The extraordinary extruder


Following on from Kossel 3D Printer, and the tutorial videos (see Kossel construction videos) the BuildA3DPrinter kit comes with an extruder stepper motor with a planetary gearbox. This results in a very high torque. However, as stated below, it has been replaced by the 3325_0, a motor with the same NEMA size and same torque.

The main take away points are:

  • 5:1 ratio
  • High torque:
    • 1.59 Nm (224.98 oz•in, 158 N•cm, 16.2 Kg•cm)
    • 1.68 Nm (237.91 oz•in, 168 N•cm, 17.13 Kg•cm)
  • 1.68 A

Product Description

This NEMA-17 motor has an integrated Planetary gearbox with a 52/11:1 ratio. It generates 16.2 Kg-cm of torque at 1.68 Amps.

When connected to a 1067 – PhidgetStepper Bipolar HC, the 3317 has a maximum speed of a little over 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.

This particular revision of the 3317 is made by a different manufacturer, but should behave very similarly to the revision 0 version.

Motor Controller and Connection

The 3317 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.


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.


Product Features
This bipolar stepper with planetary gearbox has a 0.347° step angle and 16.2 kg·cm of torque at low speeds.

Replaced by the 3325_0, a motor with the same NEMA size and same torque.


Product Specifications

Motor Properties

Motor Type Bipolar Stepper
Manufacturer Part Number 42STH38-1684A / 36JXS30K5.2G
Step Angle 0.35°
Step Accuracy 5 %
Holding Torque 18 kg·cm
Rated Torque 16.2 kg·cm
Maximum Speed (w/1063 Motor Controller) 118 RPM
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 Ω
Phase Inductance 3.2 mH

Physical Properties

Shaft Diameter 8 mm
Mounting Plate Size NEMA – 17
Weight 460 g
Number of Leads 4
Wire Length 300 mm

Gearbox Properties

Gearbox Type Planetary
Gear Ratio 5 211 : 1
Backlash Error
Maximum Strength of Gears 18 kg·cm
Shaft Maximum Axial Load 49.1 N
Shaft Maximum Radial Load 98.1 N


On eBay,



Manufacturer Part Number 17HS15-1684S-PG5
Motor Type Bipolar Stepper
Step Angle(W/O Gearbox) 1.8°
Holding Torque 1.68Nm (237.91 oz•in, 168 N•cm, 17.13 Kg•cm)
Rated Current/phase 1.68A
Phase Resistance 1.65ohms
Recommended Voltage 12-24V
Inductance 3.2mH±20%(1KHz)
Gearbox Type Planetary
Gear Ratio(Exact Gear Ratio) 5 + 2/11
Efficiency 90%
Backlash at No-load <=1°
Max.Permissible Torque 2Nm(283oz-in)
Moment Permissible Torque 4Nm(566oz-in)
Shaft Maximum Axial Load 50N
Shaft Maximum Radial Load 100N

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