Introduction: Airgun With EXplosive Air-Release Valve

Picture of Airgun With EXplosive Air-Release Valve
Forget amateurish sprinkler valves. Look no further than this type of valve for making airguns or anything where you need the air released explosively. This is my own design inspired by the valve inside an airbrush.

This instructable shows you how to make what I call the XRV (explosive release valve), which can be attached to a bicycle pump. This in turn allows you to turn an ordinary blowgun or pea-shooter into something a bit more serious.

The video does a lot of explaining, but for more detail including how it works, see the next steps.

Step 1: Materials and Tools

Picture of Materials and Tools

To make the XRV, you need a handful of easy-to-find components:


1. Flexible bike pump hose - comes with most bicycle pumps)
2. Brass or aluminium tubing (about 1-2mm) - available from hobby stores
3. O-Rings (tiny) - available from hardware stores
4. Small spring - also from hardware stores
5. Tiny screw that fits into the end of the 1-2mm tubing
6. Tiny nut or washer that fits onto the brass tubing (see video)


1. Hand drill & very small drill bit
2. Fine file
3. Blade
4. Precision screwdriver
5. Pliers or multi-grips (pictured)
6. Hand clamp
7. Superglue

Step 2: The Valve Housing

Picture of The Valve Housing

We need the valve to attach conveniently to any bicycle pump, so cut the MALE connector out of your bike pump's flexible hose.

Step 3: The Valve Shaft

Picture of The Valve Shaft

Now you need to find a piece of brass or aluminium tubing that fits nicely inside the housing. It is absolutely necessary that this tube slides freely through the housing, while being a snug fit.

Step 4: Valve Air Flow

Picture of Valve Air Flow

Air will explode through this small tube, but we need to drill tiny holes to allow this to happen.
With a tiny drill bit, carefully drill two or three small holes into the shaft.
File any rough edges smooth so the tube glides through the housing without sticking at all.

Step 5: Plugging Up the Shaft

Picture of Plugging Up the Shaft

The end of the shaft must be blocked off, so that the only escape for the air is through the tiny holes we've just drilled.

I found that a tiny screw works best, so you'll need to hunt for the perfect screw. The head of the screw MUST be very slightly larger than the shaft itself. The screw must also be very short (we don't want to obstruct the holes). I found the perfect screw inside a dead clock-radio - - old electronic components are a great source of tiny screws!

Drop a bit of super glue onto the screw and turn it in to the end of the tube. If the screw is a bit too small for the tube, you could very carefully crimp the tube a bit with pliers. Then the screw should be a tighter fit.

Step 6: Add a Nut to the Shaft

Picture of Add a Nut to the Shaft

A nut, washer or bush of some kind needs to be added to the shaft, so find something that fits and glue it about halfway along. Once the glue has dried, this valve will be difficult to disassemble, so be sure everything's in place before you apply the glue.

Step 7: Important! Allow the Glue to Dry

Picture of Important! Allow the Glue to Dry

Allowing the glue to dry deserves its own step because in the next step we're going to add a spring that holds the valve closed. If your glue isn't dry when you add the spring, then you'll glue the valve shut!

Go have a coffee or climb a tree. When you get back and the glue's dry, scrape off any excess with a blade. Again, this valve shaft must be very smooth and glide through the housing without any sticking or catching.

Step 8: Spring Loading

Picture of Spring Loading

See the distance between the housing and the nut? You need to find a spring that's about 1.5 times as long. This will ensure that the spring is always holding the valve shut.

If your spring is a little too short, you can always stretch it a little (that's why mine looks a little irregular in the image).

To how to turn the spring onto the shaft, look at the video in the Intro of this instructable.

Step 9: Seal It Off

Picture of Seal It Off

The final step is to make the valve air tight. To do this, you'll need a very small O-Ring.
Now you can see why the head of the screw needed to be larger than the shaft. The head of the screw stops the O-Ring from slipping off.

And with that, the XRV is complete!

