The goal of this project was to familiarize our team with the low-level mechanics of digital manufacturing. To do so, our team worked with a prototype 3D food printer using the gantry of an X-carve machine and using the pronterface motherboard.
In total, we did the following four items while working on this project.
During each of these subcomponents, we had to deal with finding the ideal food material to work with. It couldn't be too goopy, or the print would collapse under itself. It couldn't be too thick either or else there would be air bubbles creating an unappealing, hole-ridden mess.
All of the G-Code was also written by hand. We did not import any STL's or use a slicer during this project so we can better understand how to make the food 3D printer work better, and know what has to go into it in order to make the printer work efficiently. As a result, we made programs in MATLAB and Python that would allow a user to input their own parameters to generate how big they want their print to be, or how tall they want it be. An extrusion multiplier was also created in order to figure out how much to squeeze the syringe holding the food in order to create nice, clean lines.
Our group also decided when using two materials, to freezing chocolate on a copper plate and placing peanut butter on top of it. To create the Batman logo, the equation to create the outline was found online and the math equation for Riemann sums was used in order to fill it in. To accomplish freezing the liquid chocolate on a copper plate, Peltier elements were used in order to lower the temperature of the plate. In addition, a cooling fan salvaged from a PC and a water bath helped cool down the temperature even more.
Below is a list of all the problems associated with food 3D printing, and what measures we took to solve them.
P: Print will not extrude a consistent amount of material throughout the duration of the print
S: This is due to air bubbles, so tapping the syringe against the desk for a while will sometimes get rid of these bubbles. Switching to a material that is less viscous and thick will also solve the problem. Peanut butter works really well.
P: Print “misses” layers, skips them, or nothing comes out
S: Change the extrusion rate to make sure that enough material is extruded throughout the print
P: Nozzle starts extruding loops (meandering) or is raised high above the print
S: Change the z-step lower in order to make sure the nozzle follows along the print smoothly.
P: Nozzle digs into the print as it extrudes material layer by layer
S: Change the z-step higher so the print won’t extrude material in pre-existing structures
P: Structure falls over in the middle of the print
S: Lower the radius of the twisted triangle so that it can support itself better, or lower the pitch variation
P: Print stops on top of the object and continues to ooze
S: A line of gcode is added to move the print head away from the part once it is finished.
P: Nutella pooling around the edge of the square when it finishes making the square
S: Move the nozzle back to the beginning of the priming line
P: Material is coming out in small blobs only and then material suddenly gushes out only to stop again
S: Clean the inside of the nozzle
P: Material rolls onto the paper towel and rolls right off without adhering to the bed
S: Take off the paper towel or place another surface underneath that is easier to adhere to. A sheet of acrylic worked well for this.
P: Material is bunching up at the top of the print creating a massive lump.
S: Increase layer height so material has more room to stack
P: Material is coming out in thick lines instead of nice thin lines.
S: Lower extrusion multiplier.
P: Two extruders are printing offset from one another in the X-direction.
S: Add a nozzle offset to account for the difference in the extruder x positions.
P: Extruders are pulling back and retracting seemingly randomly.
S: Put both extruders on the same absolute coordinate system.