Z-offset with BL Touch



  • Hi all,

    I've tried to find answers to this from other questions but am still unsure so thought I'd better ask..

    I'm having trouble with my z offset (BL touch probe). I'm currently using manual bed levelling and no mesh calibration.

    So I get my bed levelled manually by probing with G30, then sending G1Z0 at the corners and centre of the bed (glass) and using thumbscrews to adjust the bed height. I then repeat this process a couple of times to ensure all locations are as close to 0.1mm from the bed as possible.

    Then I start printing and instantly the nozzle crashes into the bed and I have to raised the bed using the baby height adjustments to around 0.8mm. I don't understand what is causing this problem. Hopefully the following system files and print g-code should help identify the issue?

    config.g

    ; Configuration file for Duet WiFi (firmware version 1.20 or newer)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Wed Mar 07 2018 10:07:16 GMT+0000 (GMT)
    
    ; General preferences
    G90                                                                            ; Send absolute coordinates...
    M83                                                                            ; ...but relative extruder moves
    M555 P1                                                                        ; Set firmware compatibility to look like RepRapFirmare
    
    ; Network
    M550 Pxxxxxxx                                                           ; Set machine name
    M551 Pxxxxxxx                                                              ; Set password
    M552 S1                                                                        ; Enable network
    M586 P0 S1                                                                     ; Enable HTTP
    M586 P1 S0                                                                     ; Disable FTP
    M586 P2 S0                                                                     ; Disable Telnet
    
    ; Drives
    M569 P0 S0                                                                     ; Drive 0 goes backwards
    M569 P1 S1                                                                     ; Drive 1 goes forwards
    M569 P2 S1                                                                     ; Drive 2 goes forwards
    M569 P3 S1                                                                     ; Drive 3 goes forwards
    M350 X16 Y16 Z16 E16 I1                                                        ; Configure microstepping with interpolation
    M92 X80 Y80 Z400 E199.99                                                       ; Set steps per mm
    M566 X480 Y480 Z12 E120                                                        ; Set maximum instantaneous speed changes (mm/min)
    M203 X9001 Y3000 Z600 E3000                                                    ; Set maximum speeds (mm/min)
    M201 X800 Y800 Z100 E5000                                                      ; Set accelerations (mm/s^2)
    M906 X760 Y900 Z760 E1500 I30                                                  ; 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 X190 Y200 Z175 S0                                                         ; Set axis maxima
    
    ; Endstops
    M574 X1 Y1 S0                                                                  ; Set active low endstops
    
    ; Z-Probe
    M307 H3 A-1 C-1 D-1 ;
    M558 P9 H5 F160 R0.250 T2000 A3                                                ; Set Z probe type to bl touch and the dive height + speeds
    G31 X41 Y-47 Z3.25 P25                                                         ; Set Z probe trigger value, offset and trigger height
    M557 X18:182 Y18:182 S25                                                       ; Define mesh grid
    
    ; Heaters
    M301 H0 S1.00 P10 I0.1 D200 T0.4 W180 B30                                      ; Use PID on bed heater (may require further tuning)
    M305 P0 T100000 B3988 C0 R4700                                                 ; Set thermistor + ADC parameters for heater 0
    M143 H0 S120                                                                   ; Set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4725 C0 R4700                                                 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S280                                                                   ; Set temperature limit for heater 1 to 280C
    M307 H0 A90.0 C700.0 D10.0 S1.00 V0.0 B1                                       ; PID tuning - set automatically (M303) and moved from config-override.g
    M307 H1 A458.2 C201.5 D3.2 S1.00 V24.0 B0                                      ; PID tuning - set automatically (M303) and moved from config-override.g
    M307 H2 A340.0 C140.0 D5.5 S1.00 V0.0 B0                                       ; PID tuning - set automatically (M303) and moved from config-override.g
    M307 H4 A340.0 C140.0 D5.5 S1.00 V0.0 B0                                       ; PID tuning - set automatically (M303) and moved from config-override.g
    M307 H5 A340.0 C140.0 D5.5 S1.00 V0.0 B0                                       ; PID tuning - set automatically (M303) and moved from config-override.g
    M307 H6 A340.0 C140.0 D5.5 S1.00 V0.0 B0                                       ; PID tuning - set automatically (M303) and moved from config-override.g
    M307 H7 A340.0 C140.0 D5.5 S1.00 V0.0 B0                                       ; PID tuning - set automatically (M303) and moved from config-override.g
    
