4 axes systems are generally used as follows: 3 axes for x, y and z, and the 4th axis would turn the work piece being milled, or to turn the router/spindle for reach in specific applications. (4) NEMA 24 425 oz-in stepping motors (4) Drivers (3.0Amp 24-40 Volts, 1-1/64 microstepping) (1) 36v 8.8a Power Supply (1) Interface Board (USB or P