November 2020 I’m here after watching all your newer vacuum cannon videos to finally find this cannon design I’ve been looking for. You have been putting out good content for quite a while now, and your videos just keep getting better and better.

As far as speed is concerned, it opens just about as fast as a pneumatically actuated sprinkler valve. However it does not force the air through as many corners as does a sprinkler valve. In that way the air flow is faster. At this size a well modified sprinkler valve would be just about on par with this piston valve, but this is a very small piston cannon. The valve can be scaled all the was up to say a 4" chamber with a 3" end cap as a piston. No contest at any size larger than this.

Seen this over a decade ago, now seen this again; Still a great video.

Yes. That is what I use the sock for on my piston. A spring or rubber bumper will also do nicely.

At a local hardware store. If you cannot find a nice brass one like I did at a store it may be replaced by a common rubber one. Or a brass valve may be bought online.

This is already quite a small cannon, but yes, it can be done.

Well thank you

@sidthekid13 Sorry for the delay. You might have to look for it online. Look for a brass 'schrader valve'.

I have built several cannons using only ball valves, but I chose to not make this video about one because I don't think anyone needs me to tell them how one is made. Not to mention that they are far weaker than a piston gun.

What you describe is the ideal piston. That will work nicely. The simplest way to make a one way valve is to drill the hole so that the edge of the rubber gasket that seals the barrel covers it. When you fill the chamber the edge of the gasket is pushed up allowing air to pass, but when the dump valve is opened the negative pressure behind the piston pulls the gasket against the hole sealing it.

@farmboyEN You would likely need to use a larger chamber than 2".

See it or not, it is drastically more powerful. Take it from a guy who has built over 20 air cannons. The slim loss in pressure is negligible. The real thing that makes or breaks an air cannon is the speed of the valve.

PVC cement is a must, any other sort of glue is not suitable for PVC. PVC cement does not 'glue' but instead welds the plastic together. Primer is important to prepare the surface of the PVC to be chemically welded.

Cool, convenient

Nothing is absolutely permanent, but the design yields a solid cannon. The rubber barrel seal may need replacement every once in a while, or it may survive for years if it never sees high pressures. Either way, that is an easy fix and all that is ever likely to go wrong.

I read all of my comments. I do not have written plans for this cannon. I am however working on a new video making a larger version that should be published in a few weeks.

There are a few things that will help. A larger or faster acting release valve is a good start. Up to 1/2" ball valve perhaps. Secondly, a better sealing piston would do wonders. It shouldn't be entirely airtight because you need some air to pass and fill the chamber, but it should be close. Cutting a slot for an O ring around the piston would work well. A cut under the ring would allow for a slight passage of air.

You have two choices. You could add it on the opposite side of the coupling from the fill valve, showing you the pressure of the rear chamber, the highest pressure in the gun during filling - Or in front of the piston through the wall of the male adapter, showing you the front chambers pressure, the pressure the projectile will be fired at. Wherever you decide to place a gauge, make the hole through a fitting as well as the pipe itself. The double thick wall will help maintain chamber integrity.

I should have back when I made the video. I no longer have the drawings. Just watch the video and write the parts down as you go. Having the understanding of what each part is used for is much more valuable than a list anyhow.

Thanks. Sch 80 is nice, but not really needed for an air cannon unless you're bringing it above 150 psi...Even then, Sch 40 can technically handle it, though I would not be comfortable. I myself would only use Sch 80 if I were building a hybrid. If you're building cannons for others though I understand. You never want someone else getting hurt from something you built, no matter how slim the chance.

@ExplodingGrandma I'm sure you could find something if you looked up brass schrader valve on google.

I use a schrader valve. The chamber is filled with the same fitting as a tire. Some people have used a quick attach fitting for a compressor hose and screwed it right into the chamber.

Your welcome, and thank you.

@bauerds Sounds good. Be sure you do not fire it enough times in a row for the CO2 to cool the PVC. It becomes very brittle when it's cold.

The weather is a bit better now, but my compressor has been acting up. I'll get a video up ASAP. If it takes much longer for me to fix my compressor I may just bring the cannon over to a friends garage to use his compressor.

Yeah any large hardware store should have everything if they're properly stocked. Usually plumbing sections are a mess and you'll have to dig through boxes of various parts to find just what you need. I always assemble a cannon in the store to the best of my ability just to be sure it'll all fit together and nothing's missing.

Yes, if you have enough threads coming through. It is not really necessary though. Even at 100+ psi, the surface area of one of those valves would only have maybe 15 pounds of pressure acting upon it. If the threads dig into the PVC even a little, it should easily hold. I would never tell anyone not to take a precaution they felt was needed however. Always best to be safe.

That's right

The length of the chamber that extends in front of the piston doesn't matter, but you want as little space behind it as possible while still allowing it to move. If the rubber is sealing against the barrel enough for the cannon to be filled at all then it doesn't need to be made larger.

