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During Print Bed Lowering in Center

Discussion in 'Troubleshooting' started by JWald, Feb 19, 2026.

  1. JWald

    JWald New Member

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    RoboOS 2.0.0-r2.6

    I have gone through z axis set up many times, bed leveling.

    Prints come out very nice if positioned on the edge of the bed. Larger prints or printing in center the bed actually lowers and the filament doesn't stick.

    I use Cura to slice and also sliced on board the Robo 2, same result.

    I've replaced the bed surface, but clearly the z axis lowers during print.

    Help! roboR2 print.jpg
     
    #1 JWald, Feb 19, 2026
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Is it going through the autoleveling dance where it probes the bed 9 times or so?
     
    #2 mark tomlinson, Feb 21, 2026
  3. JWald

    JWald New Member

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    Yes it does the nine point dance. What sensor does it use to do that calibration?
     
    #3 JWald, Feb 22, 2026
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    #4 mark tomlinson, Feb 22, 2026
  5. JWald

    JWald New Member

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    Thanks Mark, I checked that and it seems to be working correctly when it does the 9 point dance. The red light comes on and the table descends. I wondered if the white on the print matt was causing an improper reading so I blacked it out. Still would not print in the middle. I tried to print a benchy and the raft won't adhere to the bed. If I print it on the edge it has no problem. Still confused.
     
    #5 JWald, Feb 22, 2026
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Well, the ugly truth about the "bed leveling" that Robo uses is that it is not really intelligent.
    There are different versions across the various models (R1, R2, C2, E3) although the R2/C2 are pretty similar. It also varies by which version of the firmware that is installed.

    Start by getting me the following data and we can get it tuned in (also put a small carpenters level on the bed itself when it is at "home" and see if by chance the plate is uneven). Ideally that would be moot, but depending on the slicer settings it may matter.

    • Slicer settings (capture screenshots).
    • Find the startup GCODE section of the slicer and let me know what in there. Screenshot or copy/paste.
    • The slicer and exact version would be handy as well - you already have provided the exact version of the Robo FIrmware.
    Zip all that up and email it to : teambarracuda@gmail.com with a Subject line that includes "ROBO3d Forum"
     
    #6 mark tomlinson, Feb 23, 2026
  7. JWald

    JWald New Member

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    I sent in the info, hope it's what you need to help solve my problem!
     
    #7 JWald, Mar 1, 2026
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    It has not shown up yet.
     
    #8 mark tomlinson, Mar 1, 2026
  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You can try posting it here, but the forum does not allow large attachments so you will likely need to do multiple posts and poerhaps resize the screenshots if they are too large
     
    #9 mark tomlinson, Mar 1, 2026
  10. JWald

    JWald New Member

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    I sent it again via adventureguy@hotmail and ilihune@gmail I can post what I have here:
    • Slicer settings (capture screenshots).
      • Screen shots are included but I couldn't find "slicer settings" in Cura 2.5.0
    • Find the startup GCODE section of the slicer and let me know what in there. Screenshot or copy/paste.
      • I've included a slice generated in the zip folder
    • The slicer and exact version would be handy as well - you already have provided the exact version of the Robo FIrmware.
      • Cura 2.5.0
    I've checked the bed with metal straight edge and it is flat.

    I've also tried to slice on the Robo R2 itself and it still will lower when printing in the middle and not adhere to the build plate

    I think this started when I had the black screened display and had to create a new image on an SD card to start over. I used the zip file R2_2.0_replace with the image file R2_2.0_decisive-evans image file

    Thanks!
     
    #10 JWald, Mar 2, 2026
  11. JWald

    JWald New Member

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    Here is the zip file
     

    Attached Files:

    #11 JWald, Mar 2, 2026
  12. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    So in your GCode file:

    ; -- START GCODE --
    ;-- end of START GCODE --

    There is nothing between the comments. There should be a G29; in there (a HOME command is a good ide as well)

    ; -- START GCODE --
    G28 ; Home
    G29; Auto-Level again as G28 resets results.
    ;-- end of START GCODE --

    I can't assist you in getting that added to Cura, but it needs to be there.
     
    #12 mark tomlinson, Mar 2, 2026
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    #13 mark tomlinson, Mar 2, 2026
  14. JWald

    JWald New Member

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    So I put in the start up code in Cura, but that did not help. I kept thinking the IR sensor is picking up a reflection or something so I put a piece of black electrical tape where the IR sensor is at the middle of the bed. Well crap. That worked. What the cow? R2bad.JPG R2good.JPG
     
    #14 JWald, Mar 4, 2026
    Last edited: Mar 4, 2026
  15. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The UV sensor does want a black bed (or a very dark color), in fact the bed cover sheets they used for the C2 were just a 5 inch square chunk of black tape (similar to painters tape). Try putting that on the bed; painters tape comes off clean and easy. I thought the R2 had the same sheets (but larger)
     
    #15 mark tomlinson, Mar 4, 2026
  16. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    So I went to the workshop and looked... The one I have has a metal plate that I had been covering with the blue painters tape. Apparently I did not have the black bed tape/sheets for it (if they ever did sell them). Been a good while since I fired up the R2 so I guess I am not surprised. Try covering the bed with black or blue painters tape.

    I have used that on the C2 as well at times (and both have the same sensor)
     
    #16 mark tomlinson, Mar 4, 2026

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