The spring is always holding the valve closed so air will not escape.
You can test this with your mouth. Seal your lips around the housing of the valve and blow.. build up a little air pressure in your cheeks then pull the washer/nut backwards (don't push it down your throat!) The air should escape through the tube.

Note: if air is leaking through the valve, then it could be that your O-Ring isn't sealing it too well. Try adding a second O-Ring.

Step 10: How It Works

Picture of How It Works

The spring constantly keeps the valve shut.
When the valve is shut, the O-Ring seals off any escape.
Air cannot escape unless the O-Ring fails.

Pulling back on the nut (green arrow) opens the valve by exposing the holes in the shaft.
Once the holes are exposed, the compressed air explodes through the shaft.

Step 11: Attaching to a Bicycle Pump

Picture of Attaching to a Bicycle Pump

As we made the XRV from a male connector, it will attach perfectly to any bicycle pump.

You will however, need a bicycle pump that doesn't allow air to go backwards. In other words, it needs to have its own built-in one-way valve. If you don't have this, you won't be able to compress more than one plunge of the pump.

Many pumps (bicycle pumps, sports ball pumps) come fitted with a one-way valve, but the 'BBB Airshock' pump that I use has a one-way valve PLUS a reinforced hose. When the end of this hose is blocked (with my XRV), it acts as a small air tank. Air will be compressed in that tiny space and will only be released when I open the XRV.

Opening the XRV into any type of blowgun (simple pea-shooter or deadly ninja blowgun) is the aim of the whole exercise :D


joshbecker made it! (author)2015-01-20

I used your design and upped the sizing a little for a little more oomph. And instead of using superglue I used solder for added strength.
Awesome design on your behalf, works an absolute treat!! Keep up the good work!

chluaid (author)joshbecker2015-01-20

fantastic work! I'd love to see your finished valve in action when you're done. I'm in the process of upsizing mine too :)

wolfy_9005 (author)2013-09-19

The completed project. 5/32 tubing, JAMEC style quick release male connector with a 5/32 hole in the middle and suitably sized everything else. For the people who want a little more top end in their project. Good for 4mm BBs

nancyjohns (author)2015-08-17

instead of just a nut try a wing nut :!

try it with a double nut with a bigger washer in between

sanshipratham1 made it! (author)2017-04-14

made with pvc and is powerful enough to penetrant a nail in a wooden blok

joshbecker (author)2015-01-21

i tested it using my compressor and needless to say the compressor could not create enough pressure to make the valve fail, got it to 250psi and hoping it will go to at least 600psi haha

chluaid (author)joshbecker2015-01-21

haha wow. At what pressure does it become too difficult to pull the valve in? I started designing a trigger system that uses a tubular hammer to hit the valve and release the air but never got around to building it. With something like that, you'd be able to get multiple shots from a single tank.

TheBrainMaster (author)chluaid2016-08-23

Im making some thing like this an you helped me in the good derection. A shame you never finished it. Im hoping i can make just like you inof time to finish mine.

IAmTHESpaz (author)2016-03-07

Did you ever get to making that trigger system I'm currently trying to figure out how to make one that will have an outer valve over the exhaust that when I pull the trigger pushes forward the outer valve closing off the magazine (I'm making a semi auto airsoft air gun) so that air pressure isn't lost into the magazine and also pulls the valve back to release the pressure

Phoghat (author)2015-03-22

clever idea

MetalworkingMaster123 (author)2014-11-02

If the author does not reply to this, I assume he got arrested.

yes. I'm replying from jail.

ICWiener (author)2014-07-16

Hello chluaid,
Thanks a lot for your tutorial, very good mechanism. I tried to make one and integrate it inside a Nerf N-Strike Relfex, here is the description :

The testing has yet to be done.

chluaid (author)ICWiener2014-07-16

hey man, nice job. Looks great!

