Nema 17 - gearbox 1:5 - is this right for DUET 2 wifi?

  • Hi there,

    I've got this Nema 17 with gearbox 1:5 :

    Manufacturer Part Number: 17HS24-2104S-PG5
    Motor Type: Bipolar Stepper
    Step Angle: 0.35 deg
    Holding Torque without Gearbox: 65Ncm(
    Rated Current/phase: 2.1A
    Phase Resistance: 1.6ohms
    Voltage: 3.36V
    Inductance: 3.0mH ± 20%(1KHz)

    I'm trying to use it with my duet 2 wifi RRF 2.05.

    I'm getting really weird driver faults and sometimes short-grounds.. I've tried several main boards and expansion boards. I am not sure that's it the motors' fault but that my main suspect at the moment..

    is that the case?


    ; Configuration file for Duet WiFi (firmware version 1.21)
    ; executed by the firmware on start-up
    ; generated by RepRapFirmware Configuration Tool v2 on Thu May 02 2019 17:36:54 GMT+0300 
    ; General preferences
    G21 ; Work in millimetres
    G90 ; Send absolute coordinates
    M83 ; ...but relative extruder moves
    M555 P2 ; Set firmware compatibility to look like Marlin
    M568 	; tool mix ratios on
    ; Axis Limits
    M208 X0 Y0 Z0 S1               ; Set axis minima
    M208 X300 Y500 Z400 S0         ; Set axis maxima
    M564 S0 H0						; Allow axis move without home and outside boundries
    ; Network
    M552 S1                 ; enable network and acquire dynamic address via DHCP
    M586 P0 S1                                   ; Enable HTTP
    M586 P1 S0                                   ; Disable FTP
    M586 P2 S0                                   ; Disable Telnet
    ; Drives
    M569 P0 S1                    ; Drive X goes backwards
    M569 P1 S1                     ; Drive Y goes backwards
    M569 P2 S1                     ; Drive Z1 goes forwards
    M569 P3 S1                     ; Drive E0  FEEDER
    M569 P4 S1		       ; Drive Z2 (E1) forwards 
    M569 P5 S1			
    M569 P6 S1			
    M569 P7 S1			
    M569 P8 S1			
    M584 X0 Y1 Z2:4 E3:5:6:7:8      ;  Use E1 for Z axis 
    M350 X32 Y32 Z16:16 I1                      ; Configure microstepping with interpolation
    M350 E16 I1		;microstepping without interpolation 
    M92 X157.63 Y158.96 Z400:400 E115:180:115:315:8                    ; Set steps per mm
    M566 X1200 Y1200 Z24:24 E800                       ; Set maximum instantaneous speed changes (mm/min)
    M203 X30000 Y30000 Z600:600 E15000                 ; Set maximum speeds (mm/min)
    M201 X500 Y500 Z100:100 E600                     ; Set accelerations (mm/s^2)
    M906 X800 Y800 Z800:800 E2500:1000:2500:1050:1200 I30                  ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30                                                ; Set idle timeout
    ; Endstops
    M574 X1 Y1  S1 ; Set active high endstops
    ; Z-Probe
    M558 P0 H5 F120 T6000                        ; Disable Z probe but set dive height, probe speed and travel speed
    ; M557 X15:0 Y15:195 S20                       ; Define mesh grid
    ; Heaters
    M307 H0 B0 S1.00              			 ; Disable bang-bang mode for the bed heater and set PWM limit
    M307 H1 B0 S1.00             			  ; Disable bang-bang mode for the Hotend heater and set PWM limit
    M305 P0 T100000 B4138 C0 R4700 			; Set thermistor + ADC parameters for heater 0
    M307 H0 A107.3 C652.0 D0.6 S1.00   		; Bed PID 
    M143 H0 S120                 			  ; Set temperature limit for heater 0 to 120C 
    M305 P1 T100000 B4138 C0 R4700			 ; Set thermistor + ADC parameters for heater 1
    ; M307 H1 A284.4 C163.5 D1.5 S1.00 V12.1 B0   ; Hotend PID
    M307 H1 A105.3 C77.4 D1.5 S1.00 V12.1 B0 ; 
    ;M143 H1 S250                		  ; Set temperature limit for heater 1 to 120C
    M302 P1 S0				 ; Allow cold extrusion minimum of 0
    M140 H-1	; no bed heater
    ; Fans
    M106 P0 S1 I0 F500 H T45                     ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P3 S1 I0 F500 H1 T45                    ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    ; Tools
    M563 P0 D0:1              ;Define tool 0                 
    M563 P1 D2:3 		    ;Define tool 1 
    M563 P2 D0:1 			    ;Define tool 2 
    M563 P3 D0:2			    ;Define tool 3 
    M563 P4 D4 		    ;Define tool 4 
    M567 P0 E3:1				    ;MIXING RATIO tool 0
    M567 P1 E1.5:3			    ;MIXING RATIO tool 1
    M567 P2 E1.5:3			    ;MIXING RATIO tool 2
    M567 P3 E1:1			    ;MIXING RATIO tool 3
    G10 P0                                ;Set tool 0 axis offsets
    G10 P1 X0 Y0                            ;Set tool 1 axis offsets
    G10 P2 X-30 Y10                            ;Set tool 2 axis offsets
    G10 P4 X-100 y-2                            ;Set tool 4 axis offsets
    ; Automatic power saving
    M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; Set voltage thresholds and actions to run on power loss

    any thoughts?? I'm lost here...

  • administrators

    Are you using this motor for axes, extruder, or both?

    Short-to-ground error reports normally mean that you really do have a short to ground, or a short across one of the moor phases, or a short between phases, or (most likely) that the phase wires haven't been paired correctly. So I suggest that you unplug the motor from your Duet; then use a multimeter to measure the resistance between pairs of pins on that 4-pin connector. It should read 1.6 ohms between pins 1 and 2, 1.6 ohms between pins 3 and 4, infinity between other pairs of pins, and infinity between any pin and the motor casing.

  • @dc42

    it seems fine.
    just a thought, the step angle of the motor is 0.35deg.
    can that affect other factors than my steps per mm?


  • @CJ-BRAVO You have a planetary gearbox with ratio of 5+2/11:1. The gear ratio and step angle are irrational, so there are no settings that can yield a whole number of steps for any specific travel distance. The error for any given setting will depend on the value you use (0.35, 0.347, 0.3474, 0.347368, etc...) and the way that math is handled in the controller.

  • You're ultimately going to use the gear ratio to set steps per mm. 200 steps/rev x 5.18.. = 1036.36... steps/rev at the output. I can't tell from your steps/mm settings what you're using this motor for, but it doesn't matter. The irrationality of the gear ratio will probably not lead to any significant error.

  • If you're using both of them for the two Z steppers, I would change the construction to use only one stepper and connect the two spindles (or belt system) with a belt, because the gear has a backlash error of 1 degree each, wich means for a e.g. 20 teeth 40mm/360 = 0.11 mm error on every side, so it will be difficult to level the two Z axes.

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