MPCNC: 12V or 24V?



  • I am thinking about (or rather try to not think about 😂 ) building a MPCNC. Since it does not have any heater components (with high currents) and probably won't move very fast (at least not while cutting) I think 12V would be sufficient assuming the spindle will be powered separately.

    Is there anything I am missing that would be improved by using 24V?



  • you want 24v for the nema motors.
    You will get more torque out of them.



  • @veti Why would 24V result in more torque when the motor drivers are current based? 😕



  • @wilriker At high speeds. Read about BackEMF.
    When the motor BackEMF exceeded the power supply voltage stepper motors are losing torque.
    And a stepper driver can not push more then the power supply voltage.
    That is why stepper motors in CNC a driven often with 40-50V



  • @dragonn I know about the high speed part. But for a MPCNC high speeds are only for travel and I could live having them at say 100mm/s max. I don't think I will be cutting with 100mm/s. Except maybe paper. 😂



  • 100mm/s doesn't really tell much because what matters is the rotating speed of the motor.
    https://reprapfirmware.org/ here is a nice EMF calculator, just do you math for 12V and 24V



  • @wilriker
    Manuel,

    Turn your question on it's head. Then it becomes "why would a 12v PSU be better than a 24V one"? Generally, they seem to cost the same. The answer may be a factor of what other peripherals do you want to power ( fans, lights etc) and are these peripherals available one voltage but not another?



  • @dragonn I know the EMF calculator. It was probably the most visited webpage in my browser's history for quite a while while I was selecting new motors for my printer. 😁

    @deckingman I think your idea is the better approach here. Also currently this is all in the just-wanna-have-it stage. I have absolutely no need for a MPCNC I would just build it to have it built.

    And you are right, peripherals are (in my experience) more widely available for 12V than for 24V.


    I am going to mark this question as solved with: 24V is always better for your steppers because they could run faster than with 12V. And a buck-down converter can always take 24V to 12V in case of peripherals not available at native 24V.


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