thats right forgot about that tho its not using any gui or output like hdmi wander if any info on amp draw when its running in console only mode.... (just looked up ok this isnt going to work tho a pi uses little amps when not running a full gui the usb ports with a wifi dongle will.)
ok looks like a change of plans ill do direct to 12v from psu and use a voltage regulator to step down to 5v.
but to be sure ill have to test the draw and see what the pie is actually using at full tilt printing with Repetier-Server if its 800 or less should be ok to power the pie.
thanks for schematic not sure how i missed that.
will update with what i find out.
(Update: Well that didn't take long to figure out MX1 VCC and GND tho is 5v the rambo won't be able to supply the power so will have to use a voltage regulator just so happens i checked my parts draw and i have a few DC-DC Buck Converters bought a 10 pack on sale some time ago and forgot about them :D )