I sell allot of motor packages bundled with the Gecko G540, and most questions usually in one form or another are about the stepper motors in the package. Stepper motor ratings can be confusing, but in general are all pretty straight forward. The "Stall Torque Rating" is really the rating at which the motor will fail to produce holding torque, and if exceeded will rotate in the opposite direction. The reality is the torque that's usable is any force under the stall torque rating provided by the manufacturer.

If you purchase 300oz in motors your usable torque for motion control is 299oz in, and under. The amp rating of the motor is the current reached when the stall torque rating was established. When the motor was tested to its 300oz in rating it was drawing 3.5a of current. This then gives you the maximum current rating of the motor. It doesn't mean your motor is pulling a 3.5a at all times. The motors will only draw the amount of current required to provide motion pending the load your trying to move is in the usable torque range provided by the motor.

If one axis only requires 800ma to move then that's all it will draw as long as your controller has the ability to provide the current required as well. Another setup test to perform is to check your motors on a new system for amp draw with a multimeter to make sure the steppers aren't under excessive resistance from your mechanics. The exception would be the Z axis as it's lifting the spindles weight. If you take the time to check the X, and Y and find one motor has a significantly higher amp draw it may be due to your mechanics. Check every axis for smoothness to assure the motors aren't under abnormal resistance.

Remember the less current you require to get the job done the more efficient your supporting mechanics are calibrated. Resistance=more current=more heat=more wear. The benefit of a system requiring less amps means your equipment lasts longer.
Here's a very good explanation in an easy to understand format explaining exactly what I'm writing about. It also explains about steppers in a much easier to understand format.
Stepper Motor and Controller Primer - Phidgets Support.

Here's another video of steppers being measured on a 7.3a power supply moving a G0704. Interesting to watch considering the size of the steppers he's using (570oz in 5a motors).G0704 3 Axis Amperage Test - YouTube

I'm here to help, and provide less confusion. If you have any questions please let me know.

Vince
Edealers Direct