Our previous blog post focused on us finding a way to dispense boba; using the Archimedes’ screw pump. However, there were issues that we had to solve before we could truly settle on the auger being our final solution.
The first problem about using the auger was that the boba would get stuck and pour out of the top of the auger. This was not ideal as we wanted the boba to dispense out of the spout we created instead so it would pour into the cup smoothly. Additionally, if the liquid from the boba spilled onto the stepper motor, it could damage the motor. As such, we 3D-printed a connecting shaft to force the boba to dispense through the spout.
The connecting shaft had two main parts, the auger attachment that fit into the auger and the second part was a hole designed for the stepper motor to fit in snugly. This allowed the motor to spin the auger from a distance so that the boba would not reach the stepper motor. We also 3D printed a motor holder, with a flat-edged hole for the motor. The base of the motor holder also acted as a form of cap for the auger. This helped ensure that the boba would not be dispensed from the top of the tube and would instead dispense out of the spout.
Secondly, we realised that the auger did not dispense boba in a consistent manner when kept upright. However, when we rearranged the set-up such that the auger was tilted, the dispensing of boba became more consistent. Through experimentation, we tried to determine the angle at which the auger should be placed to dispense boba mostly consistently, and we realised that when the auger is tilted at an angle of 45 degrees, it is able to dispense our desired amount of boba.
To keep the setup tilted, we 3D-printed a boba support so that the auger could spin and dispense boba more accurately.
One more issue remained; we needed to solve the speed and amount of boba being dispensed by the auger and stepper motor.