Z probe Trigger value has no effect

[too]

Hello Guys,

I am currently helping a friend build a Voron 2.4 with a Duet3 6HC + 3HC expansion. We are running RRF 3.3.0.
The machine is mostly done, however we are fighting with the proper setup of the Z-Probe.
The issue is that we cannot get a good Z=0 datum after the start.g routine, we always have to baby-step -0.75mm in order to get to a nice first layer.

The start.g homes X and Y with their endstops, then homes Z with a Z-Probe in the center of the bed. Then we run a G32 that probes next to the four Z axes and aligns the printer gantry to the printbed (following this guide) . after that we do another homing run for Z to establish the right Z=0 datum.

The initial Idea was that we made a mistake when setting up the Z Probe height, so we went ahead and followed the "Test and calibrate a Z probe" guide to make sure our trigger height was set correct, which it was.

We then tried to play around a bit with this value and started to increase it, to trick the duet into coming closer to the true Z=0. Somehow it doesn't matter what we change this value to, it does not reflect to the machine, and I don't understand why.

Anyone has an idea where I am messing up?

config.g:

; Configuration file for Duet 3 (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.5 on Sun Nov 07 2021 21:03:00 GMT+0100 (Mitteleuropäische Normalzeit)
 
; General preferences
G90                                          ; send absolute coordinates...
M83                                          ; ...but relative extruder moves
;M550 P"Duet 3"                               ; set printer name
M669 K1                                      ; select CoreXY mode
 
; 	A0.0		U1.1
; 	20/280		280/280
; 	
; 	B0.1		C0.2
; 	20/20		280/20
;
; 	AAAAA 	FRONT 	AAAAA
 
; Drives
M569 P0.4 S0                                 ; physical drive 0.4 goes forwards B
M569 P0.3 S1                                 ; physical drive 0.3 goes forwards A
M569 P0.0 S1                                 ; physical drive 0.1 goes forwards Z1
M569 P0.1 S0                                 ; physical drive 0.1 goes forwards Z2
M569 P0.2 S1                                 ; physical drive 0.1 goes forwards Z3
M569 P1.1 S0                                 ; physical drive 0.1 goes forwards Z4
M569 P0.5 S0                                 ; physical drive 0.5 goes forwards E
 
M584 X0.3 Y0.4 Z0.0:0.1:0.2:1.1 E0.5         ; set drive mapping
M671 X20:20:280:280 Y250:00:00:250 S10
 
M350 X64 Y64 Z64 E64 I1                      ; configure microstepping with interpolation
M92 X640.00 Y640.00 Z1200.00 E1746.16         ; set steps per mm
M566 X900.00 Y900.00 Z60.00 E120.00          ; set maximum instantaneous speed changes (mm/min)
M203 X60000.00 Y60000.00 Z18000.00 E1200.00  ; set maximum speeds (mm/min)
M201 X6000.00 Y6000.00 Z4000.00 E250.00      ; set accelerations (mm/s^2)
M906 X1200 Y1200 Z1200 E400 I30              ; set motor currents (mA) and motor idle factor in per cent
M84 S30                                      ; Set idle timeout
 
; Axis Limits
M208 X0 Y0 Z-1 S1                             ; set axis minima
M208 X300 Y300 Z250 S0                       ; set axis maxima
 
; Endstops
M574 X2 S1 P"io8.in"                         ; configure switch-type (e.g. microswitch) endstop for high end on X via pin io8.in
M574 Y2 S1 P"io6.in"                         ; configure switch-type (e.g. microswitch) endstop for high end on Y via pin io6.in
M574 Z1 S2                                   ; configure Z-probe endstop for low end on Z
 
; Z-Probe
M558 P5 C"^io4.in" H5 F120 T12000            ; set Z probe type to switch and the dive height + speeds
G31 P500 X0 Y25 Z1.3                         ; set Z probe trigger value, offset and trigger height(mehr Z=näher am Bett)
;M557 X15:250 Y15:250 S235                    ; define mesh grid
 
; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out0" Q10 T0                       ; create bed heater output on out0 and map it to sensor 0
M307 H0 B0 R0.603 C260.8 D1.69 S1.00 ;V24.3
M140 H0                                      ; map heated bed to heater 0
M143 H0 S120                                 ; set temperature limit for heater 0 to 120C
M308 S1 P"temp1" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin temp1
M308 S1 H63 L-172							 ; Thermistor Offset correction
M950 H1 C"out1" T1                           ; create nozzle heater output on out1 and map it to sensor 1
M307 H1 B0 S1.00                             ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S280                                 ; set temperature limit for heater 1 to 280C
 
