@jay_s_uk Thank you! I tried B4092 but it is still off by exactly 20 degrees Celsius after re-tuning. I think I just need to contact the manufacturer of the bed and ask them which thermistor they used.

@dougal1957 That was exactly the issue. I looked at the top of the lead screw and it has a 4 start. I changed Z steps per mm to 800 and now it is perfect.

Ignore this one please. I can't delete it. I rephrased the posted a better question here:
https://forum.duet3d.com/post/230220

@droftarts Thanks, this is exactly what I was looking for.

@o_lampe Thanks, that was a typo, but the question still remains, how do you change the home offset to compensate for the print head being offset?

Ignore this one please. I can't delete it. I rephrased the posted a better question here:
https://forum.duet3d.com/post/230220

I have a 6HC and I'm almost done configuring this custom printer. I have a 330x330mm build plate and the print head is not center on the bed when I go to X=115 Y=115. I have a lot of experience with Marlin and I would adjust the HOME OFFSET to fix this issue (M206). I can't find a similar command in RRF. The closest thing I found was a tool offset but I don't believe that is going to achieve what I'm after. Can someone point me in the right direction with this one?

Here is my config.g file

; Configuration file for Duet 3 (firmware version 3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.2.3 on Fri May 07 2021 11:46:55 GMT-0500 (Central Daylight Time)

; General preferences
G90                                                ; send absolute coordinates...
M83                                                ; ...but relative extruder moves
M550 P"Duet 3"                                     ; set printer name

; Drives
M569 P0.0 S0                                       ; physical drive 0.0 goes backwards
M569 P0.1 S1                                       ; physical drive 0.1 goes forwards
M569 P0.2 S1                                       ; physical drive 0.2 goes forwards
M569 P0.4 S0                                       ; physical drive 0.4 goes backwards
M569 P0.5 S1                                       ; physical drive 0.5 goes forwards
M584 X0.0 Y0.1 Z0.2:0.3 E0.4:0.5                   ; set drive mapping
M350 X16 Y16 Z16 E16:16 I1                         ; configure microstepping with interpolation
M92 X160.00 Y160.00 Z800.00 E420.00:420.00         ; set steps per mm
M566 X900.00 Y900.00 Z60.00 E120.00:120.00         ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00:1200.00    ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00:250.00         ; set accelerations (mm/s^2)
M906 X800 Y800 Z800 E800:800 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 X330 Y330 Z400 S0                             ; set axis maxima

; Endstops
M574 X1 S1 P"!io0.in"                              ; configure active-high endstop for low end on X via pin !io0.in
M574 Y1 S1 P"!io1.in"                              ; configure active-high endstop for low end on Y via pin !io1.in
M574 Z1 S2                                         ; configure Z-probe endstop for low end on Z

; Z-Probe
M950 S0 C"io7.out"                                 ; create servo pin 0 for BLTouch
M558 P9 C"^io7.in" H5 F120 T6000                   ; set Z probe type to bltouch and the dive height + speeds
G31 P500 X21.73 Y30.22 Z2.5                        ; set Z probe trigger value, offset and trigger height
M557 X15:215 Y15:195 S20                           ; define mesh grid

; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B4116.93    ; 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
M307 H0 B0 S1.00                                   ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0                                            ; map heated bed to heater 0
M143 H0 S120                                       ; set temperature limit for heater 0 to 120C
M307 H0 R0.126 C377.1 D2.42 S1.00 V23.9		       ; pid tuning settings
M308 S1 P"temp1" Y"thermistor" T100000 B3950       ; 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
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
M307 H1 R2.275 C212.6 D10.63 S1.00 V23.9

; 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 H-1                                     ; set fan 1 value. Thermostatic control is turned off

; Tools
M563 P0 D0 H1 F0                                   ; define tool 0
G10 P0 X0 Y80 Z0                                    ; set tool 0 axis offsets
G10 P0 R0 S0                                       ; set initial tool 0 active and standby temperatures to 0C
M563 P1 D1 F0                                      ; define tool 1
G10 P1 X0 Y80 Z0                                    ; set tool 1 axis offsets
G10 P1 R0 S0                                       ; set initial tool 1 active and standby temperatures to 0C

; Custom settings are not defined

; Miscellaneous
M575 P1 S1 B57600                                  ; enable support for PanelDue
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss

Thanks much

Hello,
I am working on a new custom build with a 6HC board. I did my initial RRF config using the RRF config tool. Everything is working great but the tool offset doesn't appear to be changing the offset. I have a 330x330mm bed. To find the offset, I am putting painters tape all over the bed, used a straight edge from corner to corner and a marker to find the exact center of the bed (where the X crosses), then issuing "G1 X115 Y115" to have the printer go to where it thinks the center is. I have two extruders so the 2nd extruder is set up as P1. X was somewhat good but Y was way off so I set the Y offset to -80 just to see if it works and get it in the general area. When I change the offset in config.g and restart the board, and re-issue the "G1 X115 Y115" command, it goes exactly to where it was before and it appears changing the tool offset is not affecting the location of the print head. I tried changing it to 80 instead of -80 and tried putting the settings in both P0 and P1, but these didn't work. Any ideas?

