@dc42 said in z axis random reverse homing:
I don't understand...
-wires checked ok
-switched z motors to x and y connectors they work
-plugged x motor in to z plug plus jumpers in the unused z connector it work ( switched between z1 and z2 connectors +jumpers ---all ok)
-plugged x and y motors in to both z connectors ----just one work when i home Z (no sense!!)
-plugged both z motors in to both z connectors homing z -----1 motor go fast 1 motor go slow (O.o)
NOW:
i have reduced M203 in config.g for Z to 900
i have reduced in homez.g and in homeall.g F to 250 for z

ALL WORKS

thanks for the help if other strange things happen I will let you know

i'have changed using y motor in to z plug...home z no movement

M120
G91
G1 Z10 F6000
M121

Error: G0/G1: insufficient axes homed
Error: Pop(): stack underflow!

done...but i think z drivers no longer work.
z motors vibrates and z axis don't move

M906 X800 Y800 Z1000 E1000 I30 config.g
G1 S1 Z-400 F900 ; move Z down until the switch triggers homez.g

Help...

Hi and thx
-2 z motors connected using double slot of duet wifi EDIT---(parallel i think)

• 800mA M906
  -400 steps/mm EDIT--- 16 microstep interpolated
  -100 acceleration in M201
  -12,2 V EDIT---PSU
  i'have used your excel.
  i'll change to 24v but for now 12,2V

The SL42STH40-1684A motor specs are:

Step Angle: 1.8°
Step Angle Accuracy: ±5% (full step, no load)
Voltage: 2.8V
Current per phase: 1.68A
Resistance per phase: 1.65Ω
Resistance accuracy: ±10%
Inductance per phase: 3.2mH
Inductance accuracy: ±20%
Holding torque: 3.6 Kg·cm (0.4 N·m)
Moment of inertia: 54 g/cm^2
Weight: 0.28 kg
Orientation torque: 150 g/cm
Length: 40 mm
Temperature rise: 80°C max (rated current, 2 phases on)
Ambient temperature: -20°C ~ +50°C
Insulation resistance: 100MΩ min, 500VDC
Shaft radial play: 0.02 mm max (450g load)
Shaft axial play: 0.08 mm max (450g load)
Max. radial force: 28N (20mm from the flange)
Max. axial force: 10N

hi all and sorry for my bad english.
That's the problem:sometimes , randomly, my z axis homing in reverse direction.
I have core xy and my home for z is on the top

config.g :
; Drives
M569 P0 S0 ; Drive 0 goes forwards
M569 P1 S0 ; Drive 1 goes forwards
M569 P2 S1 ; Drive 2 goes forwards
M569 P3 S1 ; Drive 3 goes forwards
homeall.g:
G91 ; relative positioning
G1 Z5 F6000 S2 ; lift Z relative to current position
G1 S1 X-360 Y-340 F1800 ; move quickly to X or Y endstop and stop there (first pass)
G1 S1 X-360 ; home X axis
G1 S1 Y-340 ; home Y axis
G1 X5 Y5 F6000 ; go back a few mm
G1 S1 X-360 F360 ; move slowly to X axis endstop once more (second pass)
G1 S1 Y-340 ; then move slowly to Y axis endstop
G1 S1 Z-400 F1800 S1 ; move Z down stopping at the endstop
G90 ; absolute positioning
G92 Z0 ; set new Z position
;G1 Z5 F100 S2 ; uncomment this line to lift the nozzle after homing
homez.g:
G91 ; relative positioning
G1 Z5 F6000 S2 ; lift Z relative to current position
G1 S1 Z-400 F1800 ; move Z down until the switch triggers
G92 Z0 ; set Z position to trigger height

; Uncomment the following lines to lift Z after probing
;G91 ; relative positioning
;G1 Z5 F100 S2 ; lift Z relative to current position
;G90 ; absolute positioning

any idea?
thx for suggestion