• NEMA-11 Bipolar Stepper with 27:1 Gearbox (28STH32)

This NEMA-11 motor has an integrated Planetary gearbox with a 26103/121 :1 (27:1) 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. At low speeds this motor produces 14 kg·cm of torque.


Motor Properties

Motor Type Bipolar Stepper
Manufacturer Part Number 28STH32-0674B / 28JXS40K27
Step Angle 0.067°
Step Accuracy ± 5 %
Holding Torque 16.1 kg·cm
Rated Torque 14 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 Voltage 12 V DC
Rated Current 670 mA
Coil Resistance 5.6 Ω

Physical Properties

Shaft Diameter 6 mm
Rear Shaft Diameter 3.9 mm
Mounting Plate Size NEMA - 11
Weight 217.5 g
Number of Leads 4
Wire Length 300 mm

Gearbox Properties

Gearbox Type Planetary
Gear Ratio 26 103121 : 1
Backlash Error 1 12°
Maximum Strength of Gears 20 kg·cm
Shaft Maximum Axial Load 25 N
Shaft Maximum Radial Load 35 N



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

Wire Color Black Green Red Blue
Board Connector A B C D



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.

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NEMA-11 Bipolar Stepper with 27:1 Gearbox (28STH32)

  • Brand: Phidgets
  • Product Code: 3321
  • Availability: In Stock
  • 46.20€

  • Ex Tax: 38.18€

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