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: 3Member

    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: 2,967Administrator

    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: 3Member

    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: 2,967Administrator

    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.

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