naevaTheRat

Inconsistent results with auto bed levelling. Creality ender 3 s1.

https://lemmy.dbzer0.com/post/564436

Inconsistent results with auto bed levelling. Creality ender 3 s1. - Divisions by zero

See attached photo for the results of the bed levelling test using superslicer’s calibration test. This is using the uhhh mriscoc firmware after heating to thermal equilibrium, tramming to tolerance, doing a 9x9 mesh which found a high point at the super messed up bottom left corner (higher than tramming result? but slightly further out). I have M420 S1 in my custom gcode, and for insanity’s sake checked the gcode of the part and it’s in the custom block and start block. Any ideas what’s going on? every other section is okay, although back right is a bit distant.

Jul 10, 2023 at 11:17pmWeb
Show threadCameronDevJul 10, 2023

How are you determining the bed is at temp? The sensor is in the middle, could the outer corners still be heating up?

Is the bed leveling actually being used? On my printer you can see the z screws move slightly as the print head moves across the board. Easiest to look at the couplers or put a text mark on the screen.

Show threadnaevaTheRatJul 10, 2023

  • waiting half an hour while I cook breakfast :p

  • I haven’t checked for motion. It would be subtle and lead screws are at the back. Will give it a squiz after gathering suggests. What do you mean text mark on the screen? I could just eyeball Z coords right as they should shift?

    • Show threadCameronDevJul 11, 2023

    Seems like you have worked it out, but you can usually see the z couplers on my print move about 1/4 of a turn as it moves across the bed. I usually look at the grub screws, but you could put a texta mark on the z screws to see if it was moving.

    I don’t think the Z height as reported by the printer will be moving though, it’s an internal movement.

    Show threadnaevaTheRatJul 11, 2023

    So it looks like the autolevelling isn’t working during the print. This prompted me to go read some documentation and I figured out a couple of things.

    Firstly my Z feed during probing was too fast and causing issues, fixed that and did repeated sampling with the probe. I get very consistent tramming and mesh results.

    I set the mesh to 9x9, then saved it to slot 0

    I read that UBL leveling gets turned off by G28 (maybe) and doesn’t use the M420 code. This is now my startup gcode in the “custom G-code” in superslicer

    G90 ; use absolute coordinates M83 ; extruder relative mode M140 S[first_layer_bed_temperature] ; set final bed temp M104 S150 ; set temporary nozzle temp to prevent oozing during homing and auto bed leveling G4 S10 ; allow partial nozzle warmup G28 ; home all axis G1 Z50 F240 G1 X2 Y10 F3000 M104 S{first_layer_temperature[initial_extruder]+extruder_temperature_offset[initial_extruder]} ; set final nozzle temp M190 S[first_layer_bed_temperature] ; wait for bed temp to stabilize G29 A ; Activate UBL G29 L0 ; Load mesh in slot 0 G29 J ; Correct for skew M109 S{first_layer_temperature[initial_extruder]+extruder_temperature_offset[initial_extruder]} ; wait for nozzle temp to stabilize G1 Z0.28 F240 G92 E0 G1 Y140 E10 F1500 ; prime the nozzle G1 X2.3 F5000 G92 E0 G1 Y10 E10 F1200 ; prime the nozzle G92 E0

    The printer loads the mesh in 0, does the skew correction (which amusingly f’d the mesh up in my test because it hit a blob of PLA stuck to the bed at the edge), then does the strip down the side and starts printing. However there is no Z travel (as determined by a flag attached to the leadscrews) duringing X/Y movement while printing.

    After aborting the print the mesh is correctly loaded still and adjusted with the skew.

    Thoughts?

    Show threadffheinJul 11, 2023

    What kind of ABL is your Marlin compiled with? If it is bilinear, which is very common, G29 J does the following:

    Jettison the leveling data stored in SRAM and turn off leveling compensation. Data in EEPROM is not affected.

    Show threadnaevaTheRatJul 12, 2023
    I’m pretty sure I do as I have all the mesh editing and viewing features as well as manual levelling for unreachable points. Wifey installed this firmware though and idk what binary she chose specifically.
    Show threadffheinJul 12, 2023
    When you run the “G29 J” command, you see it take 3 measurements at different points, right? This ought to mean that it does the tilt correction, so it’s probably unified ABL.
    Show threadnaevaTheRatJul 12, 2023
    yep
    Show threadffheinJul 13, 2023
    If you haven’t, try removing the G29 J command from the slicer start code. I’ve seen a few cases where it made things worse. Personally I don’t use it because my printer keeps levelling for a couple of months, at least after I replaced the soft bed springs with silicone dampers. If more time has passed I just redo the entire bed mesh.
    Show threadnaevaTheRatJul 13, 2023
    post has updates, currently just m420
    Show threaddackJul 11, 2023
    What does the probed mesh look like? If you run multiple probe cycles, are the results consistent?
    Show threadnaevaTheRatJul 11, 2023
    Yes, I posted a comment reply with further information here
    Inconsistent results with auto bed levelling. Creality ender 3 s1. - Divisions by zero

    See attached photo for the results of the bed levelling test using superslicer’s calibration test. This is using the uhhh mriscoc firmware after heating to thermal equilibrium, tramming to tolerance, doing a 9x9 mesh which found a high point at the super messed up bottom left corner (higher than tramming result? but slightly further out). I have M420 S1 in my custom gcode, and for insanity’s sake checked the gcode of the part and it’s in the custom block and start block. Any ideas what’s going on? every other section is okay, although back right is a bit distant.

    Show threadrambosJul 11, 2023
    If that was printed without ABL, you could probably go without one
    Show threadfroh42Jul 11, 2023

    I had inconsistencies in my print on an Ender 3pro with sprite, no kind of manual or ABL level fixed it.

    It turned out one of the eccentric v nuts in. my gantry was too tight, so it didn’t run smoothly - the right side of the gantry lagging to the left. (Ender 3pro has only one z screw)

    So check for mechanical problems, lubrication of the z rod etc.

    For the V wheels - they need to be adjusted so thight that you can just turn them manually with one finger then one ministep thighter.

    Show threadnaevaTheRatJul 11, 2023

    So if you check my other comment in the thread the Z axis isn’t moving at all with XY translation which suggests to me the mesh isn’t being used period.

    There could be mechanical issues too but I think focusing on the software first is likely to be fruitful.

    Show threadnaevaTheRatJul 11, 2023

    If you check my edit the second it’s seeming that something like this might be the case?

    Do you know if this problem sounds like a mechanical issue?

    Show threadNanomerce Jul 11, 2023
    hey, after finding the mesh did you send m500 to save the mesh?
    Show threadnaevaTheRatJul 11, 2023
    Yes, the mesh saves and loads correctly. I had the Gcode wrong which you can see in my comment and the post edit. Ongoing issues though
    Show threadFogleJul 14, 2023
    So is it just g29 L0 that I need to add? I suspect mine is not using the mesh either
    Show threadnaevaTheRatJul 15, 2023

    So all I have currently is M420 L0 S1 as I mention in my post. Make sure it comes after g28 in case that’s configured to unload autolevelling. Make sure L# matches the slot number your mesh is saved to.

    To see if it’s working. Print a skirt around the whole bed. Put an Allen key in the grub screws of the couples between the Z motors and the screws and watch or feel for deflection. The movements will be subtle.

    It’s also worth seeing if comparing manual levelling using a feeler gauge or paper sheet and the nozzle tip creates the same mesh as automatic levelling using the probe. plus or minus Z offset of course. If there’s a skew to the manual mesh you need to fix axis alignment.