DanTDM (author)2014-02-02

Hurry up and buy this:


wolfy_9005 (author)2013-09-19

I slightly messed up by screwing an ever-so-slightly larger nut into the end. I mean, it will still lock in but the clearance between the housing I'm using and the tube is already very slight. On the plus side it doesn't need super glue, but it will mean it needs some wet/dry on the outside to fix the clearance or a simple trigger to push it back into it's spot after firing.

wolfy_9005 (author)2013-09-15

Go to any good hobby store and they will have the small tubes. Brass, copper, aluminium. 1, 2, 3, 4, 5, 6, 7mm brass, equal for the others. 305mm lengths, but they sell imperial sizes(1/16th, 1/8th, etc). Depends what you want I guess. If you want to experiment with the same size, just buy a 1m/36" length of the tube and have at it.

I ended up with 5mm(4.97~4.99mm) because darts like the extra air, however the connections to the air supply will be the hard bit. I managed to find a strong spring and the right sized screw in my box of bits, so now making a housing will be tricky. If you order something, make sure it is slightly small than required and either use a small file to make it bigger by the require amount, use some wet/dry on the shaft, or use some valve lapping compound and slide the two bits together to make the fit perfect. The better the fit, the less air escapes, and the more pressure you can put into the tube to shoot whatever you're shooting out the end.

420 O-rings on ebay of various sizes for $15.50

Anyway my thoughts on making this for a semi-auto;

1. Use thick walled tubing, you'll want to run a large amount of pressure behind the valve(3-400psi perhaps)
2. Use a strong spring. Remember, a trigger provides some mechanical advantage, so if you can barely compress the spring because of it's stiffness, then just modify the trigger to suit.
3. You need a way for the valve to release when the trigger is pulled and return whilst the trigger is still depressed, so you don't drain the reservoir or fill the barrel with BB's

Everything else will be simple enough. A paintball tank for the air, the valves/regulators will be the same as from the paintball gun, but the gun itself is expensive to import to countries like Aus(permits, fees, licences, blah blah).

Of course for a single shot this isn't a problem, just remember to take your finger off the trigger. Also be careful with paintball tanks, some are good for 5000PSI(average 3000psi), so you'll definitely need a regulator to get the right amount of pressure. Otherwise, a copper tube with ends brazed on and a schrader valve(like from a bike tyre) will probably work for a few shots so you don't have to keep pumping.

Just some thoughts

wolfy_9005 (author)wolfy_90052013-09-19

Some extra information;

I've been looking at making a slightly larger one using off the shelf parts. Anyway, I found a quick release connector(the male bit). It has threads on the inside, with a 5/32 hole in the middle. You can easily get 5/32 brass tubing, and it is a nice size to work with due to the weaknesses of tiny drill bits(plus the tollerances are tight,. The upside of using premade connectors like this is that there is usually a barb fitting with the opposite threads and it all screws together(just get some teflon tape). 10mm hose connected to a tank to hold some pressure and you're in business.

4-500psi may be safe through this depending on the wall thickness of the tubing used, the seal in the fitting and the tube, the tube construction(extruded or drawn), etc

Clonedone (author)2013-05-02

For y'all who be wondering where this guy got the little tubes, wonder no more!
Took me forever to find. Enjoy!

cbass2272 (author)2012-11-09

What about water? How would this do shooting a stream of water?

milamber (author)2011-05-11

i machined a much larger version of this for my air rifle would anyone like to see a slideshow or ible??? credit to chluaid
of course

Phoghat (author)milamber2012-07-22

I'd like to see it myself I'm at
p a ll a d i n 9 8 0 0 0 at g m a i l period c o m
I'm an old dude living in Mexico building slingshots and crossbows a la J sprave for fun and profit

hbelanger (author)milamber2011-11-28

I would love to see what you have

biolethal (author)milamber2011-08-15

yeh a slideshow would be nice.

merchantofdeath (author)2012-02-21

PLZ RESPOND can a larger version be created with this design obviously stronger materials though. and i was wondering if instead of a bike pumb could i use a co2 cartridge. the cartridge wont be hook up directly to your device but will instead be put on a reservoir with a shut of valve and all that good stuff. btw never made a air gun but know how and what to make a gun the shoots 5 canadian quarters attached together. hopefully somewhere around 700+fps. something that will put a hole through a wall and another wall and so on. by the way AWESOME DESIGN

tinker234 (author)2012-02-04

could i modify this gun to be automatic to shoot darts

pyrotech25 (author)2009-08-11

I have been looking for this video for years. im making an automatic bb gun (pistol) and this is perfect for the trigger. thanks a lot man!

