Introduction: Launch Supersonic Spuds With a PVC Air Cannon!

Have you ever felt a desire to launch a potato into the sky at a high speed? Or maybe on the colder side, be a one man army in every snowball war with a pneumatic snowball launcher? Yes? No? Maybe? Well, in this tutorial I am going to show you how to do just that, with your very own air cannon! Before we get started though, I have to add a disclaimer:

Disclaimer: I am not responsible for any injuries related to or having to do with this device. I am also not responsible for any property damage caused by this device. Use at your own risk!

Equipment List!

~ A hacksaw, or other saw to cut the PVC pipe

~ PVC primer and cement, to fasten the PVC together

~ A drill and assorted drill bits, to make the various holes for the fill valve, pressure gauge, etc.

~ A tapping set, for making the threads in the holes we will drill

~ A Dremel, or other rotary drill/tool and a sanding drum, to cut the muzzle cutter

~ An adjustable wrench, or an assortment of regular wrenches for tightening the various fittings on the sprinkler valve

~ A bike pump or air compressor (air compressor highly recommended!), to fill the air tank with...surprise! Air!

~ A pair of Vise-Grips, helpful for tightening different fittings, but also for holding the larger tapping cutter.

~ Teflon tape, for sealing all threaded connections

~ Epoxy, I used 5 minute epoxy, we will use it to seal up parts of the sprinkler valve

Materials List!

For the air tank-

~ 16" length of 4" PVC pipe (schedule 40 works great for all PVC parts)

~ 4" PVC end cap

~ 4" to 4" female-to-female PVC coupling

~ 4" to 2" PVC reducer

~ 2" to 1 1/2" PVC bushing

~ 1 1/2" to 1" female threaded PVC reducer/adapter

~ 0-100 psi pressure gauge

~ tire fill valve, like you would find on a car or bike tire

For the sprinkler valve-

~ sprinkler valve (duh!). I got mine from Amazon since I couldn't find one at any nearby hardware stores

~ 1/2" male-to-male compressor fitting

~ blowgun (the kind used to blow dust off things) with a 1/2" opening

For the U-connector-

~ 2 2" 90 degree PVC street connectors/elbows

~ 1 1/2" to 1" female threaded PVC reducer/adapter

~ 2" to 1 1/2" PVC bushing

~ 2" to 2" female threaded adapter

For the barrel-

~ 4' length of 2" PVC pipe

~ 2" to 2" male threaded PVC adapter

That's it for materials, so let's get started!

Step 1: Assembling the Air Tank

(air reservoir, if you want to be really technical)

So that you may better understand the way the parts fit together, I have made an exploded view of the air tank.

We will be working from the back of the air tank to the front, starting with the fill valve assembly, so first things first, we have to drill the hole for the fill valve. The final hole size will be 7/16", but to get a clean hole we will drill in stages. Before we start drilling the holes, we need to make a small indentation so the drill bit doesn't skate across the PVC. After you make the indent, use a 1/8" drill bit to bore out a small hole. Next, I used an 11/32" bit to enlarge the hole.

Our next drilled hole will be the final size of 7/16". I had a bit of trouble (I'm so phunny) with the bit grabbing the plastic too hard. Just go slow, and don't push on the drill too much, and you should be fine. I used a countersink bit to make the valve fit perfectly into into the hole.

After putting it into the hole, screw the washer and nut (in that order) onto the threads on the valve.

Now we have to glue the end cap onto the pipe, so get out the PVC primer and cement. First, use the primer to swab the inside of the end cap and the outside of the pipe. Do the same with the cement, then push the two pieces together and rotate the end cap on the pipe a quarter turn.

Next, we need to drill and tap a hole for the pressure gauge. The overall width of the threaded end of the gauge is 1/2", but the hole we must drill has to be slightly smaller to accomodate the threads we will tap, so use a 7/16" drill bit to bore the hole.

