The origin of the machining in X and Y, the point from the tool have reference to move correspond with the origin of
coordinate system in your drawing in the machining preparation software.
Insert the GT2 pulley 20 teeth in the shaft of X axis stepper motor
a ) Check is the fixing screw of pulley go down exactly in flat part of motor shaft
b ) Check if the pulley be correct align with the 2 guiding wheel