GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: woogie_man on July 19, 2011, 01:58:55 PM
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Ok guys, bear with me on this one for a little bit :P
I am taking possesion of my metal lathe at the end of the month. So I have been thinking of a few projects that I am "needing" to do. I already have a few lined up for my real steel rifles, and a few for the QB79 as of right now. But as I was thinking I remembered an idea I had some time ago....
I have always loved the Theoben style of rifles, with the large buddy bottle up front. But I know there is probably no way I would be able to get one, and be able to mod it up to where I am wanting it. BUT!! I do have a QB79 that I have been working on and already have a few things for her right now. But I am lacking the monster bottle at the front of the rifle.
So I was wondering this....... Would one be able to make a hole in the bottom of a regular CO2 tank and install a fill valve so you don't have to remove the bottle every time to fill? Or if not, as I am not sure how thick the bottom of the tanks are, what would be the thickness needed to be able to fill a cylinder with C02? I know that Co2 is normally around 800 psi or so, if I remember correctly.
So if needed I would have to get a billet chunk of alluminum, or steel and turn out the inside and what not to make a custom cylinder for the tank.
So that is why I am coming to you guys. I am needing some help, because as always the thoughts in my head say that it will work, no problem.. But I don't want to make something that is going to be dangerous and pose a risk to those that are shooting around me.
Thanks in advance guys.
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Hi
The project you have in mind is risky from a couple of points.
You are talking about making a threaded piece to be welded into the base of the rifles tank.
The quality of the weld would have to be of the highest.
The thickness and the material of the base has to be thick enough to stand the stresses of the weld and then the pressures of the CO2.
The finished tank should be pressure tested to a level about double thee pressure of the co2 in liquid form. above 900psi
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Of course on the PSI test... I have seen first hand what happens to stressed tanks and all of that good... well bad stuff, back when I was in college.
I know that it isn't an "every day" build.
Is there anything out there like this right now? Or would be nice to have a long straight cylinder that is about the same size as a BSA Sportsman HV air tube, but have it be used for C02.
Was thinking of either the Theoben or of the Edgun.... making a copy of one of those using a QB rifle.
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woogie..... honestly seems it would be easier and better to just cut down the existing gas tube and make you a drop adapter for a 9 or 12 ounce co2 tank .... would be much easier to fill the tanks if they can be removed.....
honestly much easier since co2 is filled by weight not volume or pressure.... to make sure you have a proper fill it would be much easier to hang a tank from a scale and fill then to hang and tare out the entire gun and then fill.....
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I honestly forgot about that MichaelM, should have known that but it slipped my mind.
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How about a tank from an Air Force rifle? Or check out all the adapters and tanks they have for paintball. You might be able to find something off the shelf, or that requires only minor mods.
Modifying any type of pressure tank brings up significant questions of risk, IMHO.
Lloyd
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Just a note. Some places may not fill a modified tank for liability (CYA) reasons.
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Drill a Hole in a tank ?...
Get any pressure tank cut it in half & you will see why
you should NOT drill a hole for a new fitting..
The neck area of a pressure tank is like 3X the
thickness of the body..to retain strength..
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That is why I came hear to ask you guys.
And I figured that the bottom of a regular tank would be to thin, but always better to ask first rather than blow myself up :D Espically since I am planning to fill it myself at home from a larger bottle anyway.... though always better to ask first and find out it is a bad idea.
I have been trying to find something like this as well. Didn't think about the AF tank for the Edge. That may work to be honest. Either that or something the same size as the Co2 tube for the QB's, about that same size but instead of the end cap coming off to put in the bulbs, just unscrew and fill with Co2.
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You need to design the tank for a pressure of at least 3000 psi.... CO2 can reach a pressure of ~1800 psi at 120*F even when properly filled by weight.... and CO2 tanks are rated for 1800 psi.... Hydrostatic testing is done to 5/3rds of the rated pressure, which means 3000 psi....
Bob
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what you want is something like this. ;)
(http://i559.photobucket.com/albums/ss33/walrus_01/Picture040.jpg)
or this ;D
(http://i559.photobucket.com/albums/ss33/walrus_01/Picture038.jpg)
could try this :o
(http://i559.photobucket.com/albums/ss33/walrus_01/Picture005.jpg)
And of course there is this ::)
(http://i559.photobucket.com/albums/ss33/walrus_01/Picture008.jpg)
Then this
(http://i559.photobucket.com/albums/ss33/walrus_01/boltmods042.jpg)
and the good old .25 cal on CO2 before fitting the riser and going full on pcp ;D
(http://i559.photobucket.com/albums/ss33/walrus_01/boltmods044.jpg)
The long tubes are far better with CO2 than mucking about trying to get a PCP type performance out of the gun with the standard gas valving.You only get a piddly amount of shots from air anyway ???Why bother when there is a Disco waiting for your attentions.????
Co2 is Cool dude.And 19fpe on CO2 for a shedload of shots, is way better than a pisspot full on air at ever decreasing power :o
Accuracy always wins out over power anyway,no good being able to kill something at 90 yards if you can't hit a barn door at 30 :o ;D ;D ;D
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I don't know how the QB loads co2, but for my co2 guns I put the removable tank into the fridge for 30 min to cool it down. Then the tank can fill with more co2 than a room temp tank, and it is still under spec weight so I'm safe. That would be a problem with a rifle that you directly load co2 into, as you can't cool down the internal tank.