How to Make a Vacuum Cannon





Introduction: How to Make a Vacuum Cannon

About: I like turning boring things into awesome things! Usually on video.

A vacuum cannon is an interesting physics demonstration that shows how much atmospheric pressure there is at the earths surface, though we do not feel it because our bodies have the same amount of pressure both inside and out. By removing air pressure from inside of a length of pipe the balance with atmospheric pressure is removed, and if the seal is broken on one end air pressure will rush in quickly enough to throw a projectile with a good deal of force.

To learn how I made the vacuum pump used to operate this cannon, take a look at this video:

The pump is very high quality, and pulls a vacuum much faster than most commercially available pumps, making it ideal for large tasks such as this cannon. Most other pumps would take many minutes to bring a chamber that size down below 25 in/Hg of vacuum.

I first learned of vacuum cannons thanks to this Instructable, and was interested enough to take the project on for myself:

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    Can a pump work for the cannon if it is singe stage?

    Is there something wrong with this page? I do not see an Instructable anywhere - just lots of sincere comments and a drawing of what looks like a sound suppressor.

    Ok thanks! I might just try it...sketch time.

    So a question... What if you evacuated the air from the cannon, but pumped that same air into another resovoir that is connected to the vacuum cannon by a ball valve from the back? This way you can use the atmospheric pressure as well as the principles from a regular pneumatic cannon? Would it be worth the trouble?

    1 reply

    It wouldn't be worth the trouble with a ball valve, but maybe with a fast acting sprinkler or piston valve.

    I came up with an upgrade for your vacuum cannon, I am working on a smaller version of yours, with my modification

    Is this more powerful than your coaxial piston cannon ?

    I have one all made up and ready to go, and wouldn't you know it, the 40mm pipe isn't actually 40mm, it's some obscure size, but is just referred to as 40mm as it's the closest whole number!! the ping pong balls won't fit!! grrrrr my science class was so disappointed!!

    This would be awesome in slo mo. Thanks for sharing

    1 reply

    I agree! Get this to the Time Warp gang!

    would it work to use some sort of quick valve on the breech end so you only have to change one burst disk? I'm curious if that would work because it would save you a lot of time and tin foil

    Neat cannon, voted, and went to my Blog:

    Very cool. An idea for the foil: Maybe you can build a little square frame out of wood or metal that you tape the foil to. The frame would then slide into a bracket that's always mounted on the pipe. Once you start vacuuming, the foil [might] create a seal on the PCV edge and the frame will keep it from giving in..... This way you can quickly change the burst disks.

    Why the swinging mount? It seems you would get a lot more range and accuracy with a rigid mount.

    4 replies

    Because making a rigid mount for a pipe that size would have taken more time and resources. That's the only reason. The swinging mount worked fine for the video demonstration. I didn't need anything permanent since chances are i'll be slicing up the pipe for other projects soon anyway.

    You could have turned the ladder 90 deg and zip tied it to the frame.

    Yes, that would work, but it wouldn't have been as aesthetically pleasing that way. With the pipe hanging from the ladder I could keep it out of view most of the time. I would want something that looked nicer than a ladder if it were going to be ziptied right to the cannon in full view the entire time. Making sure my projects look good to the camera is pretty important to the success of my videos.

    Well you have well over a quarter million subscribers, so, what are doing must be working and I am not one to argue with success. It's a great project anyway. Cheers.

    Wouldn't a sharp object, or a knife on a long stick work as well as the mallet?

    Once the structural integrity of the aluminum foil is violated it will shred on its own due to the pressure differential.

    It looks like the inflow of air would be partially obstructed by the mallet head and cut back on the power on the exit end.