Here is my config.g file:

; Configuration file for Duet 3 (firmware version 3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.2.3 on Fri May 07 2021 11:46:55 GMT-0500 (Central Daylight Time)

; General preferences
G90                                                ; send absolute coordinates...
M83                                                ; ...but relative extruder moves
M550 P"Duet 3"                                     ; set printer name

; Drives
M569 P0.0 S0                                       ; physical drive 0.0 goes backwards
M569 P0.1 S1                                       ; physical drive 0.1 goes forwards
M569 P0.2 S1                                       ; physical drive 0.2 goes forwards
M569 P0.4 S0                                       ; physical drive 0.4 goes backwards
M569 P0.5 S1                                       ; physical drive 0.5 goes forwards
M584 X0.0 Y0.1 Z0.2:0.3 E0.4:0.5                   ; set drive mapping
M350 X16 Y16 Z16 E16:16 I1                         ; configure microstepping with interpolation
M92 X160.00 Y160.00 Z800.00 E420.00:420.00         ; set steps per mm
M566 X900.00 Y900.00 Z60.00 E120.00:120.00         ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00:1200.00    ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00:250.00         ; set accelerations (mm/s^2)
M906 X800 Y800 Z800 E800:800 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 X330 Y330 Z400 S0                             ; set axis maxima

; Endstops
M574 X1 S1 P"!io0.in"                              ; configure active-high endstop for low end on X via pin !io0.in
M574 Y1 S1 P"!io1.in"                              ; configure active-high endstop for low end on Y via pin !io1.in
M574 Z1 S2                                         ; configure Z-probe endstop for low end on Z

; Z-Probe
M950 S0 C"io7.out"                                 ; create servo pin 0 for BLTouch
M558 P9 C"^io7.in" H5 F120 T6000                   ; set Z probe type to bltouch and the dive height + speeds
G31 P500 X21.73 Y30.22 Z2.5                        ; set Z probe trigger value, offset and trigger height
M557 X15:215 Y15:195 S20                           ; define mesh grid

; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B4116.93    ; 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
M307 H0 B0 S1.00                                   ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0                                            ; map heated bed to heater 0
M143 H0 S120                                       ; set temperature limit for heater 0 to 120C
M307 H0 R0.126 C377.1 D2.42 S1.00 V23.9		       ; pid tuning settings
M308 S1 P"temp1" Y"thermistor" T100000 B3950       ; 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
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
M307 H1 R2.275 C212.6 D10.63 S1.00 V23.9

; 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 H-1                                     ; set fan 1 value. Thermostatic control is turned off

; Tools
M563 P0 D0 H1 F0                                   ; define tool 0
G10 P0 X0 Y-80 Z0                                    ; set tool 0 axis offsets
G10 P0 R0 S0                                       ; set initial tool 0 active and standby temperatures to 0C
M563 P1 D1 F0                                      ; define tool 1
G10 P1 X0 Y80 Z0                                    ; set tool 1 axis offsets
G10 P1 R0 S0                                       ; set initial tool 1 active and standby temperatures to 0C

; Custom settings are not defined

; Miscellaneous
M575 P1 S1 B57600                                  ; enable support for PanelDue
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss

Here is a photo of the printer at X115 Y115:

Thanks mucc

@dc42 Thanks! I put the glass bed on before the tuning exercise so the temp of the surface of the bed matches what is displayed in the Duet3d WebUI. It is less than a degree off at both 60 degrees Celsius and 110 degrees Celsius, within the error margin of my thermometer. I am very happy with the results .

I figured out the print bed temperature issue in case anyone else runs into this. I put a thermometer probe on the surface of the bed. I performed a PID auto-tune on the print bed and heated the bed to 115 degrees Celsius (using the thermometer to measure the temperature) since I believe 110 degrees is the highest I would set the bed for printing ABS. I turned off the printer and immediately unplugged the thermistor for the bed and hooked it up to an ohm meter. I watched the thermometer and as the temperature fell. When the temperature reached 110.0 degrees Celsius, I looked at the ohm meter and recorded the thermistor resistance at that temperature. I wanted to record another 2 more temperatures so I took another reading at 60 degrees Celsius and a final one when the bed got to room temperature. I plugged those values into the Steinhart-hart equation and got a beta value of 4116.93. I then updated my M308 command to this (the T value is the resistance of the thermistor at 25 degrees Celsius):
M308 S0 P"temp0" Y"thermistor" T95600 B4116.93 C0

After saving the config and rebooting the board, the bed temperature displayed in the Duet3d WebUI is nearly perfect to its actual temperature.

@dc42 Thanks for the reply! The bed is aluminum. I hooked up a multimeter to the thermistor and brought the build plate to 25.0 degrees Celsius (measuring with an accurate infrared thermometer). The resistance was 95,600 ohms at 25.0 degrees Celsius. I changed my T value to 95600. After changing the value I measured the temperature of the bed which was still exactly 25.0 degrees Celsius. At that temperature, the duet web UI showed a temperature of 27.6 degrees Celsius so it looks like it's still off by a few degrees.

I contacted the manufacturer and they couldn't provide more information on the Steinhart–Hart values. They just re-iterated the fact that it's a "Creality CR-10 replacement bed."

Here is a picture:

@dougal1957 That was exactly the issue. I looked at the top of the lead screw and it has a 4 start. I changed Z steps per mm to 800 and now it is perfect.

@jay_s_uk Thank you! I tried B4092 but it is still off by exactly 20 degrees Celsius after re-tuning. I think I just need to contact the manufacturer of the bed and ask them which thermistor they used.