Ender 3 v2 with BLTouch intermittent failure

  • I just received my v2 and Creality BLTouch kit. Board version 4.2.2. Updated to latest firmware: "4.2.2 Ender-3 v2 Marlin2.0.1 BLtouchV1.1.1without adapter board firmware.rar"

    Everything works fine 1/2 times. But, every other print or so, one of the the probing attempts fails with the BLTouch blinking red and the head crashing into the surface. When it works, it's fantastic.

    I have tried the following with no effect.

    • Reseated connectors on the BLTouch and the main board.
    • Routed the cable differently in case it was some electrical interference.

    Anyone else have this issue? Were you able to solve it?

  • @min1300 hi what do you mean to the left? meaning the wire of the bltouch not towards the hotend?

  • I'm having the same problem with the sensor, randomly failing ...

    I soldered the cables and used the correct JST connector.

    I can do some leveling correctly, but it fails sometimes.

    The original firmware does not stop the Z movement down when the sensor fails and sometimes even starts to print causing the probe pin to hit the glass from the side.

    I have been using OctoPrint to print, as it stops printing immediately when the probe fails and avoids major problems with the probe colliding with the printing table.

  • @plugh A useful reply, thanks.

    Instead of re-routing or re-wiring, it might be worth using mix 43 ferrite rings/clamp on type over the ribbon cable.

    I've had the very occasional failure when probing, but no crashes, just a blinking red light. 🙂

    I guess the general hash and crud from these printers may depend on the layout and quality of motors/motherboard used. As a Radio Ham, I'm absolutely hyper over received background 'noise' and I can't detect any from my printer on any major bands that I use. 🙂

  • I realize that I should have better articulated what intermittent BLTouch problem was resolved by replacing the cable. This is for the random bed sense failures, of a BLTouch version 3.1 probe during a autohome or bed leveling operation. The probe always deploys, then randomly fails as the probe moves up in step with the bed position, which then goes from a blue LED, to a flashing Red error indication.

    There is also a documented problem that is outlined in the ANTCLABS datasheet, where if the probe Fails to Deploy, then the setscrew can be tightened up to 180 degrees past the .3mm preset depth. That is a different problem however.

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  • I was also pulling my hair out on this one. Then I discovered that if you did not preheat the bed and nozzle, that the BLTouch worked fine with low ambient room temperatures (65F). I was preheating to 85C and 220C with the BLTouch in the auto home position, cooking above the bed. At least one out of three bed level operations (3x3 Creality firmware ABL matrix) would intermittently fail. Very maddening and damaging!. The issue is the BLTouch's signal threshold changes with temperature, like all chips do, and the PWM noise from the X and Extruder stepper motors is coupled into the BLTouch control cable due to it's close proximity to cause . BTW, there is PWM inductive noise from these steppers even when just parked, and not moving. (to maintain their position) From previous email threads on this topic over at Marlin, there is a handshake timing window for the ANTCLABS communications protocol during a bed probe sequence. If the BLTouch sends a successful Z bed probe signal, and does not receive a ACK, then it times out and errors.

    What I did to correct the problem was to replace the Creality supplied flat ribbon cable with a twisted pair 1.5 Meter replacement cable, and it has now performed flawlessly, fifteen or so bed level and auto home ops in a row, without a single failure. And the bed was at 90C, and the Nozzle was at 230C. In hindsight, I could have converted my stock flat ribbon cable to twisted pair by pushing out the five wires on the controller side connector, peel back the individual wires, twist the wire pairs appropriately using a hand drill, then re-assemble.

    You could also use shielded cable, or a shielded sleeving over the existing flat ribbon cable, for the all important first two feet or so where the BLTouch cable exits the control box, and runs parallel with the X and Extruder stepper motor cables. From what I have tested, the Hotend heater does not create appreciable interference.

    What a random problem this one was.

  • @Pico @Jwnok


    I've just spent three days trying to get the BLTouch v3.1 working with my Ender 3 v2 4.2.2 board. I had exactly the same issue with both crashing into the bed and random intermittent flashing red failures.

    This morning, purely by accident I refitted the BLTouch sensor with the connector and PCB to the left, rather than facing the hot end. Not a single issue since.

    I read that the hot end can create interference with the signal, and so maybe having the pcb etc further away has helped.

    I'm using the stock Creality BLTouch enabled firmware (4.1.1). Gave up trying to get TH3D or other custom Marlin firmware code to work.

    I am using the following scripts in Cura for Start and End G-Code:

    ; Ender 3 V2 Custom Start G-code
    M140 S{material_bed_temperature_layer_0} ; Set Heat Bed temperature
    M190 S{material_bed_temperature_layer_0} ; Wait for Heat Bed temperature
    M104 S150; start warming extruder to 150
    G28                         ; Home all axes
    G29 ; BLTouch ABL
    G92 E0                      ; Reset Extruder
    M104 S{material_print_temperature_layer_0} ; Set Extruder temperature
    G1 Z2.0 F1200               ; Move Z Axis up little to prevent scratching of Build Plate
    M109 S{material_print_temperature_layer_0} ; Wait for Extruder temperature
    G1 X0 Y20 Z0.3 F9000        ; Move to start position
    G1 X0 Y200 Z0.3 F1200 E15   ; Draw the first line
    G1 X0.4 Y200 Z0.3 F9000     ; Move to side a little
    G1 X0.4 Y20 Z0.3 F1200 E30  ; Draw the second line
    G92 E0                      ; Reset Extruder
    G1 X0 Y10 Z0.2              ; Wipe Nozzle
    G1 Z2                       ; Move Z Axis up little to prevent scratching of Build Plate

    And the End Code....

    ; Ender 3 V2 Custom End G-code
    G90                         ; Set Absolute positioning
    G92 E0                      ; Reset the extruder position
    G0 E-3                      ; Retract filament
    G0 X0 Y{machine_depth} Z{machine_height} F9000 ; Present the print, build plate to the front, Z at the top
    M106 S0                     ; Turn-off cooling fan
    M104 S0                     ; Turn-off hotend
    M140 S0                     ; Turn-off bed
    M84                         ; Disable all steppers
    M300 S2000 P200             ; Make Ending Sound 3 beeps
    M300 S0 P100
    M300 S2000 P200
    M300 S0 P100
    M300 S2000 P200

  • I am also having trouble with the head randomly crashing into the print bed even while trying to auto home. maybe 1 out of 20 times.

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