Printhead – The clay extruder is simply parts adapted from the adhesives industry. The soft clay is extruded out of the cartridge with the use of compressed air, around 30 psi (pounds per square inch) or 2 bar. The air pressure set against the consistency of the clay controls the rate of flow of the printing material. The extrusion rate is around 1mm per second. Excuse being vague with this information but, one I am not methodical about each setting as there are so many variables I relying on my tacit knowledge of working with clay and the general feel to get it right – not helpful I know. Secondly I use different setting for different scales of work and different clays and different shapes. Small work will be extruded with a 1mm nozzle while larger works will use a 2 mm nozzle. Small work is sliced at .5 to .6 mm per layer while I scale up to .9, 1mm for larger prints. Most work is printed with a single wall but forms that flare out such as bowls it can be useful to print a double wall.
Copying the Unfold technique I originally used syringes to hold the clay, as big as I could find and would glue two together to get a better volume of material. Then I found the Techcon Systems TS Series dispensing gun and so make use of the cartridges, retainer body and cap but not the gun grip. I attach a standard ¼ inch ball vale on/off switch onto the cap where the air pressure hose comes in to manually switch the pressure on at the start of a print and off at the end. During the print the flow of material is continues. A technical point that could be improved for shapes where you want the build material to stop and then begin again at another point as the print head keeps moving.