Duet3 suitability advice requested.



  • Hi All,

    I am working with a local company to see if the new Duet 3 controller and expansion modules would be suitable for their application.

    The steppers are:
    Motor 60HB87F5SG-02, special linear moving ball screw shaft
    Step angle 1.8 degrees
    Rated voltage 3.5V
    Current 5A per phase
    Resistance 0.7 Ohm per phase
    Inductance 2.75mH per phase
    Holding torque 25 Kg.cm

    I need to drive 9 to 16 steppers.
    Single movement at start of CNC job.
    Steppers move carriers to predetermined position and stay there.
    Speed and acceleration not critical. No real load as such, apart from drag and friction
    Open loop system, no real time positional feedback.
    End stops/home position switches available.
    Positional Data available as G-Code. May need post processing/formatting. RPi python script ?

    There is also a spindle, tool selector and rotational wrist for future consideration if possible.

    Do you think the Duet3 is suitable, with cooling ?
    Client is happy to purchase Duet3 hardware and let me develop.
    Non Duet solutions exist, but are big and very expensive.

    Maybe someone can comment please.

    Many thanks.

    J.

    I work at a UK University that supports local SMEs



  • @JuJuDelta said in Duet3 suitability advice requested.:

    60HB87F5SG-02

    google fail; but presumably nothing special with the motor itself, ignoring the ball screw rotor?

    if you don't have a lot of load, you might get away with driving the motors at less current and less need for cooling, but even if you push on at the max rating which seems to be close-ish to 80% of 5A mounting the board(s) vertical doesn't need a whole lot of cooling.

    Open loop system, no real time positional feedback.

    even so the duet can only do coordinated moves, so if you need things to move at the same time but finish at different times you need to work out when to move what in coordinated segments if that makes sense.

    also please review https://duet3d.dozuki.com/Wiki/Duet_3_firmware_configuration_limitations as you will require multiple expansion boards.



  • are the stepper motors 2 phase? i cant find the datasheet.

    the duet drivers are max 5a so from the current they should be fine.

    what voltage do you want to the system at? Duet 3 supports VIN in the range 12V-32V



  • Hi All,

    Thanks for your suggestions, and heads up about current firmware limitations wrt expansion boards.

    "Endstop switches and Z probes connected to the main board cannot control motors on an expansion board. This is planned to be fixed in release 3.3.0."

    I need to check whether expansion boards support their own endstops for their own motors ?

    The motor has 4 wires consisting of 2 coils and no centre tap, nothing special
    Co-ordinated moves would be fine, client suggested that it would be aesthetically pleasing for all the motors to reach set-point at the same time.

    The existing setup has 12 and 24V available. Need to check datasheets of the PSU switcher ICs to find most efficient input voltage.

    I think based on all the info so far, it's worth trying the Duet3 boards out.
    Client is willing to free issue what I need for evaluation and development having already spent a lot on older technology that he wants to replace.

    Nice project for Q4, and it gives me experience with Duet3.
    I currently have Duet2 on my Kossel XL+

    Thanks again Guys !



  • @JuJuDelta said in Duet3 suitability advice requested.:

    "Endstop switches and Z probes connected to the main board cannot control motors on an expansion board. This is planned to be fixed in release 3.3.0."

    Good luck with that.........



  • @JuJuDelta said in Duet3 suitability advice requested.:

    I need to check whether expansion boards support their own endstops for their own motors ?

    3HC and 1LC both have onboard endstop(s), you just can't mix and match between boards.


  • administrators

    @Veti said in Duet3 suitability advice requested.:

    the duet drivers are max 5a so from the current they should be fine.

    Actually the drivers are max 4.5A RMS, 6.3A peak. Still good for 5A motors.


  • administrators

    @bearer said in Duet3 suitability advice requested.:

    3HC and 1LC both have onboard endstop(s), you just can't mix and match between boards.

    Actually you can, except that at present, endstop switches connected to the main board can't control motors on an expansion board in most situations.

    A more significant limitation is that if the system has a Z probe, then the Z motors must be connected to the main board.


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