Duet 2 wifi. Bltouch sometimes doesn't work

  • Hi,
    So i have strange problem with my BLTouch (Smart V3.1). 90% of the time my bltouch is working correctly. But sometimes on homing from Home all button on web interface or homing before print from start g-code bltouch pin just slide inside body and entire bed is crashing into my nozzle. I tweaked some settings. Tried various speeds. Made another set of wires. Nothing helped. I'm using Duet 2 wifi on newest stable firmware 3.2.2 i believe. Printer is a coreXY based on RatRig V-core V2.

    On checking z height and setting true 0 for nozzle i got readings around +/-0.08mm i think its pretty ok for this type of sensor?

    ; homeall.g
    ; called to home all axes
    ; generated by RepRapFirmware Configuration Tool v2.1.8 on Wed Apr 01 2020 22:00:59 GMT+0200 (czas środkowoeuropejski letni)
    G91                     ; relative positioning
    G1 H2 Z2.5 F200         ; lift Z relative to current position
    G1 H1 X-495 Y-495 F3000 ; move quickly to X or Y endstop and stop there (first pass)
    G1 H1 X-495             ; home X axis
    G1 H1 Y-495             ; home Y axis
    G1 X5 Y5 F600          ; go back a few mm
    G1 H1 X-495 F360        ; move slowly to X axis endstop once more (second pass)
    G1 H1 Y-495             ; then move slowly to Y axis endstop
    G90                     ; absolute positioning
    G1 X230 Y238 F3000     ; go to first bed probe point and home Z
    M558 A1 F600			; Set single probing at faster feed rate 
    G30                     ; home Z by probing the bed
    M558 A3 F100 ; Set multi probing at slower feed rate
    G30 ; Probe again to get a more accurate position
    ; Z-Probe
    M950 S0 C"exp.heater3"                             ; create servo pin 0 for BLTouch
    M558 P9 C"zprobe.in" H5	R0.2 F100 T4000 A5 B1 		;set Z probe type to bltouch and the dive height + speeds
    G31 P25 X-3 Y-48.5 Z1.8	                      	 ; set Z probe trigger value, offset and trigger height
    M557 X25:440 Y25:440 S20                            ; define mesh grid
    M307 H3 A-1 C-1 D-1								   ; Unbind the Heater Pin

  • Forgot about something else. When i'm making mesh bed leveling around 400 points (500x500mm bed) this problem never occur..

  • https://forum.duet3d.com/topic/20333/bltouch-oddity/10?_=1613996928642

    Please read this. I have finally found the problem.

    It was not the cable after all but the Z min pin on the bl touch had come loose. Check the bltouch, i have original one yet i feel they are really cheaply made. The soldering had come loose on the pin on the z min on the probe(constantly giving me reading errors, red lights and z-probe 1000 red error reading

  • @BjornH currently I'm using Heater3 pin from expansion port. In the past i tried heater 5 and got the same results 😕 In My previous printer i isolated Bltouch wires from any other cable and that made a job but i dont want to make two separate cable harnesses

  • Moderator

    I don't see any problems in your config. With the BLTouch 90% of the time it's a wiring problem.

  • @Phaedrux Okay thanks i'll check it soon

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