Cool, let me know how it goes. They can be tricky, don't be discouraged if it doesn't work first time you pressurize it. The piston may need work, barrel end might need to be sanded so it seals better, might need a larger release valve...Tricky to get right, but sure worth it.

The piston likely needs to be a tighter fit. A wider washer on the front end might be enough to seal around the piston as the air pressure drops behind it. Ideally, as little air as possible should be able to pass by. If too much air can move around the piston, the area behind will never be allowed to drop to a pressure low enough to open the vacuum seal on the barrel. Even if the piston does not slide as easily, a good fit is more important. It should only have a small leak to fill the chamber.

Of course I mean a vacuum compared to the chamber pressure, it still would be above or at the standard atmospheric pressure.

That problem can be fixed by a larger valve, or a tighter fitting piston. You can use a bench grinder or a file to grind a groove around the piston to fit an O ring. That will give it a tighter seal.

Certainly. So long as you can find something suitable to act as a piston.

This is like one I made years ago . I used 4' 4" pvc and 6' 2" pvc, 3"rubber quick cap as my valve. At the valve end I cross drilled with a 1/4" 20 threaded rod and sealed the threads to hold the 2" barrel. Great Video.

Most any hardware store or even a place like walmart should have a rubber one that will work fine. They look different and are meant to be installed from the inside. They may be labeled as a tire stem. It takes a bit more looking to find a nice brass one like I did. Check the air compressor area in a large hardware store.

Yes, but it will take several fast pumps to start with to seal the piston against the barrel.

I should have measured it for the video but I did not. It is not important. For this size barrel and chamber it would be about right to have the barrel be just under 2x as long as the usable chamber. By that I mean the chamber in front of the piston.

I don't remember. Look around. Most places are not stocked as well as they should be with plumbing supplies.

This design is much more elegant than the one you built in early 2017. Much more compact package.

@MusicIsTheVeryBest The piston is made to leak slightly.

You should be fine so long as you did a good job with the primer and cement. Make sure the bumper on the piston stays in good shape as well.

The piston needs to make a tighter seal in the chamber, or you can use a bigger ball valve. Either one of those things should make it fire. To make it stop leaking you can try some grease on the face of the piston, or even better, some TFE pipe thread paste.

With literal materials you mean? It would perhaps be made from a machined piece of HDPE rod made to fit in a in a PVC chamber.

@rangersmustang It's simply a rubber washer available at most hardware stores.

@ban0003 Vacuum is relative to pressure differential. A low pressure area is a vacuum to a high pressure area.

That would work well, but you must find a piston that will fit in the smaller internal diameter.

@bauerds About 3/4".

havent seen a system like this before thats some great engineering nice work!!

Thanks for the drawings and cutaway views.Makes the operation crystal clear.

BTW, you do have a pretty decent cannon. You best be sure to get a bumper in there straight away though.

Hey thanks for all of your help. I'm building a bigger better gun so I'm designing a 3 inch piston valve. Another note, Microsoft excel is an amazing program. I just recently learned what it could do. So if your into the math behind your potato guns, you might want to play around with it. It has made thing so much easier and faster for me. Thanks again.

It's not a matter of where I live, but what the brand is. Some brands in my area are round also. You can call other hardware stores and you may find flat ones. My new cannon video does show how to make a nicer model overall though.

Unless you have very extensive experience working with PVC, 50 psi is all I would recommend. I go much higher because I am confident in my ability to glue fittings and the like. I have thought about adding an air gauge, but I designed this cannon to be inexpensive. It is simple enough to regulate pressure at the compressor. Many of my other cannons have pressure gauges. I thought I had mentioned in the video to let the glue fully cure before pressurizing. I meant to anyhow.

I have not clocked it.

That's a fairly simple task. If you go into any half decent hardware store and explain what you need to do they should be able to get you what you need with no problems. They make portable air canisters just for that sort of thing. Anywhere between 3 and 90 gallons are typically available. In this case, making your own would not be a good idea. PVC is not meant to hold air pressure in the first place, it could not stand up to the rigors of commercial use.

I did not actually build an actual working model of that cannon, I simply made the drawing to explain function. I would suggest a 3" end cap as a piston. If it will fit in sch 80, it could be a tight fit.

@SpankeyMe95 Central. I won't get much more specific that that.

You can also sand it if you make a mess out of the glue. But anyhow, this project is SUPER COOL and I wanna make one! These cannon videos also inspired me to make videos about cannons of my own design.

Does it not seal against the barrel or does it not release when opening the valve to fire?

@KSCPERFECT It is a close fit, but it is not airtight.

The piston is a 1.25" end cap. 1.25" is the inside diameter of the pipe that the cap is meant to fit over. Therefore the outer diameter of the cap itself is much larger. Barrel and chamber lengths are not crucial, so long as the barrel extends a few inches out of the back of the chamber. My chamber is ~2.5', barrel ~4'. The piston slide is ~4" long. The piston must have enough room to move 1/2 the dia. of the barrel away from it, but no more than the full ID. So 1/2" min. for this gun, 1" max.

