## Our ProjectBy stefan haroldsson

" A journey of a thousand miles begins with a single step" -Lao Tzu

This quote describes this project very well. At the beginning of the project, it seemed almost impossible. We had to build a cannon using PVC, build barrel stabilizers for it, build a base that could control both its vertical and horizontal rotation, and program it to fire using a program that we created ourselves on Arduino. We broke this entire process up into 4 main parts: Base and barrel control design, Arduino design, construction of cannon, and construction of base.

Our Ball Bearing Design, which allowed for easy horizontal rotation

We started this project by beginning to design a base that could allow our cannon to rotate both horizontally and vertically. We used our drawing board and Onshape to complete this task. We tended to use our drawing board for calculations like finding the third side of a rectangle using Pythagorean Theorem or looking for the correct distance between two lines. We did much more of the actual designing on Onshape, where we used the tools provided to create accurate and precise designs that could put our mental ideas into the real world.

Our 3-d printed out Ball Bearing Design

Although we were very successful printing out our ball bearing design for horizontal rotation, we faced some challenges in successfully printing out other parts of our project. Because of extremely slight inaccuracies, we spent a lot of time sanding parts down in order to get them to fit into other parts of our designs. Although a lot of the times these errors were simply because of slight mathematical or measurement errors, these also occurred because on multiple times we failed to adjust for the size of the tool we were cutting with, such as the drill of the Shopbot. However, we did eventually overcome our mistakes and were able to cut out all of our pieces and use them in our design.

One of our initial designs for the spikes of our base

Another challenge that we consistently faced in the design phase of the project was a result of the small size of our cannon. Because our cannon was quite small, we faced the continuous challenge of ensuring that all of our dimensions were big enough that they would not be weak points and break when they were cut out or when we were constructing the base. This problem was compounded when because of some Shopbot issues, it became clear that we would only be able to cut with the 0.5 inch drill on the Shopbot. This made us adjust all of our measurements again on almost all parts of our design shortly before we had to print to meet a deadline.

Our Design

We used the assembly feature in Onshape to put together a complete model of our base design. The assembly feature is useful because it allowed us to ensure that all of our pieces fit into each other and that we were not forgetting any parts of our base design before printing. The assembly feature was also very easy to use because it allowed us to easily select the parts from part studios that we wanted to use in our assembly.

Our Barrel Support Design

The second part of our design for this project was the barrel supports. A good barrel support system should prevent the barrel from twisting or turning and make the two barrels parallel to each other, not in a V-shape. A good barrel support also must no inhibit the design's function in any way. When we created our barrel support, we had a good idea of what we wanted it to be, but we had a lot of difficulty figuring out how to get there. We spent many days prototyping our design on the laser, but consistently ran into the problem of the support not lining up perfectly with the barrels. Some of these problems included the holes being to big/small for the barrel, the design not being the right size to go around the barrel, or the hole in the middle not being perfectly symmetric. We combated the first problem by adding Plexiglas inserts into our barrel supports so that the barrel would fit exactly. We combated the second problem by being persistent, and not giving up when our design was slightly to large or small. We combated the last problem by not creating one rectangular hole, but creating four smaller touching rectangular holes that were not symmetric in their own, but came together to form one symmetric rectangular.

After we finished our barrel support and base design, we investigated Arduino to see how we could use it with our cannon. Because of the complexity and the lack of experience that we had with Arduino, it took countless hours and nights for us to get accustomed to the Arduino language and the different types of functions that we could accomplish through the Arduino. In order to get to better understand how Arduino worked, I read through the Arduino guidebook and took a section of notes (https://docs.google.com/document/d/1ZaooP7RuGA6od_2fqGeUfGcYTUfPDn5BaURX-31WeoI/edit?usp=sharing ).

Though Arduino was very difficult for me, I did complete the 12 basic circuit exercises both hands-on and online using 123d Circuits. Some other accomplishments that I achieved in the world of Arduino were learning how to play any song using the Piezo Element and learning how to extremely accurately measure the temperature of anything using the Heat Sensor. On the other hand, I ran into some major challenges. I may have been able to much more accurately complete the hands-on portion of Arduino because I had some experience with circuitry, but I lacked much of any type of knowledge on coding. I used the Arduino guidebook A LOT to help me get through this section of Arduino, adn was able to fix my initial errors in coding that mostly came as a result of punctuation errors or capitalization errors.

A hooked up Arduino Board

Although we spent a lot of valuable time on Arduino, we decided not to use Arduino in our project because we had a deadline to meet and it didn't seem we would be able to meet the deadline with a working Arduino attached to the cannon. In reflection, I do regret this because our design was very easy to adjust and therefore could have easily been shot off by the Arduino which would have made our design stand out from the rest of the class.

The next part of the project was the construction of the cannon itself. The materials primarily involved in this were PVC pipe, PVC cement, and PVC primer. We only spent two days on this part of the project; but I did learn a lot about how PVC is joined. To build our cannon we adjoined all of the PVC pieces, threaded the sprinkler valve to the PVC pieces, drilled a hole in the PVC pipe, and then used epoxy to put in the bike valve so that we could pressurize the cannon. This process went very smoothly for our group, especially because we worked quickly and stayed focused the entire time. If we had not stayed focused, it is possible that we could have allowed the rubber cement or epoxy to dry to quickly, preventing us from obtaining a successful connection between two pieces. It is also possible that losing focus could have led to catastrophe when attaching the bike valve to the pipe, because if we covered the valve with epoxy we would have been unable to pressurize our cannon.

In the process of Constructing our Base

The last part of our cannon project was the construction of the base itself. After constructing the base, we would be ready for testing. We started the process of construction of the base by printing our Onshape design out on the Shopbot.

To use the Shopbot, we learned the ins and outs of the Shopbot program that allowed to print our design. We used the drawing of our Onshape design to transfer our design from Onshape to the program, resulting in a diagram that looked like this.

After our pieces finished printing out, we began sanding, gluing, and connecting them together. Through this process, I learned how awful it can be to sand pieces, especially when you have to sand a lot off to get them to fit. We began our construction from the base up, starting by gluing on the stakes to the base followed by epoxying the ball bearing holder to both the wooden base and the wooden piece on top of it. We decided to use epoxy because epoxy is much better at connecting wood to plastic than wood glue it.

After we finished constructing our base and adding our cannon to it, our final product looked like this.

After we finished our project, it was time for testing. The test occurred behind Mount on the practice football field. Here is a video of our cannon at testing.

As you can see from the video, our cannon design was very accurate at testing. We finished 1st in our class with 20 points over 5 shots. Here is our data and results from the accuracy testing.

My Final Reflection

Throughout this project, I learned many things that were not only useful in the final production of this project, but also in the future of my engineering career. The first design tool that I was able to gain a stronger mastery of was Onshape. I learned how to use Onshape to create assemblies to create working models of my designs with multiple parts. During this project, we actually did use assemblies to check our measurements and whether or not they would fit together. This seems on the outside like a good thing, but it actually contributed to a bit of a downfall because we thought that designs would fit together and therefore didn't account for the cutting diameter of the tools. The second design skill that we used in this project was Arduino, which we used to try and control are cannon. Although we did not use the Arduino in the final project, I learned some valuable skills through Arduino such as how to work with circuit boards and what functions certain types of things that you can add onto the circuit boards are. I also learned some basic coding through this, such as the language and how to begin/close code. In the construction of the cannon part of this project, I learned how to use PVC primer and PVC cement to build a cannon. In the construction of the supports part of this project, I learned how to adjust for slight inaccuracies in measurements from sanding and adjusting on other saws. From testing I learned that... (completing when more testing occurs)