Author Topic: Simplified Balanced Valve (Read 116268 times))

MJP · « **Reply #560 on:** January 25, 2019, 08:47:01 AM »

Rkr, you need to buy a lathe!
Much easier to make stuff even with a small chinese mini lathe.

I hope you didn't buy that stem, it looks kind of rough.

Marko

rkr · « **Reply #561 on:** January 25, 2019, 09:18:40 AM »

Quote from: MJP on January 25, 2019, 08:47:01 AM

Rkr, you need to buy a lathe!
Much easier to make stuff even with a small chinese mini lathe.

I hope you didn't buy that stem, it looks kind of rough.

Marko

I've considered getting one but it would be a real squeeze to fit one in my garage, perhaps one day. That's standard BSA valve stem that has seen some use, new ones are 19£ + postage with a poppet.

Hobbyman2007 · « **Reply #562 on:** January 25, 2019, 09:32:27 AM »

RKR,

I agree with MJP , a lathe would make the task a lot easier to accomplish . However I’m pretty sure you’re more than able to polish the valve stem if it was needed with some Emory cloth while spinning in a drill . I’m impressed with what you get done with the tools you have .

Marco ,
I’m not sure if it’s the Finn to English translator you use or maybe you’re just arrogant . It might be a good idea to read your posts a few times before posting them on a public forum . For the most part you come across as quite the D%=K . Good luck to you , I was always told to treat others as you wished to be treated . I sure hope it’s a translator problem and not the latter .I know I’d hate to go through life with a demeanour that made EVERYONE think I was an A-$#*le.

rsterne · « **Reply #563 on:** January 25, 2019, 12:23:33 PM »

*LOL*….

Marco, the only way I can make this valve machine-gun is to run the SSG in so that there is "negative" gap.... ie the preloaded spring is pressing against the stem by a couple of turns.... Since there is already about 3.5 lbs. of preload on it, that means about 4.5-5 lbs. of preload against the stem, just to try and introduce runaway hammer bounce.... I have not even tried to induce machine-gunning with the latest version of the valve, although I did try a turn of preload (negative gap) without getting it.... It's pretty hard on the valve, and since I have to force the gun to do it, in a mode I have no reason to ever use because it is past the point where the hammer is bouncing off the back of the valve, and past where the maximum plateau velocity occurs.... I don't see anything to worry about.... Nor do I see a reason to try it, just to see if I can abuse the valve....

Bob

MJP · « **Reply #564 on:** January 25, 2019, 12:52:21 PM »

Quote from: rkr on January 25, 2019, 09:18:40 AM

Quote from: MJP on January 25, 2019, 08:47:01 AM
Rkr, you need to buy a lathe!
Much easier to make stuff even with a small chinese mini lathe.

I hope you didn't buy that stem, it looks kind of rough.

Marko

I've considered getting one but it would be a real squeeze to fit one in my garage, perhaps one day. That's standard BSA valve stem that has seen some use, new ones are 19£ + postage with a poppet.

You can make pretty good stems out of m5 or m6 long 12.9 bolt that are only partially threaded. Saw drill file type of deal.

rsterne · « **Reply #565 on:** January 25, 2019, 01:06:57 PM »

OK, guys, that's enough.... The thread, IMO, has a lot of valuable information, but I will lock it if necessary.... or delete posts if they are simply insulting or derogatory.... Some guys have impeccable machining (and life) skills, others, me included, do not.... but that is no reason to make negative comments that have no purpose other than to hurt or insult.... Please be considerate of others, and offer constructive criticism only.... Treat others the way you wish to be treated.... If you do not wish to follow these simple rules, the door to the workshop is over there.... *pointing*….

Bob

ezman604 · « **Reply #566 on:** January 25, 2019, 01:26:46 PM »

Sorry Bob, I beat you to it and removed a post. We do not want nor allow such attitudes. They don't belong here. And we don't bow to anyone when it comes to keeping the forum positive.
Thank ya sir and to all that contribute to our goal.

rkr · « **Reply #567 on:** January 25, 2019, 04:12:27 PM »

Quote from: MJP on January 25, 2019, 12:52:21 PM

Quote from: rkr on January 25, 2019, 09:18:40 AM
Quote from: MJP on January 25, 2019, 08:47:01 AM
Rkr, you need to buy a lathe!
Much easier to make stuff even with a small chinese mini lathe.

