All problems are solved - and just completed a first print with the new Duet2. Thanks again to all who helped - I'm very grateful!

@droftarts My x- and y-axis homing problems are now solved. After reading the the stall detection and sensorless homing guide, I changed the speed settings in the G1 command lines homex.g and homey.g from F1800 to F4800 so that the homing speed is greater than the minimum F2400 that derives from the default stall detection threshold of 200 steps/second. I also commented out the lines associated with the second slow fine homing moves. Now, when I command home x or home y, the build platform moves quietly to the endstops and the platform stops as expected. Thanks so much for pointing me in the right direction

I have final question related to specifying a stall detection configuration using M915. I haven't yet added M915 line to my config.g. because the changes I made in the homex.g and homey.g seem to have solved my homing problems. I take this to mean that the default M915 settings do not need to be modified by adding a M915 line to config.g. Is this the right way to think about this, or would it better for me to add the M915 line to config.g? And if I add the line would you please confirm where it should be placed? I'm thinking it should follow the two M574 commands in the Endstops section of config.g?

Again thanks to all for your help.

Thank you all! One problem seems to be solved: I double checked to ensure the motor phases are correctly wired as recommended by @Phaedrux. That aspect of the wiring is OK. I then found one bad crimp on a wire inserted into one of the new z-axis connectors. I repaired it and verified that all the other connectors are sound. The z-axis now moves smoothly and quietly following issuance of the commands provided by @droftarts.

My remaining problem is that x- and y-axis homing is not yet working properly. When the build platform reaches either the x or y end stop after a home x or y command is issued, it hits the end and does not stop running until I hit the emergency stop. The error message, homing failed, is shown. I'm going to run through the motor stall detection configuration procedures in the link recommended by @JamesM above. Please LMK if you have other suggestions on what I might need to do to solve this one.

Thanks again everyone. I'm very grateful for the kind help you've provided.

@droftarts: slowing speed to F60 does not resolve the problem. I will recheck the wiring on the stepper motors. I've done a visual inspection to ensure that the wire are inserted into the correct pin locations. They all look correct. I'll double check each connector to make sure I don't have a bad crimp - I needed to re-wire/re-crimp all the connectors to make the transition and I may have missed one. I'll also try the suggestion of @elmoret after I check the integrity of the connectors.

@droftarts : I've just rechecked what happens when I send the command G1 H1 Y-10 X-10 F1800. There's no grinding and no error messages are shown. The problem appears to be with the z-axis, not x or y as I originally thought...

@droftarts: the z-axis grinds and does not move with the command G1 H2 Z10 F6000. I am also seeing the following error message: Warning: motor phase A may be disconnected reported by driver(s) 2.

@droftarts - there is no grinding with normal axis movements using the G-codes you provided. Movement is smooth and quiet.

I have installed a new Duet2 3D as an upgrade into a 3D printer that was built from a kit provided by our local makerspace. It’s a cartesian printer with 2 z-axis motors, and one each on x, y and e. All are NEMA 17 motors marked with the following information: 17HS5005-20B JUGTEK 174501.

My initial testing shows that the lcd display works and the bed and extruder heat as expected. The cooling fans also work as expected. On initialization, the IR bed sensor provides the expected 4 led flashes, z-probe measurements are indicated on the web interface and the numbers change when I move a white piece of paper under the probe.

Unfortunately, when I try to home the x- and y-axes the motors start with a terrible grinding/vibrating noise, and then the build plate moves smoothly toward home until it hits the endstop and resumes the grinding/vibrating noise until I kill the printer with the emergency stop button. If I let it run a bit longer, the printer stops and I receive the following error message: M112 M999 error homing failed.

Prior to installing the Duet2 into this printer I was using an Einsy Rambo controller. Sensorless homing worked without problems and the printer otherwise worked well.

I suspect the cause of my problems is that I’m not using the correct sensorless endstop settings but I’m not sure where to start resolving the problem. I’m wondering if anyone can help me resolve this problem?

I’m running RepRapFirmware for Duet 2 WiFi/Ethernet 2.05.1 (2020-02-09b1).

Thanks in advance for your suggestions.

