Minitaure Potato Gun

Well, I thought it's about time that everyone have a tiny little potato gun, so here goes:

While I was working on my thesis and teaching during grad school, I spent a lot of time in my office "grading papers" and "coming up with class stuff" so, obviously, I had a lot of free time on my hands. Time which was usually fueled by a lot of caffeine and occasionally some Jim Beam. There's only so much fun you can have making lady-finger mufflers for covert fireworking, so the obvious next step is to build a wee little potato gun. Right?



You'll need the following material:
- A barrel: you can't get much better than a ballpoint pen tube. One of those cheap white ones that you can pull the ink-thing out of one end and the little plug out of the other end. That's what I use here.
- An expansion chamber: A small pill bottle or something similar. I used one of those gas station aleve bottles that has about 4 pills in it and will run you about $217 USD.
- Ignition source: Commonly referred to as "the clicky thing from the grill lighter." It's a little piezo thing that you push the button on and it makes a little spark. It's powered by gnomes.
- Ignition probes: I couldn't think of a better term for these, but I like saying "probe." You'll need two safety pins, push pins, or thumb tacks. I opted for one of each, safety pins would probably work best.
- Sealant: Epoxy would probably work best, I used duct tape.
- Fuel: Binaca breath spray, butane, hair spray...got the idea yet?
- Projectiles: Spit balls, potato (roughly 1,327,940 shots per medium potato...it doesn't take much. Pencil erasers are the absolute best projectile for this thing; they go FAR, they bounce and they're the perfect size.
- Ramrod: Something to push the projectile to the breech of the barrel. The ink thing you removed from the pen is perfect.

Do this stuff:
1. Make a hole in the center of the bottom of the expansion chamber bottle roughly the diameter of the barrel.

2. Stick the barrel into the freshly created hole. Seal around the barrel with epoxy, duct tape, used chewing gum or what-have-you. I think these materials are probably listed in order of best to less than ideal.

3. Poke your pins into the sides of the expansion chamber about mid-way along the length of it. You want them pointing toward each other at a slight angle with the tips about 1/8" apart or so; the spark from the piezo-thing will need to be able to arc across them. Make sure they're securely held in place with epoxy, duct tape, etc.



4. Hook your grill lighter piezo-thing up to the two pins with one lead going to each pin. If your piezo-thing doesn't already have some handy wires for this connection, pretend like they were in the materials list and go get them. You can attach this trigger mechanism to the launcher if you wish, but in my pictured example, it's just hanging off.


To use it:
1. Place your projectile in the muzzle end of the barrel. Poke it down most of the way toward the expansion chamber so it has plenty of time to build up some speed before setting sail.

2. Add your propellant to the expansion chamber. I find one to two squirts of binaca breath spray works best. You'll need to have the right fuel-air mixture in the chamber for it to fire properly; this will likely take a bit of practice to find the right mixture. If you find that it's not firing properly, try wafting some air into it or lightly waving the whole thing around a few times to let the air mix with the propellant.

3. Put the cap back on the chamber.

4. Point it in a SAFE direction. The projectile will come hauling out of there at a pretty good clip and we don't need anyone's eyes put out!

5. Click your piezo-thing and let 'er rip.


You've now got yourself a miniature potato gun that you can use to hurl spit-wads and pencil erasers at Trinity on The Matrix poster on your bedroom wall in your mom's basement.

tschüß