3MEMS3: Launcher Assembly and Problem

With both parts of my launcher designed and made it was time to fully assemble it for the first time.

As can be seen in the CAD renders below the aim was to keep it simple and effective, and while the design is straightforward there have been some niggles that need sorting in order to get it working 100% but more on that later.

Once I had all parts in order I began assembling the launcher. Before I committed to securing the parts using sealant I decided to assemble them using tape for some initial tests. This was to be a first dry run with temporary fixtures so I had no plans to record it — a mistake.

With all parts relatively secure I fired the pressurised canister with a ping pong ball in place in the funnel. Upon releasing the pressure, however, various parts of my entire launcher were sent scattered across my room. The launcher went from 1 to 5 separate pieces in one swift action, straight out of a Buster Keaton film (see below).

Despite this, I was encouraged by the potential and energy store obtained from the canister so I proceeded as planned in assembling the launcher with some adhesive.

With the launcher now built as planned, I was ready for a more successful test. Once again, pumped the canister, loaded a ball. When the gas was released though, to my surprise, nothing (once again, see below).

The pressure was released but did not launch the ball. The main reason for this seems to be the clearance between the funnel and the ball. In order to not restrict the balls progress with wall surface friction, the diameter of the funnel is larger than the diameter of the ball. Unfortunately, it seems I've overcompensated and much of the gas is escaping around the ball and not launching it out of the funnel.

Tonight I’ll try to fix this by adding to the internals of the funnel to create more of a seal. The ball hopper might also be claiming some of the pressure before it can be put to use so that's something I'll look into as well.

Some good news though is that the programming for the robot has been complete and that will be ready to share soon. In the mean time though my social media pages will be the first to get updates on my launcher progress.