Ender 3 BL Touch gives inconsistent results



  • I bought the BL Touch from Creality
    Updated the firmware from the Creality Store (Ender-3Marlin1.1.6BLTouch.rar)
    I ran the First Layer gcode from TeachingTech 3D Printer Calibration website
    I ensured that the gcode has the following

    M140 S70 ; set bed temp
    M190 S70 ; wait for bed temp
    M104 S200 T0 ; set hot end temp
    G28 ; home all axes
    G29 ; probe ABL
    M109 S200 T0 ; wait for hot end temp

    I get very inconsistent results
    Sometimes the front square prints are too light and the back is perfect
    Sometimes the Front right print is not even close enough to print anything
    Sometimes all print squares are too light.
    Sometimes the front left square is too low and smears
    I ran the G29 repeatedly and analysed the results.
    All readings are consistent within the matrix to within 0.01 so it appear that the BL Touch is operating correctly
    It is as if these figures from the BL Touch are being ignored

    Any help appreciated



  • Dear @IanH

    You can Level the platform manually before using the BL-TOUCH, if it not solved, you can come to our official after-sales platform: https://www.creality.com/service-request



  • Just thought of something else. If you can send a terminal command, issue a M420 V1 command, and verify that in the information that it returns has "Recv: echo:Bed Leveling ON", if it is OFF then that is the issue. You can also just add a
    M420 S1 Z4 ; Set ABL on with 4 layer fade to your gcode, to insure that it is enabled each time you print.



  • I just configured the same setup, a Ender 3 V2 with the Creality BLTouch kit, latest BLTouch firmware from their site. I have not however had a chance to fully scrutinize it's accuracy yet. Just a couple thoughts. With these kinds of resolutions, how do we measure the flatness of a bed to determine if perhaps BLTouch is wrong? Are the metrics that BLTouch reports back from say G29/M500/M503 repeatable from multiple runs? If not could it be that the bed is shifting from something like the bed rollers/springs not being snug enough? And at the risk of annoying Creality, I always prefer a second opinion. Is this issue intrinsic to a Marlin code release, and later fixed? That's where I use some of the pre-compiled stuff that Smith3D has on their site as a quick comparison. They also by default use a more precise 5x5 ABL grid. And I have had no issues reverting back to the stock Creality firmware for support if necessary. One of these days I really need to setup a Marlin code build environment of my own, there are soo many possible tweaks, not to mention always having the very latest bug fixes and enhancements.


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