At the beginning of the school year, we were introduced to the first project of our Design and Engineering II class. We were told we would be building air propulsion cannons. Immediately, my team and I began brainstorming. For the first week or so, we were mainly tossing around different ideas, trying to so what we could possibly create within the guidelines of this project. We were also spending a lot of the time during this month searching around Google to get ideas for our cannon and to better understand different ways we can make our cannon rotate and elevate. From our research, we mostly found that a very efficient way to rotate our cannon would be to use a “lazy susan” type design. This design consisted of one platform rotating on top of another. We not only focused on this design, but we also explored other designs, such as a tripod type design, but after realizing the amount of weight our cannon would have to hold, we quickly ditched this idea.
Throughout the rest of the month, we began to translate some of our ideas into 3D modeled sketches on a online CAD program called Onshape. We first began by translating our first idea, which consisted of a large circular base that would include a lazy susan, and a holster for our cannon. This initial first visualization helped us realize multiple flaws and problems within our design. We first saw that with this design would require an amount of wood that was out of our limit. Secondly, we saw that this design had no elevation method. After analyzing our flaws, and brainstorming for a bit more, we drafted another sketch.
First Onshape Design (Version 1.0)
In our second sketch, we focused mainly upon working with a new design. In this sketch, we still focused on using the “lazy susan” idea, but we elaborated upon it. We wanted our “lazy susan” design to also include our elevation system too. With this in mind, we designed a “microwave-based lazy susan”. This would allow our cannon to rest in between the “lazy susan”. The problem with this design is that it limited our elevation range.
Second Onshape Design (Version 1.1)
From all the problems we encountered so far, we created our third design. Within this design, we focused on having our elevation system on top of our “lazy susan”. Within our third design, we sketched our base with the “lazy susan”, and an elevation system that would work off of two guiding pieces of wood. We would have a base board that we would rest our cannon upon, and raise and lower it with our guiding pieces. This became our main design for the next couple of months.
Third Onshape Design (Version 2.0)
Throughout the month of October, we shifted our focus from brainstorming and designing to Arduino. Arduino is an open-source electronics program based upon the ideology of being easy to use. Our initial purpose of learning Arduino was to be able to create our own circuits and code that would be able to fire our cannons remotely. Over time, this purpose was dropped due to time restraints. Throughout the month, we mainly read over manuals. And practiced making circuits in order to fully understand Arduino. Although many teams had great success with building the circuits, a lot of teams struggled with the code. Since the code we already premade for all of the circuits, many groups skipped the code, including our group. This was our greatest drawback when attempting to make our own code for the Arduino.
Once November hit, we shifted our focus from Arduino, back to our cannons, specifically, the construction of the cannons. We began by discussing over basic safety instructions and practicing with the machines in the shop to become more familiar with them. Once we did this, we began constructing our cannon. The construction was mostly cutting up pieces of PVC pipe into the specified lengths and fusing them together with primer and glue. We had to follow a set of instructions the whole time to avoid any possibility of creating a cannon that would be dangerous in any sort of way. The whole process of creating and finishing our cannon took quite longer than other groups due to the main factor that my group had three people, including myself, compared to other groups that had four or five members. Overall, we ran into little to no problems when creating our cannon.
Group Member Chris C. and Josh Dial Priming and Glueing
Once we finished our cannon, we shifted back into the focus of designing our cannons. After having a whole month of being away from designing and brainstorming, my group and I came back disappointed. As we looked onto our design, we just felt it was too simple and we felt like challenging ourselves. We were eventually introduced to the idea of ditching the “lazy susan” and instead installing a planetary gear system to take its place. This idea intrigued us, but we needed to do more research before attempting to create a platform that could have this design. We spent the rest of this month mainly researching and brainstorming ideas for a planetary gear system.