After drilling the hole, I used a 1/4"-18 NPT tapping drill to cut the threads into the air tank. I did not have a tapping wrench big enough to fit the tapping bit into, so I used (carefully) the Vise-Grips to hold it. The proper way to tap a hole is to turn the bit clockwise, then back slightly counterclockwise. Continue this pattern until the bit has traveled all the way through the material, then unscrew the bit.

Now we need to screw the pressure gauge into our newly tapped hole. Take the teflon tape, wrap a few turns onto the threads of the gauge and start screwing it into the hole. Once it gets hard to turn, use a wrench to tighten it as much as possible; we don't want any air leakage.

Great, we're almost done!

Now get the 4" to 4" coupler, because we are going to glue it onto our pipe (with the end cap, pressure gauge and fill valve already attached). Glue it on following the same procedure as before (swab both with primer, swab both with cement, push together and rotate a quarter turn). After the coupling comes the 4" to 2" reducer. Glue it onto the coupler. Next, put on the 2" to 1 1/2" reducer, followed by the 1 1/2" to 1" threaded reducer. You know the drill...

After you complete this, congratulations! You have completed one of the three main components of the air cannon! Next up, the sprinkler valve...

Step 2: Modifying the Sprinkler Valve

Now, we could leave the sprinkler valve as-is, and trigger it electronically, but who wants to do that when we could modify it to open ten times faster? It all comes down to performance. In order to work properly, the valve needs to dump all of the air stored in the air tank into the barrel as fast as possible. This is why an ordinary valve operated by hand won't work; a human simply cannot open it fast enough, so we use a sprinkler valve normally triggered electronically. We are going to modify it to work pneumatically, however, since it will open faster that way. I won't go over how the valve works, but if you want to find out how it works you can find a diagram and explanation of one here. Let's get started...

I used an Orbit sprinkler valve for my build, which seems to be a popular choice for many air cannon enthusiasts. Unfortunately, I couldn't find one at any nearby hardware stores, so Amazon to the rescue! This is the valve I bought, and no, it is not actually that color green.

First things first: get rid of the solenoid. It's the black cylinder screwed into the top of the sprinkler valve. Then you need to remove the cover of the sprinkler valve, so unscrew all of the screws that go around the edge of the top. Once you have that off, put the screws in a safe place; we don't want to lose them. You can also move the whole bottom assembly aside, since we are only interested in the top. When I took the top off, the diaphragm assembly was stuck to the top. Carefully peel it off the top and set it onto the bottom assembly, making sure not to get anything on it.

Now that we have the top separated from the diaphragm, we need to drill a hole in the center of the top to fit in our male-to-male compressor fitting, so we need to get our 7/16" bit (I know it seems like this is the only bit we use, but the pressure gauge and the male-to-male fitting are both 1/2" compressor fittings, so it makes sense that they would use the same bit). Make a mark as well as you can in the center of the sprinkler valve, but do it from the inside since we need to make sure it doesn't get in the way of any of the parts. Use the center punch to make an indent in the plastic, and then drill out the hole with the 7/16" drill bit. Tap the hole as before, using the 1/4"-18 NPT thread tap.

In order to make the valve pneumatically operated, we need to epoxy the holes that normally connect to the solenoid, which controls the valve. Mix up the epoxy, but keep in mind that you only need a tiny bit because the holes we need to block are really small. Then cover both of the holes in the solenoid's socket, one which is right in the center, and another that looks like a slot positioned in the side of the socket. On the inside of the lid/top, there is another two holes, one of which is on the end of a black plastic piece, and one that is square-shaped (this one will require the most epoxy). These two are the most important, so you could probably get away with not gluing the holes in the socket, but just to be on the safe side I am gluing all of them.

Take some Teflon tape and wrap it around both sides of the male-to-male fitting, and screw it into the tapped hole. Be careful that you don't screw it in too far, or the sprinkler valve won't function correctly.

Screw the blowgun onto the compressor fitting, making sure to use Teflon tape. Tighten it, and you're done!

