GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: tyerant on March 24, 2024, 06:36:01 PM
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I am looking to make a pressure tube to fit into my 2240 stock main tube. My plan is to use a piece of 6063-T5 Aluminum tubing at 18mm od and 7mm id. I will tap in a foster fitting to press against the valve as a 12gr cartridge would and plug the other end with a ss grub screw and locktight. The stock cap will be used to press it into the valve. Then the tube will be tapped into with a hydraulic elbow fitting and an hpa rated tube from the fitting to a reasonably regulated bottle. I also intend to pin the valve.
I have looked for a pressure calculator that would give me an idea of what pressure it can hold based on the material, wall thickness and length. All I can find is a 6061-T6 calculator.??? Does anyone know of a calculator that will give me specs on 6063-T5 aluminium? Based on the Calculated results for the 6061-T6 I would imagine I will be well within safe specifications. I will just have to make sure that the tube and valve is well secured!
I saw this and thought it was interesting and spurred my idea... (https://lh3.googleusercontent.com/proxy/nRxxGS50GzJu2XtZHV0r760pktdgRrYp5d3IwXqk_uacsM9FlJ2uP9-MuhgboNArQUYcd31Nr4gtoDSOzrM5RLijM1qz_Ktb5_QN53LwwRGdz_Lno24miFE1zQ)
Critique away.... Know a better way? I would love to hear your thoughts!
Any assistance is greatly appreciated
TyeRant
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6063-T5 is a relatively soft alloy with about half the tensile and yield strength of 6061-T6....
Bob
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If I recall correctly, 2024 and 7075 are better choices for a pressure tube, with a nod towards 2024. Think 2024 may have better corrosion resistance. But if it were me, I'd be spending some time on a materials website or two, checking out your choices for the appropriate properties. HPA is no joke, so do your homework. If you have a design and can share it, then more experienced eyes can review it here for gotchas. It's amazing how a small design element can totally derate the safe pressure rating. Bob @rsterne has a thread here about dos and don'ts on HPA vessels. Definitely worth a read.
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Very new to making my own stuff. Many thanks! Yes I want to be safe! I have read a bunch of Bob's posts on the Cannucer Forum Just can't seem to source the same materials he used! I've been trying to buy online but perhaps I should go to the big city Toronto and get what I need. Any suggestions? Tot worried about weight. Would love to make an extender between the valve and the intake but just don't know the best way to go. New to this fabrication! If I could extend the valve portion and cap the intake to make a decent reservoir, What would be a good spacer between the valve and intake? What would the shreds be?
Many thanks,
TyeRant
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Well, the threaded in end cap will still be a weak link, because nothing will change there. And sleaving the OEM tube would reduce the volume. It would probably simpler to just buy a Diana pcp pistol from PA.
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You can search for material properties on matweb, think you use a search term like matweb 6061-t6, or matweb 2024. Here's the link for 7075-T6 https://www.matweb.com/search/datasheet.aspx?MatGUID=4f19a42be94546b686bbf43f79c51b7d
It's more than material choice however. You need to check every detail to ensure you have a safe design. This stuff can blow up and kill you, or maim you, so it's good to triple check your design. If you have CAD drawings post a pdf of the drawings so (smarter people than myself) can review it for issues.
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If you are in Canada, you are in luck.... I buy my tubing here....
https://www.aircraftspruce.ca/catalog/mepages/alumtube_2024.php
They have 6061-T6 and 4130 CrMoly as well....
Bob
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Tyerant,
What you are looking to do is to basically build a Safepac. It does what you want to do by screwing into the valve in place of the front half of the valve. Search eBay, he has several models, including a short one for tethering your gun. Might be a better way to go, but you will need a heavier hammer spring. I have a longer unit to fit a carbine But I back burnered the idea for now.
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Sounds something along these lines?
(https://i.imgur.com/yiW0Tebl.jpg)
That lower is slated for the purge bin. If interested shoot me a pm.
You mention "better way"...it's subjective, but I think these qualify ... if you have access to a lathe.
Pin the valve and bulk fill the tube...fittings are easily made. 2000psi fill
(https://i.imgur.com/uiRQUTal.jpg)
Make a "more robust" version of the hipac.
(https://i.imgur.com/lSUo7Tdl.jpg)