RUG/Pennsylvania/State College/Paste extruder

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Revision as of 20:48, 22 January 2014 by Aem28 (talk | contribs) (Generating the gcode and printing)
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Paste extruder overview

The ability to print pastes, and not only plastics, opens a door to many new objects: ceramic pastes can be used to make buildings, chocolate or sugar can be used to print food. The first paste extruder we made was using a motor and a belt to push the plunger of a syringe containing the paste. Even though we were able to print basic objects with this kind of extruder, it rapidly shows its limits since retraction isn’t possible (thus creating leaking problems). We switched to pressurized gas based systems to improve the extrusion. The extruder described on this page is compatible with OHM carriages, therefore all the other components (mechanical axis, electronics) of the printer can be kept. See the OHM page for more information (Ohm).


Here is the list of the non-printable components required to build a paste extruder. Refer to the component name if the web link is broken.

Name Quantity Link Price
Air compressor (100 PSI) 1 $62.99
Air compressor's hose 1 $12.99
Air compressor's hose to nylon hose adapter 1 $0.94
Solenoid valve (12 V) 1 per extruding syringe $16.76
Solenoid valve to nylon hose adapter 3 per extruding syringe $0.94
Nylon hose to syringe adapter (10cc) 1 per extruding syringe Not on website, ask for the price catalogue ([email protected]
Plastic syringe (10cc, luer-lock) 1 per extruding syringe Not on website, ask for the price catalogue ([email protected]
Nylon hose 1 $10.37

Syringe holder

The syringe holder uses the same X-Carriage as the Open Hybrid Mendel (OHM X-Carriage). The .STL file can be downloaded here:



Assembling the syringe holder is pretty straight forward: once all the components are printed, put them together with M3 and M4 screws. Use Nyloc nuts to make sure that the screws will remain tightened.

Note: picture coming soon.


Pneumatic components graph
Pneumatic components photo

To assemble the pneumatic circuit:

  • Screw the air compressor's hose (yellow) to the air compressor. Wrap the male thread in teflon tape to guarantee sealing.
  • Screw the other end of the air compressor's hose to the nylon hose adapter.
  • Screw all three solenoid valve to nylon hose adapters.
  • Cut the nylon hose to pieces of the right length, and plug them (see the graph).
  • Add a stopper on the last solenoid valve. You can make one by bending the nylon hose and holding it with a zip tie.
  • Plug the solenoid valve to the fan port one the Ramps board or RAMBo.

Generating the gcode and printing

Slic3r ( can slice a CAD file into a gcode for the paste extruder, however it requires specific settings. To setup Slic3r:

  • Go to Preferences and turn Slic3r into expert mode
  • Print settings:
    • Layers and perimeters:
      • Set the layer height to the right value (this value depends on the paste, and must be determined through experimentation)
      • Set first layer height to 100%
    • Speed:
      • In the set for print moves sub-section, all the values should be identical, and equal to the printing speed determined through experimentation (it depends on the paste, the nozzle and the pressure)
      • The speed for non-printing moves can be left to its default value
      • Set the first layer speed to 100%
    • Advanced:
      • Set the first layer to 100%
  • Filament settings:
    • Cooling:
      • Disable both options (fan always on and auto cooling)
  • Printer settings:
    • General:
      • Set the G-code flavor to MakerWare (MakerBot)
    • Extruder 1:
      • Set the nozzle diameter to the right value (this value depends on the paste, and must be determined through experimentation)
      • Set the retraction length to 0 (disabled)