Airgun homebuilding thread

[maverik94]

we just have to design a valve that would offer better performance than a hammer valve and would be cheap to machine

Just a thought, what about a homemade qev with a hammer valve as the pilot, it would get multiple shots and it would be very powerful. Just look at Old Shatterhand. I think it is definatley pretty simple, use a hammer like this Shouldn't be that hard.

[twizi]

your url is bad

[velocity3x]

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

I think that's an excellent idea but......for some reason it does sound vaguely familiar.

[Skywalker]

Well gents, I've just enrolled in a machine tool class, so there's a chance I might be building something soon. I need to come up with a project. I'm thinking semi or auto. I've got three ideas: 1) Jack's rattlesnake 2) a pump-action or self-cocking hammer-valve gun 3) maybe a hammer-triggered piston valve (like BTB's Shatterhand). Other suggestions? (I'm nixing cartridges and pop-off triggered pistons.)

[POLAND_SPUD]

@gippeto & twizi
well brocock catridge is, too some extant, close to what I had in mind

I am leaning toward a design that would act to some extend like a 3 way valve...

for some reason it does sound vaguely familiar

well I've been thinking about this since summer... the fact that there are valves operating on this principle suggests that I might be on the right track...

[velocity3x]

Poland
IMO the positive pressure valve would be the easiest to build and have the most potential. The ends of the valve body could be redesigned as end plates and attached to butt the ends of the cylinder perimeter using screws. My only concern would be the possible damage caused to the spool seals as they pass the ports (barrel, chamber and source). However, overall I think it's a cleaver design.

[inonickname]

I have pictures drawn for a balanced hammer valve, I'll have a look soon.

I don't think there's any problem as long as you build them to have enough flow (smooth), fair opening time and enough duration. Hammer valves aren't that evil.

[POLAND_SPUD]

well I've really been trying come up with a good design for quite a long time... I've seen dozens of pics of valves used on paintball guns and similar stuff...

a couple of days ago I drew this 'postive pressure (actuated/piloted) valve' and I though 'ohh this could work and seems to be pretty simple'

then I looked at it again and I realized that it looks exactly like an air piloted 3 way valve (meaning those off the shelf DCV valves that I talk about all the time, 24/day 7 days a week... you know that stuff that you normally skip when you see I mention it again )

this really is just a scaled up version of them...
possibly it isn't even necessary to machine the valve as there are off the shelf DCV in larger sizes (3/8", 1/2")...


you'd just have to make sure that it is:

-an air operated direct acting spool valve (as indirect/assisted valves often don't handle high pressures well;similarly poppet valves are no good as they are not balanced)
-that its housing is thick....
-check if the spool is made of metal or not
-is normally open or bidirectional valve (depending on which port you choose it can be both NO and NC valve)

@inonickname
well yeah I know that hammer valves are not that bad... if you think of it there isn't really that much difference between the hammer valve, the piston valve and the QDV

but I find the QEV + DCV + air cylinder combo to be the simplest and most reliable way to achieve semi auto and full automatic operation of the gun... so I am looking for a design that would allow me to utilize this system at HPA pressures

just think of all those pb guns that rely on exactly the same principle of operation

[jackssmirkingrevenge]

In order to achieve exhaust valve performance without pilot waste, I would say this would be by far the easiest solution:



As to a "valveless" design, you could have a collar around the breech, a bit like a quick connect fitting holding the projectile in place with a series of bearings, which would release it when the collar is moved back, along the ideas expressed here.



This would be definitely the ultimate "valve", zero opening time and instant maximum flow.

The problem with these as opposed to hammer valves though is that they are essentially dump valves so useless on their own for multi-shots.

By the way, as to the Caselman, instructions and plans available here (part list and drawings are on the last page)

[spudamine]

I'm struggling myself for a valve choice for my next project, I was planning on something similar in function to old Shatterhand with a modified QEV piloted by a hammer valve, the hammervalve would be based on Brians push button valve. But now I'm thinking if I scale up the hammervalve I could use this as a main valve and do away with the QEV and pilot wastage. Only problem I can see is a hammer valve needs quite a lot of deadspace to ensure good flow at the exit so my usual trick of using a much bigger valve than necessary to ensure good flow might backfire.

[maverik94]

your url is bad

Ok, thanks, i fixed it.
Jsr, I like your idea for an efficient gun, but you forgot to add some sort of o-ring where the purple piston meets the gray body. Anyway, I kinda like that Idea Jsr, simple, yet it should be pretty good. The Spring will cut performance though.

[POLAND_SPUD]

By the way, as to the Caselman, instructions and plans

hmmm who said you need a spring powered hammer ? use an air cylinder to strike the valve

[jackssmirkingrevenge]

Jsr, I like your idea for an efficient gun, but you forgot to add some sort of o-ring where the purple piston meets the gray body.

I took that for granted

The Spring will cut performance though.

Not really, it doesn't have to be very strong. It's job is not to hold back pressure, but to reset the piston once the pressure in the firing chamber has dropped.

hmmm who said you need a spring powered hammer? use an air cylinder to strike the valve

Is air free in Poland

[twizi]

what about electro pentamic paintball guns it would work for somthin like polands idea

[POLAND_SPUD]

you can have a look here -> http://www.zdspb.com/tech/misc/anim_spool.html

you'll see that even though my design does look different it operates pretty much like some PBguns

(though, they use solenoid valve, which allows for a greater degree of control)

EDIT


here you can see the similarity...


the valve which controls the main valve on both: this and my design is just a 3 way valve

you can also see that the spool/main valve really is a 3 way valve... there is no chamber port in it as the internal volume of the valve is the chamber here (which also could be achieved with the design I proposed)

the only difference is the fact that the spool acts also as a sort of air cylinder that loads ammo and 'switches' the valve from one position to the other
(the design I created could be used in the same way... but I don't know yet if it's any sense in introducing this feature)

also notice that the PBvalve vents air to pilot the valve while mine pressurises... IDK which one would be better ??


if you can visualise stuff well you might notice similarity between this particular PB valve and the modification of the QDV proposed by iknowmy3tables and me a couple of months ago... I don't know about you guys but for me all those similarities are not just a coincidence... it might be that this is just a way it should be done