@Phaedrux, same bad behavior... G28 X is the problem.

The below sometimes solves it, but it's not repeatable... Appreciate your thoughts.

Without lines 9,10,11 in there, the X-axis just refuses to engage the end-stop.

G91               ; relative positioning
G1 H2 Z5 F6000    ; lift Z relative to current position
G1 H1 X-325 F1800 ; move quickly to X axis endstop and stop there (first pass)

G1 X10 F6000       ; go back a few mm

G1 H1 X-325 F360  ;try fine-homing (fails)

G1 H1 Y-0.1 F360  ; jiggle the y-axis one way
G1 H1 X-325 F360  ; try to fine home X axis again (seems to always succeed)
G1 H1 Y0.1 F360  ;  jiggle the y-axis back

G1 H2 Z-5 F6000   ; lower Z again
G90               ; absolute positioning

Hey there @Herve_Smith,

Thanks for the suggestion, I tried this out. My printer fails exactly in the same place, the fine-homing move. It just stops somewhere along the axis (does not show activation of XStop in object-model, light on the board does not light up as the circuit remains closed, and it then merrily executes the next line...

G1 H1 X-455 F360     ; Slowly move to the X axis endstop once more (Fine Adjustment)

@deckingman - good idea I did already swap in other X end-stop switches to no avail. Given the switches have a 100% success rate in catching the rough-passes, I can't see how it's anything electro-mechanical at this point.

To your other point, the system is failing to execute the latter X-move when both axes have just been successfully homed and positioned at X,Y:10,10. It fails when only one axis is being asked to move, namely

G1 H1 X-100 F360

So...what I'm finding is (and I fully appreciate that this looks odd) that if I repeat the request multiple times in a row, while splitting up the drive it's addressing, seems to be catching the error every time (I've done 30 home cycles and it's 'jerky' but it works.

G1 H1 X-100 F360
G1 H1 Y-100 F360
G1 H1 X-100 F360
G1 H1 Y-100 F360
G1 H1 X-100 F360
...         

@Phaedrux , good idea I've hosted them here, along with videos showing some wierd behaviour - more on that below... Google Drive

@deckingman - 100% agree. Why does executing the same command not elicit the same response? I 'feel like' the machine is holding onto a guess of where 0,0 is after rough homing and is trying to predict it rather than use the stops.

Retyping the line didn't make a difference, nor did the use of M400 between commands.

What I discovered this evening that does seem to 'work' is the following, and I can't make heads or tails of it...

1. Rough pass X,Y similtaneously (Always triggers the stops):

G1 H1 X-425 Y-365 F1800 ; move quickly to X or Y endstop and stop there (first pass)
G1 H1 X-425             ; home X axis
G1 H1 Y-365             ; home Y axis

2. Trying to fine tune the X position (Always fails):

G1 H1 X-100 F360        ; move slowly to X axis endstop once more (second pass)

3. Going for a Y home (Always triggers):

G1 H1 Y-365             ; then move slowly to Y axis endstop

4. Then doing X again (mostly triggers):

G1 H1 X-100 F360        ; move slowly to X axis endstop once more (second pass)

5. Doing X again-again (99% sure this is capturing all)

G1 H1 X-100 F360        ; move slowly to X axis endstop once more (second pass)

@Phaedrux

Apologies I meant to add to this earlier. I've checked all the grubscrews, and they're rock-solid.

I'm frankly amazed how much torque the NEMA17's have in this COREXY configuration. I've tried to stall them by holding onto the carriage but they pull right through.

@Phaedrux - great catch, thank you for the U-axis catch.

• I added a dwell (G4 P2000) between each command so I could see what was being done and also reported, and I've also done as you say with the console.
• The issue is definitely the second move, which ends abruptly, and seemingly randomly.
  -- H1 X-100 F360

@deckingman - Thank you for weighing in, I really appreciate it.

• I've definitely changed the H4 back to H1 (Checked it for 1 vs I, and yep I'm good there too)
• I've checked the switches for hysteresis, and they're all lightning quick (I've just been manually tripping them to fool the homing process when the head's nowhere near. Wherever the head is on the bed, it acts the same way
• I've been watching the 'object model' to see if/when the stops get triggered, and they (X,Y) DO for the first move, but only the Y gets triggered for the second.
• I've swapped the X and Y stops on the board and remapped them, and I have the same behavior.
• I've just checked the wiring again, and it all looks solid.

