Hi, what is a good power supply and control board for me?
I’d like something that I don’t have to upgrade in the future.
Thoughts:
Should I go for an SKR 1.2 Pro with 2209 drivers? 24V power supply or 12V? How many Amps?
Thanks.
The SKR Pro is supposed to be somewhat “future proof” although Biqu seems to be stopping production of them. Some users have also had issues with the end stops, but that’s manageable.
It is one of the supported boards for the MPCNC and LowRider machines, so getting it running and starting you learning is relatively easier.
The TMC2209 drivers are nice to haves. The quiet aspect isn’t a big deal, but they’re solidly capable drivers that can deliver current.
12V vs. 24V is a whole kettle of worms by itself. These machines are all designed to work fine with a 12V supply. Give or take 6A for current requirement should be OK. I might go a bit higher for headroom, but that should handle almost all usage cases, except possibly adding a diode laser, which might require that much or more just for itself. Most diode lasers seem to run on 12V so if you are planning to add one, you can save a bit of trouble if you get a bigger power supply (12-15A? Depends…) off the top.
24V gets you higher speed limits, but does not seem to deliver any additional motive power. (From my experiments.) While working, the machine should stay within the limits that 12V allows. Also, 24V accessories like fans are harder to find and often more expensive. You also need the same current from a 24V supply.
I went with skr pro and 2209. I had a 24v power supply already so I used that. I am very very new to this stuff and have managed to get this setup going with help from the forum.
I got the tft as well.
I’d stick with the skr pro+2209; the combo is well supported here and it should work great for almost anything.
12V is going to be fine for most things, but I found 12v falls short on performance for 3d carving operations, especially with heavier routers. For example, milling a deep relief carving with steep details using 12V you will have to go painfully slow to avoid skipping steps. So if 3d operations are something you want to get in to, I’d recommend using 24V. If you do go 24V, like Dan mentioned you might still want to have a smaller 12v supply to go with it. That way you have a lot more options when adding/upgrading accessories like lasers, fans, relays, solenoids, etc.
Amps… the motors are going to be limited to less than 2A, probably 1.2A nominal in practice, times 5 for 5 motors. Laser diodes, the newer ones can draw 4-5A alone. Fans, relays, etc I’d leave about 2-3A budget for those. So if you go 12V, I’d go with at least 10A, probably 20A for overhead/safety so you can handle whatever laser you get later (they keep upping the power on new ones so…). If you go 24/12V, then a 10A 12V and 10A 24V is a good choice. 10A/24 is a bit overkill for the motors alone, but it gives extra for some other 24V accessories later on.
What they said. LOL
Even if the motors are getting 2 amps each, they draw less than that from the supply because the drivers act like buck converters. They convert high voltage low current from the supply into higher current at lower voltage for the motors. Somewhat like a transformer.
So 6A at 12V supply should be fine even for 5 motors at 2 amps each because the number of amps is not equivalent between the power supply and the motors.
At 24V the motor drivers will consume even less current from the power supply, and 6A is beyond plenty.
Yeah if I remember right, last time I actually checked the mpcnc only drew about 16W with everything moving at once. I really need to check that again.
Pretty sure I ran my LR2 on a 12V6A supply and never had a problem, with 4 motors at 1100mA and the X motor at 1400mA. No fans or other stuff though.
Stepper motors are not intuitive. We set the drivers for current, but it’s averaged, and its an inductive load which makes the math complicated, but the motors “see” a max average voltage of only 2-3V. More than that and they dissipate too much heat and things burn out.
It gets MORE complicated by the fact that the motors turning generates voltage backwards to the driver. The faster they turn, the more voltage. (Freaked me out a little the first time my unplugged 3D printer lit up the LEDs when I picked it up and the print head moved.) This means that the motors need a higher duty cycle (more power) to move faster. This is why 24V gets you a higher speed limit on the machine. There are claims that it gets more power, but I have never seen practical evidence of this until speeds exceed the limits of the voltage.
Anyway… the practical upshot of all this is that a 12V 6A supply will do, unless younwant the supply to also power a diode laser, in which case, I’d probably look for 15A. Maybe 10A if you’d be satisfied with a 5W (output) laser for engraving.