Introduction: Qev Air Gun

To build the QEV air gun you will need a list of parts

What you need:

1kg dry powder fire extinguisher

Tubeless tyre valve

Quick exhaust valve (QEV)

2X Double 1/4" male adaptor

Double 3/8" male adaptor

1/4" female to 3/8" female adaptor

20mm X 1.6mm Aluminium plate

2X big hose clamps

Air duster trigger

Epoxy glue

Step 1:

there are three ports, the top one used to have a pressure guage and is now filled with epoxy to fill the gap.

Step 2:

Emtpy out the fire extinguisher and paint it. Then separate the to peices and drill a hole somewhere in the fire extinguisher for the tyre valve to fit in. Drill another hole in the 20 X 1.6mm aluminium plate and put it over the tyre valvle and secure with two big hose clamps as shown in the second image.

Moving on to the second piece which is shown in the first image. Grab the double 3/8" male adaptor and Using plumbing tape rap it around one of the ends. Using a shifter tighten it on the end where the nozzle used to be. You will find it hard to screw it on because the fire extinguisher has a thread that is different thread which is hard to find, so you will have to force it in as tight as you can and put some epoxy or silicon around it so it doesn't leak.

Step 3:

Using the QEV, two double 1/4" male adaptors and a 1/4" female to 3/8" female adaptor screw them all on the the QEV as shown in the picture.

You may notice some aluminium plate on top of the QEV, that is my homemade scope railing I make from the left over 20 X 1.6mm plate and some 10 X 3mm aluminium plate.

Step 4:

And after that all you need to do is make a barrel.

If you have any questions please leave them in the comments bar below and I will try the answer them

Comments

author
FaZeN1 made it!(author)2016-05-04

wow bro sick stuff

author
TargetOz made it!(author)2016-01-03

Hi again, feeling a bit confused. When I power up your setup above using compressed air (temporarily) instead of the fire cylinder it just blows air out of the discharge,but when I put the compressed air on the inlet and block off the supply and then disconnect the air sup the outlet spits some air. So I plumbed it as per the pic below to try and get the same effect but when I released the trigger the qev didn't spit. So not sure what I'm doing wrong. Appreciate your help.

20160103_193303.jpg20160103_191532.jpg
author
Lukuky made it!(author)2016-01-15

This is my solution

your imput is from the bottom left wich will have one of those hand valves connected to it.

And at the top right will be another hand valve and in-between all that at the elbow section there is a one way valve.

And a spring that you will put inside the QEV to hold the rubber disk against the metal tube.

How it works:
When you hold the hand valve on the bottom left that is connected to an air source, the chamber will fill and air will go into the QEV from the bottom and at the same time air will go passed the one way check valve and into the QEV from the right hand side one it has filled you will let go of the hand valve.

Normally if you had tested it with out the one way valve and the Spring it would just flow out because there are equal pressures coming from the bottom of the QEV and the right hand side which cause it to flow out, because of that and the way the rubber disk inside the QEV is positioned it will just flow out.

What is happening in the QEV is that the spring is helping the air from the right to keep it closed and when the air is released from the back by pressing the hand valve it will release the air from the top section. The pressure coming from the bottom will be too strong for the spring so it will open and let the air out. And then when the air runs out the spring will close and you will repeat the process.


image.jpeg
author
Lukuky made it!(author)2016-01-15

this it the picture

image.jpeg
author
Lukuky made it!(author)2016-01-15

Also asu ini what the top right is where your air is imputing from can you please explain what connects to the bottom left section of the setup in pic one

author
Lukuky made it!(author)2016-01-15

Hi TargetOZ, sorry for such late reply. I think I have came up with a solution to your problem.