Thanks! I have 5 guns right now, but no piston valve cannon. This is really helpful!

Who says I didn't? This isn't my first time around the block. Also pvc only gets brittle if exposed to temperature extremes or sunlight for an extended period of time, like any plastic. It maintains itself at room temp indefinitely.

Yes it would...But you would certainly want to use wadding of some kind or another to keep the dirt from falling back into the valve. You may also want to check out my video 'DIY Explosion FX (How to Make and Use a Creamora)". That will show an easier way to accomplish what you are looking for. Though It is no good to use in a dry area because of the fire hazard.

The end cap is the piston you understand right? I imagine a 3" ABS end cap might be hard to find. PVC would be much more likely. The piston should slide fairly easily, so long as it is not tight enough to get stuck it should be fine.

When is the weather going to be better!! I wanna see this baby blow up stuff! hehe I was thinking...instead of having a tut of how to design a mult-break shell, actualy make one. All of your videos have good instructionals. =] I would love that.

very good this is the time ive seen this design with the chamber an the barrel as one well sort of .nice

Then perhaps I remember incorrectly the cap size. If the 1.5" cap fits inside the 2" pipe, use it. You want as close a fit as possible. The rubber washer was bought at a hardware store among the nuts, bolts, gaskets and other things. And yes, the rubber washer is mounted on the front of the piston and seals against the 1" barrel when the gun is pressurized. Sorry I did not answer all you asked the first time. I was trying to fit everything into one comment and forgot about the washer.

I wouldn't say a diaphragm valve is all that much faster...Only in that there is usually less mass to accelerate to get the valve open. I would consider the difference in speed negligible. Though I must say, I've never seen first hand a diaphragm valve built into a coaxial cannon. It would be interesting to see how a piston cannon of the same dimensions would compare. I think the curve of a diaphragm may offer smoother airflow.

A quarter to a half inch is fine. Somewhere in between is ideal.

Yeah I was already made aware of that mistake. No way to fix it without another upload.

nice gun, well done - i have made a few airguns myself (they are on my channel) but they have only been the simple ball valve kind. i am currently in the process of making a more complex one and yor instructions have really helped. thanks!

Cool thanks I'm looking forward to building one :)

cool

@oldman32123 The cannon will still function fine, but be less powerful that one with a high quality piston valve.

Thanks so much for this tutorial :) Could you theoretically use an air cannon just to release air and use it like a blast of wind, so as to just push something rather intensely but without damage from impact?

ty so much for the help a 3 inch end cap with the bumper and the rubber added to it i would think plus the piston could be abs ? and would the tight fit affect performance of pison ty again for the help

Actually this is my 4th PVC piston cannon. I've never experienced one cracking. I usually fire around 110 psi.

You make the best instructional videos I've seen on youtube, good job, do you have a materials list you could post?

@parker5013 I would like to see it when you're done, it sounds like a very nice cannon.

Very good tutorial you made there Nighthawk, as usual. I look forward to the next one man. 5*

that is so cool im guna make it

Personally, I would still fire it. Though I would not leave it outside in winter again.

you may be able to form your own piston out of materials like epoxi, this will result in greater flexibility in sizes of pipes.

That is the reason for the bumper. Simply replacing a PVC piston with a piece of HDPE is no solution. Instead of a piston cracking you could instead have the piston assembly explode in your hands. Bumpers are an important part of a piston cannon, HDPE piston or not.

Thank you. I still haven't gotten around to a good test firing, now my compressor is acting up.

@rangersmustang use a cistern outlet washer.. theyre the best, nice n soft

Thank you for the info..One other thing could I make around the piston air tight,drill a hole in it and use a one way valve...Just a thought I had...s air goes into the front chamber through the valve...p.s your design is awesome...

No myth, of course it get's brittle over time, under poor conditions as I said. It is also unwise to use PVC in low temperatures as that also makes it brittle.

Soon as the temp goes above 15 degrees.

Nice, thats a great design. I have just one question; how much faster does this valve open than a sprinkler valve? Is it worth the time?

@harlostatus Try ebay. I found it at a local hardware store for a few bucks. They're around, but you may have to look several places.

iS IT possible to casting bait (200 yards + or less) ?? thanks in advance

For "greater than" 50 dollars! That's cool for a gun that uses "vacume".

The forums closed down a long while ago. Did they reopen?

id love to do any of these types of things but i don't have any tools or money to even get the things, i love to build things and i feel like i could have fun with anything like this if i had the supplies to even try these creations

would a 1 1/4 inch barrel nedd a longer pressure chamber. what length is your barrel and length of 2 inch pressure chamber in the plans. I could do with a bit of help as I have no experience with air cannons and want to use it for surf fishing. GREAT VIDEO

good drawing, i subscribed to you for your fireworks, and i just and starting a piston cannon and this shows up funny

@cubsfreak13 I would have to go through the video and count everything same as you. I should have written everything down back when I made it, but I didn't. Now my drawings are lost.