Great job, you're two thirds done! Get out your primer and cement because we need to do a bit of gluing in the next step...

Step 3: Making the U-connector

Okay, so the U-connector will connect the air tank and sprinkler valve to the barrel. The first thing we have to do is glue the two 2" 90 degree street fittings together to make the base "U" shape. After that, glue the 2" to 1 1/2" reducer onto one side of the U, followed by the 1 1/2" to 1" threaded reducer. On the other side of the U, glue on the 2" to 2" threaded coupling.

Okay, I know this step was really short, but only one more until we get to assemble the components and have a finished air cannon! Next, we have to make the most important part: the barrel...

Step 4: The Barrel

So, now we have to make the barrel. I won't go into detail on this part; you know what it's for. You what? Really? Oh, okay. The barrel is what we will put whatever we want to shoot into. Snowballs, spuds, T-shirts, you name it. Are we all caught up? Good. Now, the barrel is the simplest part of the cannon, but the most important too. Cut a 4' long piece of 2" PVC pipe and get out the Dremel (or other rotary tool), because we need to make the muzzle cutter. The muzzle cutter is the section of the barrel that cuts the excess potato or snowball as you load it into the cannon. Put a sanding bit on the Dremel, and set it to the lowest speed to avoid burning or melting the plastic. Now, start sanding around the end of the barrel. You may need to travel around the barrel multiple times to get the angle right, but don't worry too much about it; as long as it cuts the potato it doesn't have to be too sharp. I wanted to up the awesome factor, so I used the sanding bit to cut notches into the cutter, which will look almost like a serrated knife. I used a coarse sanding bit, so I went over the entire muzzle cutter with a piece of regular sandpaper afterwords. That's it for the muzzle, now we just have to attach the threaded adapter. Get out the primer and cement, and cement the adapter to the other end of the barrel. This will enable interchangeable barrels in the future (if you want), but it mostly helps with assembling the cannon.

Now that you're done with the barrel, let's move on to the final stage (before the test fire!), assembling the cannon!

Step 5: Assembling the Air Cannon

Finally! The time when we assemble everything together and see if it works (which it will)!

First, take the air tank and, after wrapping Teflon tape around it, screw the 1" male-to-male threaded coupling into the output of the air tank. I carefully used pliers to make sure it was screwed in tight, then I took the sprinkler valve and screwed it onto the coupling with the air tank attached to it (remember the Teflon!). Keep in mind however, that there are arrows on each side of the valve that tells the direction of airflow. Screw it on so that the arrows point away from the air tank. You should be able to just tighten the sprinkler valve by hand, but when you tighten it, make sure that in the end the blowgun lines up with the pressure gauge on the air tank.

Next, screw the other threaded coupling into the opposite end of the sprinkler valve (again, remember the Teflon!). Get the U-connector and begin screwing it onto the threaded coupling (Teflon!). Now, since the barrel is going to screw into the U-connector, we have to line it up carefully so that the barrel will run alongside the pressure gauge and the blowgun. Look at the pictures above for a better explanation, but you'll understand once we put the barrel on.

Finally, screw the barrel into the U-connector (remembering to use...guess what? Teflon tape! Yeah!).

Congratulations! You have finished the air cannon! Give yourself a good pat on the back; the hard part is over. Next, we have to take a test fire!

Step 6: 3...2...1...Fire!!!

Time for a test fire!

Air cannon operation instructions

1. Load the air cannon. Use a broomstick to push whatever your ammo is down into the barrel. Make sure it gets to within an inch (about) of the U-connector, but don't push it into the U-connector.

