I want to make a CNC machine that uses 5 NEMA 17 rated for 2A and a RAMPS 1.4 to control it all. I have a power supply that can deliver 1.5A at 12V. Is it enough? I am worried that when all 5 motors are under load, the amperage will get distributed and there will be very low amperage per motor.

  • 1
    5x2 is 10. You need at least that and more.
    – Majenko
    Commented Nov 9, 2020 at 15:10
  • So I need at least 10 amps! Commented Nov 9, 2020 at 15:25
  • Is there any cheap place I can get that type of power supply? Also how much can an ATX power supply give out? Commented Nov 9, 2020 at 15:27
  • Yes, and more than that - here's an example cpc.farnell.com/unbranded/500w-builder-black/…
    – Majenko
    Commented Nov 9, 2020 at 15:39
  • 1
    Here's one that's $14.50. I'm personally not a fan of using ATX power supplies as general power supplies. Mornsun isn't a very known brand but we using them for all our power supplies at my company and they are just as good for the faction of the cost. store.nacsemi.com/products/… Commented Nov 9, 2020 at 19:44

1 Answer 1


Figuring out your current needs is simply a matter of adding everything up. If you have 5 2 amp motors, you'll need 5 x 2, or 10 amps just to drive the motors.

You should probably have at least 20% extra capacity, so I'd suggest having a 12V power supply that can put out at least 12A.

15A would be better.

The stiffer your power supply the less it will "bobble" as the load varies.

  • That's not really how stepper motors behave in practice, since their rated currents occur at much lower voltages than Vcc under use. 5A should be fine for five such steppers.
    – towe
    Commented Nov 10, 2020 at 10:28

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