pics now!!! homemade LARGE schrader....

[jeepkahn]

This is for venting, not filling...

Yesterday, I was playing with my new copper gun, and wasn't real thrilled about the performance at lower pressures(80-125psi), not sure if pilot volume is marginally large,the piston is tight, the return spring piston, or if the schrader I was using wasn't venting quick enough...

So I said to myself, " Self, why don't you make a larger better flowing schrader?"....

Here's what I came up with...

1. Take a 1/4"npt brass plug.
2. drill a 7/32" hole through the plug.
3. take a 5mm x 35mm panhead screw.
4. dip the head in plastidip until you cover the head and the first 3 threads, about 3 coats.
5. insert the screw from the inside going out.
6. take a small coil type spring and put around the exposed screw.
7. put a 5mm nylock not on the screw(to retain the spring and apply sealing pressure) until the screw and nut are flush.

voila, you have a larger venting valve that is push button operated, is no larger than a standard screw in schrader, and so far I've fired it 40 times with 125psi, and 12 times with 275psi, and no sign of damage to the sealing face...

Performance is AWESOME, when you press the button the gun nows goes "POP" instead of "pfoomp"...

If you're not clear on anything, just ask...

[c11man]

wow nice idea! Any pics? also how high of pressure do you think this could be taken to?

[jeepkahn]

No pics right now, I'll try to get some soon...

I would imagine it'll hold enough pressure to make it really hard to push the button...500psi would require 24.53 lbs of prssure to push the button, just so you know...

[c11man]

well i guess that it would be alittle hard to push at 600 psi... that shoots down my idea of using it on a cannon i am designing
do you think that you could replace the plastic dip with a small rubber washeer that fits over threaded part?
looking forward to the pics

[inonickname]

Sounds cool, I'll wait to see the pictures and I may give it a shot, hate this ugly little BV. C11, you could use a lever to help exert force..but it may just be better to go with a different valve. I guess if you were very keen you could redesign this as a balanced piston for (nearly) 0 opening resistance.

[jeepkahn]

well i guess that it would be alittle hard to push at 600 psi... that shoots down my idea of using it on a cannon i am designing
do you think that you could replace the plastic dip with a small rubber washeer that fits over threaded part?
looking forward to the pics

600psi would require 29.43lbs to push the button.. the problem with a washer or oring is that once you unseat it, the pressure forces the oring into the area between the threaded part and the hole... I tried that fgirst..

[c11man]

i guess it would be posible to make it have a lower opening force. i am not very good at desighing this type of thing so if anyone had an idea that would be sweet. and couldnt you super glue or epoxy the rubber to the screw head?

[Gippeto]

A pretty good idea.

The only suggestion I have, would be to add a "largish" flat washer and a second nut to the bolt.

This would redirect, and disperse the flow of high pressure air away from your digits.

Or better yet, add a hammer, sear and trigger. 8)

[jeepkahn]

A pretty good idea.

The only suggestion I have, would be to add a "largish" flat washer and a second nut to the bolt.

This would redirect, and disperse the flow of high pressure air away from your digits.

Or better yet, add a hammer, sear and trigger. 8)

the diameter of the nut versus the diameter of the hole, and the coils of the spring do a surprising job of dispersing any high pressure airstream, but a 10mm diameter washer wouldn't hurt...

c11man, plastidip is cheap and easy to use, not trying to tell you not to use glue and rubber washer, but it adds extra headaches with no benefits, plus the plastidipped threads help to keep it aligned when it's seated...

and Gippeto, I was thinking the same thing about a trigger/hammer/sear... a hammer valve pilot....

[psycix]

This is a clear howto on building a hammer valve. Maybe post a few pictures, would be nice.
It will be damn hard to hammer this on a high pressure though.

[SEAKING9006]

Damn hard, but the flow at that pressure would be great for re seating any hammer mechanism. Knock it down to 250-200 PSI and throw a linear hammer on it and see what happens.

[jeepkahn]

edited to add pics....even though I forgot to turn the focus to macro...

[SPG]

Whoops Double Tapped the Submit button

[SPG]

Great idea, and nice and easy to make too. I'm not certain that 29+lbs is that bad for a hammer valve really, if you think how a hammer valve works it's a short sharp blow against the valve to momentarily open it, not a consistant pressure.

As a quick test I just flicked my kitchen scales with one finger and even that blow shot the scale up to 19lbs.

[daxspudder]

about it being hard to depress at 600psi since it need 27 lbs of force to open... a barretta 9mm takes 14 pounds to pull the trigger on the first shot, and 6 pounds on every follow up shot