For my prototype, I constructed a cabinet that opens and closes ‘magically.’ I chose this project because I wanted to build a small machine/mechanism that used the pneumatic air cylinder as its actuator. The hinged door seemed to lend itself well to using an extendable cylinder. It reminded me of screen doors that use a compressed vaccum air cylinder as its mechanism to close automatically. Here is a picture of such a screen door:
To start, I measured my home kitchen cabinets to determine the general size of my cabinet. After I cut all my pieces and assembled the side, door, and base, I attached one end of the double action air cynlinder to the base, and the other end to the door. The main challenge I had was understanding how to secure the two ends of the cylinder. At first I thought I might have to build at least one track for one end of the cylinder to slide as it pulls or pushes the door, but then John showed me this was unnecessary. It turned out that both ends of the cylinder simply need to pivot to achieve the necessary pushing and pulling of the door. The next challenge was choosing a cylinder of the proper length to successfully open and close the door completely. Luckily the first cylinder I tried ended up being best suited for the task. I aligned the cylinder along the receding edge of the base so that it was as hidden as possible. Then, I attached the air hoses and tested the mechanism. As expected, the door movement was too abrupt, and I had to adjust the valves of the cylinder to limit the speed of the air flow. However, even with the proper air flow, I noticed the door of my cabinet never fully closes. This is the primary issue that I will try to fix for the final version of this project.
Working on this project made me realize that had I observed similar hinge mechanism around me more closely, I would have realized that I didn’t have to build a sliding track, and instead focused on creating pivot. Although I had a general sense of what needed to be done and I knew it was possible based on my cursory observations, I didn’t do my research as thoroughly as I should have and almost wasted time building a sliding track.
My main challenge for the final project is to experiment with the placement of the cylinder so that the door closes fully. I expect that this might have to come at the cost of the door opening fully the way it does already, or at the cost of the cylinder being more visible, since the cylinder size is fixed. But this is only a conjecture. I hope I can find an arragement that satisfies both the requirement that the door opens and closes fully and that the actuator is hidden. I will also experiment with attaching a shelf that hides the cylinder.