Home > 20mm Series (NEMA 8) — 2-Phase Hybrid Stepper Motor
| Item | Specifications |
|---|---|
| Step Angle Accuracy | ±5% |
| Resistance Accuracy | ±10% |
| Inductance Accuracy | ±20% |
| Temperature Rise | 80°C Max. |
| Ambient Temperature | -20°C ~ +50°C |
| Insulation Resistance | 100MΩ Min. 500VDC |
| Dielectric Strength | 500V AC 1 minute |
| Allowable Radial Load | 0.02mm Max. (450g load) |
| Allowable Thrust Load | 0.08mm Max. (450g load) |
| Model | Step Angle (°) | Length (mm) | Voltage (V) | Current (A/phase) | Resistance (Ω/phase) | Inductance (mH/phase) | Holding Torque (N・m) | Rotor Inertia (g・cm²) | Leads | Weight (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| 20BYG250-28 | 1.8 | 28 | 5 | 0.2 | 24 | 8.0 | 160 | 2.5 | 4 | 0.05 |
| 20BYG450-30 | 1.8 | 30 | 6 | 0.5 | 11.5 | 1.7 | 180 | 2.5 | 6 | 0.06 |
| 20BYG250-33 | 1.8 | 33 | 4 | 0.6 | 6.5 | 2.2 | 200 | 3.2 | 4 | 0.07 |
| 20BYG250-38 | 1.8 | 38 | 6 | 0.6 | 10 | 5.5 | 400 | 4.5 | 4 | 0.08 |
*These are representative models. We can manufacture products according to customer's requirements.
What is a hybrid stepper motor?
What NEMA sizes do you offer?
Can you customize the motor shaft and winding?
What is the difference between 2-phase and 3-phase stepper motors?
How long does it take to get custom samples?
Do your stepper motors come with drivers?
The NEMA 8 stepper motor is the smallest standard frame size in the NEMA stepper motor family. With a 20mm × 20mm faceplate, it is designed for applications where space is extremely limited but precise positioning is still required. Despite its small size, a well-designed NEMA 8 hybrid stepper motor can deliver holding torque up to 60 mN · m (about 0.06 N · m), which is enough for many miniature motion control tasks.
| Parameter | Specification |
|---|---|
| Frame Size | 20 × 20 mm |
| Step Angle | 1.8° (200 steps/rev) |
| Phase | 2-phase (bipolar) |
| Holding Torque | Up to 0.06 N · m (400 g · cm) |
| Rated Current | 0.2–0.6 A/phase |
| Body Length | 28–38 mm (varies by model) |
| Weight | 50–80 g |
| Lead Wires | 4-wire or 6-wire |
NEMA 8 stepper motors are used where the motor must fit into a tight enclosure and the load is relatively light. Common applications include:
The next size up from NEMA 8 is NEMA 11 (28mm × 28mm). Here is a quick comparison to help you decide:
| NEMA 8 (20mm) | NEMA 11 (28mm) | |
|---|---|---|
| Faceplate | 20 × 20 mm | 28 × 28 mm |
| Max Holding Torque | ~0.06 N · m | ~0.12 N · m |
| Weight | 50–80 g | 100–200 g |
| Best For | Ultra-compact, light-load precision | Small devices needing more torque |
If your load requires more than 0.05 N · m of torque, or if your speed exceeds 500 RPM, consider stepping up to NEMA 11. If space is the top priority and the load is under 50 g · cm, NEMA 8 is the right choice.
Cymotorix NEMA 8 stepper motors can be customized for OEM integration. Common modifications include:
NEMA 8 motors are 2-phase bipolar motors. They work with most standard 2-phase stepper motor drivers. Because the rated current is low (typically 0.2–0.6A), a compact low-current driver is sufficient. Common compatible driver chips include A4988, DRV8825, and TMC2209. For industrial applications, a dedicated microstepping driver with current regulation gives the smoothest performance.
Recommended supply voltage is 12–24VDC. Higher voltage improves high-speed torque but make sure the driver’s current limiting is set correctly to avoid overheating the motor windings.