2. Pressurize the air cannon. Use an air compressor or bicycle pump to fill the air tank to about 80 psi. I took test shots starting at 20 psi and increased the pressure by 20 psi each shot, until I got to 80 psi. You may hear a slight hissing noise as you fill the air tank, but this is normal; the sprinkler valve has to equalize the pressure between its chambers. The hissing should stop after reaching about 50 psi, if it doesn't however, try to find any leaks. An easy way to do this is to get some soapy water and spray it onto the suspect area. If there is air leaking there, you will see bubbles from the soapy water. I wouldn't go above 100 psi; although PVC is commonly used for air cannons, it is not meant for very high pressures. For snowballs, use low pressures (20-40 psi); when I tested shooting a snowball at 50 psi, it came out as a cloud of snow. Also, I wrapped the air tank in duct tape to protect it and make it a little stronger in cold weather.

3. Fire! Find a safe area outside, and squeeze the blowgun's trigger to release all of the air and propel the projectile out of the barrel!

Comments

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everettevans11 made it! (author)2013-05-31

I built this following your design for the most part but added a few assecories... i thought that you might like pics of it as well... first time posting so lets see how it goes.

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techwhisperer made it! (author)techwhisperer2013-06-02

That looks fantastic! I think you created the tactical version of my air cannon! I like your use of the cordless tool battery. If you want to get more accuracy with the cannon, you may be interested in a rifled PVC barrel from the Spudgun Technology Center: http://www.spudtech.com/detail.asp?id=34. Thanks for sharing & keep up the good work!

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everettevans11 made it! (author)everettevans112013-05-31

Additions are the electric battery for the solenoid, shoulder rest, forward pistol grip, momentary action electrical trigger, and an iron sight.

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Masher007 made it! (author)2014-04-28

Danger: See link: This is not spam, but a warning. PVC will fail suddenly after a while. This was band member that hurt badly by a T-Shirt launcher explosion.

See the pictures and never use PVC to hold air, Please.

https://fundrazr.com/campaigns/1Zs3c
..

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Benhoward made it! (author)Benhoward2016-10-02

What was the psi it was under

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Masher007 made it! (author)Masher0072016-10-03

This is an old thread, as it happened in 2013. This one was only charged to 80 PSI. Three people hospitalized. Since then there was another at the Arkansaw Razorbacks game. It was charged and ready, 80 PSI, and just sitting in the bench on the sideline. Not sure if it got bumped, knocked over, or just went off.

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Benhoward made it! (author)2016-10-02

Do you think that the countersink for the intake valve is crucial

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techwhisperer made it! (author)techwhisperer2016-10-02

It isn't critical, but I opted to add the countersink to help seat the intake valve slightly more tightly.

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punjabian_king07 made it! (author)2015-12-31

I have made it. works perfect

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Suraj Grewal made it! (author)2015-12-18

Need advice, how's this valve for airsoft bb inside 6mm barrel?-

http://www.ebay.com/itm/1-4-Metal-CAR-Train-Truck-...

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Suraj Grewal made it! (author)Suraj Grewal2015-12-18

Ah!, forgot to mention the fact that I want to electronically trigger it thus making a bulpup easier.

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punjabian_king07 made it! (author)2015-10-18

what if we reduce the size of barrel in half (2 ft) it will effect anythng or not?
also tell me if I use sprinkle valve with batteries from a distaance, it will work same?

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techwhisperer made it! (author)techwhisperer2015-10-20

The cannon shouldn't perform any differently with a shorter barrel, but you may see a decrease in accuracy. The sprinkle valve battery extension should not make a difference either, but it may be simpler to wire up a switch on an extension as opposed to the batteries.

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matthew9876 made it! (author)2015-09-05

I made it and it worked great it has a small leak but that is because I didn't put that much glue on it.

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wywy1579 made it! (author)2015-07-14

What can I do to make the barrell bigger?

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techwhisperer made it! (author)techwhisperer2015-07-14

You could add an adapter—maybe a 2" to 3"—right after the U bend going to the barrel. Then just use 3" (or whatever size you like) PVC pipe for the barrel. The other option is to add an adapter immediately after the sprinkler valve, and make the whole barrel and U bend whatever size you prefer.

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WalterS5 made it! (author)2015-06-14

I made it with my son. He wanted one for years. He built it for a school project on Newton's Law. It worked the first test, but the valve have way under pressure. You mentioned that spring in the valve may not be strong enough the pressure. Where do I find a stronger spring. Thank you!

