NEMA 17- The High Torque Stepper Motor Working Principle

An electric motor is standard in even the simplest of electronics. Thus, it is essential, especially in systems that involve rotational motion. However, not all engines can be helpful in situations where precision is necessary. That is where the NEMA 17 stepper motors come in handy. We're going to provide all the essential insights on the working of this component. 

Next, we'll explain the basics of stepper motors. Check it out.

What is NEMA 17?

Figure 1: Disassembled electric step motor parts

NEMA 17 is a stepper motor with a 1.8° step angle. The angle is equivalent to 200 steps/revolution. During operation, each phase of the motor type can draw a current of 12A at a voltage of 12V. 

Thus, the current is sufficient to sustain a holding torque equivalent to 3.2 kg-cm.

Also, note that the motor type features six color-coded wires. Additionally, each of the cables features a bare lead. Thus, the cables are imperative in facilitating control by unipolar and bipolar stepper motor drivers. 

If you intend to use it with a unipolar stepper motor driver, then you'll require all six wires. On the other hand, to use bipolar stepper motor wires, you'll have to leave out some wires. Note, the recommended mode of use is with a bipolar stepper motor driver during actual motor control.

 Figure 2: Stepper motor, disassembled

The stepper controller features six wires or coils, each specific use. The cables are wound in two main parts. First, there are the Black, Yellow, Green wires on the first winding of the coil. Next, the Red, White, and Blue wires form the second part of the winding. 

Here is the representation of the pin configuration of the motor:

NEMA 17 Features and Specifications

 Figure 3: Precision motors fabrication concept.

Features 

• It is capable of converting current into torque
• Highly durable
• It is also exact
• The bipolar motor is a perfect replacement for Makerbot, MBot, and others
• It’s relatively medium-sized.

Specifications

• It has a Step Angle of 1.8 deg.
• It Weights 350 g (13 oz) in unused condition
• Current rating: 1.2 A per coil
• It features a 5mm-diameter output shaft 
• The actual motor control measures  42.3 mm square × 48 mm, not including the shaft (NEMA 17)
• It has a 4-wire with an 8-inch lead.
• The stepper driver has a holding torque of 3.2 kg-cm (44 oz-in)
• NEMA 17 step motor Voltage rating is 4 V
• The stepper motor kit has a current of 1.2A at 4V
• The standard size motor length is 1.54 inches
• It features an Inductance: 2.8 mH per coil
• The Lead length is 30 cm (12″)
• Has an operating voltage/ driving voltage rating of 12V DC
• It features 4 phases   
• The motor has 200 steps per revolution    
• Has a phase resistance of 3.3 Ω per coil
• Two ball bearings support the output shaft
• Has an operating temperature of between -10 to 40 °C
• Lastly, it features a unipolar Holding Torque of 22.2 oz-in

How to use the NEMA 17 

Using the NEMA 17 stepper motors is relatively straightforward. First, check out the coil diagram below. Understanding how the stepper motor will rotate about the wiring phases is imperative.  

Figure 4: 28-BYJ48 Stepper Motor Coil Diagram

Note that NEMA 17 stepper motors tend to consume high currents during use. Hence, it is mandatory to employ a driver IC like the A4988. Also, the engine has six wires that are connected to two split windings. During use, the center winding taps are wired to the positive supply. The two ends of every winding are interchangeably grounded over a drive circuit.

 Applications

 Figure 5: 3D printer with bright green filament

The step motors are applicable in systems that require precise control and other critical commercial applications. Also, they are commonplace in applications where the intention is to overcome the complexity of a feedback control system. The following are some of the application examples where the electric motor (s) are helpful: 

• CNC machines
• Printer motors, e.g., in a 3D printer motor
• Useful in linear actuators
• Precise control machines
• Hard drive
• 3D printer/CNC or prototyping machines (e.g., RepRap)
• Laser cutters

Conclusion

Stepper motors appear sophisticated in their build, but they operate under a simple principle, as we have just explained. For more queries on the workings of the NEMA 17 stepper motor, contact us. We'll reply to you promptly with the best possible responses.