    ; 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 H T45                                                       ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P2 S1 I0 F500 H T45                                                       ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on
    
    ; Tools
    M563 P0 D0 H1                                                                  ; 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
    
    ; Automatic saving after power loss is not enabled
    
    ; Custom settings are not configured
    M572 D0 S0                                                                     ; Disable Pressure Advance
    
    ; Miscellaneous
    T0                                                                             ; Select first tool
    

    homeall.g

    ; homeall.g
    ; called to home all axes
    ;
    ; generated by RepRapFirmware Configuration Tool on Wed Mar 07 2018 10:07:16 GMT+0000 (GMT)
    M280 P3 S160 I1         ; Z probe alarm release
    ; M280 P3 S10 I1          ; deploy Z probe
    G91                     ; relative positioning
    G1 S2 Z5 F6000          ; lift Z relative to current position
    G1 S1 X-205 Y-205 F6000 ; move quickly to X and Y axis endstops and stop there (first pass)
    G1 X5 Y5 F6000          ; go back a few mm
    G1 S1 X-205 Y-205 F600  ; move slowly to X and Y axis endstops once more (second pass)
    G90                     ; absolute positioning
    G1 X59 Y147 F6000       ; go to probe point - centre of bed
    G30                     ; home Z by probing the bed
    
    G1 Z5 F100.             ; uncomment this line to lift the nozzle after homing
    

    homez.g

    ; homez.g
    ; called to home the Z axis
    ;
    ; generated by RepRapFirmware Configuration Tool on Wed Mar 07 2018 10:07:16 GMT+0000 (GMT)
    M280 P3 S160 I1    ; Z probe alarm release
    ; M280 P3 S10 I1     ; deploy Z probe
    G91                ; relative positioning
    G1 S2 Z5 F6000     ; lift Z relative to current position
    G90                ; absolute positioning
    G1 X59 Y147 F6000  ; go to probe point - centre of bed
    G30                ; home Z by probing the bed
    
    G1 Z5 F6000        ; lift Z after homing
    

    print_file.gcode

    ; G-Code generated by Simplify3D(R) Version 4.0.0
    ; Jun 2, 2018 at 3:33:59 PM
    ; Settings Summary
    ;   .... abbreviated for brevity
    G90
    M83
    M106 S0
    M140 S55
    M190 S55
    M104 S215 T0
    M109 S215 T0
    G28                                    ; Home all
    M561                                  ; Clear any bed transform that might be in place
    ;G29 S1                               ; Load bed mesh analysis
    G1 Z5 F6000                     ; Move Z to 5
    G1 X5 Y5                            ; Move Head to front left
    G92 E0                               ; Zero Extruder
    G1 F200 E4                        ; Prime the extruder
    G92 E0                               ; Zero Extruder
    G1 E-2.0000 F3000
    G1 Z0.180 F1002
    ; process Process1-1-5
    ; layer 1, Z = 0.180
    T0
    ; tool H0.200 W0.528
    ; skirt
    G1 X84.105 Y87.840 F9000
    G1 E1.8000 F900
    G1 X105.895 Y87.840 E0.9566 F720
    G1 X107.160 Y89.105 E0.0786
    G1 X107.160 Y110.895 E0.9566
    G1 X105.895 Y112.160 E0.0786
    ....

  • administrators

    Check that the trigger height of the bltouch remains constant when you probe the bed multiple times in the same spot using G30 S-1. If it doesn't, then you may need to reduce the probing speed (F parameter in the M558 command).


Locked
 

Looks like your connection to Duet3D was lost, please wait while we try to reconnect.