RUG/Pennsylvania/State College/Paste extruder
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.
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.
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 (http://slic3r.org) 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
- In 'Print' settings:
- In 'Layers and perimeters