WISRD Research & Engineering Journal

Figure 11. Left: Luca and Joe setting up the printer. Middle: Luca holding the extruder full of clay. Right: The extruder fully set before a print. All taken at Joe’s house.

Figure 12. The beginning of a Lilypad print. Our design decisions so far, such as the intricate curves of the Lilypad Design, were based on our experience with plastic prints. We had an “ah-ha” moment when we realized that printing in plastic with a small nozzle is very different from printing with clay with a large nozzle. The design was made with a 0.4 mm nozzle (that of our plastic printer) in mind. The ten times larger 4 mm nozzle of the clay printer extruded in a manner we were not expecting. The resulting print was “stringy.” We contacted the manufacturer about the problem and received the following information at the end of January 2021: “This object would need hundreds of retraction movements and hops to print, and if there is no retraction or not enough, you get this spaghetti-like effect. Retraction should be used sparingly with our printers.” The extruder was unable to retract the clay, whereas the printer using PLA was able to. To extrude, the clay is under constant pressure, meaning it cannot retract, or stop extruding mid-print. This meant we could not make “jumps” while printing and caused random strings of clay to form. In addition to the retraction problem, our first few prints failed because we attempted to print onto a kiln tile that could be directly taken for firing. We eventually determined that the tile had too much mass and did not allow the printer surface to accelerate fast enough. Subsequent prints were made directly onto the platform without the kiln tile. We tested wet paper towels as well as paper taped to the print surface, which would enable us to easily slide the print onto the kiln tile (Fig. 13).

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