The Puzzle of the Bottle Opener (1 of 2)

The first project my partner, Sam, and I tackled in this course was the bottle opener.  We went through several iterations to our design, focusing mostly on how the product would 'grip' the bottle. We wanted to make sure there would be minimal slipping (and thus, minimal injuries) when using our product.

Our initial designs varied from a version of pliers (top image, subject 5) and levers (top image, subject 3; bottom image, subjects 11 and 12) to a simple circle with a slit through its center (top image, subject 2).

However, after reviewing the physics of cantilevers and torque, we had a basic idea of what we wanted out final product to look like. Our chosen design oriented the the bottle opener as a lever with the fulcrum located where it would be in contact with the bottle. Additionally, we made the handle as long as possible to achieve an easy grip as well as provide a mechanical advantage with torque.

Since torque is the cross product of force and distance, a longer handle would make the bottle opener easier to use, a feature that would not have been available with the circle and slit design, which would have kept the handle closer to the fulcrum point.

Additionally, our chosen design allowed us to utilize the thickest version of the Delrin available, making our handle thick and steady (a feature that may not have been available on some of the other designs). This also helped with the deflection of the material. Since deflection is equal to:

(F(L^3)) / (3EI)

Where F = the applied force, L = the length of the lever, E = Young's Modulus (or the ration of stress/strain, or stiffness) and I = the moment of inertia (or the lever's stiffness of it's cross sectional area). Though we had no way of controlling Young's Modulus because we only had one type of material to use, we could alter the length and stiffness (by selecting what thickness to use) in order to get the most out of the applied force.




Thus, the thick material and the design of the handle helped minimize the deflection and make the handle strong and stable. Our design united all the qualities we wanted in our final product, including sturdy handle, a solid place to grip the bottle cap and maximum torque so the user could apply less force to open their bottle. We made the neck 2' wide. The maximum length was 6'. 










Once we were happy with the dimensions, material and initial outline, we made a mock-up out of foam to visualize the final product.

                                                   

After we had our demo, we built our model into SolidWorks.

In Solidworks, we made a part file and used basic shapes, like circles and lines, to construct our model. Once the sketch was finished, we rendered a 3D model in the program and tweaked it wherever we thought was necessary, such as filleting the pointed tips so they would not wear down as easily.

Once this was completed, we printed out model and.....

It was not quite as large as we expected it to be (the first cut is on the bottom of the above image). After  a few careful measurements, we discovered that the printer had interpreted our model as half its original size.

After a few adjustments, we managed to print a correct scale piece. However, the initial test of our product did not go well. The lower tip of the pointed portion continuously broke off with each attempt and was quickly worn down to an unusable stump. We noted the problems and edited our design.

Our second iteration bore striking similarities to our first model, however it had several major differences. 

1.) The lower point was curved upwards to make it as thick as possible in the hopes this would keep it from breaking. 

2.) The upper prong was filleted and tapered in a thick curve to give it more contact on the lid and distribute the force more evenly. The first iteration made 'deep' indents in the cap.

3.) We added a half- circle to the bulb for easy storage and carrying (it originally was intended to be a second bottle opening option on our model, but was scraped when we decided to use the thickest type of Delrin)

The initial test of our second iteration revealed that the two prongs (which we had made parallel in respect to their tips) were unable to fit under the cap and onto of the cap respectively because they each prevented the other from reaching its destination. In short, they were not aligned properly. After several minutes of intense filing, we managed to remove enough of the upper prong to allow the hooked prong to fit under the cap. It took three tries, but the second model managed to remove the bottle cap. No pieces broke off this time.

Although our second model did achieve its purpose, it has problems that need to be resolved before it can be considered a finished product. The alignment problem between the upper and lower prongs nearly rendered the second model unusable. 

My partner and I plan to edit out Solidworks design to eliminate this issue, as well as add details and embellishments to make the product more eye-catching and aesthetically appealing.