As winter break began to make it’s slow approach, we were given the deadline to have our platforms done by December 22nd, which was the day before winter break. This really kicked my team and I into gear. After doing some researching, we found a CAD template for a planetary gear system. After importing it into Onshape, scaling, and resizing it, we had our start. From this, we began to sketch and create our base platform around the gear system. Our base consisted of a circular table, with interlocking legs, and a ring to hold the planetary gear system in place. Once we had this fully sketched, we still needed to create our elevation system.
Imported Planetary Gear System File
After a couple days of brainstorming, we concluded on creating a “drawbridge-based” system, in which we would rotate a wooden dowel to raise or lower the cannon. The difficult part of creating this was finding out where to position the system upon the platform. We decided on creating a platform that would rest above the planetary gear system and allow us to place the elevation system upon the platform. After drafting the platform, we then had to decide the placement of our elevation system on the platform. We did many weight tests to determine where we should position the cannon and elevation system upon the platform. After finding out the information we needed, sketching was fairly easy.
Final Onshape Design (Version 3.0)
Now, we finally had a fully sketched, working design. By the time we had finished, winter break was almost upon us, and we were now in the back of the line to use the ShopBot, which is a large scale cutting machine we were using to cut out our wooden parts. Once the day came were we had to cut, we spent about 40 minutes setting up the machine, and 10 minutes actually cutting. We sadly were not able to print all of our items before break due to the vast amount of parts we needed to print out, and the little amount of time we were given. We finally ended off our last day before break sanding and glueing some of our parts together. Our project was finally beginning to take shape.
Final ShopBot Cutting File
After winter break, we began straight away, trying our best to finish our project. Since many groups didn’t finish before break, we were given more time to work. We began by cutting out the rest of our parts and sanding them. We then focused on putting everything together. We had to make a few changes along the way due to some parts not fitting with others, but overall, this was a minimal speed bump. Once everything was glued and fit together, we began analyzing our project for things we needed to fix. One this we never accounted for was the instability of our elevation system. We fixed this mainly with by glueing a few side panels to the elevation system to add stability. Other small changes we also had to make was adding stability to our holsters, and sanding down some parts that had trouble fitting together. After this, we were finally done with our project.
We then advanced into the testing phase. Our group had to shoot tennis balls at different angles with different pressures. Overall, my group and I were very surprised with the results. We were able to reach a maximum distance out of all of our trials of 152 feet, at an angle of 35 degrees, at 75 PSI. We were very pleased to know we had the farthest distance in the whole class. All in all, this project was a great learning experience and was very fun and challenging to participate in all the way.
After completing our project, we went through a stage of self reflection and peer review. During this phase, we all, as a class, critiqued and provided feedback to everyone's cannon, including our own. During the time my group and I were given feedback from other groups and had time to reflect upon our own design. When discussing our design to the class, many groups asked why we had choose to do a planetary gear system for the rotation of the cannon. Many pointed out that this design was needed, took longer, and had no practical use, for a "lazy susan" based rotation system could have been easier to make. Although I agree that our design was not practical, it presented my group and I with a challenge that not a lot of other groups faced. Also, many groups questioned why we chose base our elevation system based upon a digital-analog hybrid. We responded by saying that we originally planned on doing a fully analog elevation system, but we had to make it a hybrid due to our drawbridge-based design. Finally, the last main thing people pointed out about our cannon was our stabilizer. Many people asked why we chose to use duct tape to secure it to our cannon. We responded by saying that we originally designed our cannon stabilizers to connect through a fishtail joint, but when we printed it out on the ShopBot, the fishtail joints did no connect securely together. This is why we had to resort to our duct tape.
When we had to reflect upon our own design, my group and I collectively focused on two main aspects on our cannon. We all believed we could have improved upon the stabilizer of out cannon. We believed that given more time, we could have redesigned our cannon stabilizer to where it could have preformed the way we wanted it too. Finally, we believed we could have improved our rotation system by adding a bearing to the design between the gears and the base board. After seeing what other groups did to remove friction from their rotation design, we believed we could have put a plastic bearing to reduce the friction present in our rotation design. Other than these two aspects of our design, we were all pretty much satisfied with our design and what we had accomplished.
Data still needs to be collected before data is imported.