22xx hpa/bulk valve screw location

[antithesis]

As usual,  forgive me if this has been covered previously

So I bungled my first drill job,  and while the tube is still usable,  it's now ugly as sin.  I bought another one,  and drilled my first hole beautifully. Now while I am plenty comfy with 2 good screws on a hipac setup,  I am both scared of goofing hole #3 and was wondering if screws at 6 (factory hole)  and 9 will be satisfactory.  Is it necessary to have screws opposing to evenly support the valve?  I wouldn't even think of it with bulk,  but how about the smaller seal area of a hipac setup?

[pecor]

 22xx hpa, Ya you need the third hole as well.   

[Ozarkairgunner]

Yes, you really need the other screw. Not sure what happened in your case, but I did the same thing the first time I tried to pin a valve on a 22xx conversion and drilled to far forward. To help keep things in line what I've found to help is get a small soft tape like out of a sewing kit and use that to line things up, just simply wrap it around the tube, try to do your best to keep it straight and use a sharpie to mark the spot for you to drill, then place some tape approximately 1/4" up from your drill bit tip so you can gauge how deep your drilling into the side.
Hope that helps

[Ribbonstone]

Mostly, will use two added retentions screws though the sides of the tube (at 3 o'clock and 6 o'clock).

Think you understand how the HiPac actually works as an insert tube.  It only pressurizes the inside of the valve, not the whole tube.


So the inside of a typical stock Crosman (brass) valve is pretty close to .5"...which works out to something like .2 square inches....so 2800psi air would push on that area with a force of about 560 pounds.

The OUTSIDE of the valve (as would happen in bulk fill) is pretty close to .75"...works out to .44 sq. inches....and at 2800psi would push on that area with force of about 1230 pounds.

(Bob and I have had some posts about this....his view is more complexand takes in some factors I'm not really sure do apply...but the ration is about the smae.)

A warning.  The screw thread (an inclined plane) can generate a whole lot of  force. If you think tighting the "p" out of it will fix a leak, you're both (1) wrong and (2) more likely to create a problem than fix one.

So lets look at if from a practical point of view.

#1 Not really sure if the retention screw spacing makes that much difference.

Does seem more likely the valve could be "cockeyed" inside the tube (there is a little slack).  But you could fix that "rattle fit" with some shims, leaving the question of  fixation at 3 o'clock and 6 o'clock being worse than 3 o'clock and 9 o'clock.

#2. What if the twoadded retention screws are not EXACTLY 180 degrees apart?

If you get the 2nd hole 1/16ths (or even more) off from a true 3 o'clock/9 o'clock retention screw hole...does it really matter?

Welll....yeah...for the visual. If too far off, it just looks awakward/asymetric and kind of irritates you. 


If you have to change valve bodies some time in the future, are going to have to drill and tap the valve body for the retention screws any way. 


These have been running on HiPAc's for years.No more mantience/leak problems that any other typical PCP (getting them to run well at the higher pressure is a whole 'nuther matter.

[antithesis]

Ribbonstone,

That's a pretty sexy harem you got there,  especially #3..anywhoo, say I were to be anal enough to shim,  any particular materials you'd use?  I'll try this way first,  if my logic is correct,  when a screw failure occurs on a hipac,  it'd break seal contact and dump well before yielding.

[Ribbonstone]

Do use that bottom valve location screw hole (the 6 o'clock hole)...just convert it/tap it to the same larger size as you used in the tube.  I'll do that even when I add the two 3 0'clock and 9 o'clock tube screws (so really there are 3 screws holding things togeter).

Is it over kill? Maybe,but the rifles have been in use for years.

Still not real use about one added screw, but would go with one added tube screw and a converted issue valve location screw (I just can't get myself to call that little, soft,screw a retention screw).


Am thinking you're going to anyway....so let us know how it worked out for you.


Yep...have done it.  But in a rifle I really wanted to keep dual use, so never used air over 2K in order to still have a quick swap to 12gr.  As I never pressed the outer limits, never had any trouble.....but I also suspect you might have thoughts of 2800psi (and to be fair, in the ones pictured above...with full rention...I dorun them at something like 2600psi).


Normally can't find a real good screw head fit in the valve retention location's hole. But if you start with a long screw,can chuck it up in a drill and reduce the diameter until it does fit that factory tube-hole.

