The Impact of Microstepping on Motion Smoothness in Nema 17 Stepper Motors

A key factor that influences how smoothly a stepper motor moves is the microstepping mode it operates in. Microstepping divides a motor’s full step into smaller sub-steps by adjusting the current in each coil more precisely. This technique can significantly improve the quality of motion, but it also introduces trade-offs. In this article, we explore how microstepping affects the motion smoothness of Nema 17 stepper motors, what benefits it brings, and where its limitations lie.

What is Microstepping?

Standard Nema 17 motors typically move in 200 full steps per revolution, or 1.8 degrees per step. In a full-step mode, the controller energizes the coils to move the motor from one fixed step to the next.

Microstepping goes further by varying the current in each coil gradually to stop the rotor at intermediate positions. For example:

Half-step: 400 steps per revolution (0.9°)
1/4 microstep: 800 steps per revolution
1/16 microstep: 3,200 steps per revolution
1/32 microstep: 6,400 steps per revolution

Microstepping aims to smooth the motor’s motion by making each movement smaller and more gradual.

Picture from: 17HS10-0704S

Motion Smoothness: Why It Matters

In motion systems, smoothness refers to how steadily the motor rotates without jerks or vibrations. This affects:

Surface finish quality (e.g., in 3D printing)
Camera stability (in pan/tilt systems)
Noise levels (in desktop machines)
Wear and tear on mechanical parts

Microstepping is often used specifically to improve these aspects by reducing abrupt changes in torque and movement.

Picture from: 17HS4401

How Microstepping Improves Smoothness

1. Finer Movement Resolution

Microstepping increases the number of available positions within one revolution. This results in smaller positional changes for each control step, reducing the mechanical "choppiness" seen in lower step modes. This is especially important at low speeds, where full-step motion can appear jittery or uneven.

2. Smoother Torque Transitions

In full-step mode, the motor produces a strong, discrete torque pulse with each movement. Microstepping smooths this torque application by gradually shifting current between the coils. This creates a more continuous torque curve, minimizing vibration and noise.

3. Reduced Resonance and Oscillation

Stepper motors can suffer from resonance, especially at certain speeds where the motor naturally vibrates due to its step frequency. Microstepping shifts the frequency content of motion, helping to dampen resonance and reduce audible noise and mechanical oscillation.

Limitations and Trade-Offs

While microstepping offers clear advantages in smoothness, it’s important to understand its practical limits:

1. Diminishing Torque at Higher Microstep Levels

Although microstepping increases positional resolution, the incremental torque per step decreases. This means that while the motor can stop at more positions, the force it can apply to reach those positions becomes smaller. At very high microstepping levels (such as 1/32 or 1/64), the motor may lack the torque to overcome friction or external loads during each microstep.

2. Actual Position Accuracy is Limited

Contrary to popular belief, microstepping doesn’t guarantee proportionally better accuracy. Mechanical imperfections, friction, and load variation can prevent the rotor from settling exactly at a microstep position. Microstepping improves motion fluidity, not necessarily absolute position precision.

3. Increased Control Complexity

Higher microstepping levels require more precise current control and faster microcontroller or driver response. While modern drivers handle this internally, tuning and performance may still vary depending on the system.

Practical Recommendations

Based on typical performance and reliability needs with Nema 17 motors:

1/8 or 1/16 microstepping is often the best balance between smooth motion and usable torque.
Use lower microstepping (e.g., full or half-step) when high torque is more important than smoothness.
At high speeds, the benefit of microstepping decreases, as inertia helps smooth out movement naturally.
If closed-loop feedback is used, microstepping can be supplemented with position correction for even better performance.

The Impact of Microstepping on Motion Smoothness in Nema 17 Stepper Motors