Potato Canon/Spud Gun

grabcad

I recently decided to give this nearly ten year old friend a little TLC. Nothing fancy about it, it's just a plain old spud gun with a few tweaks. I was doubtful about the u-bend at first, but it's held up incredibly well. I always keep it wrapped up with reinforced tape just in case. The barrel is over a meter long and the combustion chamber is HUGE. Double spark ignition and hidden inside one end cap is a 5v fan to mix the fuel and air. Another part that I thought would fail, but amazingly, the original 60mm axial fan still works despite being inside the combustion chamber. This is now modded to a 50mm blower with an insert to direct the flow and a shroud to protect the intake. The barrel sleeve holds a piezo buzzer, a DPDT switch and the battery holder. One switch position turns on the fan and the buzzer to prime the shot and alert passersby to the possibility of airborne taters in their immediate future. The other position fires the continuous-spark BBQ ignition module. Fuel can be any decent aerosol propellant or straight propane/butane if you can meter is properly. Save the acetylene for steel canons. Of all my vegetable launchers, this guy is definitely my favorite. It's named after a character on the Venture Bros. Not really a political reference. Well, the character obviously is. I just like the name.Spark plug model source: Spark PlugUpdate: Added a second version that uses pistol grips, one of which contains two momentary switches that replace the DPDT from v1. Also, two wrenches for the end cap. One is open and loose, the other is an interference fit designed to stay attached to the cap. It's very easy to lose your fuel by taking too long getting the cap on and tightened. I printed it in ASA and heated it up before squeezing it on in a vise.6.18.24 Update: Added inserts for the pistol grips. Both have tubes to hold a ramrod (I use a ~1" broomstick). One insert has a chamber for a 13mm laser diode. Adding a laser sight to a potato gun is stupid and pointless, I know. Ergo awesome.6.28.24 One last update. Polished it a bit, set it up for a build from scratch rather than the way I originally built it. v4 has the batteries, buzzer, DPDT and the HV generator inside the rear sleeve. I also changed the 18650 to a 3xAAA setup. 3.7v didn't cut it to run everything.