1. Got a question or need help troubleshooting? Post to the troubleshooting forum or Search the forums!

Auto-Bed levelling G29 ?

Discussion in 'General Questions' started by CdRsKuLL, Oct 11, 2018.

  1. CdRsKuLL

    CdRsKuLL Member

    Joined:
    Sep 27, 2018
    Messages:
    81
    Likes Received:
    35
    Hi All,

    I was wondering if someone could help me get things straight in my head regarding bed leveling.. Now, coming from different printers I've always used G29 command after the G28 (Home) command. Now on the R2 I see a G36 command which I've not seen before.

    So, my standard start gcode would have been

    G28 ; Home
    G29; Auto-Level again as G28 resets results.

    I would configure the firmware to do say a 9 point calibration before actually starting to print. Is this not the case on the R2?

    Thanks,

    Steve
     
    #1 CdRsKuLL, Oct 11, 2018
  2. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
    Staff Member

    Joined:
    Feb 18, 2015
    Messages:
    5,905
    Likes Received:
    3,593
    IMO, do not use G35/G36, they don't work any better than G28/G29. In fact they may be worse and lead to unreliable first layers. Strip all that code and continue to use G28/G29 as you have in the past.
     
    #2 WheresWaldo, Oct 11, 2018
    CdRsKuLL likes this.
  3. CdRsKuLL

    CdRsKuLL Member

    Joined:
    Sep 27, 2018
    Messages:
    81
    Likes Received:
    35
    Thanks for the reply :) Should be getting my R2 in the morning..... Tomorrow will be new printer day. yeah !!
     
    #3 CdRsKuLL, Oct 11, 2018
  4. CdRsKuLL

    CdRsKuLL Member

    Joined:
    Sep 27, 2018
    Messages:
    81
    Likes Received:
    35
    Just done a bit of reading on the RoboMarlin version re G35/G36. It seems it was introduced to combat ambient light or something. Not sure what that means to be honest, although I know they must have reasons behind it. I've been using David Crocker's sensor for a bit on my other printers and found it to return excellent results. I wouldn't mind trying the pinda sensor once I upgrade to the flexi-bed.

    I think some problems regarding bed leveling may come from users not understanding how it works. For instance, if they generate there own gcode in cura or something and it contains the G28 command, from what I understand this wipes out any bed mapping saved and will only work off the stored z-offset height. G29 has to be run after every G28, especially in the 1.1.6 version of Marlin. So it doesn't matter what set in your octoprint start gcode, if cura generated gcode contains G28 and not G29 then this would turn off autolevel. That's my understanding of it, might be wrong but I've always ran G29 after G28 and always had good results. Is this your thoughts too?

    I'll have a play with mine (hopefully) this afternoon once I've collected it. The first upgrade is the touchscreen. :)
     
    #4 CdRsKuLL, Oct 12, 2018
  5. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
    Staff Member

    Joined:
    Feb 18, 2015
    Messages:
    5,905
    Likes Received:
    3,593
    Robo was told G36 wouldn't work as coded, at least I mentioned it multiple times. It simply doesn't do what it implies, one reason is that it does not take into account historical readings nor does it actually measure ambient light. It was trying to solve a problem that some users had with the non precise nature of the sensor used. It was a stupid addition to Marlin and I think they never contributed that code to the Marlin trunk for fear of rejection and ridicule from the main Marlin developers, just an opinion with no inside knowledge.

    Using 1.1.6 is just as short sighted, We have 1.1.9 running on the R2/C2 as well as another contributor has it running on the R1+. Robo even has it in a branch on their GITHUB. I think they are fearful of using anything newer than 1.1.6 because their code additions are broken in 1.1.9.

    None of the moderators here are Robo employees, none of us are squelched in any way, so when we see something stupid, we generally point it out, G35/G36 is just plain stupid and does not enhance the user experience in any way, at least from my standpoint.
     
    #5 WheresWaldo, Oct 12, 2018
    Geof and mark tomlinson like this.
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    23,912
    Likes Received:
    7,338
    Someone has noticed @Geof member icon he uses have they :)
     
    #6 mark tomlinson, Oct 12, 2018
    Geof likes this.
  7. Geof

    Geof Volunteer Moderator
    Staff Member

    Joined:
    Nov 9, 2015
    Messages:
    6,757
    Likes Received:
    2,339
    my R2s and C2s went from not able to be in production to simply running every day with a simple "G28". Manual level the beds and love life :D.

    @mark tomlinson and @WheresWaldo as well as Robo knows how I feel about the autolevel and G36 nonsense. Everyone I help we remove it and they are MUCH happier.

    obviously your mileage may vary...but likely not by much ;)
     
    #7 Geof, Oct 12, 2018
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
    Staff Member

    Joined:
    Feb 21, 2013
    Messages:
    23,912
    Likes Received:
    7,338
    If everyone doesn't already know it I'll just say it: manual leveling is best.
    Sure, there are cases where the bed is warped enough you need something extra, but even then manual leveling helps Marlin get the job done.

    Autoleveling was an attempt to make it easier to use the printers without having to invest in the manual leveling.
    The best auto leveling routines are the ones like mesh where you are sampling effectively the whole bed too :)
     
    #8 mark tomlinson, Oct 12, 2018
    WheresWaldo and Geof like this.

Share This Page