First Rifle (1/4" BB) - Simple design w/shock pump

[cane toad]

Hi,

This is my first post, sorry for any mistakes. My work mate and I built a couple of variations of this gun last year for [COMMENT REMOVED BY BTB ]in and around the shed where we work.

There's nothing remarkable about this gun, it's simple to make, but I haven't seen any on this site that use this kind of release valve so I thought I'd put a few photos up in case it gave anyone ideas.

The release valve is an air brake valve used on big trucks (some semis, dump trucks). This one was brought brand new but the first gun we made we just pulled one out of an old truck cab.

Air is supplied via a shock pump, we do have one with a soda stream bottle mounted which we fill with an air compressor, but it's easier to walk around the shed with the hand pump model than to return to the compressor between shots.

The air chamber is just a length of air compressor hose you can buy off the roll. We experimented with different lengths and what we ended up with seemed to give us the best power/number of pumps ratio.

It fires 1/4" ball bearings and it is loaded through the front of the barrel. The pellet cannot fall out unless the rifle is tipped completely upside down, so you can shoot at downwards angles. It is a single shot gun, no magazine.

I can't think of any special tools required to make this, just a drill, rivet gun, screwdriver, hacksaw.... I think thats about all.

I usually only pump this up to ~150-200psi. Can plink a paint can pretty good at ~80feet, although most of the other shots I take are 1/2 that distance to make up for my lousy aiming.

So overall an easy gun to make for beginners. Now I'll try and upload a couple of photos.

Thanks for checking it out, feel free to ask any questions if you like.

PS if you're wondering why I don't just use an air rifle, welcome to Australia, my friend, where anything other than a pointy stick needs to have a license.


Edit by Moderator (MrCrowley): Discussion of shooting animals with homemade firearms/guns/cannons is not allowed.

[shiny455]

very nice.. extremely similar to the gun i am currently making, just a few slight differences and the stock idea is genious i think im gonna have to steal it and yeah Australian laws suck it would be easier and probly safer to just give us air rifles

[Crna Legija]

nice work., looks good but you put some side plates on the grip. the gun laws in Australia so aren't that bad, just get you licence only takes abut 20min to fill in the form and 1 month till you can buy a gun, yeah you cant get AR but you don't need one

[FragmentedSanity]

Thats pretty cool.
Im keen for any more info you have on the valve... can you get them in a normal Auto store? or do they come from more specialized place?

Also, it kind looks like its a manually operated exhaust valve... did you just make up a trigger that depresses some sort of release that sends the air in the chamber to the barrel?
How strong is the return on the "trigger"... what im getting at is - if you replaced the direct acting trigger, and had a hammer that just hit it open for a moment, could you get multiple shots? (with a bigger chamber and higher pressures of course). A factory made Aussie OTC hammer valve would be pretty sweet!

How much pressure can one of these air brakes take? Im wondering if they can take more or less pressure than a standard QEV, Also any idea how much they cost someone who dosent have an old truck they can rip apart?

Oh and how about some pics of the Soda stream bottle chamber pic's? Im curious how you go about refilling them with a compressor too!

[cane toad]

Thanks shiny455. Look forward to checking out your design mate.

Edit by Moderator (MrCrowley): Double post.

To Moderator: My apologies, will not happen again.


Edit by Moderator (MrCrowley): Double post (again). Please edit your previous post, thanks.

To Crna Legija - Thanks, I did think about boxing in the grip and the stock, its surprisingly comfortable to hold as is, maybe because it's so light. Good idea though.

Ahhh edit posts... I see.... Sorry!

FragmentedSanity - I'll try and and answer your questions (and hopefully not break any more posting etiquette)

* You can buy the valve when they sell spare parts for trucks, probably not just a car supply shop though. Ask for an air brake valve. A picture might help.

* The valve straight out of the box consists of the black plastic body (including the seals/piston inside etc), and the straight, chrome plated lever switch poking out the back. FYI the trigger is just a nail we pushed through a hole drilled in the switch and epoxied.

* I think your giving me too much credit, if you take the nail off the setup, thats how the valve comes out of the box, lever (or trigger) and all. up or down is closed, half way (or perpendicular to the mount) is open. The valve is spring loaded shut I believe. The lever is on a cam inside the body, so it 'wants' to flip to the top or bottom. There is one inlet port and two outlet ports (I screwed a brass plug fitting into the outlet i didn't need). All I did was cut the mounting bracket for the valve so it blocked the lever from ever moving past halfway. That way it always springs back to the reset position when you release the lever/trigger. I hope that makes sense??

* As for hitting the lever/trigger open for a moment rather than emptying the air chamber, I can think of two ways quickly. One would be to remove the block on the mount so the lever flicks from the bottom to the top ie off-on-off. the problem is to shoot again from the bottom you have to waste air going off-on-off to get the lever back to the bottom. the other way would be to leave the block in place and have a cog wheel turn and 'flick' the switch, each spoke of the cog would fire one shot. If you've ever had one of those wooden rubber band guns you know what I mean by the cog. It wouldn't have to be big, I can detail more if you want but this is getting too long.

