Retrofitting a WAR valve with balancing valve internals ( Another conversion )

[Motorhead]

This time I've gotten serious about building a balanced valve and this one for POWER !    Starting out with a basic WAR valve that we're all familiar with, took it apart and found the largest "Seat set" I had which turned out to be a .280" throat with .250" transfer.  The seat was previously modified to to have 10* sealing surfaces and lapped very flay against PEEK poppet heads.  Had been using like this for a few years now without leakage issues.  As the NEW balanced design poppet head was fabricated it to has a 10* sealing surface and gets lapped in.  ( hope it seals at the greatly reduced seat pressure ? )
* Seat seals on a .332" diameter and chamber end is .250" which is pretty aggressive ^ should open and flow like crazy ! ... if it seals ?

The misc pictures show the parts well, balance chamber is Aluminum with a precision reamed bore. Poppet spring a stiff short one that just goes coil bound at max lift giving me minimal chamber volume and increased seat pressure
Poppet head again is PEEK using the very small 1mm x 4mm o-ring/s ( Did with a single ring at first, then added a second for redundancy having little effect on felt drag. )

Also shown is the location of the stem bleed hole relative to transfer port. The assembled stack of parts that make the assembly become clearer and may help those better understand the mechanics of how the Simplified balance valve works.

This configuration is ON THE EDGE of Ratios being at a 57/43 and will have a cracking / opening force just 43% of a non balanced poppet which equates too an @ 56% reduction 

[rsterne]

As long as you keep the passage through the stem as large as possible, and the volume inside the balance chamber as small as possible.... I think you should be able to get some adjustability.... Good Luck !!!!

Bob

[oldpro]

 Bobs quite correct and i find there is simply no magic to making the balanced valve in this configuration simply get close to 50% reduction and make the volume in the thimble as small as possible and the bleed hole up the stem as large as possible.

[PikeP]

While you can certainly achieve a functional valve that operates with reduced cracking force by minimizing volume in the balance chamber and maximizing transfer passage between it and the valves throat...it is certainly more ideal to run calculations or follow the footsteps of those that have achieved success and have both vent size and balance volume be optimized or you may sell yourself short on the overall desired effect of a force reduction chamber.

I prefer calling these valves force reduction valves, where the true balance is the relationship between the force reduction chamber diameter and the time required to equalize the chamber with the plenum pressure (determined primarily by, working psi, vent length, vent size and chamber volume). Outside optimal parameters you get a valve that is either not tunable, or one that operates nearly identical to a valve without any cracking forces reduced..the goldilocks zone certainly leaves narrow requirements to meet optimistic conditions..that 'zone' is well documented in bobs simple balance valve.

Just my 2c. Glad youre enjoying building and retrofitting these valves Scott.

Should add your recent builds to the stickied thread in bob and lloyds sub forum, Ill share my unique design one day there that directly fits into an oem valve without any added modifcation required, but for the time being I cherish my work and its privacy.

[Motorhead]

dang, I bet your gun is ackuric 

  not hardly, but is quiet ... hint hint 


Installed the valve into the WarP carbine, air up and no seat leakage ... Yea !!!
Staying with a super light MDS hammer ... WOOF !! full power shot sailing a H&N 21 grain barracuda to 1040 fps.   And a lot of excess air behind it to !!  having massive over dwell happening.  ( stroke has been at .800" ) using the JSAR SS2 valve.
So started de-stroking hammer until at just 1/4" ( .250" ) of stroke was still over dwelling.  Ok pulled the SSG spring set and put in a much lighter spring being also shorter, tested much better and when at the 1/4" hammer stroke mid 800's.   Ok so we start increasing the hammer stroke and just 1/10th of an inch more stroke were back at 1000 fps ! That being a total hammer stroke of just .350" 

This honestly a pinky only required gun to cock now.  You can full open the breech & load a pellet and actions still not cocked.
Cocking the action only takes a light single finger tug for @ .350" and it's ready to fire.  Just crazy easy on all accounts while making massive power.( .22 cal at 48 ft lbs ! )

Have to agree what been stated on other Balanced valve threads that this design is really a "Reduced Opening Force" design and not really balanced per-say.  Also the fact that as you get a easier to open valve ANY changes in strike energy, drag from hammer ... ANY thing that changes strike energy will have an effect on velocity.  Were running regulated and that's a plus, but it still IMO does not take away the valve sensitivity to settings and ultimate ES stability.

