Rear tank gauge
Hi All,
First time here…
Reading some posts over the last couple of days, learning and having fun simultaneously, I decided to tell also my experiences.
I think that for a PCP tank, a gauge is a must.
Although I have used the gauge mounted in the neck of the bottle, it does not pleasing me 🙄 for two main reasons:
1º The gauge in the bottle neck is very small, and difficult to read (and the useful zone of reading even more) and I believe that it is not accurate enough.
2º I dont like the the asymmetric protuberance of the gauge in the bottle neck turning around while I screw the tank on. I see it fragile and dangerous if it receives a blow.
Then I decided to mount a real good gauge in the only position that is possible: the bottom of the bottle.
To do it, is indispensable to do drill a hole in the thank ( this is forbiden in some countries), but as a experiment I decided to take the risk, but with the due precautions of safety .Please note that I don´t say to anybody to do that.
The first thing of all, to locate a suitable gauge. In my case I had to order it do, since I did not find what was searching in the shops of pneumatic and hydraulics.
In two weeks they made a gauge of 40 mm of outside diameter and 250 Bar on a large scale, with a rear thread of 1/8 G and 11mm length:
After, measure and verify the thickness of the bottle bottom wall,mesuring the outside and after the inside, I found that the wall thickness is 7 mm. More than enough for my purposes.
Afterwards, centre the tank on the lathe as best as possible and drill and thread the wall of the bottle….Yes, as natural as it sound , a hole in the bottom. 😀
For cutting the thread I help my self with a little drop of cutting fluid.
Nevertheless I do not want to allow that the whole pressure of the tank should push on the threads of the gauge and I decided to install a nut from the interior to hold safely the gauge. It has also an O ring to avoid leaks: 😉
I had to do also the special key for this nut:
To install the nut inside the tank with the special key, was tricky and difficult due to the narrow space, and especially because you work blindly!! 😕 😕 😕
Once installed the gauge and its nut, I protected the whole assemble with a cover of aluminium specially designed to embrace the tank and to protect the gauge of possible shock and blows.
In addition it gives more resistance to the whole set. And it gives me the confidence of not having the gauge sticked into my shoulder.
Before installing it, I tried that the gauge fits very nicely inside its new housing:
Once quite mounted, the test-proof of pressure was satisfactory, I sprayed the tank rear with soapy water,charged the bottle very slowly, no bubbles at all, and for 20 days I left the tank loaded on 200 bar without losing only one bar of pressure. 😀 😀 😀
Already I have neither to count pellets nor do calculations simply I begin to shooting in 185 bar and finish on 100 bar. With good consistency of speed. I also have a good control of the presure while charging from the scuba. 8)
At the same time as I began this project, also I did an anatomical butt adjustable in length and height to do more ergonomic the set. Also it protect the glass gauge when not in use.
The screws that hold the support of the butt to the bottle are nylon pointed, to not damage or to create points of pressure on the surface of the tank
And this way there stays the whole set mounted and ready to shoot.:
Postscript
I do not recommend to anybody to do the same thing that I have done, since this is potentially dangerous specially if you dont have the proper tools….And knowledge
Each one calculates his own risk and do in consequence
Hope you like it
All Replies
Well said. Although one thing does come to mind….he must have his own compressor or they don’t do hydro testing over there?????
My post wasnt aimed at you YN, or anyone in particular. I think everyone gets the point that this mod may be dangerous. He stated that in his first posts. Personally I like the mod. The work is top notch. I wouldn’t do it because of the added length to the gun though. I would however, drill the rear of my tank for other mods if it was ever made clear on the safety issue.
Posting the reply from the manufacturer really proves nothing to me. The response they gave looks like it came right out of the legal department. Most likely they have never even tested their own tanks with a hole in the bottom like this. They have to respond that way just to cover their own ass. How many of those modded rapid bottles have blown? You know it would be all over these forums if one ever did. Dont they run those tanks at a higher pressure than we do ours as well?
If you asked Airforce if its safe to mod their valves or even replace them with a home made one what would the response from them be?
Shadoh…..
Uhhh I was replying to a post made today…
Damn, cant we drop this already? He said its just for him and doesnt recommend anyone else do this mod. I agree that warning of the dangers of such a mod is in order and clearly has been done so in this thread. What else can be said? We have the guy on total defensive mode now.
I would hate to chase away a new member, especially one who has talent in custom fabrication. Personally I find the Mods/Machinists section the most interesting and love seeing new stuff.
Sorry, I have not expressed well, I mean kill someone by accident, not intentionally of course.
And I have already said many times that I do not recommend anyone do this I have done so only for me, nobody is in danger, nor ask anyone to use, or copy or nothing at all.
