Status: version 2.0.1, in testing (photo shows version 2.0)

View 3D CAD file: Extruder_2.0.1.step - 3D view

Github repository:


ItemAmountDescriptionSource of supplyComment
Extruder Screw1extruder screwcustom part, steel, drawing/parameters
Extruder Block / Kühlblock1holds barrel; integrated water coolingcustom part, steel, drawing
Extruder Barrel / Schneckenzylinder1screws into extruder blockcustom part, steel, drawing
Nozzle1standard 3D printer nozzle, type E3D V6 1.75mm; optionally hardenede.g.
NEMA 23 Stepper Motor with gear box1see notes below

Shaft Coupler1rigid shaft coupler 10mm to 12mm, D=max30, L=40e.g.
do not use flexible couplers, they cannot take vertical load
Heating Element1230V heater spiral, ID=15mm, h=40mme.g. around barrel
Metal Cage1several laser cut aluminum partscustom parts, aluminums 3mm, see laser-cutting folder on github
Pellet Inlet1
custom part, PLA, 3d printed, see 3d-printing folder on github
Pellet Tank1
custom part, PLA, 3d printed, see 3d-printing folder on github
Temperature Sensor1standard thermistor for use with 3d printer controller board (e.g. 100K NTC)


or thermocouple integrated in above heater element, then use this temperature controller (not compatible with typical 3d printer hardware):

M5 x 1204steel screw

To run the extruder you will also need a water chiller for cooling. Alternatively, just use a water pump and a water reservoir (>3 liters)

We are currently mainly using PolyMIM materials, as these feedstocks can be debindered easily in a water bath.


The extruder uses a NEMA23 stepper motor with gear box. It needs to have the following specs:

  • The gear box needs to have 4 M5 threaded holes for mounting, lying on a circle d=45mm
  • The gearbox shaft should have a diameter of d=12mm. Use a different coupler if the shaft has a different diameter
  • The gearbox diameter should be D=56mm or smaller
  • The length of the motor and gearbox are noncritical for the design. Typical sizes are L1=60mm and L2=56mm
  • The gear ratio should be in the range of 1:15 to 1:47. A gear ratio of 1:28 seems to be a good compromise, but is hard to get

Sources of supply:

Copyright FabLab München e.V. 2021
Licensed under the CERN-OHL-P v2
You may redistribute and modify this documentation and make products
using it under the terms of the CERN-OHL-P v2 (https:/
This documentation is distributed WITHOUT ANY EXPRESS OR IMPLIED
CERN-OHL-P v2 for applicable conditions

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