Although a common everyday item such as a bottle opener is seen an elementary and transparent device, the engineering and physics behind it can prove to be far more complex. Over this project my partner (Chloe Shi) and I created and iterated a number of bottle opener designs to construct a functioning and elegant bottle opener out of DelrinTM plastic.
Our designs were limited by the type and thickness of plastic (1/8’’, 3/16’’ or ¼’’). After first being presented with the task, we brainstormed a number of bottle opener designs specifically focusing on the size and shape of the bottle cap.
We opted for a more classic bottle opener shape. As seen from the image below, we wanted a longer grip that could sit comfortably in a consumer’s hand and based the opening on the diameter of the bottle cap. We decided to adopt a triangular opening, as we believed a triangular shape would increase stability and grip the bottle cap at pivotal opening points.
However, upon testing a physical mock-up of the design using foam core, the top band seemed extremely flimsy. Moreover, the dimensions of the opening did not adequately circle the bottle cap.
Hence, we redesigned the original bottle opener by widening the triangular opening, increasing the width of the band, shortening the grip and increasing the breadth of the opener.
Although the bottle opener now fit around the bottle cap, the group was not satisfied with its bulky shape. Essentially, we wanted to create a bottle opener small enough to be used as a keychain. Therefore, we further modified the shape to allow for a thinner handle and curved edges.
The new foam core model proved to satisfy all the major criteria our group idealized. However, did not show promise on being able to open a bottle easily. Therefore, we began to focus more on the key points of contact and ways in which consumers would open a bottle.
We began to place a huge emphasis on the duality of opening a bottle, as seen in the images below. Design 4, was a bottle opener modeled to open a bottle both ways, however after we created the first plastic prototype, we encountered major chipping on the hooks. The sharpness of the hooks, although functioning in opening the bottle both ways, added an element of instability.
Ways in which you can open a bottle.
Design 4
Design 5 improved this weakness through the increased thickness of the hooks, however we still noticed visible chipping.
Design 6 played with the overall shape of the bottle opener. We used the same bottle opener design, but instead changed the shape of the handle to add a playful element to the design. As visually appealing as this was, the rabbit was not able to provide a comfortable grip.
Design 6
Given the deadline of the assignment, our group would not have been able to successfully create a dual bottle opener. Therefore, we decided to focus more on the hook and grip. The final design (Design 7) incorporates a thin but relatively sharp hook. We bypassed any fragilities of the hook, but decreasing the arc and increasing the overall breadth of the area around the hook. Furthermore, we rounded the hooks to provide an easier opening motion, as depicted in the diagram below. We also provided a bulbous region around the primary end of the hook to add finger support when opening the bottle. The opener also included a small hole to allow for it to function as a key chain.
Solid Works Mock up
Final Design Elements
Design 7 Foam Core Model
Bottle Opener in Action
A bottle opener can be also be analyzed as a cantilever. A cantilever is defined as a long projecting beam fixed at one end. It is a largely seen in bridge construction and can be used as a method of lifting heavy objects. The cantilever beam equation evaluates the deflection of the beam dependent on the length of lever (L), Young’s modulus (E, material stress and stiffness), moment of inertia (I, cross sectional area stiffness) and force applied (F). The moment of inertia is defined by the breadth and height.
Deflection Formula
Moment of Inertia Formula
Ideally, we would like to minimize deflection of the opener.
We can roughly assume that the force required to open the bottle and Young’s modulus (due to the material) is constant. Therefore, we can only manipulate the moment of inertia and length of the opener. We could not further decrease the length of the opener, as a comfortable grip would not be achieved. Instead, we increased the moment of inertia by increasing the DelrinTM width. (1/4’’). Overall, increasing the inertia decreased the overall deflection of our bottle opener.
Upon reflecting on this experience I have been given a larger insight into the intricacies of engineering. Often, small elements of a design can be easily overlooked however play important roles in the holistic function of a device. Had we had more time and a larger variety of resources to choose from, Chloe and I would have liked to be able to create a metal opener with dual opening functionality.
Your incorporated images are awesome and go along really nicely with your process description.
I enjoyed how some of your designs went beyond a normal bottle opener, like the ability to use either side and the bunny shape. Although these aspects were not included in your final design for this project, I think that this way of thinking will be helpful in future projects. I also think that your blogpost does a good job of clearly summarizing the evolution of your bottle opener.