Just a mod for me and if the manager deems it inappropriate, he can delete the entire post if he want .
Sorry, but there’s a difference between a tank exploding and someone shooting at a person.
The gun is an inanimate object – it does not desire or wish to do anything. Therefore, just sitting there it can cause no harm. The worry with the tank mod is that instead of just an inanimate object causing no harm, we have a potential time bomb that could go off at any moment.
Picking up a gun and shooting at someone is in the hands of the person and is not dependent on the size and caliber of the gun. Your argument FOR your mod is similar to the argument used by gun control advocates who forget that its the person not the tool who decides to take a life.
Plus, teaching safe gun handling and responsible shooting would in most cases (and barring mental deficiencies of the shooter) prevent any loss of life.
Maybe we could talk to the tank and teach it to not explode?
I wasn’t going to post on this subject – You say your a machinist and its safe, so long as your the only one using the gun I don’t have a problem with that – its been brought up that some people think it unsafe and if anyone else feels the need to try the mod – they should now be aware of the potential danger involved – But your latest argument is no argument at all.
I think your work is very good, your a skilled machinist obviously – would I let your tank in my house – no way.
I see that several people here are very concerned about the safety of my tank, but I also see, very often in this forum, that discussed the change of barrels to large sizes and powers without giving importance …. And I think that’s much more dangerous … you can kill someone!
In Spain we have limited the power of air weapons to 24 J and if we change the barrel to a greater power would be an offence for illegal possession of weapons.
I don´t have problem because have Fire Arms Certificate.
However modify thebarrel size and power over 24J is not allowed
Clearly, the response from the manufacturer can not be otherwise. I agree.
I myself do not advise anyone to do so, nor would use a deposit drilled by someone other than myself. That is what I have very clear.
Something else, I see a lot more dangerous the pressure gauge of the bottleneck because it is in the outside and without any protection. If it falls to the ground and is struck, it can break the thread and shoot the pressure gauge or your teeth…
Are these guys the one who makes airforce tanks? Would one of these suit an airforce valve?
Posted: Thu Jul 10, 2008 9:35 am Post subject: Drilling into Clylinders…Catalinas Official Response
——————————————————————————–
I thought I would go straight authorities in HPA tanks to answer this question. Catalina Cylinders.
Here is the email correspondence about the matter:
From: Adam Vigil
Sent: Wednesday, July 09, 2008 8:59 PM
To: Ward Dekker
Subject: Question…
I have a question. I read on a airgun forum of a person drilling and threading a hole into the bottom of a 490cc 3000psi tank and installing a gauge to read the pressure inside the tank. He has been warned this is not safe.
Could you please give your position on this so it can be relayed to others who might attempt this modification.
Thank You,
Adam Vigil
The Response:
RE: Question…
From: Ward Dekker (wdekker@catalinacylinders.com)
Sent: Thu 7/10/08 6:16 AM
To: Adam Vigil (hexcanemakerAThotmail.com)
Cc: Joe Wolff (jwolff@catalinacylinders.com); Jim Goodill (jgoodill@catalinacylinders.com); Bob Zimmerman (rzimmerman@catalinacylinders.com)
This is an unacceptable practice and can be very dangerous. Catalina Cylinders in no way, supports such an action. Any cylinder that has been altered in this way, should never be charged again and pulled from service.
Respectfully,
E.A. Ward Dekker, Jr.
Director of Quality Assurance
Catalina Cylinders
office 714 890-0999
_________________
Adam aka WalkonKing
When something is as well made as that it becomes art imo. Where form matches, if not exceeds, function.
But then I’m a bit of a fetishist when it comes to machinery. 😆
Just because the machining is ‘artful’ that will not and does not make the practice any less foolish.
The poster from Argentina is doing the guage and fill the safe way.
Xaloc’s tank mutilation is not to be promoted.
Walter….
I don’t argue with you because i don’t know how much knowledge you have in these matters. Would you please tell us why it’s unsafe?
Ive seen that done as well. Is it a factory mod or something they did later? Those bottles sure look identical to the ones we use.
Thats the Alan Zasadny Quick Fill Mod…. They banned all talk of it on the AirgunBBS (among other things).
Thank XALOC,
Looking forward to your other work.
Thanks to all, but one …… 😆
I have several jobs that are more interesting, both in mechanical modifications and accessories, such as repairs of optical viewfinders etc. ..
Now that I have a little time, because of a broken leg, I´ll try to have something of my others works in other posts
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I believe they are the supplier of air force tanks. Why in the HELL don’t they just offer an “extra cost” option from A.F. to order a gun and or tank with a factory installed gauge????? If they can put a gauge on a 4500psi scuba tank they can put one on a 3000psi A.F. bottle/tank. Are you listening Catalina????