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Top » Catalog » Controllers » Motors » 3325_0 » 42STH38 NEMA-17 Bipolar Stepper with 5.18:1 Gearbox [3325_0]

This bipolar stepper with a rear shaft and a planetary gearbox has a 0.35° step angle and 18 kg·cm of torque at low speeds.

42STH38 NEMA-17 Bipolar Stepper with 5.18:1 Gearbox

This bipolar stepper with a rear shaft and a planetary gearbox has a 0.35° step angle and 18 kg·cm of torque at low speeds.

This NEMA-17 motor has an integrated Planetary gearbox with a 52/11:1 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 3325 has a maximum speed of approximately 900 RPM. At the output of the gearbox, the step angle is a little under 0.35°. When using the step angle in calculations, you should derive the exact step angle by dividing 1.8° by the gearbox reduction ratio.

At 1.7 Amps, this stepper motor can produce a maximum torque of 18.6 kg-cm. However, the gearbox is only rated for 18 kg-cm of continuous torque. Loading this gearbox stepper beyond the torque rating of the gearbox will shorten its useful life.

Motor Properties

Motor Type Bipolar Stepper
Manufacturer Part Number 42STH38-1684B
Step Angle 0.35°
Step Accuracy ±5 %
Holding Torque 18 kg·cm
Rated Torque 18 kg·cm
Maximum Speed (w/1067 Motor Controller) 904 RPM
Acceleration at Max Speed
(w/1067 Motor Controller)
410000 1/16 steps/sec2

Electrical Properties

Recommended Voltage 12 V DC
Rated Current 1.7 A
Coil Resistance 1.7 Ohm
Phase Inductance 3.2 mH

Physical Properties

Shaft Diameter 8 mm
Rear Shaft Diameter 3.9 mm
Mounting Plate Size NEMA - 17
Weight 457 g
Number of Leads 4
Wire Length 300 mm

Gearbox Properties

Gearbox Type Planetary
Gear Ratio 5 2/11 : 1
Backlash Error 1 1/2°
Maximum Strength of Gears 18 kg·cm
Shaft Maximum Axial Load 49.1 N
Shaft Maximum Radial Load 98.1 N

The 3325 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.


Mounting Bracket

The mounting holes on this motor are compatible with the 3338 - Mounting Bracket (NEMA11).



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.

This product was added to our catalog on Wednesday 08 October, 2014.
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