Airgun With EXplosive Air-Release Valve
Intro: 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.
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
To make the XRV, you need a handful of easy-to-find components:
Materials
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)
Tools
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
Materials
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)
Tools
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
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
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
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.
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
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.
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
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
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.
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
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.
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
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.
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
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.
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
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
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
262 Comments
wolfy_9005 10 years ago
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
Kelvind5 2 years ago
dark-kad 4 years ago
Looks very practical.
I will upload picture once done with project. Thanks guru ji.
B17_FlyingFortress 4 years ago
nancyjohns 8 years ago
instead of just a nut try a wing nut :!
frank villegas 6 years ago
try it with a double nut with a bigger washer in between
joshbecker 9 years ago
chluaid 9 years ago
TheBrainMaster 7 years ago
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.
Phoghat 9 years ago
clever idea
MetalworkingMaster123 9 years ago
If the author does not reply to this, I assume he got arrested.
chluaid 9 years ago
yes. I'm replying from jail.
ICWiener 9 years ago
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 : https://www.instructables.com/id/Nerf-N-strike-Refl...
The testing has yet to be done.
chluaid 9 years ago
hey man, nice job. Looks great!
DanTDM 10 years ago
Hurry up and buy this:
QUICK EXHAUST VALVE
wolfy_9005 10 years ago
wolfy_9005 10 years ago
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 10 years ago
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 11 years ago
http://www.amazon.com/gp/product/B000BRHE4M?ie=UTF8&force-full-site=1&ref_=aw_bottom_links
A
Took me forever to find. Enjoy!
cbass2272 11 years ago