; Fans
M950 F0 C"out7" Q500                         ; create fan 0 on pin out7 and set its frequency
M106 P0 C"HOTEND" S0 H1 T45                  ; set fan 0 name and value. Thermostatic control is turned on
M950 F1 C"out8" Q500                         ; create fan 1 on pin out8 and set its frequency
M106 P1 C"PARTS" S0 H-1                      ; set fan 1 name and value. Thermostatic control is turned off
M950 F2 C"1.out6" Q500                       ; create fan 2 on pin 1.out6 and set its frequency
M106 P2 C"CASE" S1 H-1                     ; set fan 2 name and value. Thermostatic control is turned off
M950 F3 C"out9" Q500                         ; create fan 3 on pin out9 and set its frequency
M106 P3 C"CASE" S1 H-1                     ; set fan 3 name and value. Thermostatic control is turned off
 
; Tools
M563 P0 S"EXTRUDER" 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
 
 
; Miscellaneous
T0                                           ; select first tool
 

bed.g:

; bed.g
; called to perform automatic bed compensation via G32
;
; generated by RepRapFirmware Configuration Tool v3.3.5 on Sun Nov 07 2021 21:03:00 GMT+0100 (Mitteleuropäische Normalzeit)
M561 ; clear any bed transform
 
G28 ; home all axes
 
 
; Probe the bed at 7 points
G91              ; relative positioning
G1 H2 Z3 F1200  ; lift Z relative to current position
G90				 ; absoluet positioning 
 
G30	P0	X20		Y250	H0	Z-99999
 
G91              ; relative positioning
G1 H2 Z3 F1200  ; lift Z relative to current position
G90				 ; absoluet positioning 
 
G30 P1	X20		Y0 		H0	Z-99999
 
G91              ; relative positioning
G1 H2 Z3 F1200  ; lift Z relative to current position
G90				 ; absoluet positioning 
 
G30 P2	X280	Y0 		H0	Z-99999
 
G91              ; relative positioning
G1 H2 Z3 F1200  ; lift Z relative to current position
G90				 ; absoluet positioning 
 
G30 P3	X280	Y250 	H0	Z-99999	S4
 

homeall.g:

; homeall.g
; called to home all axes
;
; execute homex.g, then homey.g and last homez.g
 
G91              ; relative positioning
G1 H2 Z25 F1500  ; lift Z relative to current position
G90				 ; absoluet positioning 
 
M98 P"homex.g"
M98 P"homey.g"
M98 P"homez.g"
 

homex.g:

; homex.g
; called to home the X axis
;
 
G91              ; relative positioning
G1 H1 X305 F3500 ; move quickly to X axis endstop and stop there (first pass)
G1 X-5 F12000    ; go back a few mm
G1 H1 X305 F360  ; move slowly to X axis endstop once more (second pass)
G90              ; absolute positioning
 

homey.g:

; homey.g
; called to home the Y axis
;
 
G91              ; relative positioning
G1 H1 Y305 F3500; move quickly to Y axis endstop and stop there (first pass)
G1 Y-5 F12000    ; go back a few mm
G1 H1 Y305 F360  ; move slowly to Y axis endstop once more (second pass)
G90              ; absolute positioning
 

homez.g:

; homez.g
; called to home the Z axis
;
G90                 ; absolute positioning
G1 X150 Y150 F12000 ; go to first probe point
M558 P5 C"^io4.in" F1500 T12000            ; set Z probe type to switch and the dive height + speeds
G30                 ; home Z by probing the bed
M558 P5 C"^io4.in" F120 T12000            ; set Z probe type to switch and the dive height + speeds
G30

start.g:

M117 "start.g ausgefuehrt"
 
M564 S0			; disable axis limits
G32
G28 Z			; home Z
M564 S1			; enable axis limits

[Phaedrux]

@too said in Z probe Trigger value has no effect:

M558 P5 C"^io4.in" F1500 T12000

You're calling the full M558 line here in homez. I'm not sure, but I think this may be resetting your g31 to default values. If you only want to have two speeds for the G30 it would be easier to simply use two values for F in your M558 in config.g.

Ex: M558 P5 C"^io4.in" F1500:120 T12000

Otherwise, if you just want to alter a value in M558, just call it with the parameter you want to change.

Ex M558 F1500

The other thing that I notice is that your Z motors appear to be spread across the mainboard and expansion.

M584 X0.3 Y0.4 Z0.0:0.1:0.2:1.1

This may run into a limitation in RRF and it would be better to have all Z axis motors on the mainboard where the z probe connects.

https://duet3d.dozuki.com/Wiki/Duet_3_firmware_configuration_limitations#Section_Temporary_limitations

Due to CAN latency the motors connected to expansion boards may slightly overshoot the position at which the endstop or Z probe was triggered. This would not usually matter for an endstop switch, but it does mean that if the Z motor(s) is/are connected to an expansion board then repeated probing with a Z probe (e.g. for mesh bed compensation) is not advisable. This will be fixed in a future release