For your Industrial CNC Router to cut accurately, the motors need to be tuned. Basically this means that every pulse sent from the computer to the machine needs to translate correctly to produce the units you measure with (inches or millimeters.) When motors are tuned properly the machine will cut the distance your job requires. If not, your measurements and jobs will be the wrong size.
You will start out with your X and Y axis at around 2,000 steps per unit. And your Z axis at around 4,000 steps per unit. These are ballpark numbers, so some tuning is required. Fortunately Mach has an automated motor tuning feature that will make this easy. Go to the "SETTINGS" tab and you'll find "Axis Calibration" right over the "RESET" button.