m122
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 3.4.4 (2022-10-20 16:17:41) running on Duet WiFi 1.0 or 1.01 + DueX5
Board ID: 08D6M-95AK9-NG3SD-6JKDJ-3S46J-96R9X
Used output buffers: 1 of 26 (15 max)
=== RTOS ===
Static ram: 23860
Dynamic ram: 76532 of which 0 recycled
Never used RAM 11616, free system stack 124 words
Tasks: NETWORK(ready,14.0%,237) HEAT(notifyWait,0.1%,333) Move(notifyWait,0.0%,306) DUEX(notifyWait,0.0%,24) MAIN(running,85.8%,438) IDLE(ready,0.2%,30), total 100.0%
Owned mutexes: WiFi(NETWORK)
=== Platform ===
Last reset 00:10:14 ago, cause: power up
Last software reset at 2022-11-12 23:57, reason: User, GCodes spinning, available RAM 11688, slot 1
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0041f000 BFAR 0xe000ed38 SP 0x00000000 Task MAIN Freestk 0 n/a
Error status: 0x00
Aux0 errors 0,0,0
Step timer max interval 0
MCU temperature: min 10.0, current 19.5, max 19.9
Supply voltage: min 24.4, current 24.6, max 24.8, under voltage events: 0, over voltage events: 0, power good: yes
Heap OK, handles allocated/used 0/0, heap memory allocated/used/recyclable 0/0/0, gc cycles 0
Events: 0 queued, 0 completed
Driver 0: standstill, SG min 0
Driver 1: standstill, SG min 0
Driver 2: standstill, SG min 0
Driver 3: standstill, SG min n/a
Driver 4: standstill, SG min n/a
Driver 5: standstill, SG min n/a
Driver 6: standstill, SG min n/a
Driver 7: standstill, SG min n/a
Driver 8: standstill, SG min n/a
Driver 9: standstill, SG min n/a
Driver 10:
Driver 11:
Date/time: 2022-11-13 12:20:29
Cache data hit count 4294967295
Slowest loop: 11.24ms; fastest: 0.17ms
I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0, resets 0
=== Storage ===
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest read time 1.2ms, write time 0.9ms, max retries 0
=== Move ===
DMs created 83, segments created 3, maxWait 214299ms, bed compensation in use: none, comp offset 0.000
=== MainDDARing ===
Scheduled moves 33, completed 33, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 13], CDDA state -1
=== AuxDDARing ===
Scheduled moves 0, completed 0, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 0], CDDA state -1
=== Heat ===
Bed heaters 0 -1 -1 -1, chamber heaters -1 -1 -1 -1, ordering errs 0
Heater 0 is on, I-accum = 0.0
=== GCodes ===
Segments left: 0
Movement lock held by null
HTTP is idle in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
LCD is idle in state(s) 0
Daemon is idle in state(s) 0
Autopause is idle in state(s) 0
Code queue is empty
=== DueX ===
Read count 1, 0.10 reads/min
=== Network ===
Slowest loop: 29.24ms; fastest: 0.00ms
Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0)
HTTP sessions: 1 of 8
= WiFi =
Network state is active
WiFi module is connected to access point
Failed messages: pending 0, notready 0, noresp 0
WiFi firmware version 1.27
WiFi MAC address 5c:cf:7f:2c:27:b3
WiFi Vcc 3.34, reset reason Turned on by main processor
WiFi flash size 4194304, free heap 24056
WiFi IP address 192.168.1.142
WiFi signal strength -46dBm, mode 802.11n, reconnections 0, sleep mode modem
Clock register 00002002
Socket states: 0 0 0 0 0 0 0 0

@Phaedrux

; Configuration file for Duet WiFi (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.14 on Sun Nov 06 2022 15:34:07 GMT+0000 (Greenwich Mean Time)

; General preferences
M575 P1 S1 B57600 ; enable support for PanelDue
G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"My Printer" ; set printer name
M669 K1 ; select CoreXY mode

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

; Drives
M569 P0 S0 ;X physical drive 0 goes backwards
M569 P1 S0 ;Y physical drive 1 goes backwards
M569 P2 S0 ;Y physical drive 2 goes backwards
M569 P3 S0 ;E0 physical drive 3 goes backwards
M569 P4 S0 ;E1 physical drive 4 goes backwards
M569 P5 S0 ;U physical drive 5 goes backwards

M584 X0 Y1 Z2 E3:4 U5 ; set drive mapping
M671 X-0.0:305.0:305.0:0.0 Y0.0:0.0:205.0:205.0 ; Z leadscrews are at (0,0),(305,0),(305,205),(0,205)

M350 X16 Y16 Z16 E16:16 U16 I1 ; configure microstepping with interpolation
M92 X200.00 Y200.00 Z1600.00 E30.578 E5273.00:5273.00 ; set steps per mm
M566 X900.00 Y900.00 Z60.00 U50 E120.00:120.00 ; set maximum instantaneous speed changes (mm/min)
M203 X3600.00 Y3600.00 Z180.00 U9000 E1200.00:1200.00 ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 U800 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
M906 U670 I60 ; set motor currents (mA) and motor idle factor in per cent
M84 S20 ; Set idle timeout

