Home JGAurora A5S, A1 & A3S-V2 Modifications & Upgrades

A5S Community Firmware rams nozzle into printbed


I just tried out the community firmware on my brand new (not so much anymore) A5S. When I tried printing (after leveling the bed), it started the print by heating up bed and nozzle, but right after that rammed the nozzle into the bed (going way past the z-endstop), pusching the bed down by 3mm or so and then proceeded to print, scratching the bed as the motors moved along until I could block the process by turning off the printer...

I would still like to use the community firmware, but is there a way to fix this issue?! The thing is, that I don't want to experiment too much, as the stepper motors not only run the nozzle into the bed, but also ram the z-stop switch pretty hard, so I guess if this keeps happening the switch will break off :(

My starting g-code (which worked fine with the factory firmware) is:

G28 ; home all axes
G1 Z5 F5000 ; lift nozzle

I thought it might be missing the leveling data, so I also tried to do a M420 S1 after the G28... Same result...


  • mu5famu5fa Posts: 7Member

    Update: I just found the "Caution" text box on the download page... Unfortunately it seems to be right in my brain's "banner ad region" and so I didn't find it when I was actually searching the download page for some kind of Readme or documentation... Guess I would have expected that next to the download links...
    However, all the steps in https://jgmakerforum.com/discussion/896/how-to-use-mesh-bed-leveling-on-custom-firmware are exactly what my 2nd attempt (with the M420 S1) was... So, it doesn't seem to help in my case

    I also noticed that the "Enable Bed Leveling ON/OFF" option is no longer available after I restart the printer and selecting Save/Load config results in a beep sound... So, is the issue that the firmware cannot store the settings on my machine?

  • Samuel PinchesSamuel Pinches Posts: 2,985Administrator

    Dear @mu5fa -- I'm sorry, I did not see your post until now! Which exact version of the firmware are you using? On the latest version 2.0H there is no need for an SD card to save the settings.

    I would recommend to plug the printer into a computer, connect with "pronterface", and send "G29 S0" to print out the currently saved mesh.

  • mu5famu5fa Posts: 7Member

    Hi @Samuel Pinches! Thanks for getting back to me.
    I am using the latest version 2.0H. I will give it a try with pronterface later today.

    I remember that I did get it working once, after doing the mesh leveling. But since then I turned the printer off/on and it seems to have forgotten everything and also doesn't work anymore right after doing another mesh leveling.

    Is there some way to set a safety stop to make sure that the printer doesn't go too far into negative-z territory, no matter what commands it gets? I was really surprised to see it actually go a couple millimeters below what would be zero. Is that normal?

  • Samuel PinchesSamuel Pinches Posts: 2,985Administrator

    Unfortunately, the mesh level may be slightly below the z endstop, and normally this is not an issue for up to +/- 1mm.

    There's no backup safety system -- but normally this is not an issue.

    You can create a workflow to check for yourself that the mesh is on, accurate and working, before hitting print. Pronterface is one such way.

  • mu5famu5fa Posts: 7Member

    Hi @Samuel Pinches. It took me a bit longer to find time to get back to this, sorry about that. In the meantime I had already reinstalled the original firmware. Now my steps were as follows:

    -- Install marlin fw 2.0H
    -- Start printer, connect with pronterface
    -- pronterface: run G29 S0 and get Mesh Bed Leveling OFF but otherwise reasonable data (between -0.3 and 0.0).
    -- Perform mesh leveling on printer
    -- pronterface: run G29 S0 and get Mesh Bed Leveling ON and a reasonable mesh (between -0.2 and 0.0).
    -- Perform a print, pronterface echoes "Bed Leveling ON" and "Fade Height 10.00". THEN:
    -- At the beginning of the print, the nozzle is moved to -3mm at the starting position (had to move it 3mm up to get back to its level position).

    So... The problem seems to be independent from the mesh data and the printer goes far beyond the +/- 1mm range :(

  • Samuel PinchesSamuel Pinches Posts: 2,985Administrator

    Can you please upload your full gcode file here?

  • mu5famu5fa Posts: 7Member

    Full file is attached. It was generated with slic3r and worked with the original firmware.

    The beginning is:

    ; generated by Slic3r 1.3.0 on 2021-07-12 at 11:48:04
    ; external perimeters extrusion width = 0.44mm (3.18mm^3/s)
    ; perimeters extrusion width = 0.56mm (8.27mm^3/s)
    ; infill extrusion width = 0.50mm (9.14mm^3/s)
    ; solid infill extrusion width = 0.56mm (6.20mm^3/s)
    ; top infill extrusion width = 0.56mm (1.55mm^3/s)
    M190 S70 ; set bed temperature and wait for it to be reached
    M104 S210 ; set temperature
    G28 ; home all axes
    M420 S1 ; Load leveling data
    G1 Z5 F5000 ; lift nozzle
    ; Filament gcode
    M109 S210 ; set temperature and wait for it to be reached
    G21 ; set units to millimeters
    G90 ; use absolute coordinates
    M82 ; use absolute distances for extrusion
    G92 E0
    G1 Z0.300 F7800.000
    G1 E-5.00000 F600.00000
    G92 E0
    G1 X127.921 Y136.165 F7800.000
    G1 E5.00000 F600.00000
    G1 F1800
    G1 X128.972 Y135.253 E5.04090
    G1 X130.000 Y135.029 E5.07182
    G1 X175.000 Y135.029 E6.39427
    G1 X176.335 Y135.421 E6.43517
    G1 X177.247 Y136.472 E6.47607
    Thanked by 1Samuel Pinches
  • mu5famu5fa Posts: 7Member

    Is there anything else I could try? Is there a way to enable additional debug output by recompiling the firmware with some other flags?

    Thank you!

  • Samuel PinchesSamuel Pinches Posts: 2,985Administrator

    @mu5fa -- could we do a zoom call or similar to chat?

  • mu5famu5fa Posts: 7Member

    @Samuel Pinches that would be cool. I sent you a direct message.

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