BL Touch Z Offset Problem



  • Ill Setup BLTouch using https://forum.duet3d.com/topic/7972/bl-touch-install-success
    But the Offset will not be used the Nozzle always is more then 5mm over the bed.
    Ill stored the M31 commands in config.cfg AND in config Override but if ill Use G1 Z0 after homing ist stay too high over the bed.

    ; Configuration file for Duet WiFi (firmware version 2.03)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v2.1.8 on Sat Apr 18 2020 21:13:11 GMT+0200 (Mitteleuropäische Sommerzeit)
    
    ; General preferences
    G90                                     ; send absolute coordinates...
    M83                                     ; ...but relative extruder moves
    M550 P"Ender 5 Pro"                     ; set printer name
    M918 P1 E4 F2000000                     ; configure direct-connect display
    
    ; Network
    M551 P"XXXXX"                         ; set password
    M552 S1                                 ; enable network
    M586 P0 S1                              ; enable HTTP
    M586 P1 S1                              ; enable FTP
    M586 P2 S1                              ; enable Telnet
    
    ; Drives
    M569 P0 S1                              ; physical drive 0 X goes forward
    M569 P1 S1                              ; physical drive 1 Y goes forward
    M569 P2 S0                              ; physical drive 2 Z goes backwards
    M569 P3 S0                              ; physical drive 3 goes backwards
    M584 X0 Y1 Z2 E3                        ; set drive mapping
    M350 X16 Y16 Z16 E16 I1                 ; configure microstepping with interpolation
    M92 X80.00 Y80.00 Z800.00 E415.00       ; set steps per mm
    M566 X1200.00 Y1200.00 Z24.00 E300.00   ; set maximum instantaneous speed changes (mm/min)
    M203 X9000.00 Y9000.00 Z180.00 E6000.00 ; set maximum speeds (mm/min)
    M201 X500.00 Y500.00 Z100.00 E5000.00   ; set accelerations (mm/s^2)
    M906 X800 Y800 Z800 E1000 I50           ; set motor currents (mA) and motor idle factor in per cent
    M84 S30                                 ; Set idle timeout
    
    ; Axis Limits
    M208 X0 Y0 Z0 S1                        ; set axis minima
    M208 X220 Y220 Z300 S0                  ; set axis maxima
    
    ; Endstops
    M574 X1 Y1 Z1 S1                        ; set active high endstops
    
    ; Z-Probe
    ;M307 H64 A-1 C-1 D-1                    ; disable heater on PWM channel for BLTouch
    ;M558 P9 H5 F600 T6000                   ; set Z probe type to bltouch and the dive height + speeds
    ;G31 P500 X-50 Y-16 Z-3.495                ; set Z probe trigger value, offset and trigger height
    ;M557 X15:150 Y15:150 S20                ; define mesh grid
    
    M557 X10:150 Y10:150 S20 ; probe from X=10 to 150, Y=10 to 150mm with a mesh spacing of 20mm
    M307 H3 A-1 C-1 D-1
    M558 P9 H5 F100 T6000
    G31 X0 Y0 Z-3.495  ; (I dropped the P25 because I think the P value is used for Non contact probes and the BL-Touch is a contact Probe)
    
    ; Heaters
    M307 H0 B0 S1.00                        ; disable bang-bang mode for the bed heater and set PWM limit
    M305 P0 T100000 B4092 R4700             ; set thermistor + ADC parameters for heater 0
    M143 H0 S150                            ; set temperature limit for heater 0 to 150C
    M305 P1 T100000 B4092 R4700             ; set thermistor + ADC parameters for heater 1
    M143 H1 S275                            ; set temperature limit for heater 1 to 275C
    
    ; Fans
    M106 P0 S0 I0 F500 H-1                  ; set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
    M106 P1 S1 I0 F500 H1 T45               ; set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P2 S1 I0 F500 H1:0 T45             ; set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Tools
    M563 P0 D0 H1 F0                        ; define tool 0
    G10 P0 X0 Y0 Z0                         ; set tool 0 axis offsets
    G10 P0 R0 S0                            ; set initial tool 0 active and standby temperatures to 0C
    
    ; Custom settings are not defined
    
    ; Miscellaneous
    T0                                      ; select first tool
    M501                                        ;Load Override.cfg    
    
