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Is this a bad idea?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Is this a bad idea?

Unread postAuthor: vng21092 » Thu Mar 27, 2014 9:07 pm

Hey guys so I've never built a hammer valve before and now I want to build one. I've done a little homework snooping around the site and it seems simple enough, except I don't have any springs lying around, btw, are those springs high tension? Where do you buy them? Not the one behind the hammer, the one that keeps the chamber closed. So I thought of a workaround

Image

Basically on top of the 1/4-->1/2 adapter there will be an o-ring, when there is air in the chamber, the marble will push against the o-ring sealing it off, now the marble can't fall into the chamber because it doesn't fit through the hole in the 1/2 pvc male adapter. So I can just have a hammer hit the marble (will replace with something more durable) to open the chamber temporarily. Will this work? Is this a bad idea?
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vng21092
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Re: Is this a bad idea?

Unread postAuthor: fenrir » Thu Mar 27, 2014 10:40 pm

Normally, the only role the spring plays is reseting the valve, so it doesn't require much tension. Also, a marble's surface area is too large, and it will be hard pushing it open, even at low pressures. A blowgun can be bought for cheap, and it is basically a ready made hammer valve. Here's an excellent how-to on this http://www.spudfiles.com/how-to-database/topic23202.html
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Re: Is this a bad idea?

Unread postAuthor: dajoro » Fri Mar 28, 2014 10:04 am

Well , you've made a giant one-way valve. The marble is usually a rubber ball and much smaller. A thick rubber flap over a tiny hole is also an effictive one-way valve , and more compact.

The only way I see that opening is shoving a full-length stick / ram-rod down the barrel until it hits the marble :shock: boom, stick in the face ... :shock: DON'T DO IT!
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Re: Is this a bad idea?

Unread postAuthor: bravootome » Sat Mar 29, 2014 12:42 am

vng21092 wrote:Hey guys so I've never built a hammer valve before and now I want to build one. I've done a little homework snooping around the site and it seems simple enough, except I don't have any springs lying around, btw, are those springs high tension? Where do you buy them? Not the one behind the hammer, the one that keeps the chamber closed. So I thought of a workaround



most items in household contains a spring..i dont buy..i reuse..an umbrella for example...
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Last edited by jrrdw on Sat Mar 29, 2014 6:18 am, edited 1 time in total.
Reason: Fixed quote tag.
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Help with hammer valve?

Unread postAuthor: vng21092 » Sat Mar 29, 2014 11:49 am

I need help making a stem, I don't have any fancy metal cutting machines/tools and I can't seem to find anything that would seal off the chamber. I tried making a stem out of a 8/32 bolt with a rubber washer, only problem is the only washer that seems to fit is nearly the same size as the I.D of the half inch coupling and it barely allows the air to flow through.

Image

O-ring on top of 1/4-->1/2 adapter:

Image

Stem I tried to make but restricted air flow too much:

Image

What I ultimately want in the end (kinda):

Image

Any help/advice please? Appreciate it guys
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