A way to send halloween treats into the sky, without wadding or dangerous projectiles.video
see the video. 3 sec. hang timefor the candy. container didn't leave the barrel because of loose seal.
Step 1: First you need a large barrel potato gun.
This is the threaded end, where the fuel goes (I use ether). I added screws in addition to the ABS glue for extra strength, although it probably isn't necessary. It is also your access to the ignitor (see next step) and how you ventilate the cannon between shots, to get some fresh air inside quickly.
Step 2: The ignitor.
I put mine about 8 inches from the end cap. Close enough to work on. It is a replacement barbeque ignitor that comes with a AAA battery powered ignition switch. I sealed the holes with silicone. You can bend the wire electrode until you get the gap that's right for you. On the outside, I reinforced and protected the connections with epoxy, since they are a little fragile for this application.
Step 3: The firing button.
If you are unfamiliar with barbeque ignitors, the battery is underneath the red button. I put mine too far along the barrel to use fasteners which might protrude into the barrel. So it's two-part epoxy and lots of black tape. I stretched out the supplied wires as far as they would go.
Step 4: The most important part.
Once you have built a 4 inch barrel potato gun, you will probably realize that pototoes are too small to touch the sides and you can't build any compression. Rutabegas work, but firing off 2 dozen of those gets expensive. Wads of wet newspaper is labor-intensive and messy. Bigger suddenly isn't better. However, if you take a yogurt or cottage cheese container, and trace around it snugly in the barrel, you get a perfect fit.
When you are done, cut off the excess, and see if it fits tightly.
Now, for a little strength and better compression, wrap the surface that will contact the barrel with some electrical tape.
Step 5: Almost ready.
You have put some tape around the lip of the container for a better seal. Push it down to the last 12 inches of your cannon with a broom stick. Put your candy in. and you're in business.
The finer points of potato guns are widely available on the internet. This one is probably pretty crude. The point of this instructable is again, about delivering candy without dangerous projectiles. A giant slingshot, or pneumatic cannon might be better alternatives, but I like the explosion, and so do the neighborhood kids. Their parents not so much.
- leaves or toilet paper or confetti can enhance the effect.
- Rice cakes are another safe item to add to your load
- you fill it up with water if you like, or paint for that matter, but I find even the moisture from the combustion makes for a lot of mis-fires.
- to make retrieval of the container easier, i tried attaching a tether and it tore right off. good luck with that!
-for a good shot keep in mind, the projectile's friction holding it in the barrel is crucial. the longer the pressure can build up, the better the force of the cannon. a loose fitting container may not even leave the barrel, but still move the candy out.