Can a Duet be setup to support dual Z AND dual Y steppers?



  • Can a Duet be setup to support dual Z AND dual Y steppers?

    Thanks.

    Frederick


  • administrators

    Yes, although if you want to use a separate stepper driver for each motor then obviously you need to use an expansion board to get the 6th driver.

    RRF supports up to 4 motor drivers for each axis, subject to the total number of drivers supports (i.e. 10).



  • @dc42:

    Yes, although if you want to use a separate stepper driver for each motor then obviously you need to use an expansion board to get the 6th driver.

    RRF supports up to 4 motor drivers for each axis, subject to the total number of drivers supports (i.e. 10).

    I understand that a expansion board would be needed.

    JOOC when using separate drivers do the two steppers stay in "sync" (or whatever the correct term is) as well as when they are connected, say, in series on one driver.

    It would seem very important that both Y (or Z) positions were as close to the same as possible.

    Thanks.

    Frederick



  • They would be in sync as long as the power is on, after the power turns off there's no way to guarantee sync since the steppers can freewheel.


  • administrators

    In particular, when you power the printer on and first energise the motors, the motor currents will flow in a particular ratio between the phases and the motors will jump to the nearest multiple of 4 full steps that matches those currents. If the motors were mid way between two such positions when you powered down, then it is possible that the two motors will jump in opposite directions, thereby losing sync by 4 full steps.

    I have it on my list to add an option in the firmware to move the motors by up to 4 full steps when you power down so that they are in the right position for power up. Ths may help to keep them in sync.



  • @dc42:

    In particular, when you power the printer on and first energise the motors, the motor currents will flow in a particular ratio between the phases and the motors will jump to the nearest multiple of 4 full steps that matches those currents. If the motors were mid way between two such positions when you powered down, then it is possible that the two motors will jump in opposite directions, thereby losing sync by 4 full steps.

    I have it on my list to add an option in the firmware to move the motors by up to 4 full steps when you power down so that they are in the right position for power up. Ths may help to keep them in sync.

    Thanks much for the info.

    Frederick


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