24 Volts

I was digging through my box of random electronic goodies and found a 24VDC power supply. I’m wondering if their is a benefit to using it with my LR2 build. I have Ryan’s Mini-RAMBO kit.

The mini rambo can handle it. The steppers can handle it. If you have any fans, then you need 24V fans. If you have a laser that was on the fan or 12V port, it might need some work.

You need to make sure it is capable of enough current. IIRC, the 12V ones Ryan sells are 6A. You don’t want to change the current limits, even though it’s twice thw voltage because the drivers will just leav the voltage on half as long.

The major benefit (besides the Tim the Toolman Taylor laughs you’ll get) is more torque at higher speeds. At lower speeds, it’s actually going to send the same power to the steppers. At high speeds, the 12V can saturate and then it won’t be going full speed. With 24V, that ceiling is higher and you can get more speed before you start losing torque. The machine has other speed limits. It won’t affect your acceleration and you can’t carve at 50mm/s, but it might speed up some travel moves (especially Z) without skipping steps.

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Wow, learnt something again today. I was running my MPCNC on an old Laptop charger 19V/6A, until I started to play with the laser. At first I connected it on D9, that was when I found out that the input voltage is going straight to that output. Never checked it for the steppers, but then it seems true for them too.

As most boards can handle 24V, would you say that’s the better choice?

Not necessarily. At the 8-12mm/s range we usually work at, the 24V doesn’t really make a difference. The drivers use constant current to the stepper motors. The drivers turn on and off the input voltage to achieve that.

So if the 12V is on for 50% of the time to get our constant current, the 24V might be only on for 25% of the time. If the motor is moving faster, it will have higher resistance so it will need to be on longer. At some speed, it will be resistant enough that 12V would need to be on 100% of the time to reach our current. Over that speed, we’ll be losing torque.

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