Airgun homebuilding thread

[inonickname]

'Airgun' as in the more traditional type- usually using a hammer valve and in the configuration of a rifle or pistol. Basically, not PVC fittings.

Eg.


I'm thinking with some members now owning machine tools it would be good to create a thread of knowledge to do with home building more professional airguns.

Any resources, information, pictures, diagrams etc. are welcome here. I'll start the ball rolling.

Home building of airguns. Rifling, crosman mods, CNC work etc.
Showcase of modified and homemade airguns, as well as homemade parts
Very nice stocks and homemade guns.

And so on. My computer recently crashed so I lost a lot of my good bookmarks. I have a PDF file with plans for the Caselman AMG if anyone wants it uploaded (or I can find a link with some looking).

[jackssmirkingrevenge]

I have a PDF file with plans for the Caselman AMG if anyone wants it uploaded (or I can find a link with some looking).

It should all be here

[inonickname]

I have a PDF file with plans for the Caselman AMG if anyone wants it uploaded (or I can find a link with some looking).

It should all be here

It isn't. It downloads a 10kb file which is damaged.

[POLAND_SPUD]

it seems like a good idea... though, I am not a big fan of hammer valves

it would be cool if we could come up with a design of relatively simple to machine high performance valve

[D_Hall]

it would be cool if we could come up with a design of relatively simple to machine high performance valve

I'll see what I can do about getting something on paper (I've had one in my mind for a few years....I just don't have the equipment to build it.).

[jackssmirkingrevenge]

it would be cool if we could come up with a design of relatively simple to machine high performance valve

What's wrong with exhaust valves? Or perfecting the "valveless" detent system...

[john bunsenburner]

I say our main problem with this is the fact that we need rifeling in our barrels for pellets, beyond that its pretty simple. Hammer valve or inline piston valve(barrel sealing, DUH) for single shot designs. Pre-charged cartidges( or PCC as i shall call them from now, standign for pneumaticly charged cartridge) would be a great alternative.

Valveless designs are, IMHO the future of this along with PCC when it comes the the discussed cannons especially for semi auto action, i am working on a valveless semi auto design, with a slowly finishing prototype(missing ammo, a few O rings, trigger and chambers).

I say the most important things are barrel making or cheap purchase, alternative valves and maybe stock making.Then there are things like reloading, onboard air supply, and trigger mechs but those can be thought of later, and we have viable ideas for all of those already.

I sense a group project. How about we try design a "normal" gun, perhaps a replica of something people like and if its any good we see who can build it, lets worry about that last.

[POLAND_SPUD]

exhaust valves

did you mean QEVs and piston valves ? well there are a couple of problem with them...

first of all, their pilot volume is wasted with each shot.. and while this isn't such a big deal at 200 psi (as the volume of wasted air is just a couple of ccm of pilot volume multiplied by pressure in bars) but at 1000 psi and higher pressures it becomes quite wasteful

secondly, you need a pilot valve to pilot them but there are not too many off the shelf valves and other parts rated to HPA pressures... I know that some of you would say that you can always machine your own but it's not always practical

sure I think I could probably use the DCV that I mentioned in one of my posts (the one which has no soft seals) at 700 - 800 psi as well as the QEV.
But that's seems to be the upper limit

That's why I think that it would be a good idea to design a simple to machine high pressure valve.
I've been thinking about this and I think that a valve piloted/operated by regged down low pressure air might be the right solution

[psycix]

You could strip the barrel from a commercial airgun and build your own powerhouse behind it.
2 stage pneumatic anyone?

[Demon]

What would be great would be a detailed drawing of a hammer pcp airgun. As i just got a mini-lathe, i might try to make one.

[POLAND_SPUD]

that's more less what I am talking about... we just have to design a valve that would offer better performance than a hammer valve and would be cheap to machine... I think that if we spend some time designing this we could come up with something that could be built using only a drill press (and possibly some parts of the piston/spool could be built using a lathe... (or afgan lathe... if you know what I mean))

the main aluminium block could also house a loading mechanism... or in order to make the gun modular the loading mechanism could be a separate part attached via screws or threads to the valve... in this way the gun could use different calibres and both spherical ammo and cartridges/darts

just think about all the possible advantages - compact construction, low weight, good performance thx to the use of HPA, fully self contained construction

we could turn this concept into a kind of community project... simplicity, low cost and good performance would be the main criteria... then we could create a CAD design of the valve so that everyone could download it and machine one for themselves...

I think that the easiest way to build it is to use a positive pressure piloting piston valve... but I'd like to know what's your opinion?

[twizi]

i plan on making somthin like this
http://www.fieldandstream.com/photos/ga ... r-big-game

[daberno123]

As far as rifled barrels go, Crosman sells replacement barrels that are 24" long in .177 and .22 and they are both under $20 I believe. Anyone who has modded a Crosman gun probably knows this but I don't think I've ever seen anyone use one of their barrels in a conventional "spudgun" design.

[Gippeto]

Personally, I'm leaning toward a modification of the Brocock cartridge as a valve. Basically, they are a partially balanced spool valve. (But then...so is every piston valve ever built....think about it. )

http://www.google.com/patents?id=_Pk0AA ... q=&f=false

Pneumatic actuation could be accomplished via hammer valve, or simply use the hammer directly by retaining the directional differential of the brocock cartridge.

Forget barrel making though...by the time you get just the hole drilled, you'll have invested enough to purchase several Lothar Walther barrels. Crosman barrels are MUCH cheaper yet.

Track of the wolf is another source for...larger caliber barrels. Up to .750" in smooth bore... IIRC.

As far as breech design goes, I've been tossing around two alternatives. The Air Force "sliding breech cover", and a swinging breech, which also allows loading directly into the barrel, but would allow for a "tapered" section between the valve and the barrel ( or minimized dead space). I've only seen this breech type used on one type of philippine built air rifle...cannot remember which one.

I rather like the idea of the Air Force tube frame, which is used to mount the barrel in bushings...it would allow quick "allen wrench" caliber changes. 8)

Enough of my idle ramblings...anyone else have a thought to share??

[twizi]

also found this thought it may help

http://www.ora8i.rivington-riflemen.org ... ctors.html



this design would be perfect for a chamber sealing pistion valve idea
the pic that polandspud posted it could be acuwated with a ball valve or blow gun or we could use btb 40 bar balanced push button valve we could up the presure say to 1500psi

i say we should have a 50 cal bore or bigger [/img]