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techwhisperer made it! (author)techwhisperer2015-06-14

Great news! I'm not sure the exact specifications of a new spring, but McMaster-Carr would definitely be the place to start looking, as they have quite a few in stock. Good luck!

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ssssrrrr4000 made it! (author)2015-04-10

could I shoot other things like cement or glass?

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ssssrrrr4000 made it! (author)ssssrrrr40002015-04-19

it is time to put this on steroids. I am going to put this on metal barrel and use special carved ammo

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techwhisperer made it! (author)techwhisperer2015-04-19

Yes, but I definitely wouldn't recommend it since launching glass/cement is so dangerous. As a general rule of thumb, if it fits down the barrel, you can shoot it.

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CanadianKitsune made it! (author)2015-03-14

Here's what I'm thinking: (note: been planning to make a small paintball cannon) replace part of the barrel where the projectile is loaded with a slightly wider tube, and cut away halfway around the larger tube allowing for a shell to be loaded (may take some messing around with to keep air tight) allowing for a quicker and more convenient loading system

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pirateschoolfamilyshow made it! (author)2014-12-02

Hey techwisperer: Great instructible! My question is why the U-fitting for the design? I'm looking to make a two shot "hand cannon" replica for my pirate show. I think I can get two barrels/tanks side by side (one to shoot a fake cannon ball, the other to fire confetti). Might you have any advice for making more SLIM holding tanks or for that matter a DOUNLE shot, DOUBLE barrel device? THX!

Check out my site: www.mypirateschool.com

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techwhisperer made it! (author)techwhisperer2014-12-06

Thanks for your comment, and great site! The U fitting basically just makes the design more compact; some air cannons are configured with the barrel, valve, and air tank in-line. By adding the U fitting, my design cut down on the length of the cannon, and, I felt, made the cannon sturdier. I have heard that by forcing the air through the U as opposed to an in-line system, performance will decrease as the air will not have the same velocity. In my case, at 100 psi, the cannon will launch a potato VERY far (over 300ft), so I don't find it to be an issue. Your idea for a double barrel/shot device sounds interesting; while I'm not an air cannon expert, I may be able to help with a few tips. In order to bring down the size of the cannon, you could use a smaller diameter PVC pipe for the air tank(s) (keep the tank cylindrical). This would deliver a lower volume of air, thereby decreasing the power, but the tank should be able to handle the same amount of pressure as the full size version. If you intended the cannon to fire two separate shots, then the design would consist of two separate air tanks, valves, and barrels. If, however, you wanted to launch the confetti and cannonball simultaneously, it would be easier to have a moderately-sized air tank, and insert a Y fitting after the release valve, splitting part of the air into the barrel with the cannonball, and part into the barrel with the confetti. I hope this helps at least somewhat with your build, so thanks, and good luck! The Techwhisperer

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theegghead made it! (author)2014-04-14

I am DEFINITELY going to build this soon I have most of the materials right in our tool shed!

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jopenshaw made it! (author)2014-02-19

One troubleshooting idea, sometimes the sprinkler valves spring simply isn't strong enough to hold back the first bit of air, and when you fill it up the air leaks out the barrel, solve this problem by simply getting another spring, one slightly stronger.

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DanTDM made it! (author)2014-02-14

Your pipe and several fittings are not pressure rated. I can tell. Please replace them.

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Cambot339 made it! (author)2013-07-06

If you try this PLEASE only use pressure rated PVC. If it says DWV (Drainage waste ventilation) and doesn't have a PSI rating DON'T USE IT FOR COMPRESSED AIR.

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DanTDM made it! (author)DanTDM2014-02-01

You are right.

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DanTDM made it! (author)2014-02-01

You used drain waste vent pipe and fittings, do not use them. Don't use plastic at all, it will shatter and may kill you. Use metal pipe instead.

