The drawling board ( the beginning)
The beginning of me Samaje and Toby's journey to building our air cannon started here on the drawling board. Our goal was to come up with an original design for an air cannon that could launch a ball through pvc pipes using air pressure and the angle of the cannon could be adjusted horizontally and vertically. We had many ideas but we eventually decided to base our design on the idea of a lazy susan with a pulley system. The lazy susan platform consists of two circular wooden boards one atop of the other, the base remains stationary and is connected to the top circle which can rotate 360 degrees. The idea was to have the support device which consisted of two large triangular uprights with a dowel rod going through them and our support. They would be attached to the lazy susan and the dowel rod would be connected to a pulley allowing for the cannon to be adjusted at its vertical launch angle.
Before we started in our design for the base we had to design, test and build a barrel support to ensure the barrels couldn't move. To do this we needed to use a box designer that would make the barrel support the precise size it needed to be. We measured how far apart they were and how thick they were. We then did many tests to ensure we had made the correct measurement needed. This process of trial and error, while tedious, helped us make a very good support which we made with the 3D printer.
This was one of our first failed designs we encountered
Our first box design as seen above had a few issues we had to address. We did tests on the diameter of the circles and they weren't the correct size they needed to be. Another problem was that the circles were too close to the end of the box.
Barrel support circle testing (above)
As seen above, we had to test several different sizes for our circles until we found the size that offered the best fit that wasn't too loose or too tight.
After trial and error of creating many different sized circles which we made through onshape and testing each one individually. We found the best size for our circle was 2.372 inches in diameter.
After we found the found the correct size for the circles on our barrel support, we then had to design circles in the center of the barrel support for our dowel rod. The purpose for the dowel rod was to allow us to adjust the vertical launch angle of the cannon. The dowel rod would be connected to a pulley which could adjust the vertical launch angle of the cannon.
Dowel rod testing (above)
We went through the same process of trial and error with the dowel rod circle testing as we did with the testing of the barrel support circle. It took a number of tests but we eventually found the correct diameter and implemented it into our barrel support design.
Above is our finished barrel support as well as the final sketch we made on onshape. We used the 3D printer to cut this out and we used glue to connect them.
The next step after we finished making the barrel support was to then make our actual air cannon with pvc piping. This was the easiest part of the whole design process because we just had to replicate the same cannon everybody else was required to use in their design.
Above is what the finished pvc cannon looks like (ignoring the barrel support) which was the design we all had to incorporate into our design.
First we had to measure and cut out our pipes for the air cannon.
We then used a purple primer and glue, to put together the pieces of the pvc cannon. We layered the ends of the parts that were to be connected approximately an inch with primer and glue. After we put everything together we had to put the barrel support on, then we put the cap on the end of the barrel to finish it.
The next step to our project after we finished the building of our cannon and barrel support was to finalize our design and come up with measurements. We ran into a few problems we had to solve in our design. One problem was we had to figure out the best dimensions for our triangular uprights, so that it offered elevation and stability to our cannon. We also had to figure out how we could adjust it's elevation. We decided on a pulley system that would be under the cannon, it would have a string attached to the bottom part of the cannon allowing us to use the pulley to adjust it's vertical movement.
There was many adjustments we had to make in our designs. We had to make adjustments in our bearing design for the lazy susan. We had to find the correct size for our dowel rod circles on the uprights as well as their placement. Another problem we had to solve was the attachment of our uprights to the lazy susan. We decided after talking with Mr. Twilley that we should add notches to the bottom of the uprights and the top of the lazy susan support. These Notches would offer much more support and stability.
Above is our final designs we created on onshape. We have our lazy susan pieces connected in the center with a bolt allowing for easy rotation. We designed a pulley system which would have a small dowl rod going through the two pulley supports and the small circle of wood in the middle of them.
As we finished our design and were ready to print we ran into a big problem. The shop bot's drill bit broke. We planned on using brandywine's shop bot but they also had a problem with theirs so we couldn't do that. We were forced to improvise under these circumstances. The shop bot couldn't cut with a drill size small enough that our design needed. We cut out our design with the wrong sized drill bit as we had no choice. We had to sand down many parts of the design so that they could connect, we continued to assemble it making adjustments along the way.
Samaje sanding down upright to configure to our design (above)
Gluing the uprights to the lazy susan
Below you can see we added holes to the outside of the lazy susan base and put screws in them. Toby did this so that the base wouldn't move once it's on the ground and so it would spin easier. She also put a thin piece of plastic between the two wood boards to allow it to spin easier by reducing friction.
One of the most important parts of our design we had to get to work was our pulley. As you can see below, we were able to implement it in our design. We figured everything out to get the pulley to work effectively but we needed to make adjustments. We added a piece of wood, acting as a stopper, to the end of the dowel rod on the pulley. This stopper worked by looping a string around it which was connected to holes we made in on of the sides of the uprights. This string held the stopper in place which stopped the pulleys dowel rod from spinning.
Although none of us ended up using the Arduino's during testing we did manage to come up with coding for a signal fire for the air cannon. The signal fire would have flashing led lights triggered by us pressing the button on our Arduino breadboard, it'd also have a sound go off before firing.
We finished building it on January 18th and we were ready to begin testing.
Below was our test results from two different days in which we went outside and shot a small tennis ball at different angles and PSI pressures. We did this to test our air cannons range accuracy and precision. We found that generally speaking, our cannon was accurate and precise.