zipzapper859 (author)pyrotech252009-10-31

if you make the automatic bb gun please post it on instructables because i have been also trying to make one...the hard part is making it automatic

hbelanger (author)zipzapper8592011-11-28

Got to start by saying thank you for this instructable the best I've seen so far.

I haven't settles on what I will build yet, BBMG or single shoot, but one thing is for sure I will be using your valve ins some fashion.

for you gents that are looking for an automatic simple design I found the following a while back and it seems to be a nice fit for this valve.

automatic BB gun

Have fun and stay safe...!

TimmyMiller (author)2011-09-30

how big of a pellet can this shoot?

TimmyMiller (author)2011-09-30

where did u get the hand drill?
i really,really,really, REALLY WANT ONE!!!

pdub77 (author)2011-05-23

This is a wonderful design and your video was awesome as well! Good job!

sabladask (author)2011-03-18

i want all the tubes in step 3.....
where did you get them?

sabladask (author)2011-03-18

finaly!! i found somone who actualy knows what hes doing,.'
Grate woork!
i made a simulare gun som years back:) i have made very many air guns, and the valve you made is very good :):)
see my channel i if you are intrested in a springpowerd airpistion gun.
keep up the good woork!

ostomesto (author)2010-11-15

hey im planning to make this but dont have the bike tube for it. could i use a ball inflation needle to do the same thing as it. i lost my old bike tub and hope this will work

why dont you just go out and buy the tube then there probly no more then 5 bucks?

i didnt know where to find them. but i got it. I made one well not really. I made one that is a trigger for my spudgun, it's the pilot on my sprinkler about 5 in long and never leaks air. It has a huge airflow too. I will post a pic of it and how to build it if you want me to

ostomesto (author)ostomesto2010-11-15

ahahahahaha i found my old tube. it was in my air compressor parts box. i looked in there hundreds of times and it was right in front of me. hahahhaha im so happy :)

ostomesto (author)ostomesto2010-11-16

one last thing. i made this and it worked great. i am going to try to make a larger scale one for a trigger on my sprinkler valve in my spud gun. any ideas on what materials i would need to make a larger scale one. oh and would a large scale one hold around 60-70 psi maybe 80

MadBricoleur (author)ostomesto2011-01-07

Happy late christmas.

Cheeseduck (author)2010-12-19

Rather than going through the hassle of hand-drilling, you could just use the small round hand file to make the holes. If you file perpendicular to the pipe, it'll make a good path for the air to escape.

wellbankj (author)2010-11-23

Do you have any idea how much pressure you think this little valve can take? I'm thinking of making a gobstopper gun that I can kill squirrels with and I'd like to maximize my energy output. I'm thinking of using a compressed air or CO2 tank as a power source and a regulator to tone down the pressure that's behind the valve.

freerunnin1 (author)2010-11-13

i'm going to make one of these tomorrow and im using a piece of pipe from a telescopic antenna :P, they come in loads of different sizes

ostomesto (author)freerunnin12010-11-18

ya antenna works great. just take out each pipe form it and u have lots of choices. it is a can bend and is a little flimsy though :(

freerunnin1 (author)2010-11-13

great vid! lol, how long did it take you to come up with the valve? oh and how many pumps would it take to propel a bb over say, 75 foot?

moGuyver (author)2010-10-30

Excellent animation in the video - also great valve design.

quirxi (author)2010-10-23

Cool vid - you should go to the film industry ! :)

Topunisher (author)2010-10-07

Can the hose(on the pumping stick) take on the pressurized air with-out getting it explode?

Fredock (author)2010-08-23

nice vid

About This Instructable




Bio: I make stuff!
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