Products for USB Sensing and Control
3321_0 - 28STH32 NEMA-11 Bipolar Stepper with 27:1 Gearbox
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Product Features

This compact bipolar stepper with a rear shaft and a planetary gearbox has a 0.067° step angle and 14 kg·cm of torque at low speeds.
Product Description

This NEMA-11 motor has an integrated Planetary gearbox with a 26103/121 :1 ratio. It comes with the rear shaft exposed, so you can mount an encoder or shaft coupler.

When connected to a 1067 - PhidgetStepper Bipolar HC, the 3321 has a maximum speed of 120 RPM. At the output of the gearbox, the step angle approximately 0.067°. When using the step angle in calculations, you should derive the exact step angle by dividing 1.8° by the gearbox reduction ratio.

Motor Controller and Connection

The 3321 stepper motor connects to a bipolar motor controller such as the 1067 - PhidgetStepper Bipolar HC.

The following diagram shows how to connect the motor wires to the board connectors to produce a clockwise rotation in the stepper motor when increasing position. To wire for counter-clockwise rotation when increasing position, reverse the red and blue wires.


Note: Make sure to unplug the power cord from the motor controller before switching wires around.

The rear shaft of this motor can be equipped with the HKT22 Optical Encoder for applications where you need to keep track of the exact position, velocity, or acceleration of the motor.

Mounting Bracket

The mounting holes on this motor are compatible with the 3337 - Mounting Bracket (NEMA11).

Product Specifications

Motor Properties

Motor TypeBipolar Stepper
Manufacturer Part Number28STH32-0674B / 28JXS40K27
Step Angle0.067°
Step Accuracy± 5 %
Holding Torque16.1 kg·cm
Rated Torque14 kg·cm
Maximum Speed (w/1067 Motor Controller)120 RPM
Acceleration at Max Speed
(w/1067 Motor Controller)
1.8E+06 1/16 steps/sec²

Electrical Properties

Recommended Voltage12 V DC
Rated Current670 mA
Coil Resistance5.6 Ω
Phase Inductance3.4 mH

Physical Properties

Shaft Diameter6 mm
Rear Shaft Diameter3.9 mm
Mounting Plate SizeNEMA - 11
Weight217.5 g
Number of Leads4
Wire Length300 mm

Gearbox Properties

Gearbox TypePlanetary
Gear Ratio26 103121 : 1
Backlash Error1 12°
Maximum Strength of Gears20 kg·cm
Shaft Maximum Axial Load25 N
Shaft Maximum Radial Load35 N


warning Connecting the motor directly to a power supply will destroy the motor and void the warranty. If you want to check your motor make sure it is connected to a constant current / chopper drive controller.