    
    
    ; config-override.g file generated in response to M500 at 2020-04-18 22:15
    ; This is a system-generated file - do not edit
    ; Heater model parameters
    M307 H0 A136.1 C767.5 D1.4 S1.00 V24.4 B0
    M307 H1 A419.6 C138.7 D3.5 S1.00 V24.4 B0
    M307 H2 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H4 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H5 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H6 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H7 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    G10 L2 P1 X0.00 Y0.00 Z0.00
    G10 L2 P2 X0.00 Y0.00 Z0.00
    G10 L2 P3 X0.00 Y0.00 Z0.00
    G10 L2 P4 X0.00 Y0.00 Z0.00
    G10 L2 P5 X0.00 Y0.00 Z0.00
    G10 L2 P6 X0.00 Y0.00 Z0.00
    G10 L2 P7 X0.00 Y0.00 Z0.00
    G10 L2 P8 X0.00 Y0.00 Z0.00
    G10 L2 P9 X0.00 Y0.00 Z0.00
    G31 X0 Y0 Z-3.495
    
    ; homeall.g
    ; called to home all axes
    ;
    ; generated by RepRapFirmware Configuration Tool v2.1.8 on Sat Apr 18 2020 21:13:11 GMT+0200 (Mitteleuropäische Sommerzeit)
    ;G91                     ; relative positioning
    ;G1 H2 Z5 F6000          ; lift Z relative to current position
    ;G1 H1 X-225 Y-225 F3000 ; move quickly to X and Y axis endstops and stop there (first pass)
    ;G1 H2 X5 Y5 F6000       ; go back a few mm
    ;G1 H1 X-225 Y-225 F240  ; move slowly to X and Y axis endstops once more (second pass)
    ;G1 H1 Z-305 F240        ; move Z down stopping at the endstop
    ;G90                     ; absolute positioning
    ;G92 Z0                  ; set Z position to axis minimum (you may want to adjust this)
    
    ; Uncomment the following lines to lift Z after probing
    ;G91                    ; relative positioning
    ;G1 Z5 F100             ; lift Z relative to current position
    ;G90                    ; absolute positioning
    
    
    ; 135er
    G91 ; relative mode
    G1 S2 Z0 F200 ; raise head 4mm
    G1 S1 X-240 Y-240 F10000 ; move up to 240mm in the -X and -Y directions until the homing switches are triggered
    G1 S2 X4 Y4 F600; move slowly 6mm in +X and +Y directions
    G1 S1 X-10 Y-10 ; move up to 10mm in the -X and -Y directions until the homing switches are triggered
    G90 ; back to absolute mode
    G1 X100 Y100 F10000 ; put head over the center of the bed, or wherever you want to probe
    G30 ; lower head, stop when probe triggered and set Z to trigger height
    

    What is wrong?



  • Fixt it, the Value must be Positive instead negative

    G31 X0 Y0 Z-3.495
    

    to

    G31 X0 Y0 Z3.495
    

  • Moderator

    @dezender said in BL Touch Z Offset Problem:

    G31 X0 Y0 Z3.495

    Glad you figured it out.

    Just a note though about your trigger height, when mounted correctly the base of the BLtouch should be ~8mm above the nozzle tip. This should lead to a trigger height of ~2mm. This ensures that the pin will clear the printed object when retracted, and that the pin will hit the bed and trigger before the nozzle does. It also ensures that the pin is in the sweet spot for trigger range.

    Also don't forget to measure your X and Y offset. You can get some unintended consequences if you leave them out.

    https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe

    One last thing, your G31 is missing the P value for trigger sensitivity. Use P25.



  • I have a similar problem with my z offset... so far i have tried everything but nothing works. Nozel is still 2mm above build plate. Jason Znack suggested that my home configurations are faulty. is it because i removed my z axis trigger, or is there anything else wrong. config files seamed to be ok so far as i can tell.


  • Moderator

    @4thddoughnut Please start a new thread for your issue. Please also include some useful information, for example as described here: https://forum.duet3d.com/topic/5909/guide-for-posting-requests-for-help eg printer description, Duet hardware, firmware version, config.g, homeall.g as a minimum. This should mean that your issue can be solved quickly.

    Ian


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