Building the Launcher
In my last post I was still unsure about which spring launcher concept I wanted to go with as I had doubts about how well the small compression springs I had at home would perform. Between now and then I was able to gather some materials and work on what sort of design would be feasible for me to build. I wasn’t able to find any other springs (compression or tension) so I had no choice but to use the the ones at home. This actually didn’t turn out to be such a bad option as I think I would have run into difficulties finding the right materials to build a launcher with bigger springs, that would extend a lot more.
Unfortunately when I was looking to buy some 40mm PVC pipes for the launcher I realised (in the shop) that this was the external diameter of the pipe and not the internal diameter. This made it so that the ping pong balls (which also have a 40mm diameter) just about didn’t fit through. I was able to buy two tubes of caulk though that had a larger internal diameter of about 42mm. Another part I found in my shed was an adjustable angle tilt bracket we still had from an old desk. This actually suited perfectly to be used as an angle adjustment device I was thinking of constructing at the very start of the design process.
The full bill of materials for the Launcher were as follows: Various wood panels, caulk tubes x2, 40mm PVC pipe, pipe fixers x2, tension springs x2, an adjustable angle bracket, a sink plug and some screws. These can be seen in the image below.
From this the construction and assembly was actually very straightforward with only some simple sawing and drilling needing to be done. The best way I could think of to set up the spring mechanism was to drill screws into two parallel wooden panels either side of a caulk tube and pipe and then hang the springs between the screws. Because the pipe is significantly thicker than the tubes I was able to drill into the pipe directly and actually just passed a metal rod through it. I then was able to drill the mechanism to a horizontal wooden panel. I used a thick wooden panel as the base to provide support for the launcher and keep it stable. Finally I connected the launching mechanism the the base through the tilt bracket. The assembled launcher is shown below.
Another element I wanted to add to the launcher, as mentioned previously, was a reloading container which I managed to do on my final iteration of the working launcher. This is again shown below.
I used the remaining caulk tube to build this. The design for this was similar to my original design which I had based on the compression spring launcher. The only difference is rather than the platform of the compression spring holding up the ping pong balls, the assembly is set up so only one ball can fall at a time and the ball being shot holds up the rest of them itself. I did this by having a stopper inside the firing caulk tube which doesn’t allow the balls to roll back farther than directly underneath the reloading container. This causes them to just sit on top of each other. All that was left to do was test the launcher to see if it could pass the requirements for the project. Check out the two videos below for a two successful launches, one in slo-mo.
Overall I am very happy with the launcher and how it is performing, especially with my restricted access to recourses and materials. I’ll definitely have to get a bit of practice in though and work on consistency before putting the launcher to the test in the demonstration/competition.
Please go follow my Instagram page if you enjoyed following this project so far to find out what I’ll be moving onto next. There will be an update here soon as well. Thanks.