* As for pressure, I honestly don't know what these kind of valves are rated for. The most I've had this up to is ~300psi, which is the most my shock pump can produce i think. I won't be doing that again, too much effort to pump for one shot. I do know that repeated pressures or ~210psi are no problem. How much pressure were you thinking?

* The valve brand new I believe cost approx $40aus. Not cheap but I wanted something simple and off the shelf. You could try a wreckers, but they probably won't want to bugger around looking for something that small, they might let you look though... They're mounted in the dash. The lever is a switch that comes through the front of the dash and the valve is mounted behind out of sight.

* The soda bottle just connects via various brass fittings to the inlet port same as the hose does. To fill the bottle we drilled a hole in the bottom just too small to fit a tank valve (like a tyre valve but with a thread on each end), then used a tap and die to cut a thread into the soda bottle. Screw (and seal) the tank valve in and its ready to be filled by any compressor with a tyre inflater attachment.

I hope I've answered all of you questions. Please let me know if you have any other comments or questions.

Crna Legija - I guess you could make a qev as big as you like, so you could always have more flow than this puts out (cheaper too I'm guessing). As for opening time, one of the other rifles we made has a similar valve to this but has a spring loaded trigger on a sear, no coincidence it has more power, but it took far more effort to make, this one was so easy thats why I posted it.

[Crna Legija]

Thats pretty cool.
Im keen for any more info you have on the valve... can you get them in a normal Auto store? or do they come from more specialized place?

Also, it kind looks like its a manually operated exhaust valve... did you just make up a trigger that depresses some sort of release that sends the air in the chamber to the barrel?
How strong is the return on the "trigger"... what im getting at is - if you replaced the direct acting trigger, and had a hammer that just hit it open for a moment, could you get multiple shots? (with a bigger chamber and higher pressures of course). A factory made Aussie OTC hammer valve would be pretty sweet!

How much pressure can one of these air brakes take? Im wondering if they can take more or less pressure than a standard QEV, Also any idea how much they cost someone who dosent have an old truck they can rip apart?

Oh and how about some pics of the Soda stream bottle chamber pic's? Im curious how you go about refilling them with a compressor too!

most trucks iv seen use abut 100-120psi so the rating would be in the same range as a qev, but qev would have loads more flow and a better opening time. they also look cooler

[FragmentedSanity]

Good info!
Never had much to do with trucks, So this is new to me... but the usual QEVs we see are only rated to about 145 psi, and people take them much higher.. Id be interested to know if something designed for truck brakes was a bit more robust.

As for giving you too much credit Cane Toad - I dont think so - you've taken a valve you had access to, used it well and came up with a simple and elegant solution that I haven't seen here before. If all you did was weld on a bent nail to make an ergonomic trigger - That's even better!

So its a manually operated 3 position switch, That got possibilities too, Its not what I first thought, but could be interesting none the less, Now if only the lever indicated which gas port fired

But, You could still get the result I was thinking about with your setup - simply put a spring behind the head of the nail and in front of the frame of the grip - that way when you pull the trigger it would automatically reset to the of position when you let your finger off.
Then - if instead of a finger pushing the trigger open you use spring driven hammer, you get the momentary opening and closing thats required for multiple shots.

Then all you need is a bolt action that cocks the hammer and works a loading mechanism and you've got a multi shot plinker that you built yourself! None of the "inanimate targets" around your yard would be safe then!

Now its true you could use a QEV for all this, I just like hammer valves better than I like piston valves, maybe i'm just odd.

Id really like to see some Pics of the "other" more complex build you mentioned - with the spring loaded trigger with a sear. That sounds really neat!

[cane toad]

Here's a few pics as requested of the other rifle I mentioned. Same principles only with a spring loaded trigger held by a sear, and a soda bottle air chamber.

As you'd guess, the spring loaded trigger does improve the power.

Thanks again for the comments/suggestions.

edit: The trigger guard was meant to be temporary, made from scrap, never bothered changing it.

[Technician1002]

Nice looking build.

I see MrCrowley mentioned the rule #2.

[bezza1]

hi mate where did ya get the air valve from i carnt find one anywhere PS im in australia

[cane toad]

I bought the valve from a local truck parts dealer. This is the valve:

http://www.haldex.com/en-GB/Europe/Appl ... e/N13440DN

If you live in Australia I'd imagine you could contact someone like this

http://www.atap.com.au/index.html

and order it from them. I hope that helps.

[jackssmirkingrevenge]

Very well put together, a good example of the sort of innovation restrivctive gun laws tend to inspire

[frog after toad]

Am interested in this concept seems to be ,quick, simple , cheap, affective, also looks good, was there more then one person behind this design, will look forward to more posts

[cane toad]

Thanks jackssmirkingrevenge.

Also: Yes two people worked on this setup, myself and a work mate. Sort of a "end of the day" project we tinkered with at work for a couple of weeks.

Waiting for a qev to arrive, then we might knock up another one with a simmilar setup/different valve.

[AirGunNooblet]

Hi, what was the diameter of the air compressor hose you used?