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Easiest Hammer Valve

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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Unread postAuthor: Copperboy » Sun Jan 02, 2011 8:53 am

I'm thinking a hammer housed in a tube with a weak spring. When fully extended, the spring should not have enough force to open the valve, but with some momentum, it can open the valve for just a moment.


That's how Brian did it I think. Use it.
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Unread postAuthor: Lockednloaded » Sun Feb 20, 2011 8:03 pm

I'm coming back to this project after some frustration with other things, and now I have a 700psi regulator. I'm going to use a 1/2"x12" steel chamber at 700psi, and I hope to get 6 good shots with either .177pellets @ ~1000fps or .22pellets @ ~700. Does this sound possible?
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Unread postAuthor: Gaderelguitarist » Sun Feb 20, 2011 10:43 pm

It doesn't sound right. Most commercial pcp pellet guns require a couple thousand psi per fill to reach those velocities. I realize that it is also so that it can achieve more shots.

I'm sure someone will come at you with some math and prove me wrong.
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Unread postAuthor: Lockednloaded » Sun Feb 20, 2011 10:47 pm

those numbers are probably pretty optimistic, I would be ok with 850/600, but I don't really know how I'll be able to make any calculations

If I had a 1/4" QEV piloted by this "hammer valve", would there be a huge increase in performance with out sacrificing shots per fill?
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Unread postAuthor: jackssmirkingrevenge » Mon Feb 21, 2011 5:18 am

Gaderelguitarist wrote:It doesn't sound right. Most commercial pcp pellet guns require a couple thousand psi per fill to reach those velocities.


True, however their hammer valves tend to be quite low flow. Using a burst disk valve in this project I got 720 fps for a 0.22" pellet with "only" 400 psi.

With a long enough barrel and a carefully constructed valve that keeps dead volume to a minimum I would say your ambitions are realistic in terms of performance, you will definitely get something in the 500-600 fps bracket for 0.22" pellets, and more than 6 shots per fill.

Have a look at some data for the Crosman 2240, a CO<sub>2</sub> 12 gram is very roughly analogous to your chamber size and pressure.

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Unread postAuthor: Lockednloaded » Mon Feb 21, 2011 8:02 pm

I could fill the chamber with unregged CO2 for more shots and more power, but I can experiment with that once I get a new tank of CO2. All I can do is build, but not test at high pressures, so I'm wondering if the addition of a 1/4" QEV would hugely increase velocity?

EDIT:
also, what do you think of 1417A1 on McMaster-Carr as a hammer. I got the idea from a how to for a zip gun on youtube
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 22, 2011 12:33 am

The QEV would certainly allow better performance, but you're also losing some air through the pilot so it might still even out in terms of shot count.

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Looks like it could work, assuming the spring is strong enough, and it's fitted in such a way that it doesn't continue to press on the valve when in the "fired" position.
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Unread postAuthor: Brian the brain » Thu Feb 24, 2011 2:18 pm

The spring in those is certainly strong enough.
We sell them at work.

But unfortunately they do push all the way, so the valve will remain open.

I did not use a tube and spring kind of hammer.
I used a hammer kind of hammer.... :D
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Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Fri Feb 25, 2011 12:24 am

Brian the brain wrote:I used a hammer kind of hammer.... :D


You mean there's a small person inside your launchers :D

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Unread postAuthor: Brian the brain » Fri Feb 25, 2011 4:34 pm

Yes.
That is exactly what I mean.

You should see my new leprechaun powered blowback rifle.
It is way more compact than my Pigmee gun turret.
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Gun Freak » Fri Feb 25, 2011 8:46 pm

That diagram totally reminds me of Hapland... lol... thats pretty funny. :lol:
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Unread postAuthor: Lockednloaded » Sat Feb 26, 2011 12:17 am

I made a flintlock style hammer mech with some sheet PVC, but after a few shots it cracked. Do you think polymorph would handle the force better?
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Unread postAuthor: jackssmirkingrevenge » Sat Feb 26, 2011 12:34 am

Gun Freak wrote:That diagram totally reminds me of Hapland... lol... thats pretty funny. :lol:


My generation had Lemmings on their Amiga 500 (512 kB of memory man :D)

Lockednloaded wrote:I made a flintlock style hammer mech with some sheet PVC, but after a few shots it cracked. Do you think polymorph would handle the force better?


I doubt it, no sheet aluminium?
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Unread postAuthor: Lockednloaded » Sat Feb 26, 2011 8:30 pm

I don't have the tools to make the curved cuts that I need, and I would have to order sheet aluminum as well
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Unread postAuthor: Gun Freak » Sat Feb 26, 2011 10:07 pm

I think you could manage with a dremel :wink:
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