Is this normal



  • I have followed the calibrate the Z probe trigger height documentation (have done it several times, the paper is very tight between nozzle and bed) and ran G29. I start a print but the nozzle is .7 mm too high. I compensate for it in s3d with a -.7 Z offset, first layer is now ideal. Is this how others do this or am I missing or not doing something right?

    I just now noticed the last line of my config.G , I know I put it there but can't remember why, I've commented it out for now.

    Config.G

    ; Configuration file for Duet 3 (firmware version 3)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v2.1.8 on Wed Apr 29 2020 12:52:20 GMT-0600 (Mountain Daylight Time)
    
    ; General preferences
    G90                                          ; send absolute coordinates...
    M83                                          ; ...but relative extruder moves
    M550 P"Duet 3"                               ; set printer name
    
    M669 K1                                      ; select CoreXY mode
    
    ; Drives
    M569 P0.0 S1                                 ; physical drive 0.0 goes forwards
    M569 P0.1 S1                                 ; physical drive 0.1 goes forwards
    M569 P0.2 S0                                 ; physical drive 0.2 goes backwards
    M569 P0.3 S0                                 ; physical drive 0.3 goes backwards
    
    M584 X0.1 Y0.0 Z0.2 E0.3                     ; set drive mapping Y = drive 0 X = drive 1 Z = drive 2 Extruder drive 3
    
    M350 X16 Y16 Z16 E16 I1                      ; configure microstepping with interpolation
    M92 X200.00 Y200.00 Z1600.00 E420.00         ; set steps per mm
    M566 X900.00 Y900.00 Z12.00 E120.00          ; set maximum instantaneous speed changes (mm/min)
    M203 X6000.00 Y6000.00 Z180.00 E1200.00      ; set maximum speeds (mm/min)
    M201 X500.00 Y500.00 Z20.00 E250.00          ; set accelerations (mm/s^2)
    M906 X800 Y800 Z800 E1000 I30                 ; set motor currents (mA) and motor idle factor in per cent
    M84 S30                                      ; Set idle timeout
    
    ; Axis Limits
    M208 X0 Y0 Z-3 S1                           ; set axis minima
    M208 X300 Y300 Z300                         ; set axis maxima
    
    ; Endstops
    M574 X1 S1 P"!io1.in"                        ; configure for low end, active-low endstop on X via pin io1.in
    M574 Y2 S1 P"!io2.in"                        ; configure for high end, active-low endstop on Y via pin io2.in
    M574 Z1 S1 P"!io3.in"                        ; configure for low end, active-low endstop on Z via pin io3.in
    
    ; Z-Probe
    M950 S0 C"io4.out"                           ; create a gpio servo pin 0 for BLTouch
    M558 P9 C"io4.in" H3 F120 R.350 T6000        ; set Z probe type to bltouch, set input to io 4 in, set dive height + speeds
    G31 P500 X0 Y0 Z3.96                         ; set Z probe trigger Height, X and Y offset and trigger height
    M557 X15:295 Y0:242 P6:6                     ; define mesh grid
    
    ; Heaters
    M308 S0 P"temp0" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin temp0
    M950 H0 C"out0" T0                           ; create bed heater output on out0 and map it to sensor 0
    M143 H0 S110                                 ; set temperature limit for heater 0 to 110C
    M307 H0 A236.8 C516.8 D3.0 V24.1 B0          ; disable bang-bang mode for the bed heater and set PWM limit
    M140 H0                                      ; map heated bed to heater 0
    M308 S1 P"temp1" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin temp1
    M950 H1 C"out1" T1                           ; create nozzle heater output on out1 and map it to sensor 1
    M143 H1 S260                                 ; set temperature limit for heater 1 to 260C
    M307 H1 A445.5 C173.0 D5.5 V24.1 B0          ; disable bang-bang mode for hotend heater and set PWM limit
    
    ; Fans
    M950 F0 C"out7" Q500                         ; create fan 0 on pin out7 and set its frequency
    M106 P0 S0 H-1                               ; set fan 0 value. Thermostatic control is turned off
    M950 F1 C"out8" Q500                         ; create fan 1 on pin out8 and set its frequency
    M106 P1 S1 H1 T45                            ; set fan 1 value. Thermostatic control is turned on
    
    ; Tools
    M563 P0 S"E3D-V6" 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
    
    ; Lights
    M950 P1 C"out3"                             ; Create port on out 3 to power lights, 12v lights are wired in series
    
    ; Bed leveling
    M671 X-8.0:175.0:320.0 Y-11.0:320.0:-11.0   ; Define position of bed leveling screws
    
                                        
    
    ; Custom settings are not defined
    
    ; Miscellaneous
    T0                                           ; select first tool
    ;G10 P0 2.45                                  ; Set tool offset
    

    Homeall

    ; homeall.g
    ; called to home all axes
    ;
    ; generated by RepRapFirmware Configuration Tool v2.1.8 on Wed Apr 29 2020 12:52:20 GMT-0600 (Mountain Daylight Time)
    G91                     ; relative positioning
    G1 H2 Z7 F6000          ; lower bed 7mm to ensure probe is above the Z probe trigger height
    G1 H1 X-310 Y310 F2600  ; move quickly to X or Y endstop and stop there (first pass)
    G1 H1 X-310             ; home X axis
    G1 H1 Y310              ; home Y axis
    G1 X5 Y-5 F6000         ; go back a few mm X and Y
    G1 H1 X-310 F360        ; move slowly to X axis endstop once more (second pass)
    G1 H1 Y310 F360         ; then move slowly to Y axis endstop
    G90                     ; absolute positioning
    G1 X150 Y90 F2000       ; Move probe over to the centre of the bed
    G30                     ; lower probe, stop when probe triggered and set Z to trigger height, home Z by probing the bed
    
    ; Uncomment the following lines to lift Z after probing
    ;G91                    ; relative positioning
    ;G1 Z5 F100             ; lift Z relative to current position
    ;G90                    ; absolute positioning
    

  • Moderator

    @luckyflyer said in Is this normal:

    G31 P500 X0 Y0 Z3.96

    Part of the problem could be that you don't have an X Y offset for the BlTouch. This will mean that the height map isn't accurate for where the nozzle actually is.
    https://duet3d.dozuki.com/Wiki/Test_and_calibrate_the_Z_probe#Section_Measuring_Probe_X_Y_Offset

    4mm seems pretty high for a trigger height for the BLTouch as well. When it's mounted as described in the BLTouch documentation the base of the probe should be ~8mm above the nozzle tip, which should give ~2mm trigger height, which is the sweet spot for it's reliability.


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