Am I doing something stupid? SOLVED

[DjDemonD]

So I had to fit a new fan shroud (which also holds my IR sensor) after a print went wrong and broke it. When I reassembled it I did the usual thing homed, then went down to near the bed, did a g30 s-1 to see the trigger height, then jogged down until I gripped a piece of paper. This gave me a z probe offset of 2.5mm.

I then autocalibrated and began a print, but my nozzle was about 2mm too high.

Tried the whole thing again, same result. I also tried with grid levelling on and off. same result.
No z offset in the gcode.

config.g

; Configuration file for Mini Kossel kit from Think3DPrint3D for testing Duet WiFi
 
; Communication and general
M111 S0                             	; Debug off
M550 LargeKossel			; Machine name and Netbios name (can be anything you like)
M551 ************                      	; Machine password (used for FTP)
;*** If you have more than one Duet on your network, they must all have different MAC addresses, so change the last digits
M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED 	; MAC Address
;*** Wifi Networking
M552 S1					; Enable WiFi
 
M555 P2                           	; Set output to look like Marlin
M575 P1 B57600 S1			; Comms parameters for PanelDue
 
G21                                 	; Work in millimetres
G90                                	; Send absolute coordinates...
M83                                 	; ...but relative extruder moves
 
; Axis and motor configuration
M569 P0 S1				; Drive 0 goes forwards
M569 P1 S1				; Drive 1 goes forwards
M569 P2 S1				; Drive 2 goes forwards
M569 P3 S1				; Drive 3 goes forwards
M569 P4 S1				; Drive 4 goes forwards
M574 X2 Y2 Z2 S1			; set endstop configuration (all endstops at high end, active high)
;*** The homed height is deliberately set too high in the following - you will adjust it during calibration
M665 L360 R145.548 H430.1 B140.0 X-1.125 Y-1.320 Z0.000	; set delta radius, diagonal rod length, print radius, homed height, tower correction 
M666 X1.561 Y-1.446 Z-0.115 A0.00 B0.00			; put your endstop adjustments here, or let auto calibration find them
M350 X16 Y16 E16 I1    			; Set 16x microstepping with interpolation
M92 X200 Y200 Z200			; Set axis steps/mm
M906 X1100 Y1100 Z1100 E800 I60		; Set motor currents (mA) and increase idle current to 60%
;Remember if changing the speeds/accels/jerks below to change bed.g also
M201 X3000 Y3000 Z3000 E1000		; Accelerations (mm/s^2)
M203 X15000 Y15000 Z15000 E3600		; Maximum speeds (mm/min)
M566 X1200 Y1200 Z1200 E1200		; Maximum instant speed changes mm/minute
 
; Thermistors
M305 P0 T100000 B4300 R4700 H30 L0	; Put your own H and/or L values here to set the bed thermistor ADC correction
M305 P1 T100000 B4388 R4700 H30 L0	; Put your own H and/or L values here to set the first nozzle thermistor ADC correction
M305 P2 T100000 B3974 R4700 H30 L0	; Put your own H and/or L values here to set the second nozzle thermistor ADC correction
M307 H1 A423.4 C203.6 D5.1 S1 B0	;autotune parameters for extruder 0 heater (H1) tuned 23-10-16
M307 H0 A311.7 C649.8 D3.1 S1 B0	;autotune for bed heater H0 tuned 23-10-16
 
; Fans
M106 P1 T45 H1 				; enables thermostatic mode for fan 1, will be on if heater 1/hotend is above 45 deg C
 
; LEDs
M106 P2 S255				;set leds on at max brightness. (runs off fan 1 PWM)
 
; Tool definitions
M563 P0 D0 H1                       	; Define tool 0
G10 P0 S0 R0                        	; Set tool 0 operating and standby temperatures
;*** If you have a single-nozzle build, comment the next 2 lines
;M563 P1 D1 H2                      	; Define tool 1
;G10 P1 S0 R0                       	; Set tool 1 operating and standby temperatures
M92 E333	                      	; Set extruder steps per mm
 
