Motors Commonly Used in CNC Machines Stepper motors and servo motors are the two most common motors found in CNC machine tools. Both function by spinning a screw-like shaft to move the load to convert a non-linear input from the control into linear movement at the spindle shaft and table. The main difference between them is the number of positions that they can be set to run in. A stepper motor can go from 0 to 180 degrees (or more) before having to stop and back up, while a servo motor can only spin in one direction and requires a mechanical "flag" to prevent it from spinning forever. The third type of motor commonly used in CNC machines is an electric motor. These motors produce torque and do not require gearboxes or reductions systems to change their speed. They are used instead of step motors when precision and accuracy are important, such as when cutting metals. An electric motor can also drive components such as axes that cannot be driven by a stepper motor due to space limitations. However, because electric motors do not have the flexibility of a stepper motor or servo motor, they are usually not used alone but rather with other types of motors in CNC machines. In addition to these three types of motors, CNC machines can use solenoids, which are controlled by electricity to pull or push metal objects through certain processes.