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cjs1298 made it! (author)2013-06-23

Great for the 4th of July!

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techwhisperer made it! (author)techwhisperer2013-06-23

And saluting the DIY gods! ;-)

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zombiewombat123 made it! (author)2013-05-05

that's cool But can It launch t-shirts

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cjs1298 made it! (author)cjs12982013-06-23

Don't hit Maude Flanders!

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techwhisperer made it! (author)techwhisperer2013-05-12

As long as the t-shirt fits into the barrel, absolutely! You may also want to use a lower pressure (under 50 psi) to keep the t-shirts from shooting too far.

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Randumb83 made it! (author)2013-05-30

How much did this all cost?

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techwhisperer made it! (author)techwhisperer2013-05-31

I already had some of the components (the pipe for the air tank and barrel, the blowgun and the fill valve) so I can only give a ballpark. The sprinkler valve was $15, I think the gauge was about $7 and the fittings a few bucks apiece. So about $30 not including the straight pieces of pipe. Depending on the length of pipe you get you should be able to construct this for under $50. I know this isn't a very clear answer, but hopefully it answered your question.

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claramecium made it! (author)2013-01-23

I am totally making this with my dad!

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techwhisperer made it! (author)techwhisperer2013-01-23

Great, I'm glad you enjoyed it! I am working on a shooting video to show the power and range of the cannon, which should be up within a couple of weeks. Good luck!

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diykiwibloke made it! (author)2013-01-09

Really enjoyed your instructable. What's immediately apparent is your simple design and I like that. Some of the cannons I've seen are overkill ego-trips, or something :)

A question: the PVC pipe you used - is the wall thickness standard for the different diameters of pipe or did you use extra wall thickness for safety?

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techwhisperer made it! (author)techwhisperer2013-01-10

Thanks! For both of the sections of PVC pipe I just used Schedule 40 pipe. It holds pressure well and is very readily available at any hardware store, but as I said on the last step, if you want to use pressures higher than 100 psi I would go with something thicker, or a pipe specifically made for high-pressure applications.

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Claire Fulco made it! (author)2013-01-09

So clever.Young scientist/inventor has promise.

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vfulco made it! (author)2013-01-09

Great presentation and layout of steps

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abeepath made it! (author)2013-01-07

niceee...i've got to try this one!

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techwhisperer made it! (author)techwhisperer2013-01-08

Thanks, I'm glad you enjoyed it! Hopefully I'll be able to post a video of it firing sometime soon.

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Kimbly107 made it! (author)2013-01-07

So, because I'm a cheap SOB, where would you peg the over all cost. Ive been thing of building a airgun like this one, but I need a ballpark so I can try to be fancy in places.

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techwhisperer made it! (author)techwhisperer2013-01-08

I was kind of winging it when I built this air cannon, so I didn't really keep track of cost. I know that it is under the $100 mark, however. What I did was look at some other designs, then sketched out how the parts would fit together. The most expensive component was the sprinkler valve at about $15 excluding shipping, but some of the parts (like the blowgun) I already had laying around, which kept the cost down.

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Higgs Boson made it! (author)2013-01-03

Why don't you just use the solenoid valve already on the sprinkler valve?

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techwhisperer made it! (author)techwhisperer2013-01-03

Good question! You could definitely use the solenoid valve as-is, or even wire the solenoid in place of the blowgun, however, you would need three 9-volt batteries to trigger it. This would require you to build another small housing to fit the batteries, switch and wiring, and since the blowgun is simple and triggers quickly I chose this route. I am also not exactly sure of how the actual solenoid itself works, so it may not even work in place of the blowgun.

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Higgs Boson made it! (author)Higgs Boson2013-01-03

From what I understand the solenoid simply opens when you apply voltage so if you added a button it would be just like a trigger. I've seen quite a few compressed air guns pretty similar to yours on youtube and other places that just use the solenoid, I was just wondering if the blowgun worked better, or allowed you to only release a given amount of pressure at a time or something.

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