axis) it first changes the Z to be close to the glass (paper distance) then it moves. It happens every time I do an auto home and then manually move the axis from the LCD on the BigBox. No idea if this is normal behavior with RC8. It certainly didn't happen with RC6.

    One thing that I wondered about is if calling G28 at the start of my script is losing the mesh level? It's either that or I have stuffed up my Z offset somehow. Btw, my IR sensor is mounted in the standard position and not on the bed.

    (I have not run your GCode yet - will do so tonight).
     
  7. Proto_BB

    Proto_BB Well-Known Member

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    I have run your GCode and I have found that I get a head crash when the T1 command is issued when the printer is docked. It lurches to the left and crashes, bounces, crashes in to the side of the dock. I have no idea why T1 would cause this?
     
  8. Spoon Unit

    Spoon Unit Well-Known Member

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    T1 is just a switch to use coordinates relative to T1. T1 itself shouldn't cause any movement. What's probably happening though is that the T1 offset is not correct for your printer, or perhaps you have T1 and T0 reversed. Regarding the Z height on movement, there's another setting for that I think. I like to keep those sorts of moves way about the bed. I have these settings related to Z motion

    upload_2017-3-6_16-10-57.png
     
  9. SandervA

    SandervA Member

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    Dear Proto_BB,

    In relation to your question on the G28 calling in the start script; I lost my auto bed level settings this way. Took me a while to figure it out, but G28 in the start script was definitely the problem.

    Kind regards,
    Sander
     
  10. Paul Begley

    Paul Begley Well-Known Member

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    Proto_BB is my previous post similar to your issue?
    https://forum.e3d-online.com/index.php?threads/head-crashing-when-docked.2342/#post-25178

    if so, this behaviour is by design, you need to a supply the S1 parameter
    see Alex9779’s response. I replicated his changes to my custom firmware which resolved the issue.
     

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