Z stepper motors



  • My printer has three stepper motors on the z axis how would i wire them to the board and how do i tell the firmware on a steeplearning curve. Thanks


  • administrators

    Currently the firmware does not support independently driving 3 Z stepper motors (to allow for Z motor driven bed leveling) but it is on the firmware wish list:
    https://www.duet3d.com/forum/thread.php?pid=9460#p9460

    Assuming you have fairly standard stepper motors and you just have a DuetWifi (no Duex expansion board) then your best bet is to wire the three motors in series from the Z driver on the DuetWifi. You could also run two motors from the Z driver and 1 from E1 if you only have a single extruder printer (this is the easiest to setup wiring wise.

    If you have a Duex expansion board and want to be able to use the independent Z motor movements for bed leveling once that is implemented then the best option is to connect each Z motor to a seperate driver. Using M584 to map the three stepper drivers to the Z axis:
    https://duet3d.com/wiki/G-code#M584:_Set_drive_mapping
    E.g:
    M584 X0 Y1 Z2:3:4 E5:6

    This maps:
    X to drive 0 (marked X on the DuetWifi)
    Y to drive 1 (marked Y on the DuetWifi)
    Z to drive 2,3,4 (marked Z,E0,E1 respectively on the DuetWifi)
    E to drive 5,6 (marked E2,E3 on the Duex2/5 or the expansion header)



  • Borrowing this topic shortly. Since the Duet wifi outputs are current limited I guess it's no problem running 2x1.7A stepper motors in series on the Z port? Also when configuring the Z stepper driver I set the combined current right so I have to set for example 2A (1A to each stepper). I have a pretty heavy bed with 45x45cm 3mm solid alu + 800w silicon heater so will need some power on the Z axis. Is it better to map drive 4 for Z2 maybe so I can run the steppers at 1.7A rated?


  • administrators

    @minim:

    Borrowing this topic shortly. Since the Duet wifi outputs are current limited I guess it's no problem running 2x1.7A stepper motors in series on the Z port? Also when configuring the Z stepper driver I set the combined current right so I have to set for example 2A (1A to each stepper). I have a pretty heavy bed with 45x45cm 3mm solid alu + 800w silicon heater so will need some power on the Z axis. Is it better to map drive 4 for Z2 maybe so I can run the steppers at 1.7A rated?

    The simplest option is to connect your 2 Z motors to the 2 Z motor connectors and set the current to between 1.2A and 1.5A. Both motors will get that current.

    If you need high Z motor speeds but you are only using 12V power and you find it doesn't give the speed you need, then you can connect one to the Z motor connector and one to the E1 connector (drive 4) and use M584 to map the Z axis to both drivers.



  • @dc42:

    @minim:

    Borrowing this topic shortly. Since the Duet wifi outputs are current limited I guess it's no problem running 2x1.7A stepper motors in series on the Z port? Also when configuring the Z stepper driver I set the combined current right so I have to set for example 2A (1A to each stepper). I have a pretty heavy bed with 45x45cm 3mm solid alu + 800w silicon heater so will need some power on the Z axis. Is it better to map drive 4 for Z2 maybe so I can run the steppers at 1.7A rated?

    The simplest option is to connect your 2 Z motors to the 2 Z motor connectors and set the current to between 1.2A and 1.5A. Both motors will get that current.

    If you need high Z motor speeds but you are only using 12V power and you find it doesn't give the speed you need, then you can connect one to the Z motor connector and one to the E1 connector (drive 4) and use M584 to map the Z axis to both drivers.

    I didn't think the Duet Wifi stepper driver card was rated for 3A on the steppers. Can it really handle this much safely?

