1 of 3 Z stepper hot



  • Hi all,

    Experiencing a strange issue. One of the three Z stepper motors is running very hot to the touch when compared to the other two. Its a Core XY with Duex5. Z motors are connected to Deux5. Config below.

    ; Configuration file for Duet WiFi (firmware version 1.21)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool v2 on Wed May 01 2019 22:41:50 GMT+1000 (Australian Eastern Standard Time)

    ; General preferences
    M80 ; Turns on the ATX power supply
    G90 ; Send absolute coordinates...
    M83 ; ...but relative extruder moves

    M667 S1 ; Select CoreXY mode

    ; Network
    M550 P"RatRig" ; Set machine name
    M552 S1 ; Enable network
    M586 P0 S1 ; Enable HTTP
    M586 P1 S0 ; Disable FTP
    M586 P2 S0 ; Disable Telnet

    ; Drives
    M569 P0 S0 ; Drive 0 goes forwards - X
    M569 P1 S0 ; Drive 1 goes forwards - Y
    M569 P3 S1 ; Drive 3 goes forwards - E0
    M569 P5 S1 ; Drive 5 goes forwards - Z1
    M569 P6 S1 ; Drive 6 goes forwards - Z2
    M569 P7 S1 ; Drive 7 goes forwards - Z3
    M584 X0 Y1 Z5:6:7 E3 ; Set drive mapping
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X160 Y160 Z1600 E2725 ; Set steps per mm
    M203 X15000 Y15000 Z600 E3000 ; Set maximum speeds (mm/min)
    M201 X3000 Y3000 Z120 E720 ; Set maximum accelerations (mm/s^2)
    M566 X600 Y600 Z60 E40 ; Set maximum instantaneous (jerk) speed changes (mm/min)
    M906 X1500 Y1500 Z1000 E500 I5 ; Set motor currents (mA) and motor idle factor in per cent XY-17HM19-2004S E-MT-1702HS133A Z-1702E533G6-365E
    M84 S30 ; Set idle timeout

    ; Axis Limits
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X290 Y290 Z280 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y1 S0 ; Set active low endstops

    ; Z-Probe
    M574 Z1 S2 ; Set endstops controlled by probe
    M307 H7 A-1 C-1 D-1 ; Disable heater on PWM channel for BLTouch
    M558 P9 H3 F300 T6000 A3 R0.2 ; Set Z probe type to bltouch, dive height, probe speed, travel speed, probe up to 5 times, recovery time between probes
    G31 P25 X0 Y36 Z0.619 ; Set Z probe trigger value, offset and trigger height
    M557 X25:265 Y41:281 S80 ; Define mesh grid
    M671 X-40.0:145.0:330.0 Y40.0:370.0:40.0 ; z-lead screw positions at (-40,40), (145,370) and (330,40)

    ; Heaters
    M143 H0 S140 ; Disable bang-bang mode for the bed heater and set PWM limit to 140C
    M307 H0 A244.9 C316.6 D3.7 S1.00 V24.0 B0 ; PID tuned at 120C degrees
    M143 H1 S280 ; Set temperature limit for heater 1 to 280C
    M307 H1 A302.0 C140.4 D2.9 S1.00 V24.0 B0 ; PID tuned at 240C degrees

    ; Thermistors
    M305 P0 T100000 B3950 R4700 ; Set thermistor + ADC parameters for heater 0
    M305 P1 T100000 B4725 C7.060000e-8 R4700 ; Set thermistor + ADC parameters for heater 1
    M305 P103 X6 T100000 B3950 R4700 S"PSU SSR"
    M305 P104 X7 T100000 B3950 R4700 S"BED SSR"

    ; Fans
    M106 P3 S0 I0 H-1 C"Part Fan" ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off - PART fan
    M106 P4 S1 I0 H1 T40 C"Hotend Fan" ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on - EXTR fan
    M106 P5 S0 T50 H100:101:102 "MCU Fan" ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on - DUET fan

    ; Tools
    M563 P0 D0 H1 F3 S"Extruder 1" ; 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


  • administrators

    It could be due to a faulty motor, faulty wiring, or a faulty driver on the DueX5. Try swapping two of the Z motor cables over where they plug into the Duet (one of them being the cable to the motor that is getting hot), make the corresponding change to your M584 command, and see whether the same motor gets hot or the motor connected to the same driver gets hot.



  • also check the resistance of each coil of the stepper motor.
    it can happen on chinese stepper motor, that although they look alike, they are not.


  • Moderator

    If you send M906 by itself in the gcode console, what does it return?



  • So, checked resistance of all three Z motors. All within 2.0 and 2.2 Ohms, well within the 2.1Ohm spec (+-10%) per E3D's motor spec sheet.

    I moved the Z motors from drivers 5,6,7 on the Deux5 to 7,8,9. Same motor still super hot. Its the centre Z motor which has two linear rods on either side, and I am suspecting maybe there is a misalignment or too much friction that is causing the motor to heat up.

    Will continue investigating - I suspect it maybe mechanical.

    Thanks for the tips though 🙂


  • administrators

    Also check with your multimeter that there isn't a short between one of the motor phases and the case of the motor.



  • @dc42 No short on motor.



  • Issue identified. The other two z motors are mounted with an aluminium plate. The third one that gets really hot is mounted using a printed part. Clearly the heat of the other two is been transferred onto the alu plate.

    I proped a alu piece against the third motor, and it remained as cool as the other two.

    Learn something new every day 🙂


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