Stepper Motor Nema17, Planetary Gearbox 27:1, 1.68A, 12-36V

The Nema 17 stepper motor with integrated planetary gearbox is a compact and efficient solution for applications that require high torque at low rotational speeds. The motor is bipolar, with a step angle of 1.8° per pulse applied directly to the rotor, equivalent to 0.067° at the gearbox output shaft, thanks to the 26.85:1 reduction ratio. This level of motion precision makes it ideal for 3D printer extruder systems, robotic arms, CNC linear stages, optical focusing systems, or any application where precision and torque matter.

The housing follows the Nema 17 standard (42x42 mm), with a motor length of 40 mm, placing it in the compact motor category. The rated phase current is 1.68A, phase resistance is 1.65 Ω, and inductance is 3.2 mH. The planetary gearbox, with an efficiency of 81%, increases holding torque up to 3 Nm (425 oz-in) and momentary torque up to 5 Nm (708 oz-in), while also reducing backlash to less than 1°, a very good value for precision applications. The output shaft has a diameter of 8 mm and a length of 20 mm, with a flat section (D-cut) over 15 mm of its length, allowing secure mounting of a pinion, gear, or mechanical coupling without the risk of slipping.

The motor is compatible with any platform that can generate STEP/DIR signals: Arduino (Uno, Mega, Nano), ESP32, STM32, Raspberry Pi (via external driver), as well as dedicated controllers such as RAMPS 1.4 or CNC shield-type boards. The connection cable is 500 mm long with 4 colored wires, corresponding to the two coils of the bipolar motor.

Specifications:

Motor type: Bipolar, stepper

Rated current: 1.68 A / phase

Phase resistance: 1.65 Ω

Inductance: 3.2 mH

Supply voltage: Depends on the driver (usually 12-24VDC)

Motor step angle (Step Angle): 1.8° (full step)

Output step angle (Output Step Angle): 0.067°

Number of wires: 4

Gearbox type: Planetary

Reduction ratio: 26.85:1 (nominal 27:1)

Output holding torque: 3 Nm / 425 oz-in (max)

Output momentary torque: 5 Nm / 708 oz-in

Gearbox efficiency: 81%

Backlash: ≤ 1°

Frame size: 42 x 42 mm (Nema 17)

Motor length: 40 mm

Output shaft diameter: 8 mm

Output shaft length: 20 mm

Flat section length (D-cut): 15 mm

Cable length: 500 mm

Weight: 510 g

Pinout:

Usage:

Choose a driver compatible with bipolar stepper motors that can supply at least 1.68A per channel. Recommended drivers: TMC2209, A4988, DRV8825, TB6600.

Identify the coil pairs: coil A (black and green), coil B (red and blue), and connect them to the corresponding driver outputs (A1/A2 and B1/B2).

Power the driver from a DC power supply between 12V and 36V (check the specific limits of the chosen driver).

Set the current limit (Vref) on the driver to the motor’s rated value: 1.68A per phase. Exceeding this value may cause overheating and damage to the motor or driver.

Connect the STEP and DIR pins of the driver to the microcontroller (Arduino, ESP32, STM32, or another control system). A pulse on the STEP pin produces one step, and the logic level on DIR determines the direction of rotation.

Do not connect or disconnect the motor wires while the driver is powered. This can generate reverse voltages that destroy the driver’s power stage.

Keep in mind that the 26.85:1 reduction ratio proportionally reduces the maximum shaft speed: if the motor runs at 600 RPM, the output shaft will rotate at approximately 22 RPM.

Dimension diagram: