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    Bad Repeatability with BLTouch

    Third-party add-ons
    bltouch repeatability
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    • palmhoej
      palmhoej last edited by

      I have fitted my two printers (Creality CR-10 S5 & Tronxy X5s) with a BL Touch censor and Duet 2 Wifi. Same story for both printers, but i will only give example from one:

      When i am running the following script:

      M401
      G30 P0 X250 Y250 Z-9999
      ...... (repeat 10x times probing in the same spot)......
      G30 P09 X250 Y250 Z-9999 s1

      i get the following result:
      G32 bed probe heights: -0.275 -0.245 -0.130 -0.255 -0.265 -0.248 -0.255 -0.250 -0.220 -0.287, mean -0.243, deviation from mean 0.041

      Is this acceptable? 0.16mm difference between the outliers is almost half the height of one filament layer.

      Following settings have been used:

      ; Z-Probe
      M574 Z1 S2 ; Set endstops controlled by probe
      M307 H3 A-1 C-1 D-1 ; Disable heater on PWM channel for BLTouch
      M558 P9 H5 F80 T2000 ; Set Z probe type to bltouch and the dive height + speeds
      G31 P500 X-45 Y-5 Z0.35 ; Set Z probe trigger value, offset and trigger height
      M557 X15:195 Y15:195 S40 ; Define mesh grid

      Its the same story for the other printer, which makes me think that i am doing something wrong.

      3Dreamer 1 Reply Last reply Reply Quote 0
      • oliof
        oliof last edited by

        You could try reduing the dive speed to see if the results improve.

        M558 P9 H5 F80 T1000

        <>Creality CR-20 IDEX Duet3 mini 5+<>RatRig V-Minion SKR RRF 1.1<>

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        • palmhoej
          palmhoej last edited by

          I halfed it once, with no result, but just for the fun of it, i did it again:

          G32 bed probe heights: 0.178 0.280 0.183 0.288 0.155 0.207 0.293 0.183 0.288 0.165, mean 0.222, deviation from mean 0.055

          A little bit better, but not acceptable: 0,123mm between the max and minimum. And know it is so slow that you barely can see it moving.

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          • dc42
            dc42 administrators last edited by

            Are you probing with heaters on? If so, adding the B1 parameter in your M558 command in config.g may help.

            Duet WiFi hardware designer and firmware engineer
            Please do not ask me for Duet support via PM or email, use the forum
            http://www.escher3d.com, https://miscsolutions.wordpress.com

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            • palmhoej
              palmhoej last edited by

              No heaters or hotends are turned on. But i added the B1 parameter and it did not help (it actually got worse, but i think thats just random error in the diviation, not because i added the B1):

              G32 bed probe heights: 0.115 0.202 0.322 0.117 0.122 0.210 0.322 0.217 0.317 0.190, mean 0.214, deviation from mean 0.079

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              • MortarArt
                MortarArt last edited by

                Complete side point here, but what I currently do with my printers, because I have constant repeatability issues, is I edit the gcode to delete re-homing for prints, especially when printing the same part repeatedly.

                I've considered seeing if I can figure out a way to have a check box in the web UI to enable / disable re-homing when pressing the "print another" button.

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                • palmhoej
                  palmhoej last edited by

                  The problem is i have a CR-10 S5, which means it can print 500x500mm prints... but it is impossible to get such a big surface flat enough, so i need the bed mesh to compensate for this (or tell me where i need to level the surface).

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                  • Veti
                    Veti last edited by

                    is it a clone? because they are less accurate.

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                    • gavatron3000
                      gavatron3000 last edited by

                      My genuine smart bltouch has repeatability below 0.03. I had some issues which I found to be my z jerk was too high. I assume was during the z axis retract move causing it for me.

                      1 Reply Last reply Reply Quote 1
                      • 3Dreamer
                        3Dreamer @palmhoej last edited by

                        @palmhoej Hi, was there any progress? I've the same problem, and I've made some test about that:
                        https://forum.duet3d.com/topic/11093/bltouch-m558-accuracy-test-strange-behaviour

                        3D Printing new Applications Researcher.

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