Greetings,
im going to finish my MPCNC Primo in some days and i was wondering, if I need to order an extra power supply, since I have two old ones from Laptops just laying around. One has an output of 15 V and 5 A, the other one has 19 V andd 3,42 A. Im want it to power 5x Nema 17 Motors with 2 A per Motor and 59 Ncm, an arduino uno and a cnc shield. Can I use one of these, or should I buy a 12 V 5 A power supply?
Thanks and have a great day (sorry for my bad english, im just a student from germany)
This is going to depend on your control board mostly.
A RAMPS board on a MEGA2560 can’t take more than 12V without some soldering modifications.
Anything that is ok on 24V will probably be fine with 15 or 19V. Read the spec sheets for your control board.
If you already have the Arduino and CNC shield, you’re probably better off getting a 12V 60W power supply. I got one for my ZenXY for cheap. (I started out with a 12V 600W supply which was obviously massive overkill.)
I’m running my Uno/CNC Shield stack on 19 volts, so your 15 volt power supply should be fine.
The Uno runs on power delivered through the USB connection. The motor power comes from the laptop power supply through (in my case) screw terminals on the CNC shield.
The thing about running more than 12v on Rambo or ramps is, it gets the mega’s onboard 5V ldo a bit hotter than it should get. The diode trick together with a buck regulator is a common fix for this, and will allow you to use higher voltages to your stepper drivers, which makes them work better.
If it were me, I would stick with the 12v for other reasons though; you may want to add accessories that use 12v like air valves, servo valves, relays, etc. The only benefit going 15v vs 12v is more motor torque and/or top speed, and just 3 more volts is nothing to write home about (usually you go straight to 24v or even 48v). Further from my experience more torque than 12v offers is unnecessary on an mpcnc… but I am using purple drivers at 16micros not tmc like all the cool kids. When I played with tmc a year ago, you had to run higher volts just to stop skipped steps. Perhaps the 2209 have fixed that idk.
My reply assumes that [quote=“jannik, post:1, topic:24990”]
an arduino uno and a cnc shield.
[/quote] means the CNC Shield v3.00 or later and an arduino Uno, which is different than RAMPS or RAMBO. I don’t believe the CNC Shield runs the motor power down to the UNO.
I’ve added a buck converter to my setup to allow for 12v accessory fans, but I’ve got an air solenoid valve I may add later. The fans don’t connect to the Uno or CNC shield, just to the buck converter so they run whenever power is on. I’ll use a relay connected to a coolant pin to control the air valve when I get to that point.