Do It Yourself - How To Make A Simple High Pressure Air Cannon

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• published: 18 Feb 2014
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I've been wanting to do a simple metal air cannon to work with fridge compressors and here it is. This is a quick, simple, and cheap metal air cannon made from a handful of parts from Home Depot or a similar supply house. It can take the pressure from a fridge compressor as all parts are metal. This project can be completed in less than 30 minutes. Needed parts are : 1 Milton M style coupler with 1/4" male NPT thread 1 3/4" Black Iron Pipe Cap 1 3/4" Black Iron Pipe Nipple 6" long or more, threaded at each end 1 3/4" Metal Ball Valve 1 copper reducer 3/4" male thread to 1/2" copper (solder) 1 copper pipe 1/2" by 48" to 72" long (longer barrel is better) White Thread Tape Pipe Thread Sealer I used the M style coupler because I have an M style air chuck on the high pressure hose attached to my fridge compressor. Tools needed are simple, pliers, visegrips, a wrench, and a drill. A 1/8" and a 7/16" drill bit will be required, as will an 8-32 tap and a 1/4 NPT tap. Once the cannon is assembled in this video, it gets tested with just air at different pressures, then a glass marble, an AA battery, and finally a lead slug are fired at a sheet aluminium test target with a good backstop behind it. There are much better valves for air cannons than the ball valve used here, I went with the ball valve because it is super simple for a first air cannon project and will work the first time with no issues. A more advanced design based on a sprinkler valve or a piston valve would deliver more power but is more difficult for a beginner to succeed with. The other simple alternative is a burst disk setup, this also delivers the highest velocities, but the disk must be changed for each shot. I went for the quick and simple ball valve design for this simple cannon. The ball valve could be set up so that a tension spring pulls it open when a trigger is released. The rapid opening that a spring provides can up muzzle velocity by 100 fps. Switching to a longer 3/4" nipple will also add to the muzzle velocity. Try a 10" or 12" long pipe nipple. The cannon once built could be mounted on a stock or base of some sort. A 1/4" ball valve could be attached to the air coupler, this would allow the cannon to be detached from the compressor without losing the pressure. These further mods are up to the builder, I just wanted to show the basics in this video. Be careful with high pressure air and air cannons. Like any weapon, be sure of your target, use a good backstop and be careful. An air cannon like this simple one can achieve airsoft velocities with a heavy projectile like an AA battery, so the potential for damage is always there. For those interested in the design of air cannons, google for and download GGDT (gas gun design tool). You can easily model an air cannon on it and predict velocity, etc. with this useful, free software tool. It quickly shows the effects of small design changes such as longer barrel, bigger air reservoir, faster valve, etc.