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Our initial prototype was constructed using cardboard, hot glue, and toothpicks. We created a works-like model of the Geneva mechanism and tipping subsystem, as this was the one we anticipated the most issues with. The prototype consisted of the slot gear of the Geneva mechanism, a ball and hook to catch and turn the bottle, and a stand to hold it all together. In the end, we chose to move forward with a different method of tipping the bottle because of space constraints, but the prototype did help us to visualize how the Geneva mechanism would work.
Figure 3. Geneva Mechanism Initial Prototype
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Additionally, to visualize and create a prototype for the quick return mechanism we laser cut and printed all the necessary links and roughly assembled them to gain an understanding of what our final product would look like. This prototype helped us plan for the size constraints we had in order to provide necessary torque.
4.2 Parts Manufacturing & Software Development
We took advantage of the TIW workspace and manufactured most of our parts through laser cutting and 3D printing. Our gears were made out of laser cut ¼ in wood and generated using an online gear generator which was imported into Solidworks, edited and eventually cut out. In addition to the gears, we also laser cut the links for the quick return mechanism and some of the pieces for the Geneva mechanism in order to make prototyping quicker. We used the Raise3D printers in order to make all of our mounts to attach our various subsystems to the base. We also printed our link that connects to the moto and the bottle mount, because they had very specific geometry that could not be replicated on the laser cutters. We went through many iterations of link lengths and motor placement to find the optimal setup that would provide us with enough torque and range of motion to open the bottle. In order to power the Geneva mechanism with the same input as the quick return, we had to attach a gear train directly to the motor. We used a gear train in order to circumvent the quick return mechanism and get access to the bottle mount, which would be the final action as the bottle gets poured.
The team used an Arduino script to control our servo motor. By using Arduino’s servo library and basic example we were able to provide movement to our mechanism. Since our servo was continuous we could not control position on our servo. In order to solve this, we used “Servo.write(90)” to turn off our servo after a controlled delay.
4.3 Assembly
As we began our final assembly we started with the quick return mechanism because we felt that it needed the most room and was a very important aspect of our design. Our assembly process was driven mainly by space constraints, and after mapping out all of the elements in our design we drilled holes into the wood and acrylic to fasten them to the base. Everything that is bolted together in our design uses M3 bolts, they were readily available and easy to design for. For rotating components we used 6mm axles and 6mm (13mm OD) bearings in order to keep everything the same diameter, so that we could switch out parts if needed. We positioned the quick return mechanism so that there was space for the bottle opener to attach to the bottle cap and space to fit the Geneva mechanism behind it all. Standoffs were added in order to align the bottle cap with the bottle opener and to create space for the gears and align them on the same plane. One problem we ran into was meshing our gears together, which was challenging when mounting the gears to the wall. The quick return mechanism went together fairly quickly, but the gear train and the Geneva mechanism took a lot of time to line up and get into place.