PSU Help? (4 replies)

Hey Guys,

I'm building either a Rostock or a PM i2, and using RAMPS

I haven't actually bought the electronics yet, but I know I'm going to want a heated bed, and lcd panel, and all of that good stuff.
Eventually, I hope to have a dual extruder setup.

My question is, how do I determine the amperage I need.
I've looked at this with this.
The other one I looked at was this with this.

Also, I plan to have an extruder fan cooling the print, and if I go with a Prusa, a fan cooling the Pololu z-axis stepper driver, because I read that that gets hot driving two steppers.

I already have a PSU, meant for a computer build. It is 12V, 550W. When I did the math, that came out to about 46 Amperes. Can too many amperes damage my system? Is it okay for me to use that?
I'd prefer to go with a system meant for a printer, because the supply I already have has a bunch of wires sticking out (meant for attaching to hard drives, fans, etc., etc. in a computer), and I would have no idea where to start conencting that to the Arduino, and would probably fry my electronics.

Please help me figure out what kind of power supply I should get!

PS the other reason I kind of don't want to use the computer PSU is that it's relatively big and ugly-looking...it's ATX size.


Thanks!:)