Also, I wanted to point out, I'm using Arduino/GRBL to drive drivers that are 6.5 amp... So, I'm just pulsing to drivers, but I have them on a 24v 20 amp power supply.
I'm also using the computer powersupply (converted over to a bench power supply) to handle fans, etc. Everything then ties into USB on a laptop to manage everything else. Really a fun build when you look at it all. But the regular 'cnc shields' are worthless, so 100% custom shield using what I already know how to do makes it all worth it. The motors were custom made in China with the right shafts to fit into the gears that the motors connect into.