    I don't need high speed on them but would like to use bed level compensation and then it doesn't hurt to wire them the best way. Will consider last option there 🙂

    offtopic, I'm actually testing 12v vs 24v setup as we speak so 24V isn't out of the question!

    https://youtu.be/VZNf_Y78X-Q


  • administrators

    I didn't think the Duet Wifi stepper driver card was rated for 3A on the steppers. Can it really handle this much safely

    If you wire the two motors in series( or use the two Z motor plugs on the DuetWifi which are already connected in series) then the current will be the same through both motors, and be whatever you configure it to be, 1.5A looks like a good initial choice.



  • I am in a similar position. I married z motors in parallel to the same jack and have y wired the same but with 1 motor reversed. If i understand this correctly, i should put z motors in series and move 2nd y motor to E1 correct?



  • M584 X0 Y1:4 Z2 E3

    should it look like this?



  • Example
    M584 X0 Y1 Z2:3 E4:5:6 ; Driver 0 controls the X motor, 1 controls the Y motor, 2 and 3 control the Z motors, 4 and 5 control the E motors
    Correction!
    M584 X0 Y1:5 Z2:3 E4 right


  • administrators

    @FrankNPrinter:

    Correction!
    M584 X0 Y1:5 Z2:3 E4 right

    That's correct if you have the 2nd Y motor connected to the first channel (= driver 5) on a DueX2 or DueX5.



  • i have the duet wifi no expansion board. still correct? that would be E1 motor connection for 2nd y motor right? sorry, using old xp pc since mine died. i cant even use usb or sd on this old thing so am severely limited at the moment…



  • @T3P3Tony:

    I didn't think the Duet Wifi stepper driver card was rated for 3A on the steppers. Can it really handle this much safely

    If you wire the two motors in series( or use the two Z motor plugs on the DuetWifi which are already connected in series) then the current will be the same through both motors, and be whatever you configure it to be, 1.5A looks like a good initial choice.

    What is the disadvantage of series wiring? Half the power of the steppers? Now I'm expanding to a third stepper since the bed isn't stable with only two. Will a third one mean that power/torque from the steppers now will be the same as from two steppers but spread on three steppers? I prolly don't need the power from them tho so just asking from a technical POV.

    When bed leveling with three or more steppers are introduced I guess I should have a expansion board and run separate drivers 🙂


  • administrators

    When you connect multiple motors in series, the available voltage to each reduces. This doesn't normally affect the static torque available, because the motors we choose for 3D printers normally need only 3V at their maximum current [except that there are some motors available rated at 0.4A 12V - avoid them]. However, the faster a motor moves, the more voltage it needs because of inductance and back emf. So when you connect motors in series, you reduce the maximum speed you can run them at before the torque starts dropping off. See https://duet3d.com/wiki/Choosing_stepper_motors#How_to_work_out_the_power_supply_voltage_you_need for how to estimate this.

    Z axis speed on a Cartesian or CoreXY printer isn't normally critical, so connecting motors in series works well. If you do need higher speeds, use 24V power instead of 12V.



  • i have wired two stepper motors together on the same connector pluged into za on the board and the third stepper motor pluged into zb but it does not work any thoughts 1



  • @Will:

    i have wired two stepper motors together on the same connector pluged into za on the board and the third stepper motor pluged into zb but it does not work any thoughts 1

    Sounds like you have two in series and one in paralelle with the two in series if I understand you correctly.



  • I thought that so how do i get the same power to all three motors thanks


  • administrators

    @Will:

    I thought that so how do i get the same power to all three motors thanks

    Either connect all 3 in series, or connect 2 in series to one drivers and the third to another driver, for example the E1 driver if it is free. Set both drivers to the same current, then you will get that same power to all 3 motors at low speeds.



  • I have now purchased a duex 5 expansion board and need help maping my 1 x axis stepper motor 2 y axis stepper motors and 3 z axis stepper motors .
    When using the M584 gcode does it go in any particular file and in any particular order thanks in advance Will


  • administrators

    M584 goes in config.g like the other motion configuration commands. For ordering restrictions, see the last bit of the description at https://duet3d.com/wiki/G-code#M584:_Set_drive_mapping.


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