building my first pneumatic with hammervalve full metal

[quark1980]

hi there,

i have been lurking around here for some time now. and decided i wanted to try out my ideas.

i wanted to make a multishot sniping rifle kind of airgun.
the barrel i made is ID15mm so for now i just stick with the materials i get my hands on.

the chamber is a old small helium tank, 0.4 litres volume. with a self build hammer valve on it.


i just made a platform to mount the pieces on, and nothing is really in its final form yet.

nevertheless i wanted to hear youre toughts about my design, because most of the stuff i did was just guessing as i went along.

anyway here are some pics.

the chamber with filling schrader and hammer valve:


the valve assembly:



the tank/valve mounted on the gunbody:


now for the unfinished part, the actual hammer and trigger
for the hammer i wanted to mount a weight(hammer) on a liniar bearing.
i didnt design a trigger mechanism yet, there is where you guys come in




sliding of the bearing:
[youtube][/youtube]

i`d like to hear your thoughts on my design, i will update any progress here

[wyz2285]

That slide bearing is a nice thought, well done.
For the trigger mechanism, I have a tutorial here, could be easily adapted to your gun.
For the hammer, probably anything that fits in there will work, won´t be a big problem

[quark1980]

that is basicly the mechanism i had i my head. the only difference with my hammer is the fact thats its actually just a sliding block of aluminium... not encased in a piece of pipe.

but i agree i should be able to change it so it will work

i`m searching for a piece of aluminium for the hammer atm, so im not able to make a exact design... yet.

a other difference is the orientation of the valve.
on most guns its inside the stock, on the back of the gun.

mine will be in the centre of the gun, wit the valvestem pointing to the front of the gun...

so the locking latch should be facing the other way

im going to try to build something in these lines:


next up will be the loading mechanism.. but first i want the hammer to work correctly


another thing i was wondering about, is there a way to estimate my valve?
i tried to make some simulation calculation in ggdt to see what kind of fps i would get from my setup. but the result i got where rather saddening

i tried my valve in the workbench, tapping the valve with i small spanner,and i shot trough a plastic abs container, and made a little dent in the steel garage door. so i figure i didnt put in the correct data

[Gun Freak]

Looking good. I don't really see an advantage of using the slide bearing, but maybe it will be smoother than a tubular hammer because of friction. So I guess it's a nice find.

The trigger should be pretty simple to make. I made a mod to your diagram, so it should be simpler to make.

[Hawkeye]

The secondary lever is necessary to allow the hammer to travel further and get a better swing at the valve pin.

[Gun Freak]

I don't understand Just move the one piece trigger if more hammer travel is needed.

[Hawkeye]

The idea is to have the trigger in an ergonomic position. You could move it forward but then you're reaching up the forestock to trigger it.
The secondary sear lever is pretty common I think.

[Gun Freak]

The trigger I drew is in the same position as the one he drew.

The secondary lever is only needed when there is a forware traveling striker. Since his is forced backwards, only one piece is needed to release it.

[Hawkeye]

Only needed for a forward travelling hammer? Like in the Airforce Condor? lol
Neither of the diagrams look like they have enough hammer travel but the secondary lever at least gives the possibility.
With the short travel and single trigger you're going to need a heavier spring which will make it harder to cock the hammer.
Since it's not THAT much harder to put the second lever in I' would do that to try to make the most balanced efficient system.

[Moggle NZ]

this is simaler to what i want to do

[quark1980]

yep, the travel of the hammer is yet to be decided on, but the parts i have do allow for a decent travel if it would be needed.

the trigger position is fixed in my opinion, of coarse it would be possible to adjust it a few centimeters back and forth if its possible to keep things simple.

if i cant get enough travel i need to use the second lever. i just drew it in because i expect it top be neccesary

however, tnx for the simpler design, i kinda overlooked the possibility, so i surely will look into simplifying if possible.

my design needs a sligtly heavy hammer, that the main reason i did go for a sliding blok instead of a lighter piece of metal inside a tube.

this type of drawer bearing is use in DIY cnc mini routers, so im sure it wil be up to the task the extra weight in this case is not an isseu.

my diagram isnt very accurate however(the aluminium profile is lower), so im not absolutly sure if i`m able to place the trigger underneath the block, it might be needed, to place is to the side of the block, if you know what i mean

Looking good. I don't really see an advantage of using the slide bearing, but maybe it will be smoother than a tubular hammer because of friction. So I guess it's a nice find.

The trigger should be pretty simple to make. I made a mod to your diagram, so it should be simpler to make.

with the materials i got, its easyer to mount a sliding bearing, then it would be to mount a tube.
this combined with the possibilities its easyer to find a suitable piece of hammer material, wich can me made heavier or lighter more easily, made me think it would be a good idea...

i never saw somebody else do it however, so i could be wrong

[Brian the brain]

Something like this?

[quark1980]

should be perfect... the pullrod can be place to the side of the block.

the green catch would grab into a stud or so on the side of the block so that way i could get it to fit inside the aluminium profile...
the inner side of the profile is 4cm so i should be able to get it to fit

[quark1980]

update:

i didnt got the chance to get my hands on some metal for the hammer...

so i tried to make me a nice handle and zip-tied that to the stock to see if what kind of a trigger mechanism i would be making

im quite happy with the looks, and it seems like the one-lever trigger setup will be te best choice after all
also still need to think of some breach loading to build into the t-piece.




the barrel will be a combination of steel t piece combined with a aluminium tube.

[Gun Freak]

Looks a lot better than before I need to get off my butt and do something on mine now