Dual Z motor setup issue, one motor stalls, other turns

greecher · 28 Sept 2017, 06:28

So i'm finishing up the wiring on my corexy, and all is going well except when I tried to run the dual Z motor setup, as only 1 motor will turn at a time, with the other one stalling. I can start the other turning by giving a little assist, but then the other one stalls, only one will turn, the other just stalls. I have validate that they turn in the same direction (still may need to reverse them later with S1/S0 motor setup). I have tried running the motor current up from the default 800ma up to 1.6amp, with the thinking being maybe not enough current, but this didn't help. I also did a full pin swapping around, partially to make them turn in the same direction, but also to see if it had an effect on getting both to turn. As a reference, X/Y work with no issue (haven't hooked up E0 yet).

Motor Specs:
Step angle: 1.8 deg (200 steps per rev)
Number of phase: 2
Rotor inertia: 57gcm^2
Mass: 0.3kg
Resolution in full step mode: 0.04mm per step
Rated Voltage: 12V
Rated Current: 0.48A
Resistance per phase: 25Ohm +/- 10%
Inductance per phase: 50mH +/- 20%
Holding torque: 420mNm
Thrust (full step mode): 8kg (at 300pps)

my config.g (just top portion):
; Configuration file for Duet WiFi (firmware version 1.17)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool on Fri Sep 22 2017 16:10:34 GMT-0700 (US Mountain Standard Time)

; General preferences
M111 S0 ; Debugging off
G21 ; Work in millimetres
G90 ; Send absolute coordinates…
M83 ; ...but relative extruder moves
M555 P2 ; Set firmware compatibility to look like marlin output

M667 S1 ; Select CoreXY mode
M208 X0 Y0 Z0 S1 ; Set axis minima
M208 X290 Y300 Z350 S0 ; Set axis maxima

; Endstops
M574 Z0 S0 ; Define active low and unused microswitches
M574 X1 Y1 S1 ; Define active high microswitches
M307 H3 A-1 C-1 D-1
M558 P5 X0 Y0 Z1 H5 F100 T2000 ; Set Z probe type to unmodulated, the axes for which it is used and the probe + travel speeds
G31 P600 X0 Y0 Z2.5 ; Set Z probe trigger value, offset and trigger height
M557 X15:185 Y15:205 S20 ; Define mesh grid

; Drives
M569 P0 S0 ; Drive 0 goes forwards
M569 P1 S1 ; Drive 1 goes forwards
M569 P2 S1 ; Drive 2 goes forwards
M569 P3 S1 ; Drive 3 goes forwards
M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
M92 X80 Y80 Z4000 E420 ; Set steps per mm
M566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
M203 X30000 Y30000 Z180 E1200 ; Set maximum speeds (mm/min)
M201 X2000 Y2000 Z250 E250 ; Set accelerations (mm/s^2)
M906 X800 Y800 Z800 E800 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

dc42 · 28 Sept 2017, 17:36

Those motors are a poor choice for a 3D printer. Instead of 12V 0.4A rating you should choose more like 2 to 3V at 1.5 to 2A. See the wiki page on choosing stepper motors.

You may be able to get them working reasonably at low speeds by connecting the two Z motors in parallel instead of in series, or by connecting them to separate motor driver outputs.

greecher · 28 Sept 2017, 20:56

Would that change for a 24v setup? I did get them working on z/e1, but may look at better ones anyways.

dc42 · 28 Sept 2017, 21:03

They will be much better on 24V than on 12V, but you may still be unable to reach high speeds. See https://duet3d.com/wiki/Choosing_stepper_motors#How_to_work_out_the_power_supply_voltage_you_need.