Don’t Fall In Love With Your Own Design

A professor once told our class never to “Fall in love with your design”, I thought I understood what he had said, but my recent experiences have brought new meanings to the words.

Rewind to the beginning of April. I have the basics of my launcher locked down, the tasks at hand include improving accuracy and damping power output. The original modification that I made to my nerf gun included the altering the air chamber component to physically hit the ball rather than shoot it with air (I struggled to use the air effectively to get enough force behind the shot). With this new spring action shot I had ping pong balls hitting ceiling and not coming within a metre of my projection area. I knew I needed to reduce this power somehow.

To take force away from the launcher, I attached small cardboard pieces to the tip of the air chamber using superglue and wrapped an elastic band around the gun. Through much trial and error I found the perfect setup to have just enough power for my device.

Cardboard pieces added to chamber to spread the impact onto ball
Inserted chamber with positioned elastic band

With the power problem sussed, I moved my thoughts towards the accuracy of my shots. I loved the idea of the rotating chamber, I thought it looked very professional and worked as smoothly as I had hoped. Not willing to scarp this idea I focused on making the dimensions of each chamber identical to each other. This step involved cut ting the chambers to equal lengths and cutting holes in the base very accurately using a small stanley knife. Shooting was gooood. Felt like Michael Jordan, I couldn't miss.

Revolving chamber

I realised that the longer shooting barrels were a bit flimsy and interfered with the balls projections. I made no changes to the original rotating plate except for the addition of the cylinders.

Written plans for developing launcher
Final Launcher

For the next week, my plan was to take it easy and build a stand for the launcher. A simple design that would support the main body of the design.

Nerf gun/Launcher design perfected. BOOM. I’m in the money. The Don. The Godfather. I am Jason Bourne. It was plane sailing once I perfected my launcher and I was feeling real good. Listening closely in class the following week I discovered and found that all though my design did automatically reload, its energy source was not a supply and had to be reloaded before every shot. Heart-breaking, but thats the game we play. Did I give up and cry? No! (I need the marks). Again I set out for a completely new design without hesitation.

I required a potential energy source to base my design around. I could only think of a pushing force or the use of air. Scarred from my previous endeavour, I wondered with the idea of air. The example told to us from the start by our professor was the use of a balloon. With not long to go until submitting my assignment I thought I’d give it a shot.

With a quick idea, I went out to shops and bought a packet of balloons and rubber bands. I thought I would try and salvage anything I could from my nerf gun attempt so i planned to use the remaining cardboard chambers. I attached the balloon to the outer rim of the toilet paper tube but it quickly buckled under the force. I started to think of different materials I could use as a barrel, some sort of plastic or metal, something that air cant get through. It was at this moment my mother called for me to bring the hoover down the stairs for her. Then it hit me, the attachment for the hoover. Hard plastic with a small circular end, perfect. I had my supplies, now i needed to put them together.

The shtuff

The balloon easily fitted over the narrow end of the hoover attachment. I then tightened a rubber band around the end the the attachment to air seal the balloon. I blew into the circular side of the washed attachment and was happy with the result. Next I needed to find a mechanism that would pinch the base of the balloon without popping it. A close line peg would do the job. I attached the peg but air was still coming through the hoover attachment. Not ideal. To solve this I taped the circular cuttings from my nerf gun revolver to the inside of the pegs grips to form a larger flat surface.

close peg with attachment
Final Assembly

It’s defiantly not as aesthetically pleasing as my nerf gun launcher, but it is powerful enough and an accurate shot. Instead of having a revolver I will have multiple of the same launchers positioned to shoot a single ping pong ball.

With my launcher complete, the last remaining task is the programming of my elegoo robot to be able to navigate through the obstacle course and catch the balls. Should be good craic.

Mechanical and Manufacturing Engineering