Scott S

[rsterne]

Balanced valves can be fully balanced, like a spool valve, that once cracked stay open until the reservoir dumps.... OR they can have just a minor reduction in cracking force.... or anything in between.... Generically, for PCP use, they are called balanced valves.... Technically, virtually every design in use today is "semi-balanced".... and require less hammer strike to open than a "conventional" strike open valve.... You can prefer to call them "force reduced" if you like.... but most people will not know what you are talking about.... 

Bob

[oldpro]

dang, I bet your gun is ackuric 

Thats funny I dont care who says so LOL

[KnifeMaker]

 

[Rocker1]

 ;)Yeah I know.   David

[oldpro]

While you can certainly achieve a functional valve that operates with reduced cracking force by minimizing volume in the balance chamber and maximizing transfer passage between it and the valves throat...it is certainly more ideal to run calculations or follow the footsteps of those that have achieved success and have both vent size and balance volume be optimized or you may sell yourself short on the overall desired effect of a force reduction chamber.

I prefer calling these valves force reduction valves, where the true balance is the relationship between the force reduction chamber diameter and the time required to equalize the chamber with the plenum pressure (determined primarily by, working psi, vent length, vent size and chamber volume). Outside optimal parameters you get a valve that is either not tunable, or one that operates nearly identical to a valve without any cracking forces reduced..the goldilocks zone certainly leaves narrow requirements to meet optimistic conditions..that 'zone' is well documented in bobs simple balance valve.

Just my 2c. Glad youre enjoying building and retrofitting these valves Scott.

Should add your recent builds to the stickied thread in bob and lloyds sub forum, Ill share my unique design one day there that directly fits into an oem valve without any added modifcation required, but for the time being I cherish my work and its privacy.

How is it more ideal? Have you ever built a balanced valve yourself?

[Motorhead]

Update on this WAR / Balanced valve ....

So this valve now sits in my WAR WarP carbine with the regulator at @ 1900 psi.  A VERY light hammer of only 20 grams having @ 5/8" Less stroke that normal.  Fairly soft hammer spring being still one finger cockable.
20" green mountain .25 cal barrel. Transfer path choked down to @ .210" rather than the full .250" I would normally use. * The slight choking of transfer INCREASES the pressure transfer threw valve stem having valve shut faster and is more efficient than full size .250" ports at the same power.

Any who ....
JSB 25.4 @ 980 fps making @ 54 ft lbs
JSB 33.95 @ 890 fps making @ 60 ft lb
Cast Slug 33 grains @ 880 fps making @ 57 ft lbs

What a BEAST !! being easy shooting, really low muzzle report and very accurate.
* Thinking it's time to get the screaming rabbit call working and bring in some neighborhood Coyotes for a RECKONING 

Scott

[Blutroop]

Very interesting how choking the transfer port actually closes the valve faster.

[Motorhead]

Very interesting how choking the transfer port actually closes the valve faster.

Yup, the sealed balance chamber gets a stronger signal ( More intense pressure ) within the throat area which transfers threw the stem hole/s creating a faster rise in pressure within the chamber which speeds up the force that drives the poppet closed.  There is no change in lift because the pressure that caused the reaction happen just moments before the pressure ramps up and valve is releasing maximum flow. the slight transfer choking just adds a bit of resistance increasing the pressure amplitude within the throat.

[Motorhead]

One last SMALL mod that appears to make a big difference.

Within the balance chamber sits the return spring that is a fairly stiff one and when at coil bind which is when the stem goes flush to valve body being @ .100" travel available.
Took out the spring and crushing it to coil bind in a pair of calipers ... stopped at .180 over all length.

** So to make the volume small as possible made a small stub of acetal at the coils inner I.D. of .165" and .180" in length.  This fills empty space within the chamber and bottoms out on poppet the same time spring goes to coil bind.

Reassemble gun changing absolutely nothing else and lost 25 fps due to a faster closing valve ( less dwell ) 980 to 955 fps with JSB .25 cal Kings.

YUP ... keep the balance chamber volume low as you can 

[Bigragu]

You guys with all your valve tweaks amaze me. One day, I’ll be able to fully understand it all, but reading thru all your posts back n forth, it is all but a mystery to me.

You three, OldPro, Motörhead, and Sterne, should write a book on “Tweaking and Accurizining the factory Airgun”, or better yet, “Fundamentals of PCP Airgun Design”.
It would be a one of, and I guarantee it’d be a seller. Take over where Beeman left off, but design the book instead on all tech, theory, and hands on.

Just my take on things.

[skorec]

YUP ... keep the balance chamber volume low as you can 

At my case ( Puncher )  OD of valve seal is 8mm which represent area 43mm2 after minus area of poppet . Cracking up to 2mm should be enough
( 3,14*8*2=50mm2 ) ?