My config files are as follows:

config.g:

; Configuration file for Duet WiFi (firmware version 2.03)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v2.1.8 on Thu Apr 09 2020 13:36:42 GMT-0400 (Eastern Daylight Time)

; General preferences
G90                                      ; send absolute coordinates...
M83                                      ; ...but relative extruder moves
M550 P"Nova300"                          ; set printer name

; Network
M552 S1                                  ; enable network
M586 P0 S1                               ; enable HTTP
M586 P1 S0                               ; disable FTP
M586 P2 S0                               ; disable Telnet

; Drives
M569 P0 S0                               ; physical drive 0 goes backwards
M569 P1 S1                               ; physical drive 1 goes forwards
M569 P2 S0                               ; physical drive 2 goes backwards
M569 P3 S1                               ; physical drive 3 goes forwards
M584 X0 Y1 Z2 E3                         ; set drive mapping
M350 X16 Y16 Z16 E16 I1                  ; configure microstepping with interpolation
M92 X80.00 Y80.00 Z1600.00 E146.50       ; 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 X1100 Y1100 Z1300 E1100 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 X300 Y300 Z350 S0                   ; set axis maxima

; Endstops
M574 X1 Y1 S3                            ; set endstops controlled by motor stall detection
M574 Z1 S2                               ; set endstops controlled by probe

; Z-Probe
M558 P1 H10 F120 T6000                   ; set Z probe type to unmodulated and the dive height + speeds
G31 P500 X0 Y-15 Z2.5                    ; set Z probe trigger value, offset and trigger height
M557 X25:275 Y25:275 S83                 ; define mesh grid

; Heaters
M305 P0 T100000 B3950 R4700              ; set thermistor + ADC parameters for heater 0
M143 H0 S120                             ; set temperature limit for heater 0 to 120C
M305 P1 T100000 B4725 C7.060000e-8 R4700 ; set thermistor + ADC parameters for heater 1
M143 H1 S280                             ; set temperature limit for heater 1 to 280C

; 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 H1 T45                ; set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on

; Tools
M563 P0 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

; Custom settings are not defined

homeall.g:

; homeall.g
; called to home all axes
;
; generated by RepRapFirmware Configuration Tool v2.1.8 on Thu Apr 09 2020 13:36:42 GMT-0400 (Eastern Daylight Time)
G91                     ; relative positioning
G1 H2 Z10 F6000         ; lift Z relative to current position
G1 H1 X-305 Y-305 F1800 ; move quickly to X and Y axis endstops and stop there (first pass)
G1 H2 X5 Y5 F6000       ; go back a few mm
G1 H1 X-305 Y-305 F360  ; move slowly to X and Y axis endstops once more (second pass)
G90                     ; absolute positioning
G1 X25 Y40 F6000        ; go to first bed probe point and home Z
G30                     ; home Z by probing the bed

; Uncomment the following lines to lift Z after probing
;G91                    ; relative positioning
;G1 Z10 F100            ; lift Z relative to current position
;G90                    ; absolute positioning

homex.g:

; homex.g
; called to home the X axis
;
; generated by RepRapFirmware Configuration Tool v2.1.8 on Thu Apr 09 2020 13:36:42 GMT-0400 (Eastern Daylight Time)
G91               ; relative positioning
G1 H2 Z10 F6000   ; lift Z relative to current position
G1 H1 X-305 F1800 ; move quickly to X axis endstop and stop there (first pass)
G1 H2 X5 F6000    ; go back a few mm
G1 H1 X-305 F360  ; move slowly to X axis endstop once more (second pass)
G1 H2 Z-10 F6000  ; lower Z again
G90               ; absolute positioning

homy.g

; homey.g
; called to home the Y axis
;
; generated by RepRapFirmware Configuration Tool v2.1.8 on Thu Apr 09 2020 13:36:42 GMT-0400 (Eastern Daylight Time)
G91               ; relative positioning
G1 H2 Z10 F6000   ; lift Z relative to current position
G1 H1 Y-305 F1800 ; move quickly to Y axis endstop and stop there (first pass)
G1 H2 Y5 F6000    ; go back a few mm
G1 H1 Y-305 F360  ; move slowly to Y axis endstop once more (second pass)
G1 H2 Z-10 F6000  ; lower Z again
G90               ; absolute positioning

homez.g

; homez.g
; called to home the Z axis
;
; generated by RepRapFirmware Configuration Tool v2.1.8 on Thu Apr 09 2020 13:36:42 GMT-0400 (Eastern Daylight Time)
G91              ; relative positioning
G1 H2 Z10 F6000  ; lift Z relative to current position
G90              ; absolute positioning
G1 X25 Y40 F6000 ; go to first probe point
G30              ; home Z by probing the bed

; Uncomment the following lines to lift Z after probing
;G91             ; relative positioning
;G1 Z10 F100     ; lift Z relative to current position
;G90             ; absolute positioning