Best valve head shape?

Best valve head shape?

Joined: August 20th, 2006, 5:36 am

May 13th, 2012, 10:35 pm #1

Stem, poppet, whatever you want to call it . The stock arrangement on the QB relies on a raised, v-shaped ridge in the valve that the resilient seal on the head seats against. Seems like a recipe for turbulence, and air flow restriction. The design I'm using is conical, and seems to make power, but I'm not sure it's the best choice. Just to be clear, here's a pic of mine:

[/IMG]

The step at the rear is just the spring seat. This SEEMS like it should flow well, and yes, the seat has been re-contoured to match the valve head, but I've long since found that lots of things related to air guns are counter-intuitive . So I'm just wondering if there are other designs that might work better.

And I think I've asked this before, but is this plain nylon the best material choice? I also have Nylatron, Delrin, and even some Teflon on hand, I used this because that seemed to be what everyone else was using . If it matters, I'm strictly running this on air (well, nitrogen, actually), with no intention of ever using CO2. And to reiterate, my goal is max power, so if a different material might make a difference, I'm all ears. Later.

Dave
Reply
Share

Joined: January 10th, 2005, 4:28 pm

May 14th, 2012, 12:47 am #2

I have made a couple valves and use the very same "V" valve shape on the valve and in the valve body (which I think you might have done if I read it right) Plain nylon is what I have used with very good results. 1 of them I use on co2 and the other just on air. Both rifles (22cal) are going on 3 years now and work great still. I did not go for max power on those but the one that is a PCP when I was tuning it there was ALOT there on tap that had to be toned down to get what I wanted. So yea I think your max power goal with no problems. Going to be an air hog though but I have a feeling your OK with that
Reply
Share

Joined: June 7th, 2010, 12:14 am

May 14th, 2012, 3:01 am #3

It holds that such geometry would suit an air gun valve.

Exhausts valves and such.
Reply
Share

Joined: October 21st, 2001, 3:36 am

May 14th, 2012, 3:02 am #4

Stem, poppet, whatever you want to call it . The stock arrangement on the QB relies on a raised, v-shaped ridge in the valve that the resilient seal on the head seats against. Seems like a recipe for turbulence, and air flow restriction. The design I'm using is conical, and seems to make power, but I'm not sure it's the best choice. Just to be clear, here's a pic of mine:

[/IMG]

The step at the rear is just the spring seat. This SEEMS like it should flow well, and yes, the seat has been re-contoured to match the valve head, but I've long since found that lots of things related to air guns are counter-intuitive . So I'm just wondering if there are other designs that might work better.

And I think I've asked this before, but is this plain nylon the best material choice? I also have Nylatron, Delrin, and even some Teflon on hand, I used this because that seemed to be what everyone else was using . If it matters, I'm strictly running this on air (well, nitrogen, actually), with no intention of ever using CO2. And to reiterate, my goal is max power, so if a different material might make a difference, I'm all ears. Later.

Dave
I haven't made any yet but it's is getting very close to the top of the "To do" list. I've been reading the posts of the people that are doing it now, researching for mine, and Delrin seems to be the material of choice, unless I'm mistaken.

Last edited by bigbore on May 14th, 2012, 3:03 am, edited 1 time in total.
Reply
Share

Joined: April 1st, 2009, 3:18 am

May 14th, 2012, 3:42 am #5

Stem, poppet, whatever you want to call it . The stock arrangement on the QB relies on a raised, v-shaped ridge in the valve that the resilient seal on the head seats against. Seems like a recipe for turbulence, and air flow restriction. The design I'm using is conical, and seems to make power, but I'm not sure it's the best choice. Just to be clear, here's a pic of mine:

[/IMG]

The step at the rear is just the spring seat. This SEEMS like it should flow well, and yes, the seat has been re-contoured to match the valve head, but I've long since found that lots of things related to air guns are counter-intuitive . So I'm just wondering if there are other designs that might work better.

And I think I've asked this before, but is this plain nylon the best material choice? I also have Nylatron, Delrin, and even some Teflon on hand, I used this because that seemed to be what everyone else was using . If it matters, I'm strictly running this on air (well, nitrogen, actually), with no intention of ever using CO2. And to reiterate, my goal is max power, so if a different material might make a difference, I'm all ears. Later.

