SpudFiles

at last i build a piston valve and he work great
it's 3/4" T copper (or bras !!)
the piston made from wood , sweeper stick turn it on a lathe and he is about 18mm

and here is the video hoe fast he dump the air. the pressure is about 130 psi
dont forget to watch the video in HD .you know how
[youtube][/youtube]

Congratulations on getting it right so it pops open. Nice home built QEV.

Very nice job Far Cry.

You may have some trouble with the sealing face being retained at higher pressures, but only time (and pressure) will tell for sure.

You did a nice job rounding the piston seat too.

:thumbright: :thumbright:

Your Piston looks friggin' beautiful lol. It' looks so cleanly built.

Nioce Job.

Gorgeous!

Could probably cut down on Pilot volume in the back, And use a smaller Ball valve, But otherwise I'm Envious.

Whatcha gonna put it on?

Technician1002 wrote:Congratulations on getting it right so it pops open. Nice home built QEV.

thank you technicaian . you the Technician

littlebro05 wrote:Your Piston looks friggin' beautiful lol. It' looks so cleanly built.

Nioce Job.

i love my work to look beautiful so this take time
thank you

Gippeto wrote:Very nice job Far Cry.

You may have some trouble with the sealing face being retained at higher pressures, but only time (and pressure) will tell for sure.

You did a nice job rounding the piston seat too.

:thumbright: :thumbright:

and Gippeto thanks for the compliment
and what you did mean by You may have some trouble with the sealing face being retained at higher pressures
so may i have some leaks or the seal face stuck ? if so what i can do,, and the piston is temporary from wood .i will turn one from hard plastic or aluminium

VH_man wrote:Gorgeous!

Could probably cut down on Pilot volume in the back, And use a smaller Ball valve, But otherwise I'm Envious.

Whatcha gonna put it on?

Envious you can do this too, its easy
and the pilot volume is big , i know i just test the piston valve ,it's a temporary install.
and the pilot valve , i want to make i hammer valve to pilot the piston like Gippetos canon
the air gun will take some time to build the stock mostly

[quote="Gippeto"]You may have some trouble with the sealing face being retained at higher pressures quote]

What I mean;

With my bbgun, the teflon seat was "sucked" right out of the hole it was pressed into. This would seem to demonstrate that the flow creates a vacuum at the front of the piston.

Your sealing face "may" be pulled over the head of the screw by the flow.

If this does present itself as a problem, you could turn a washer from teflon or some other softer plastic (hdpe?) to use as the sealing face.

Harder sealing surfaces take more work to be successful, but also yield some small improvements in performance.

The screw should then be entirely adequate.(This was the case with my bbgun.)

i understand , the seal face will sucked into the barrel with high pressure because the strong vacuum
i will find solution after all

and , can this piston valve handle 1000 psi ? agnor the seal face issue

and i have alittle problem the long part ,seat face i put allot of teflon but he still leak what can i do

Id be weary of 1000, But 500 Definetly. My copper one holds 500.

Cant wait to see what this thing will be able to do.

the leak is here what can i do ?

If you have access to a product called "Loctite", the blue variety should provide a seal.

Clean off the teflon tape, apply the loctite and tighten the pieces together.

Then leave it for a day or so. It'll seal.

500psi I think would be fine. Since I've not tested any brass/bronze fittings, I am hesitant to suggest more.

The "turned" fittings would be fine. It's the casted ones you need to watch out for.(the tee)

What do you estimate the minimum casting thickness to be?

Can you provide accurate dimensions as well?

Gippeto wrote:What do you estimate the minimum casting thickness to be?

Can you provide accurate dimensions as well?

2-3 mm APPROX the T thickness. if the T dont have enofh thickness i will replace it with stell or another copper T but with a very good brand T

dimension i am not in the home right now but its standard 3/4" T ,

Very nice gun Far_Cry. I love it. Be careful with the piston though. I used lathed timber for a while until the wood swelled from the condensed air and vapor and the piston completely got stuck.

I solved this problem by putting on a coating of "super glue" to more or less seal it.

I now use hand machined aluminum. It's very easy to machine on a wood lathe, it just takes a little more time.

Sweet mate! I have to post up my brass piston, brass FTW!