Choosing a Stepper Motor

Hobbyists are choosing to use stepper motors for a number of different projects from robotics to homemade CNC machines. Each project is different and may require for the builder to choose from an assortment of different stepper motors. It is important to learn how stepper motors work before jumping into a project and purchasing a stepper motor that may not function how you need it to.

The first step to choosing a stepper motor is to determine the resolution needed. There is a property within stepper motors that is called “step angle”, which measures the number of degrees the shaft turns. This is based on per input signal from the control circuitry. Some of the most common step angles include 0.9 degrees, 1.8 degrees, and 3.6 degrees. This translates as 400, 200, and 100 steps per rotation and greater the number of steps the greater the precision by the motor. In the cases of projects like CNC machines and robotics a stepper motor with a high degree of precision may be required.

Now that we have learned a bit about the resolution, it is time to move onto the winding scheme of a stepper motor. The two stator wounds that stepper motors can be found in are bipolar or unipolar configuration. The type of stator wound will determine which type of controller is needed. With a unipolar configuration the current flow of the stepper motor needs to be reversed for it to change direction. A bipolar stepper motor does not need to be reversed, instead it provides two windings per pole, one for each direction. Many hobbyist will choose the bipolar configuration since it offers the simpler controls.

Time to talk torque. Once you have determined the torque that will be required for your project you will next need to consult the stepper motor’s specifications. You will need to figure out which stepper motor you need, the matching controller, and if the stepper motor will provide enough holding torque.

The final step is to determine the size, weight, and power requirements for your stepper motor. Since stepper motors are relatively lighter than many other designs they are great for mobile applications. The project may also require a particular voltage and current draw which may alter your stepper motor selection. It’s important to keep in mind that the motor controller will be running at a higher voltage than the motor’s rating.

These steps will make selecting a stepper motor a bit more easy for many. With the different sizes, powers, and brands it can be tough choosing through the many types. This blog will help narrow your stepper motor search.