cnc and 3d printer - repost

im student from iraq and i want theory project about all mesurment required for small big and all caluclation needed for it and how i can chose suitable motor size depend on body and size of pitch of shift hold the x,y and z and important things the desgin of motor driver bord and exaplin it in details and how it depend on motor size any one can do this or part from this let him leave his skype id for discuss