RUG/Pennsylvania/State College/Universal Paste Extruder

Overview

This page is dedicated to providing detailed information on how to build and use a universal paste extruder. These types of extruders are becoming more and more popular as can be seen in the media timeline.

Related Projects and Results

Below are details about paste extrusion projects that have been completed by students using this extruder.

Name	Students	Link	Description

Components

Name	Quantity	Link	Price

Generating the gcode and printing

Slic3r (http://slic3r.org) can slice a CAD file into G-code for the paste extruder. It requires specific settings:

• 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%
  • Output options
    • Download the perl script to turn extrusion commands into fan commands (Paste-perl.zip), and place it in any folder (don't forget to un-zip it). Then add its absolute path to the post-processing frame. On Unix, open the terminal and run the command "chmod 755 /path/to/the/script". Make sure that there aren't any white-spaces in the script's path (it may result in a crash). On Windows, you need to download and install a Perl interpreter: http://www.perl.org.
  • 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 2 (disabling it provokes a bug)

The post-processing script used turns the extruding commands into fan commands. If you plug the solenoid valve on the fan port, you won't need to re-flash the printer. Note that if you don't re-flash it, since there is a temperature security, you must left the regular extruder's thermocouple or thermistor plugged (considering that you took a working printer and replaced the extruder).

In order to determine the right values (this hasn't been done yet, and must be followed with caution):

• The layer height is close to the height of a printed paste line.
• The nozzle size shouldn't be set to the actual nozzle size, but rather to the printed paste line width.
• The speed depends on the nozzle size, the viscosity of the paste and the air pressure. Try to find values that result in a good print for these 4 parameters (including speed).