External Drivers for Nema 34 Steppers



  • alt stepper motor

    alt Stepper driver

    Hi,

    Hoping someone may assist me.

    I am building a large scale Cartesian Printer(2000mm/2000mm/2000mm).

    Ball skrews being used for all axes-20mm.

    Same Nema 34’s and DQ860MA External drivers being used for X(1 of), Y(2 of), and Z(4 of).

    The Duet WiFi will be on a 24V PSU

    The external drivers are being supplied from a 48Volt PSU.

    The decision was only recently made to make use of a Duet WiFi board, but I failed to research enough as I see now that external drivers require 5V and the Duet provides 3v.

    My concerns at this point are as follows:

    (1) Will the 3v signal from the board be sufficient to run the external drivers? Keep in mind that Z axis for example has 4 drivers that will need to be controlled from the Duet.

    (2)If so, how are they connected ?

    (3) Can the connections be made directly to the expansion plug on the Duet WiFi.


  • administrators

    Some external drivers are happy with 3.3V signals. You select a set of STEP, DIR and EN pins from the expansion connector or form CONN_SD. Connect driver PUL+ to STEP, DIR+ to DIR, EN+ to EN. Connect PUL-, DIR- and EN- to ground. In your M569 command for that driver, use R1 to invert the direction of the EN signal.

    Alternatively you can buy this https://www.duet3d.com/DuetAddons/Expansion_Breakout to boost the step/dir/en signals and make it easier to connect 5 drivers. You don't need to invert the EN signal, that's done on the breakout board. For your remaining 2 drivers you can connect 5V level shifters/buffers to the outputs on the CONN_LCD connector. One 74HCT365 or 74HCT367 chip could be used to convert all 6 signals (two sets of step/dir/en).



  • Thank you for your response.

    Could I make use of expansion plug pins for my XY and Z?

    So useE2 for my X
    Use E3 for my Y
    And use E4 for my Z.

    Do you think I may have a problem with one pin feeding signal to upto4 drivers?


  • administrators

    @darnz said in External Drivers for Nema 34 Steppers:

    Could I make use of expansion plug pins for my XY and Z?

    So useE2 for my X
    Use E3 for my Y
    And use E4 for my Z.

    Yes, use the M584 command in config.g to specify which drivers your axis motors use.

    Do you think I may have a problem with one pin feeding signal to upto4 drivers?

    You might be able to drive 4 drivers from one expansion breakout board output. Or you could use E4 and E5 to drive 2 Z drivers each.


 

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