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Unresolved Rear Right Corner of Bed Has Prints Not Adhering

Discussion in 'Troubleshooting' started by Doug Gebhart, Mar 23, 2017.

  1. Doug Gebhart

    Doug Gebhart Member

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    So recently on one of my Robo3D R1s, the back right corner of the bed is not adhering. It looks like the z-offset is incorrect, and the print head is not printing close enough to the bed, but it only happens in one corner. I have used a level to check the bed and the x-axis, and as far as I can tell, it is level. Also, it seems to me that if the x-axis was off level, it would happen all along one side, not just on back right.
    Also, when I manually auto-home and then move the print head to that area, it seems to be the right z height. It only seems to happen during prints. Is this a problem with my auto leveling?

    Edit: Forgot to mention, I am using Simplify3D, with a G29 command in the startup code. It is ABS filament, extruded at 230C and bed temp of 80C with hairspray on the bed. I have done several successful prints using these settings, it is only when the print is big enough to go to the back right corner that its a problem.
     
    #1 Doug Gebhart, Mar 23, 2017
    Last edited: Mar 23, 2017
  2. daniel871

    daniel871 Well-Known Member

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    The shortest explanation I can give you is to tell you to raise the extruder up to about 180mm from the bed, then pick the glass up and look at the heater placement on the bottom.

    Depending on how good a job they did taping the cork on, you'll be able to feel around on the cork and tell where the actual heater element is located and tell how far off-center it is.

    There isn't much you can do short of replacing the heater, but you'll have a good physical explanation of why the one section of the bed isn't working properly.

    Also, this has been a known problem on the R1-variants since the very beginning. That's why there have been people modifying their printers to use larger silicone heaters that actually cover the bottom of the bed (the stock heater is hilariously undersized for the stated print area of the printer).

    EDIT:

    Also, as @mark tomlinson says below, "level" isn't the correct term for what you're checking.

    "Flatness" and "Parallelism" are the things you actually want to check/adjust for assuming the heater problem I wrote about above isn't the actual root cause.
     
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  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The autoleveling as used in the version of Marlin for Robo R1/R1+ does not do a great job of accounting for portions of the bed that are off. "Level" is not what you think the term means either (which is why using an actual level to read this is pointless). It does not mean "level" it means that the position of the nozzle with respect to the bed is constant across the entire bed. How "level" it actually is does not matter. How even the bed and nozzle are to each other is the point.

    Your only adjustment for this is the M565 (Z offset) command in the startup GCode. What is yours?
     
  4. Doug Gebhart

    Doug Gebhart Member

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    Here is my start up g-code:

    M92 Z2560 ; set extruder calibration

    M565 Z-0.775 ; set the offset for auto-leveling mechanism

    G28 ; home all axes

    G1 Z10 ; Raise Z

    G28 X Y ; home X and Y Axis

    G30 ; probe bed to clean nozzle

    G29 ; run auto-level
     
  5. Doug Gebhart

    Doug Gebhart Member

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    So I just looked, and the heating element is under that area, or at least I feel a bulge under that area.

    EDIT: word
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    M565 Z-0.775 ; set the offset for auto-leveling mechanism

    Should be after a G28; and before a G29;

    Find your last G28; and put it after that.
    Fact in your case I would put it directly before the G29; given the other stuff you are doing.
    Should work, even though it wants a HOME ALL first.
     
    #6 mark tomlinson, Mar 23, 2017
    Last edited: Mar 23, 2017
  7. Doug Gebhart

    Doug Gebhart Member

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    OK I will give that a try.
     

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