Auto Z adjustment with 2 steppers? Error



  • I am attempting to perform auto bed adjustment with 2 Z steppers. I have them separated in the config file. However, when running G32 it says there's an error, attempted to adjust bed with 2 points, need 3,4 or 5.

    Bed.g file

    [[language]]
    G28                         ; home
    M401                        ; deploy Z probe
    G30 P0 X0 Y0 Z-99999     ; probe near a leadscrew
    G30 P1 X0 Y250 Z-99999   ; probe near a leadscrew
    G30 P2 X180 Y250 Z-99999	;
    G30 P3 X180 Y0 Z-99999 S2	;
    M402                        ; retract probe
    
    

  • administrators

    Are you running firmware 1.19? Did you define the two leadscrew positions first using the M671 command?



  • I may only be running 1.18. I am not home to check for sure. I can check in the morning when I get off work.

    I did define the two positions. When I attempted to probe near the locations it gave me an error about probing clockwise, starting near x0y0. So I changed it to probe all 4 corners. The final S# command is done with S2. It probes fine, but when it's done, it gives me the error

    [[language]]
    Attempted to adjust bed with 2 points. Need 3,4, or 5.
    
    

    However, I do think I'm on 1.18. So I'll look into that in the morning.



  • After getting home, I confirmed I was still on 1.18. After the upgrade it's working as intended. Thanks for the help!


  • administrators

    I'm glad it's working for you. How well does it correct the level? You can check this by running it a second time. Ideally the adjustments will be zero the second time. In practice they won't be, but they should be smaller.



  • If I might ask coffman34 what does your setup look like? I am thinking about upgrading the z axis on one machine to utilise the true auto levelling features, and am curious as to how you built it to work with 2 points of adjustment.



  • I have a d-bot. The 2 screws are centered front to back. I do have additional wheels on the front of the print bed, which are normally not included. The added cross bar in the front, as well as the large heated bed introduced problems when the machine lost power, causing the 2 z steppers to lose sync as the bed would drop down almost to the bottom. With the auto leveling with 2 screws, I can guarantee that the 2 steppers come back in sync when the printer is homed.

    In homeall and homez I have it setup to do the G32 (Z leveling) automatically at the end of homing, which I am going to switch to the start of homing, because I think it caused some Z offset issues on my last print. So, performing a G32 to level the bed, then homing it should set the Z height correctly.



  • @dc42:

    I'm glad it's working for you. How well does it correct the level? You can check this by running it a second time. Ideally the adjustments will be zero the second time. In practice, they won't be, but they should be smaller.

    I generally run it twice just to make sure. The first time I found out that my lead screws were backwards in the config file. Causing it to adjust the first time the opposite, which made it more out of alignment. Might want to add something to the wiki about that.

    Once I got that setup correctly, it would fix within 0.02mm of level, as reported by BLTouch. After doing the bed leveling, I did a mesh bed compensation, and it looked way better than what I was able to get by hand.

    To put it simply, I actually placed an order for a Duet X5, another stepper, and lead screw setup to actually convert my whole bed to a 3 lead screw system, without using belts.


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