I hope you didn't buy that stem, it looks kind of rough.

Marko

I've considered getting one but it would be a real squeeze to fit one in my garage, perhaps one day. That's standard BSA valve stem that has seen some use, new ones are 19£ + postage with a poppet.

You can make pretty good stems out of m5 or m6 long 12.9 bolt that are only partially threaded. Saw drill file type of deal.

Good point, I hadn't considered that. It's 3,2 mm shaft so I could order some 1/8" bolts from ebay. I've used drill bit shafts previously, do you reckon there's any difference?

Edit, I'm a metric guy so I ran in to trouble with terminology when checking e-bay. What would you guys across the big pond call/name/number a bolt that would fit the purpose?

MJP · « **Reply #568 on:** January 25, 2019, 04:19:27 PM »

I have used good quality 12.9 bolts for stem material many times with zero problems.
It's hard enough to take the hammering with no problem.
And there's the plus side it has threads already on one end.

Drill rod planks work just the same, and dont cost much.

Edit: drill the valve to accept 4mm stem and everything will be easier.
Or send it to me and I will drill it for you.

Marko

shorty · « **Reply #569 on:** January 25, 2019, 04:39:09 PM »

I was planning to use a shoulder bolt.Grind the head off,drill the hole, and then harden. They even make some shoulder bolts that have internal threads and you can run a die over it to thread it then cross hole it.

https://www.mcmaster.com/92183a152

https://www.mcmaster.com/96655a116

rkr · « **Reply #570 on:** January 25, 2019, 04:57:58 PM »

Quote from: MJP on January 25, 2019, 04:19:27 PM

I have used good quality 12.9 bolts for stem material many times with zero problems.
It's hard enough to take the hammering with no problem.
And there's the plus side it has threads already on one end.

Drill rod planks work just the same, and dont cost much.

Edit: drill the valve to accept 4mm stem and everything will be easier.
Or send it to me and I will drill it for you.

Marko

BSA uses JB's self centering firing valve system where the valve stem is supported by only the o-ring. I just checked and 3mm drill shaft falls through while 3.2 (or 3.175 to be more precise) works. Larger valve stem would require enlarging the o-ring holder and all parts associated so it would be easier to just get a fitting 1/8" bolt. Besides, as you can see from photo there's not that much space in between the 3.2mm shaft and 6.5mm poppet head. But yes, I'll work it out - that's part of the challenge and makes things interesting

shorty · « **Reply #571 on:** January 25, 2019, 05:04:55 PM »

Vented screw too. 4/40 has .035"vent and 10/32 has .046" vent.

https://www.mcmaster.com/93235a116

https://www.mcmaster.com/93235a250

TPL · « **Reply #572 on:** January 26, 2019, 04:48:23 AM »

I wouldn't use stainless for any moving part. It has high galling tendency.

rsterne · « **Reply #573 on:** January 26, 2019, 08:41:35 PM »

I installed the 22 CI bottle today, along with the .357 cal. barrel.... The final version of the valve has the internal spacer to reduce the balance chamber volume and the 0.052" vent.... along with a reduction in stem length to limit the travel to 0.125".... This means that when the SSG Gap is set to zero, the hammer bounces off the back of the valve and the velocity drops a bit below maximum.... However, I never shoot my guns maxed out anyways, because they waste air and end up with a Korean Cliff tune.... so the fact I have to run a bit more SSG Gap is not an issue... I am running the steel hammer, which weighs 113 gr. including the cocking handle.... The SSG is using an 11 lb/in. spring with 0.30" of preload (3.3 lbs) and with 2 turns of gap it takes 15 lbs. of force to cock the gun, which is wayyyyy less than the 23 lbs. it required with the conventional valve.... At 8 turns of gap, the cocking effort is less than 12 lbs.... Here is how the velocity works out at various SSG Gap settings....

As you can see, the tuning range is much increased with the small balance chamber volume and larger vent.... The gun can be tuned over a 300 fps range, which is way more than I would ever need.... The maximum velocity occurs at 2 turns of gap (260 FPE), at which point the efficiency is 1.09 FPE/CI.... With the conventional valve, at slightly less FPE, I was only getting 0.74 FPE/CI.... At 5 turns of gap (240 FPE), which is about 3% below the peak, the efficiency has increased to 1.19 FPE/CI, and with 8 turns of gap it is up to 1.36 FPE/CI, and the gun is still producing 210 FPE.... At a similar power level the original version of the Hayabusa was getting 1.13 FPE/CI, so I am getting the same power on 17% less air.... Here are some sample shot strings....

