Axes Designation - X-Axis
The X-axis is the principal motion direction in a plane perpendicular to the Z-axis. It is perpendicular to the Z-axis and should be horizontal and parallel to the work- holding surface wherever possible. When an operator is standing in front of the machine tool, the positive (+) X is to his right side.
For turning machines, it is radial and parallel to the cross slide. X is positive while the tool recedes from the axis of rotation of the work piece.