How to further mod a sprinkler

[sanaka]

Thanks for this tutorial, noname.

I finished my first launcher last week, using a stock 1" valve. It rocks pretty good, 2" barrel potato hang time is ~9 seconds.

But theoretically I can lots more power from this gun, so I'm trying to make your mod sprinkler valve work.

I think I'm having the same problem as VH_Man. I made a thin rigid disc that fits in the valve with about 1/32" clearance all around, and laminated some rubber sheet to it. I removed the spring, thinking that just helps force the valve closed, and mine closes no problem.

It doesn't open, however. The chamber simply depressurizes out the blowgun. Any ideas what's up? Thanks!

Peace,
Sanaka

[noname]

Don't leave any amount of gap between the edges of the diaphragm and the "walls" of the inside of the valve. To make the diaphragm, get some 1/8" sheet rubber. Cut it into a perfect circle about 1/4" bigger in diameter than the place it fits into in the valve. Push it in equally on all sides until it won't go any further. It should be pressed tightly up against the barrel opening.

It's hard to get right, but it'll work great it you manage. Try making a coaxial pneumatic that uses a diaphragm first; it'll help you understand exactly what you need.

[sanaka]

Thanks for getting back so quickly, noname.

What you say makes sense in that an oversized rubber circle would make a 'roll' that seals on the valve wall but lets the center rigid disc move up and down.

So are you saying push the center rigid disc (the coin/token) in and let the rubber part roll up, so that it makes a 'bowl' shape, or do you tuck the edges of the rubber down and make an upside down bowl? Or does that question make no sense whatsoever?

The pilot fills via leakage around the edge of the rubber?

In your photos it looks like the rubber disc is a loose fit in the valve and the whole rubber/coin unit remains flat as it moves up and down (not to mention your circle is far from 'perfect'! .

This is what I was unsuccessfully trying.


Peace,
Sanaka

[sanaka]

Has anyone else successfully done this sprinkler valve mod?

I've done what you said, noname. I got thick rubber sheet, cut it over size and glued a smaller rigid disc in the middle. This unit then is pushed, with difficulty and small tools, down into the valve and seals tightly all around the valve wall. First try it wouldn't seal to the exit of the valve because the air feeding into the chamber had no way to get to the pilot area to push the diaphragm/piston down. So air just leaked right through to the barrel.

So I drilled a tiny equalization hole close to the outside edge of the rubber. This allows the pilot to operate and the valve seals and the chamber pressurizes. But evacuating the pilot just does not force the disc away from the valve exit, so the launcher does not fire - the whole chamber just empties through the blowgun, just like in my other attempts.

What exactly is supposed to make the disc fly away from the valve exit when the blowgun is operated?

I still say, noname, that your diaphragm/piston in the photo looks like a loose fit inside the valve.

Further, nitty gritty explanation would be much appreciated. Thanks!


Peace,
Sanaka

[avlaxmidi09]

My "normal" modded sprinkler valve also just lets all the air escape out of the blowgun when i squeeze it, why? I do plan to do this further modof my valve but i have a few questions. Does the new diaphram need an equalization hole in it? Do i need to mod the blow gun also or is it just an even better thing to do? Could i unstead of buying an O ring that might not fit perfectly just cut out the middle of my old phram and use the outer part as the O ring?

[Maniac]

some air is supposed to go out the blow gun how do you know it comes out the blow geun is it on a cannon

[avlaxmidi09]

I know air comes out the blow gun cause i can feel it when i put my finger in front of it as i hold the gun open. The valve is attached to the chamer when i test it. But i take it off when i check it or open it up.

[noname]

Sanaka, the diaphragm should be in a regular-ish bowl shape. The one in the picture is far from perfect, and that particular one didn't actually work.
Also, a coin or something isn't really necessary. It is just to ensure the diaphragm will not tear in the middle when going to pressures like 200 psi in a steel gun.

You explanation of the setup you're using is exactly as it should be. I really have no idea why it won't work though. It sounds as if everything is set up the way it should be. Have you tried using a bigger pilot valve, like a 3/8" ball valve or something? Your equilization hole may be too big.
I'd highly advise you to make a coaxial diaphragm gun, using a female adapter and threaded plug. It'll help you figure it out, believe me.

[avlaxmidi09]

So you think the hole is too big where the air would just rather leak out there and out the blow gun instead of pushing up the diaphram and out the other side, right? If that is the case think i might try doing the further mod where you make your own phram. And are there instructions for a coaxial diaphram gun anywhere?? Thanks for all the help.

[noname]

Avlaxmidi09, your equilization hole is probably too big. Cover part of it with a piece of tape to see if it helps, and it if does, cover it with something more permanent like epoxy.

[avlaxmidi09]

ok, thanks il try that tomorrow its kinda late. Orbit is also mailing me a replacement phram, they said that the pinhole should not be there so im hoping the replacement comes soon and does not have a hole in the same spot. If it does and the epoxy doesnt work.... time for some super moding

[sanaka]

Thanks again for getting back noname.

I'll try without the center backup disc. Do you think the rubber needs to be a full 1/8"? Mine is that red gasket material from the plumbing section. It's fairly firm, but only maybe 3/32" thick. I'll try it out of course, but if it doesn't work just wondering how important you think the thickness is.

How do you craft your eq hole? Just poking a hole with a pin, the hole is like invisible. Or is like a 1/16" drilled hole better?

I was wondering if the higher flow pilot valve was a requirement for this to work - I've been trying it with my my unmodded blowgun, figuring I'd do the blowgun mod later. I have a 1/4" ball valve I can try screwing right on to the sprinkler valve - but it seems so much slower to open a ball valve than the blowgun....

Since this mod approaches a piston like action, I was thinking well... maybe just making it into a piston would be cool - a large rigid disc with a groove around the outside edge to capture a big o-ring that seals to the valve wall... whaddaya think?

I'll definitely post up if I have success. Thanks!

Peace,
Sanaka

[avlaxmidi09]

[quote="sanaka"]Thanks again for getting back noname.

How do you craft your eq hole? Just poking a hole with a pin, the hole is like invisible. Or is like a 1/16" drilled hole better?

The eq hole in my phram is whats giving me issuses if you read back a few posts. It is about 1/16 of an inch mayb a tiny bit smaller. Since noname thinks i may be too big i would go with a little needle or something. But i never mentioned how big the hole looked i just said pinhole, so.......... i guess just wait for nonames response but my guess is that 1/16 is gonna be too big.

[noname]

If you fill from on top of the valve (this helps it seal as well), you will not need an equilization hole and the whole thing will be simpler.
You can try making a piston for it, but if it's a thin rigid disc, it'll most likely flip and won't work. You can try it, but don't expect anything.

[avlaxmidi09]

fill the top of the valve in addition to the comp tank? or do you mean fill both from the top of the valve? Is that even pissible? Im hoping the new phram theyre sending me works cause building your own is seeming to become more and more complicaed.