 Wasn't made to take a screw with a head that sticks up; there just isn't any room in the trigger units. Can make a shallow recess for that screw head in either (plastic 2260 or metal 2240type frame) for one that just barely sticks up. So grind/file it until itjust barely sticks up (which can ruin an allen head, but you can always slot the top).

Once it fits there,go ahead and cut it to the right length for the newly tapped hole.

Shinning to get the valve cenetered is probably just a mental thing....can't proove it does "jack" pther than get the HiPac tube alinged with the do-nut sealing ring evenly.  If it's seriously cock-eyed, then the end of the HiPac tube will tend to dig in and ruin that little Do not seal.

Does have a risk if you wrap the valve to shim it. 

IF (and there hasn't been) the retention screws fail, a close fitting valve would act more like a piston being driven back than a losse fitting valve.  Do belivce that once the valve  moves away and breaks the seal between it and the HiPac unit, the gas would dump pretty quick....but would dump faster if the valve was a loose fit to the tube.

If you want to, figure the best way would be to GLUE 3 little strips (running in the same direction as the valve) to the valve body.  Drink can Al. seems to work. That gets it centered without increasing it's air sealing too much.

Of the 3 Crosmans shown (top one is a QB), only one really needed to be shimmed....and I retro-fitted it with the "3 strip" type shim. (it'sthe oldest one of the batch, 3rd down from the top).



JUST TO MENTION :

There was a vid a couple years back of a guy who blew up his rifle (supossedly with a HiPAc unit installed) and sent the valve though his leg.

However, there are a few things wrong with that idea just by looking at the old posted vid (have no idea if it's still availaible).

1. The valve shown could NOT have been used with a HiPAc.  It's a bulk valve without the 12gr. sealing end.

2. Likely he was filling the whole air tube with air and just using part of a HiPac with that bullk fill valve.  As noticed above, pressurizing the  tube more than doubles the force pushing back.

3. No evidence of added valve retention.  Might have been there and not shown, might just have trusted the little issue valve retention screw.

4. He was taking apart a pressurized rifle.

[cobalt327]

JUST TO MENTION :

There was a vid a couple years back of a guy who blew up his rifle (supossedly with a HiPAc unit installed) and sent the valve though his leg.

However, there are a few things wrong with that idea just by looking at the old posted vid (have no idea if it's still availaible).

1. The valve shown could NOT have been used with a HiPAc.  It's a bulk valve without the 12gr. sealing end.

2. Likely he was filling the whole air tube with air and just using part of a HiPac with that bullk fill valve.  As noticed above, pressurizing the  tube more than doubles the force pushing back.

3. No evidence of added valve retention.  Might have been there and not shown, might just have trusted the little issue valve retention screw.

4. He was taking apart a pressurized rifle.

Video: https://www.clipzui.com/video/34v2q5i4i4x5x2i484t4y3.html

[antithesis]

Haha yeah I saw that vid,  using half a hipacto bulk.. Epic fail. I just bought a premade valve tapprd for 8-32, complete with custom (purpose made) screws.  If no alignment issue, I feel OK bout it

[Ribbonstone]

Good!


Would be really hard to put in too much valve retentiuon....too easy to put too little.  Definately a case of "more be better (or at least safer)".

As you might guess from my use, I've no complaints about the system as issued. Do have come complaints about how it often gets used,and the reflection of that missue cast upon the system.  Understand the system, respect how it was designed to be used, and you're good.



I am not in love with the extention tubes...adding another o-ringed thin metal joint in the middle of an airgube is just not somthing I feel is a great idea,,,,althougth there are folks that use them/love the concept. I'd much rather have to fill it more often without an extention tube.


Be hard pressed to date the 2260 HiPAc you liked in the photo.

Was a couple of things before HiPac (12gr. and bulk fill co2), and that HiPAc tube in the above picture is an "odd ball". Actually is a prototype before production, that (to my shame) I bugged him about until he sent it.  The front part (part sticking out the tube) is a touch longer than he used in production, was bright steel at first, but no internal changes I can find (other than being a little longer/little larger volume).

Been togehter in about that form for about 8 years...resealed twice...re valve stem seal once in that time.  Maybe a little worse than the average PCP over that time frame (Although I;ve had to rebuild/resal qa Disco 3 times over the same time frame).

It's tradtion... the air gun I take out for the first hunting season squirrel hunt...will contiune that tradition this season.


So....put it togeter as "right"as you can...adjust it's blance (the force of the striker hit to the air pressure holding the valve closed) and maybe you'll still be shooting it come 2026.