About 6Amp would be enough for three motors.
Leo..
Even that seems to be a little bit oversized 
its 4 motors i have a z axis or torch height control
ill run 7 amp fuse four steppers 1.7 amps per stepper 6.8 amps will leave me some headroom for upgrade later
Note that a driver set to 1.7Amp won't draw 1.7Amp from the power supply.
Leo..
It isn't that easy with stepper drivers .To calculate the needed PSU power, you cannot simply add the set amps of the driver, as @Wawa already stated. You must calculate the power the stepper needs. That's why you need the electrical characteristics of your steppers - not only the rated current.
Let's start with the stepper that Leo linked in #10 ( I'm not quite shure if it is the correct one, because the pictures differ - but anyway ...). The rated power per coil is I² * R = 1.7² * 1.2 = 3,47W ( fairly few for a NEMA 17 ... ). With 2 coils you need 7W. Double this to get headroom for losses and mechanical work. So your PSU needs to deliver 14W per motor. 4 motors = 56W. With a 24V PSU, this means >2.5A is sufficent.
But be shure to get the correct datasheet for your steppers. Usually a NEMA 17 needs about 5W per coil.
i thought they will only pull what they need
Steppers work very very differently from DC-motors. The A4988 defines the current through the coils. The motor itself 'pulls' nothing. Stepper drivers like the A4988 work very similar to a (short-circuited) buck converter. High current at the coil side, Low current from the PSU.