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Hammer valve ideas

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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Hammer valve ideas

Unread postAuthor: wyz2285 » Fri Aug 05, 2011 1:11 pm

Hi everybody :)
In this post I have nothing special to say, I just want to know if anybody have build a hammer valve that can take more than 800 psi but still be able to open with a light hammer and a weak spring.
right now I´m trying to build a full auto bb/paintball gun with a hammer valve, so the hammer have to recock just using air. I´m thinking about using a tyre valve, but the air flow is poor :roll:
Any tips/ideas are appreciated
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Unread postAuthor: Gippeto » Fri Aug 05, 2011 1:28 pm

Currently using a 2500psi fill. Cocking is easy.

http://www.spudfiles.com/forums/little- ... 21083.html


Ideas for autococking? Small bleed hole in the transfer port that bleeds air to the front of the striker. Striker tube will need to be vented off at extent of rearward travel to allow direction change. (think co2 motor :wink: )
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Unread postAuthor: wyz2285 » Sat Aug 06, 2011 8:18 am

Amazing build man :shock:
yes I know that I need a bleed hole in the transfer port that bleeds air to the front of the striker, but if the spring of the striker is to strong, the striker won´t get back to it´s position to fire again :roll: , I mean that the projectile may left the barrel before the striker is pushed back enough to open the valve again right? and can you post a diagram of you valve, maybe a picture of the valve´s partes.
I thought that pressure first will push the strick back, when the strick is pushed back, it lets open the way for the air to get out to barrel, then the pressure that accumulate between the projectile(with a air tight detent?) and the striker.Finally when the pressure is enough for the striker to go back to it´s initial position, the projectile lefts the barrel :roll: right?
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Unread postAuthor: Gippeto » Sat Aug 06, 2011 10:20 am

You don't need a heavy spring...increase the travel and use a lighter spring. Gives the striker more distance to accelerate to speed using the lighter force. Will also help reduce ROF. You can further adjust ROF by altering striker mass, and altering valve spring strength. :)

Going to use as much or more air to cycle the action as for the actual shot though. :(

An RVA (rear velocity adjuster) built into the design will help you balance forces as well. :)

A shot of the RVA/stock mount, striker spring and striker.

Image

Valve body and valve stem.

Image
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Unread postAuthor: wyz2285 » Sat Aug 06, 2011 12:52 pm

Nice idea about the spring, but I´m still not sure if the striker will recock :roll: how the air is going to push the projectile and recock striker in the theme time?
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Unread postAuthor: jackssmirkingrevenge » Sat Aug 06, 2011 1:09 pm

Here's one brain fart I had:

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Unread postAuthor: Gippeto » Sat Aug 06, 2011 11:43 pm

I'm not talented with paint, but here goes....

This is a rough (VERY) approximation of my valve as a "cut away", with a bleed hole added.

This allows the majority of the charge to be used for the projectile, while siphoning off a bit of that same charge to re cock the striker.

Hope that's of some help.
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Unread postAuthor: wyz2285 » Sun Aug 07, 2011 3:19 am

I thought something simular to JSR´s diagram, as the air will re cock the striker first, Gippeto in your diagram, if the projectile is too light or the barrel is too short, it may not re cock :roll: I think
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Unread postAuthor: Gippeto » Sun Aug 07, 2011 10:29 am

It will.

Too much bleed past the valve stem was enough to cause "full auto" operation....without a pellet.

Had to bore out the back of my valve body and add an o-ring to eliminate it. :wink:
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Unread postAuthor: wyz2285 » Sun Aug 07, 2011 2:02 pm

But you use 2500 psi :roll: I will only use about 500 psi in full auto mode :(
can you show me your trigger´s diagram in scale? thx
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Unread postAuthor: Gippeto » Sun Aug 07, 2011 9:59 pm

Yup, I use 2500psi. BUT....I don't have a bleed hole.

The volume of air that was making it run full auto was coming past the 1/8" pin with only ~.001" clearance. Use a 1/16" bleed hole, and you're talking a HUGE increase in flow.

More than enough to re-energize the striker at 500psi.

It takes ~6 pounds force to cock the striker on that rifle. The tube id is .75".

The pressure required to re cock the striker is ~2.6psi....that's not much....it wasn't MUCH of a leak. :wink:

Trigger group came from a Crosman airgun, and I think there's a nice cutaway posted in the rifle thread near the end. Will check and post here if it's not there.
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Unread postAuthor: wyz2285 » Wed Aug 10, 2011 2:19 am

Thanks :P all these datas were very helpful
sorry only answered now, the site wasn´t working for me :?
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Unread postAuthor: LovableAirGuns » Wed Aug 10, 2011 3:41 am

Quick question do you use delrin plastic has sealing face on the valve part or another type of hard material?
(the valve stem, what is that black part made from?)
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Unread postAuthor: wyz2285 » Wed Aug 10, 2011 6:08 am

Well now I have finished a concept prototype, full automatic re-cock :)
But it doesn´t work as I thought :( probably because the low flow of the tyre valve, the air that´s coming out is very weak, and the strick-recock cycle is too fast, the air comes out almost continually :? not like da-da-da
Anyway, here is a pic of the prototype, any tips welcome :)
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Unread postAuthor: LovableAirGuns » Wed Aug 10, 2011 6:23 am

Pretty good for a prototype but surely soon it would be one of the most awesome guns on spud files when you get it working :)
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