Dave
On a recent air rifle system I built, the design was used. Many tests have been conducted. Then many tests conducted using the "pluger seal" method. My results show that both performed the exact same in regards to velcoity AND shot count.

So, for me, it is a matter of what seal is easier to make. Opted for the plunger seal shape. For my seals, using 3/8" diameter, 1/2" long nylon bushings with a 3/32" hole in them (my stem is 5/32" diameter; press fit). I can make them with a drill and an 82 degree reamer bit. I leave .035" as a rim to seat against the flat face of the valve. Turn down the seal in the drill like a lathe. Put a .25" diameter hat on top to seat the valve spring upon (like your picture), and put a grub screw in so the stem is not driven through the seal after continuous impact of the striker/hammer.

Here is the 48ft/lb .22cal monster the stem design is used in. Still got to get a riser breech and full shroud together for it along with a forward hand hold:




"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
Reply
Share

Joined: October 21st, 2001, 3:36 am

May 14th, 2012, 4:11 am #6

who selects a purple purse to go with that gun when clearly it should be basic black.

Reply
Share

Joined: April 1st, 2009, 3:18 am

May 14th, 2012, 4:21 am #7

Went in drag for a police interview. That way, if they decided against me, I could have a discmination claim! Just kidding!

My little girl's playroom floor became the photoshoot area. We sold that house, sadly. Her first home

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
Reply
Share

Joined: August 20th, 2006, 5:36 am

May 14th, 2012, 4:12 pm #8

On a recent air rifle system I built, the design was used. Many tests have been conducted. Then many tests conducted using the "pluger seal" method. My results show that both performed the exact same in regards to velcoity AND shot count.

So, for me, it is a matter of what seal is easier to make. Opted for the plunger seal shape. For my seals, using 3/8" diameter, 1/2" long nylon bushings with a 3/32" hole in them (my stem is 5/32" diameter; press fit). I can make them with a drill and an 82 degree reamer bit. I leave .035" as a rim to seat against the flat face of the valve. Turn down the seal in the drill like a lathe. Put a .25" diameter hat on top to seat the valve spring upon (like your picture), and put a grub screw in so the stem is not driven through the seal after continuous impact of the striker/hammer.

Here is the 48ft/lb .22cal monster the stem design is used in. Still got to get a riser breech and full shroud together for it along with a forward hand hold:




"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
Thanks. Interesting that the "plunger" worked as well as the cone, that would certainly be a lot easier to make. Since I have a decent lathe, I could just chuck up a ball end end mill and make the cut, much simpler than the setup to cut a cone . Will definitely give that a try soon. BTW, I'd love to see any pics of your valve assembly you might have, as well as any detail pics you have of the rest of your build. Looks like the only thing QB on that is the upper. 48 fpe, huh? Bet it uses LOTS of air ! My goal is 900 fps with Kodiaks, call it 38 fpe. Less than 10 fpe to go !

Speaking of the multi-angle valve grind used in car engines, I got to thinking about material again. Cars use steel on steel with a careful grind, and lapping for the best seal. We tend to use plastics in our air guns, it's comparatively soft and (hopefully) conforms to any defects in the seal interface. But I'm thinking that a harder material with a higher polish might actually flow better, so I ordered some Ultem, a much harder, stronger plastic than Delrin or nylon. I'd love to try a metal on metal valve, but I don't think my fabrication skills are up to that (YET!). I'll keep ya'll posted on the results. Later.

Dave
Reply
Share

Joined: April 1st, 2009, 3:18 am

May 14th, 2012, 11:37 pm #9

Not one single component in the central main tube sees pressure form the air, only the valve internals itself. All the radially placed screws secure items from twisting and are under no load what so ever. The tube and other parts could be made of plastic due to this. The only part to ever fail, which is doubtful, are the threads where the bottle adapter threads into (ASA extension). A simple valve designed to hold and flow air. No magic here. The stem is 5/32" in diameter with 7/32" transfer port relief passage way.

The blue aluminum part is an ASA extension, which the valve is threaded for. The ASA extension then houses the valve stem and spring.






"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
Reply
Share

Joined: June 7th, 2010, 12:14 am

May 15th, 2012, 12:00 am #10

Automotive valves are not allowed to slam closed. Cams are ramped to control deceleration.
May last a lifetime though. I sure don't shoot at 2000 reps per minute
Reply
Share