Using Duet 3Mainboard with external stepper drivers



  • Hi,

    one of the best things of the Duet2 is than is the best board working with external stepper drivers.
    In my opinion (and in my case) the next Duet3 (expansion or special board) never can have LESS external connections than the actual Duet2, the same number or more.

    Now have for 5 connections (if i don't remember wrong)...

    Thanks


  • administrators

    @fbg you can add a lot of expansion boards. If we decide to put 3 external driver connections on each then potentially up to 8 of those expansion boards = 24 drivers!



  • @t3p3tony No words.... incredible



  • @dc42 Are there any news on this topic ?


  • administrators

    @mpentenr said in Using Duet 3Mainboard with external stepper drivers:

    @dc42 Are there any news on this topic ?

    Not yet. Now that we have the prototype Tool Board, there are two ways we could support external drivers without needing a new main board:

    1. Do a version of the EXP3HC board with outputs for 3 or just possibly 4 external stepper drivers instead of on-board drivers. This would probably be best for those who are actually using external drivers, not step-servo motors. But we don't expect many people to need external drivers with Duet 3.

    2. Do a version of the Tool Board that has a single set of step/dir/enable outputs, to drive a single external driver or step-servo drive. I think this might be better for those using step-servo motors with built-in controllers.



  • @dc42 said in Using Duet 3Mainboard with external stepper drivers:

    @mpentenr said in Using Duet 3Mainboard with external stepper drivers:

    @dc42 Are there any news on this topic ?

    Not yet. Now that we have the prototype Tool Board, there are two ways we could support external drivers without needing a new main board:

    1. Do a version of the EXP3HC board with outputs for 3 or just possibly 4 external stepper drivers instead of on-board drivers. This would probably be best for those who are actually using external drivers, not step-servo motors. But we don't expect many people to need external drivers with Duet 3.

    That would be my favorite, because of my 2pt100(bed) and 3K-Type Thermocouple (Pellet Extruder) which I cant connect to the tool board or is it possible to use thermo connectors on one board and step/dir/ena on another board for one "axis/extruder"? I also would need 2 of these boards, because of the 3 (X/Y/Z)axis with external drivers and up to 3 external drivers for the (pellet)extruders.

    1. Do a version of the Tool Board that has a single set of step/dir/enable outputs, to drive a single external driver or step-servo drive. I think this might be better for those using step-servo motors with built-in controllers.

    Please take into account, that the Vin for example for my pellet extruder is 48V, when designing the driverless Tool Board with step/dir/ena output.

    Thanks
    Marc Pentenrieder


  • administrators

    @mpentenr, what motors and drivers do you plan to use on that machine? Although we don't support as much as 48V at present, we are considering making variations of main and/or expansion boards that support up to about 54V. The TMC5160 drivers can take 60V, it's just the voltage regulators we use that limit us to around 35V.



  • @dc42 Hi, on the 3 axis I am using 1KW 380V Servo Motors and on the pellet extruder, I am using the following:
    Motor Driver: https://us.nanotec.com/products/1768-c5-e-2-09-motor-controllerdrive-for-canopen-or-usb/

    Stepper motor: https://us.nanotec.com/products/574-st8918m6708-a/


  • administrators

    Thanks. Are you using the encoder input on the stepper driver for the pellet extruder? What is the maximum rotation speed needed by the pellet extruder motor? Have you established that you really do need 48V to drive it?



  • @dc42 said in Using Duet 3Mainboard with external stepper drivers:

    Thanks. Are you using the encoder input on the stepper driver for the pellet extruder? What is the maximum rotation speed needed by the pellet extruder motor?

    No, I am not using the encoder input (at the moment, perhaps I need to).
    The max rotational speed will be around 500 rpm, because of an 10:1 gearbox on the stepper, so up to 50 rpm at the pelletextruderspindle



  • @mpentenr said in Using Duet 3Mainboard with external stepper drivers:

    @dc42 said in Using Duet 3Mainboard with external stepper drivers:

    Thanks. Are you using the encoder input on the stepper driver for the pellet extruder? What is the maximum rotation speed needed by the pellet extruder motor?

    No, I am not using the encoder input (at the moment, perhaps I need to).
    The max rotational speed will be arounf 500 rpm, because of an 10:1 gearbox on the stepper, so up to 50 rpm at the pelletextruderspindle

    At the moment the pellet extruder is highly experimental, so I don't know the exact values. Time and experiments will show 😉


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