I just need to know what your planing on using as your trigger.

what your using to supply your air (example, fire extinguisher tank, directly to air compressor or co2 tank/ paintball tank)

And where your is is imputing from (example, pic one bottom left, pic one top right)?

author
TargetOz made it!(author)2015-11-28

Nope I'm happy to give the qev a go. Re the 1/4 qev you posted a link to ebay is it important to get just that one or will any 1/4 qev work?

author
Lukuky made it!(author)2015-11-28

hi again, yes you can get any type you like just make sure it's 1/4" so that it fits. If you end up using a fire extinguisher check the rating for the pressure, you may have to convert it. And then look at the rating for the QEV you want and check if it can hold that pressure because if the QEV is made to hold 100psi and you pump the tank to 200psi it will probably leak.

author
TargetOz made it!(author)2015-11-27

Great simple design, well done. Question, rather than using a tyre valve on the cylinder, would it work if you held open the red cylinder trigger and the air gun trigger then pumped air through the bottom of the air gun where it vents?

author
Lukuky made it!(author)2015-11-27

Hi TargetOz, Your idea about pumping air through the barrel while holding down the two valves could work but it will firstly take longer to pump and there can not be any leaks from the barrel to the connector, maybe put some silicone around the connection or putty for extra strength. But I wound suggest doing it the way I did because it's a lot easier. BTW you don't have to use those metal straps that hold the valve if that's what's stopping you from doing it my way. Please ask as many questions as you like and don't forget to tell me how you go.

author
Lukuky made it!(author)2015-11-27

Oh sorry I didn't read the question properly. Yes your way should work, just don't forget to take off the pump when it is finished being pumped

author
TargetOz made it!(author)2015-11-27

Thanks again. Some dude here says there's no need for a qev. Why would he say that?

author
Lukuky made it!(author)2015-11-28

hi, the reason he said that is because the fire extinguisher has a similar valve to the QEV so you could just connect the barrel to the valve on the fire extinguisher but it would be hard to shoot because the trigger would be facing the other direction. The reason I did it my way is because the air comes out more suddenly making it shoot Faster, but if you want an even more simple design then you could just connect the barrel to the fire extinguisher valve.

author
seesee357357 made it!(author)2015-07-08

would it go further with a CO2 tank and were did you buy the qev

author
Lukuky made it!(author)2015-07-13

Hi there, if your looking for a QEV than eBay is the place to go:

http://www.ebay.com.au/itm/1-4-BSP-Pneumatic-Quick-Exhaust-Valve-Quick-Release-Air-Aluminum-Alloy-/121364964567?pt=LH_DefaultDomain_15&hash=item1c41ea64d7

This QEV ships worldwide from China, so might take a while to get to you depending on where you live.

Also with the co2 tank, it doesn't matter what you use as your tank, whether you use a pvc pipe, a fire extinguisher tank, a paintball tank or a soda stream co2 tank. It doesn't really matter what you use because it just depends on the amount of pressure there is in the tank.

author
MrE made it!(author)2014-07-20

seems like a really cool idea but you could use some more instructions. Although I do like the idea it just doesn't seem quite complete. But good job anyway.

author
Lukuky made it!(author)2014-07-25

this I my air gun complete. ? the barrel is 8mm carbon fibre tube with a 6mm inside diameter which I got off ebay, and a 10mm aluminium tube with a 8mm inside diameter to make it stronger. If you have any question I would be happy to answer them.

image.jpg
author
jack.green.146 made it!(author)2014-12-06

I know its has been 4 months but how many shots do you get from one tank and what psi do you fill it to? thanks in advance

author
Lukuky made it!(author)2015-04-21

hi sorry for the late response, I've been having troubles with my account. The air gun I made does about 6 powerful shots, and my tank does 200 psi but may be divergent depending if you choose a different size to the one I used.

author
Lukuky made it!(author)2014-12-07

as other people have said, you do not need to use a QEV. Using a qev you will only get one shot from it, if you don't use a qev and hook a barrel directly to the fire extinguisher you will get about five. Also the psi rate depends on what your fire extinguisher you are using. You may have to convert the measurements. If you get one like mine you should be around 200psi.

author
MetalworkingMaster123 made it!(author)2014-09-28

Cool idea, but you do not need the QEV. It does nothing. Mine is filled from the nozzle of the fire extinguisher, and the existing valve is just like a QEV. If you add a QEV it hurts power because of flow restriction. At 30 psi a foil ball shot 100 feet!