Series or parallel motors



  • I have a cartesian printer with 2 steppers on the Y axis. I an upgrading from RAMPS to Duet 2 WiFI. Which configuration is recommended, the 2 stepper motors in series or parallel?
    I am also upgrading to 24volts.

    Anthony


  • Moderator

    @gforge It will depend on the stepper motors. If you wire in series, you set the motor current at the normal value for an individual motor (assuming the motors are identical), eg for a 1.6A motor you set 50-80%, so up to 1.3A. If you wire the same motor in parallel, you have to double the current to get the same torque, so would have to set the driver current to 2.6A, which is pretty much the limit of the TMC2660, so the board will need cooling.

    From (I think @dc42 wrote this) https://www.reddit.com/r/3Dprinting/comments/a6lsn1/connecting_two_z_stepper_motors_serial_or_parallel/

    Series works best if the motors are low inductance high current types. The same current flows through both motors, so you don't need to double the motor current setting on the Z motor driver. If your printer uses 24V power then series will work well for any motors except very high inductance types (e.g. motors with a phase voltage of 12V at rated current). The Duet boards provide two Z motor outputs connected in series.

    Parallel works best if the motor are low current high inductance types. The current provided by the driver is shared between the motors, so you need to set the driver to double the current that you want per motor. RAMPS and many other 8-bit controller boards provide two Z motor outputs connected in parallel. Some commercial 3D printer kits using these boards provide extra-low-current Z motors to suit the parallel connection; whereas if they used the same type of Z motor as they do for X and Y then they would need to be connected in series for best results.

    If you have an extra stepper driver on your controller electronics, then wiring each motor to its own driver is best. [and combine them into one Y axis using M584]

    The Z motor pins on Duet have two connectors, and are wired in series, so you could connect the Y axis motors to the ZA and ZB and remap motor connections with M584 in your config.g. If you already have two Z motors connected there, then yes, you'll have to wire them independently of the board.

    Also see https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors

    Ian



  • @droftarts Thank you. I have a single extruder so I will use the extra stepper driver e.g. M584 X0 Y1:4 Z2 E3


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