; Axis Limits
M208 X0 Y0 Z0 U0 S1 ; set axis minima
M208 X320 Y260 Z200 U80 S0 ; set axis maxima

; Endstops
M574 X1 S1 P"xstop" ; configure switch-type (e.g. microswitch) endstop for low end on X via pin xstop
M574 Y1 S1 P"ystop" ; configure switch-type (e.g. microswitch) endstop for low end on Y via pin ystop
M574 U1 S1 P"e0stop" ; configure switch-type (e.g. microswitch) endstop for low end on Y via pin ystop
M574 Z1 S2 ; configure Z-probe endstop for low end on Z

; Z-Probe
M558 P1 C"zprobe.in" H3 F120 T5000 ; set Z probe type to unmodulated and the dive height + speeds
G31 P500 X0 Y-42 Z-8.5 ; set Z probe trigger value, offset and trigger height
M557 X40:260 Y40:160 S20 ; define mesh grid

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0

M307 H0 R0.469 K0.337:0.000 D2.38 E1.35 S1.00 B0 ; TESTED 6TH NOV
;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 S90 ; set temperature limit for heater 0 to 90C

M308 S1 P"spi.cs1" Y"rtd-max31865" ; create sensor number 1 as a PT100 sensor in the first position on the Duet 2 daughter board connector
M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S220 ; set temperature limit for heater 1 to 220C

M308 S2 P"spi.cs2" Y"rtd-max31865" ; create sensor number 1 as a PT100 sensor in the first position on the Duet 2 daughter board connector
M950 H2 C"e1heat" T2 ; create nozzle heater output on e1heat and map it to sensor 2
M307 H2 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H2 S220 ; set temperature limit for heater 2 to 220C

; Fans
M950 F0 C"fan0" Q500 ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H1 T30 ; set fan 0 value. Thermostatic control is turned on
M950 F1 C"fan1" Q500 ; create fan 1 on pin fan1 and set its frequency
M106 P1 S0 H2 T30 ; set fan 1 value. Thermostatic control is turned on
M950 F2 C"fan2" Q500 ; create fan 2 on pin fan2 and set its frequency
M106 P2 S0 H-1 ; set fan 2 value. Thermostatic control is turned off
M950 F3 C"duex.fan3" Q500 ; create fan 3 on pin duex.fan3 and set its frequency
M106 P3 S0 H-1 ; set fan 3 value. Thermostatic control is turned off

;HEATER FAULT HANDLING

M570 H0 P5 T15 ; E3D Varipower heated bed with 180s to reach 60deg -check
M570 H1 P5 T15 ; Left extruder (T0)
M570 H2 p5 T15 ; Right extruder (T1)

; Tools
M563 P0 S"LEFT" D0 H1 F0:3:2 ; 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
M563 P1 S"RIGHT" D1 H2 F1:2:3 ; define tool 1
G10 P1 X0 Y0 Z0 ; set tool 1 axis offsets
G10 P1 R0 S0 ; set initial tool 1 active and standby temperatures to 0C

; Custom settings
M555 P2 ; Set output to look like Marlin
M556 S78 X0 Y0 Z0 ; Axis SKEW compensation here

; *** Pressure Advance ; Compensates for elasticity of extrusion system
; ; extrusion_speed = requested_extrusion_speed + (S * current_extruder_acceleration)
; ; The more the system can lag, the greater the compensation required
; ; Typically S = 0.05 for a direct extruder
; ; S = 0.10 for a Bowden with a 400 mm tube
;M572 D0 S0.05 ; Set pressure advance coefficient for tool 0 (Left extruder)
;M572 D1 S0.05 ; Set pressure advance coefficient for tool 1 (Right extruder)

; Miscellaneous
M501 ; load saved parameters from non-volatile memory
M140 S0 ;CORRECT BED ISSUES
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss

;----> all below commented out, need?
; *** Load bed height map and activate bed compensation
;G29 S1 ; Load the height map from the last time you used G29 to probe the bed.
; The default height map file is /sys/heightmap.csv.
; Comment this out if you are not using automated mesh leveling.
;
;M376 H10 ; Taper off bed compensation taper
; Hnnn Height (mm) over which to taper off the bed compensation
; Setting H0 leaves compensation always on

; Set bed temperature (to get rid of the -273C reading

M98 P"config.g"
HTTP is enabled on port 80
FTP is disabled
TELNET is disabled
Warning: Heater 2 predicted maximum temperature at full power is 394°C
Error: Heater 3 not found
Error: Heater 4 not found
Error: Heater 5 not found
Error: Heater 6 not found
Error: Heater 7 not found

Hi @Phaedrux

Thanks for the speedy reply!

Homing just X-axis behaves in the same way.

1. Rough homes OK
2. Move away to e.g. X10 OK
3. Fine homing: stops somewhere between X10 and X0

Thanks RE H4, will change it back.

-X is to the left, -Y is to the front