Day 8- The Saga of The Ping Pong Ball Launcher
Here it is, the one we've all been waiting for, building the infamous ping pong ball launcher.
Firstly, it’s important to note the design brief for this section of the assignment as it’s the area that has the most constraints and requirements to guide our design. The minimum was one ball but ideally, we are aiming for more than one ball landing in Jerry’s catching attachment. It must be automatically reloaded, i.e. once the course has been started we can’t reload balls into the launcher ourselves. The energy source must convert potential energy to kinetic and no extra energy can be added once the robot has started the course.
My first thoughts on this were to have a tube attached to the main launcher pipe that would feed balls down into the pipe one by one to be launched. I first constructed this with toilet rolls and the prototype seemed promising so I proceeded to build it from the sturdier rolls from inside of wrapping paper. As you can see below, it was actually quite a precise process to make sure the two parts fit together nicely and then I sealed the whole thing off with tape to make sure no air would escape from whatever energy source I used.
I then tested this assembly using a hairdryer and it was a success, firing multiple balls in a fairly consistent arc. I then thought, ‘wait, why can't I just use a hairdryer as my energy source?’ This was great until I realised that, as a hairdryer is pulling energy from the mains, it is not, in fact, potential energy. Bummer.
I proceeded to attempt to produce a pressurised air chamber from two plastic bottles, filling it with a bicycle pump from one end and releasing air through a valve that I attempted to make from a cork some hot glue and a rubber tube at the other. Needless to say, this did not go well. At all. After a day or two, I was very ready to give up on the hope of getting this launcher working.
Meanwhile, I had started working on an alternative launcher design. This time using elastic bands as the launching energy. While it wasn’t terrible, it also wasn’t great, and in order to stay within the guidelines for the assignment, I’d have to build a few in order to launch more than one ball. I found this version was quite inconsistent in terms of distance and direction and even with some adjustments the improvement wasn’t optimal.
While it might have been doable, I was still really wanted to get my other design working so I decided to make another attempt.
So after a chat with my lecturer, I decided to go on the hunt for a battery and take apart the hairdryer to remove the transformer and all the other extra bits inside to essentially turn it into a 12V fan. My first challenge in this endeavour was, ironically, the screws which were a strange triangle shape that my poor hammer/screwdriver was just not equipped to handle.
I did eventually manage to source a tool that could open up the hairdryer and then I removed everything from inside (heating element, transformer, etc.) and cut the wires down to just the fan motor. I had some handy crocodile clips which I used to attach the motor to the batter and we had lift-off!
To be able to better direct the airflow, I reattached the front end of the hairdryer and taped everything up and then taped the hairdryer into the launcher pipe.
**One final addition from testing launching into the attachment, I added a piece of tape across the top of the loading pipe so the balls would be sucked down and no air would escape from that opening and reduce the launching power **
