HOWTO Configure Z axis sensorless homing in homey.g file?

Phaedrux

How many Z motors do you have?

Your M574 command is using Z2 S4, for multiple motors, and your M913 command in your homing file has Z50:50 for two motors but your M584 command in the config.g file indicates you only have a single Z motor defined.

The Z moves in your homing file have speeds far beyond the Z axis speed limits you have set in M203 in config.g as well.

gloomyandy

@NO1NOKAO I don't think your current setting for Z is correct, you have:

M913 Z50:50                ; drop motor current to 50%

But from the docs for M913: https://docs.duet3d.com/en/User_manual/Reference/Gcodes#m913-set-motor-percentage-of-normal-current
"Example: If you have two motors on your Z axis, physically connected to Z and E0 stepper drivers, configured with M584 Z2:3, set M913 Z50, not M913 Z50:50"

NO1NOKAO

@gloomyandy Thanks for your help, both of the Z motors are wired to Drive2 as shown below.

And does that mean that I also need to rewrite the Z50:50 into Z50?

NO1NOKAO

This post is deleted!

NO1NOKAO

@Phaedrux
I have two Z motors, and both of them are connected to Drive2.
Does that mean the command M584 X0 Y1 Z2 U3 V4 is wrong？And what do I need to change?
For the Z axis driven by leadscrew, what's the best speed for it?12000 or just lower than 1000?
And I‘m grateful for your help.

Phaedrux

If both motors are wired to the same driver they are in effect just a single motor and this will make the stall detection even less likely to work.

If you have a free driver available you should move one of the Z motors to that driver, then you can likely get stall detection homing working as you have configured, but since you have a U and V axis I don't think that's an option for you.

Are endstops not an option?

NO1NOKAO

@Phaedrux Thanks buddy, I also have a duex5 panel and I also think endstop is a more convenient option. But if I choose endstop, I need to redesign the structure. So,I'll make a try first to wire the motors to different drivers and if plan A fails, the endstop will be the last way.

Phaedrux

If you have a duex, then you have some extra drivers to use, so you may be able to get stall detection working. I would suggest keeping the Z axis on the mainboard and moving perhaps the U and V to the Duex.

This would also let you use automatic tilt correction.

https://docs.duet3d.com/en/User_manual/Connecting_hardware/Z_probe_auto_levelling

NO1NOKAO

@Phaedrux I have tried to wire Z motors to different drivers(2 and 3), unfortunatly, the Z sensorless homing seems still failed. The following is my config.g file and homez.g file. If nothing is wrong, it is definitly the right time to take the endstop in consideration.

My config.g file

;Duet WiFi(固件版本3.3)的配置文件

; General preferences
G90                                ; Send absolute coordinates...
M83                                ; ...but relative extruder moves
M550 P"Y"                     ; Set machine name
M669 K0 X1:0:0:0:0 Y0:-1:0:0:0 Z0:0:1:0:0 U0:0:0:1:0 V0:0:0:0:1;Kinematics Profile for 5-axis (cartesian)

; network
M551 P"123456"                ; set password
M552 S1                              ; Enable network
M586 P0 S1                         ; Enable HTTP
M586 P1 S0                         ; Disable FTP
M586 P2 S0                         ; Disable Telnet
M587 S"A204_printer_04" P"junhua.zhao.04"  ;Set the Wi-Fi account and password

; Drive Mappings
M569 P0 S1                         ; Drive 0 goes forwards: X Axis
M569 P1 S1                         ; Drive 1 goes forwards: Y Axis
M569 P2 S1                         ; Drive 2 goes forwards: Z1 motor
M569 P3 S1                         ; Drive 3 goes forwards: Z2 motor
M569 P4 S1                         ; Drive 4 goes forwards: U Axis
M569 P5 S0                         ; Drive 5 goes backwards: V Axis
M584 X0 Y1 Z2:3 U4 V5                ; My Driver Mapping

;Microstepping 
M350 X16 Y16 Z16 U16 V16 I1        ; Configure microstepping with interpolation
M92 X100.00 Y100.00 Z400.00 U26.667 V35.556          ; Set steps per mm and steps per degree

;Speed
M566 X480.00 Y480.00 Z24.00 U480.00 V480.00 P1        ; Set maximum instantaneous speed changes (mm/min)
M203 X12000.00 Y12000.00 Z750.00 U5000.00 V12000.00     ;  Set maximum speeds (mm/min)
M201 X1000.00 Y1000.00 Z1000.00 U1000.00 V1000.00       ; Set accelerations (mm/s^2)
M906 X620.00 Y620.00 Z560.00 U1300.00 V1300.00 I10           ; Set motor currents (mA) and motor idle factor in percent
M84 S30                            ; Set idle timeout

; Axis Limit
M208 X-125:126   Y-92.3:50  Z125:-1 U-200:200 V-12000:12000                   ; Centre of the rotating bed is set to origin 0,0
M564 H0;                           ;allow unhomed movement


; Endstops for each Axis
M574 X1 S3                         ;Set endstops controlled by motor load detection
M574 Y1 S3                         ;Set endstops controlled by motor load detection
M574 Z2 S4                         ;configure sensorless endstop for high end on Z (Detected by two motors)

; Stallgaurd Sensitivy
M915 X S3 F0 H400 R1		       ; Set X axis Sensitivity
M915 Y S3 F0 H400 R1		       ; Set y axis Sensitivity
M915 Z S3 F0 H400 R1		       ; Set z axis Sensitivity


; Z-Probe (manual)
M558 P0 H15 F120 T6000             ; disable Z probe but set dive height, probe speed and travel speed


; Heatbed Heaters and Thermistor Bed
M140 H-1                           ; Disable heated bed

; Tool
M950 P0 C"Fan0" Q250				; creat tool P0

My homez.g file

; homeZ.g
; 用于归零Z轴
;
; 由RepRapFirmware配置工具生成 版本V3.3.10 时间 Tue Nov 01 2022 15:02:12 GMT+0800 (中国标准时间)

M400                        ; Wait for current moves to finish
M913 Z50                    ; drop motor current to 50%
M400

G91                         ; relative positioning
;G1 H2 Y100 F10000           ; lift Y away
G1 H1 Z110 F700           ; move quickly to Z axis endstop and stop there (first pass)
G1 H2 Z-5 F700            ; go back a few mm
G1 H2 Z-115 F700           ; move Z axis to the mid

G90                         ; absolute positioning
M400
M913 Z100:100              ; return current to 100%
M400

Phaedrux

@NO1NOKAO said in HOWTO Configure Z axis sensorless homing in homey.g file?:

M208 X-125:126 Y-92.3:50 Z125:-1 U-200:200 V-12000:12000

Your minimum and maximum for the Z axis seem backwards in this command.

@NO1NOKAO said in HOWTO Configure Z axis sensorless homing in homey.g file?:

G1 H1 Z110 F700

How fast can you reliably move the Z axis before it stalls on it's own?

@NO1NOKAO said in HOWTO Configure Z axis sensorless homing in homey.g file?:

M913 Z50

How low can you set the Z current before the Z axis just stalls on it's own?

Try and find the minimum current and maximum speed you can move Z at, and then try and use the stall detection homing again.

NO1NOKAO

@Phaedrux It worked , I droped the current to 30% and increased the speed to 1000 and the feedback surprised me a lot. It's so kind of you to offer me so much valuable advice.