Duet 3, power distribution

  • Goodmorning, soon (Januari), I hope to receive two expansion boards to complete my Duet 3 Intending to drive 6 steppers (xyzzuv), 7 steppers for extrusion and 5 hotends. Would it make sense to distribute the expected, most active steppers over the 3 boards? Or doesn’t it serve any purpose? To be clear, the boards will be located in the same enclosure, so I’m not looking to minimise wiring.

  • @ahwitmer It's unlikely to make much difference unless you run really high stepper motor currents. In an extreme case with very high current motors, spreading those high current motors across multiple boards might allow you to use passive cooling where an active fan might otherwise be required. I run some Nema23s at 2.4 Amps to move 3Kgs of mass and the driver chips barely get above ambient with no fans or additional cooling of the board.

    Personally, I put the boards close to the motors because it makes the wiring neater. So in my case, the XY and Z motors are on one expansion board. The UVA and B motors are on the main board, and then the six extruders are connected to two further expansion boards - 3 on each.

    Unless I misunderstand your OP, I think you will need 3 expansion boards, not 2. XYZZUV is 6 drivers which is the full complement for the main board. But then you say 7 additional steppers for extruders, yet the expansion boards only have 3 stepper drivers each. Unless you intend to connect ZZ together in series and use one driver for both?

  • Dear Ian, thank you for your reply. Indeed you understand me correctly. My “cheaper” way out is to combine the two z steppers on one driver. For now I have no concerns over my the weigth of the bed plus built. I do foresee the use of heavier steppers for the uv gantridge and or perhaps the xy gantridge to improve speed.
    Thank you again for your reply.

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