With the 131 gr. bullets tuned at 8 turns of gap, to peak just below 850 fps, I am now getting 13 shots per fill averaging 202 FPE.... compared to 8 shots previously.... Not only is the new valve more efficient, I can also shoot down to 2000 psi and stay within a 4% ES, whereas before I had to stop at 2200 from the same 3000 psi fill.... At 5 turns of gap, I am getting 6 shots in a nice bell curve within a 4% ES at 240 FPE with either bullet.... If I choose to tune for maximum power, at 2 turns of gap, I am getting 260 FPE, but after 3 shots the ES drops more than 4%.... While this is OK for hunting, dialing the power back to 4-5 turns of gap gives nearly the same FPE and more velocity except for the first 2 shots....

Something interesting, and a bit unexpected occurred when I fitted the 22 CI bottle instead of the tiny tank.... I had expected a bit of a power increase, but basically it didn't occur.... It appears that with the higher efficiency the 108 cc plenum, which was only 0.42 cc per FPE, wasn't really costing me any significant FPE.... This could be because this balanced valve is opening very quickly, while the pressure is still high in the plenum.... Certainly, compared to a conventional valve, where you can continue to get a small amount more FPE by keeping the valve open a long time, that isn't happening here.... I'm not complaining, mind you.... I'm getting more power and using less air....

This concludes the development of this new balanced valve design.... I had a few nay-sayers at the beginning, but I had a gut feeling this valve was going to work, once I found the right combination.... As with any balanced valve the devil is in the details.... It was really interesting to see that Brian built one of these over 17 years ago.... My gut feeling about what was required to get this valve to work was beautifully calculated by Mike (aka Matt/akuric) in his spreadsheet, and I really do have to thank him for quantifying what was happening inside this valve.... When he showed that the flow rate into the balance chamber, relative to the volume of that chamber, was allowing the valve to "blow open" for more than 50% of the dwell, it became crystal clear that reducing the balance chamber volume and increasing the vent diameter was critical to getting the tuning range we all desired.... So, thanks to Matt for his help....

There you go, guys.... A simplified balanced valve that works, is easy to cock, tunable, and efficient.... Have fun !!!

Bob

ezman604 · « **Reply #574 on:** January 26, 2019, 09:12:29 PM »

Great work from team effort for sure!!!!

JTB530 · « **Reply #575 on:** January 27, 2019, 10:16:45 AM »

Thank you Bob and to all those who have contributed to this. I've been lurking in the background excitedly watching as this project progressed! An amazing industry changing collaboration which I have no doubt will appear in production guns in the years to come. For me the lack of tools and time leave purchasing one of them as an only option. Thank you guys again!

jackssmirkingrevenge · « **Reply #576 on:** February 02, 2019, 09:45:59 AM »

Quote from: rkr on January 25, 2019, 09:18:40 AM

I've considered getting one but it would be a real squeeze to fit one in my garage, perhaps one day. That's standard BSA valve stem that has seen some use, new ones are 19£ + postage with a poppet.

Sherline have some examples of compact workshops on their website, for making small parts you really don't need a setup that takes up a lot of space.

mann · « **Reply #577 on:** February 02, 2019, 10:39:42 PM »

Well I got peek poppet to seal in the old marauder valve with a .280 throat .250 balance chamber and a .350 lower end of the poppet and exhaust port around .175 I had derlin sealed up twice but I blew off the end of the poppet where the oring was derlin is ok at lower pressure in regulated gun but if it sits at 3000 psi for a little bit it blows apart at oring groove with a .050 vent hole threw the center

Gippeto · « **Reply #578 on:** February 02, 2019, 11:21:09 PM »

Ain't that a booger lol.

Didn't "blow" apart at all...was PULLED apart...ie failed in tension. Need to understand what happened if you're going to prevent making the same mistake over and over...

The "fix" for the problem...a delrin seat in the valve body and a one piece valve stem.

Just watch those little drill bits...they break easy.

Al

mann · « **Reply #579 on:** February 03, 2019, 12:35:00 AM »

Peek is holding up so far but That would work to thanks .

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Simplified Balanced Valve

Author Topic: Simplified Balanced Valve (Read 116268 times))