I'm thinking about a power supply for the controller and motors. (Not the laser. I will probably get the laser tube and power supply together.) The 2.x BOM calls for a 24V power supply from Bart; Bart doesn't appear to be selling power supplies any more.
My Azteeg has a 12-24V boost converter, so I actually need 12V for the motors. The motors are rated for 1.68 amps. 1.68 amps × 3 motors × 24V = 121 watts. The computers, the Azteeg and a Raspberry Pi, run on +5V, probably well under an amp for both. I also am planning to put some LEDs somewhere in the case for illumination, but they will be another fraction of an amp. Call it 150 watts total.
I'm thinking a PC power supply is the way to go. The computers can run on the +5V standby line, and I can switch the main power on and off under software control.
PC power supplies normally exhaust hot air at the end with the power plug. The power plug won't be exposed on the laser cutter; instead it will be wired to some kind of internal power bus. I'm thinking I should position the power supply against the side of the case and cut a hole in the skin so it can draw in fresh air and exhaust the hot air into the enclosure. There won't be a lot of heat -- if it outputs 150W at 80% efficiency, that's 37 watts of waste heat. And when the laser is running, the exhaust fan will be moving a lot of air through the enclosure and the heat shouldn't build up.
If I go that way, I'll have to ensure that the exhaust fan flows much more air than the PC power supply. If the PC PSU is the lowest resistance path for fresh air to enter the enclosure, the PC PSU may not even need to run its own fan. I should get a PSU with a fan thermostat.
An alternative is to let the PSU suck inside air and exhaust it back into the box. The bad thing about that is that the PSU will inhale smoke and particulates and get grody inside. Another alternative is to put the PSU outside the box and run the cables in.
This power supply has caught my eye.
SeaSonic SS-350TGM Bulk 350W TFX12V It is high efficiency, thermostatted, and small. 350W is comfortably above my requirement. And
this review says the fan doesn't come on below 200W. Because the cables unplug from the PSU, it'd make the wiring a little easier. The downside is that it's not the cheapest at $75 US shipped from NewEgg.
Is the electronics side of the box crowded? There will be a motor/electronics power supply, a laser power supply, a Raspberry Pi, an Azteeg, a power distribution panel, and some wiring. It seems like there's plenty of room -- is there?
Also, did I see something about keeping the laser power supply isolated or shielded from the other electonics?