; Z probe and compensation definition
;*** If you have a switch instead of an IR probe, change P1 to P4 in the following M558 command
M558 P1 X0 Y0 Z0 			; Z probe is an IR probe and is not used for homing any axes
G31 X10 Y-5 Z2.5 P500			; Set the zprobe height and threshold (put your own values here)
 
;*** If you are using axis compensation, put the figures in the following command
M556 S78 X0 Y0 Z0                   	; Axis compensation here
 
M208 S1 Z-1				; set minimum Z
;
T0					; select first hot end
M140 S0					; set extruder to 0 for paneldue
 
M501					;load config_override.g
 

Bed.g

; Auto calibration routine for delta printers
 
M561					; clear any bed transform, otherwise homing may be at the wrong height
G28					; home the printer
G28					;home again in case of endstop problem
 
;slow down movement to improve accuracy and magnets holding
M201 X500 Y500 Z500 E1000		; Accelerations (mm/s^2)
M203 X15000 Y15000 Z15000 E3600		; Maximum speeds (mm/min)
M566 X300 Y300 Z300 E1200		; Maximum instant speed changes mm/minute
 
G30 P0 X0.00 Y120.00 Z-99999 H0
G30 P1 X75.20 Y89.63 Z-99999 H0
G30 P2 X109.80 Y19.36 Z-99999 H0
G30 P3 X95.08 Y-54.89 Z-99999 H0
G30 P4 X38.37 Y-105.43 Z-99999 H0
G30 P5 X-40.44 Y-111.11 Z-99999 H0
G30 P6 X-103.92 Y-60.00 Z-99999 H0
G30 P7 X-118.18 Y20.84 Z-99999 H0
G30 P8 X-77.13 Y91.93 Z-99999 H0
G30 P9 X0.00 Y60.00 Z-99999 H0
G30 P10 X46.66 Y26.94 Z-99999 H0
G30 P11 X43.81 Y-25.29 Z-99999 H0
G30 P12 X0.00 Y-54.74 Z-99999 H0
G30 P13 X-51.96 Y-30.00 Z-99999 H0
G30 P14 X-51.96 Y30.00 Z-99999 H0
G30 P15 X0 Y0 Z-99999 S6
 
;restore speed settings to normal printing speeds
M201 X3000 Y3000 Z3000 E1000		; Accelerations (mm/s^2)
M203 X15000 Y15000 Z15000 E3600		; Maximum speeds (mm/min)
M566 X1200 Y1200 Z1200 E1200		; Maximum instant speed changes mm/minute
 
;G29 S1					;load grid levelling mesh
;M376 H10				;taper off compensation after 10mm
 
G1 X0 Y0 Z75 F7500			; get the head out of the way of the bed
 

Versions:

Firmware Name: RepRapFirmware for Duet WiFi
Firmware Electronics: Duet WiFi 1.0
Firmware Version: 1.17 (2016-12-24)
WiFi Server Version: 1.03 (ch fork)
Web Interface Version: 1.14-b4

[DjDemonD]

Update: Something odd is going on.

I changed my G31 command to have z probe offset 3.6mm instead of 2.5mm to see if it would help. Auto-calibrated then went down to z=0, which was not at physical z=0, jogged down exactly -1.0mm and was at z=0 physically.

So I changed the z probe offset again to 4.6mm and repeated. This time the same problem, z=0 on the paneldue/web interface positioned the nozzle exactly 1.0mm above the bed. This makes me suspicious its something I am doing wrong.

The only time the value 1.0mm appears in my config is that I set a z-minimum to -1.0mm to give me the ability to jog down to determine my z-probe offset.

[dc42]

Bear in mind that if you have M501 in config.g and a config-override.g file, the G31 command in config.g may get overridden.

[DjDemonD]

Excellent, as always you've hit the nail square on the head. Yes the config_override.g value was 1.5 giving me the approximately 1.0mm discrepancy. Thank you.

[DjDemonD]

So when changing something which effects z probe offset, try a variety of values using G31 and then when you've got the right offset save it with m500?

[dc42]

@DjDemonD:

So when changing something which effects z probe offset, try a variety of values using G31 and then when you've got the right offset save it with m500?

Yes.