GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Rabbitstopper on June 11, 2019, 05:12:20 PM
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Evening all,
I decided on a build method which I would like some thoughts on. It will be using the 2250B tube and an lengthened valve to cover front frame mounting screw, this will be my way of skinning a cat, all critism welcome, So it goes,
Tube shortened, 1.5" plug, machined andto be fixed quarterly (316SS) to take 10000psi elbow then on to bottle.
Valve with an extention to cover frame screw hole.
Valve will be full bore open faced, think 22xx without the front.
Stem will be threaded to accommodate the spring externally with a small pocket milled Into the rear of the stem exit point (valve). Tube and valve fixed in the normal third's positions for end force.
I have ommited sealing in regard orings with this build as I dislike them highly, the down side will be ease of disassembly an longevity.
Main point and thoughts looked for, everything is going to be epoxied In place, valve body (fixings to) as well as front cap.
What do you think on epoxy in a pneumatic application? I build and survey boats but my knowledge is only chemistry with regard. True epoxy is completely synthetic and very, very few boats are made from,
Vinylester/polyester resins are the norm which have well ester (organic compounds) which is the main cause of osmosis in a harshe marine environment.
Physics wise I haven't a clue. I know epoxy sticks like poo to a blanket but in terms of repeated expansion between the valve and the tube it's fixed to in my case I'm not sure.
Hope this post is understandable guys and gals I have been told my communications are below average.
Thanks,
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I can state with total veracity that Trident submarines have HPA and hydraulic valves hydro-tested to 6000PSI that were repaired with 2-part epoxy that smelled suspiciously like JB Weld.
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Evening all,
I decided on a build method which I would like some thoughts on. It will be using the 2250B tube and an lengthened valve to cover front frame mounting screw, this will be my way of skinning a cat, all critism welcome, So it goes,
Tube shortened, 1.5" plug, machined andto be fixed quarterly (316SS) to take 10000psi elbow then on to bottle.
Valve with an extention to cover frame screw hole.
Valve will be full bore open faced, think 22xx without the front.
Stem will be threaded to accommodate the spring externally with a small pocket milled Into the rear of the stem exit point (valve). Tube and valve fixed in the normal third's positions for end force.
I have ommited sealing in regard orings with this build as I dislike them highly, the down side will be ease of disassembly an longevity.
Main point and thoughts looked for, everything is going to be epoxied In place, valve body (fixings to) as well as front cap.
What do you think on epoxy in a pneumatic application? I build and survey boats but my knowledge is only chemistry with regard. True epoxy is completely synthetic and very, very few boats are made from,
Vinylester/polyester resins are the norm which have well ester (organic compounds) which is the main cause of osmosis in a harshe marine environment.
Physics wise I haven't a clue. I know epoxy sticks like poo to a blanket but in terms of repeated expansion between the valve and the tube it's fixed to in my case I'm not sure.
Hope this post is understandable guys and gals I have been told my communications are below average.
Thanks,
It looks to me that you are trying to do this build the hard way for no good reason.
To epoxy the power plant in with no way to effect any possible needed fixes in the future is not a way I'd go.
A standard Disco valve shuts off any leakage to the trigger frame screw hole.
All you will need is to add two anchor screw holes in the tube.
Sometimes hiding from o rings produces more difficulty than just changing them when needed.
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Sounds like you're only relying on the epoxy to do sealing and not actually retain anything. It also sounds like you might have an above average understanding of surface prep to get epoxy to bond properly...so we'll skip over that. ;)
I LOVE the lowly o-ring. So simple, inexpensive and so very good at it's job when selected, used and treated appropriately. 8)
Epoxy can be pretty amazing stuff too....Jack will be along soon to expound the virtues of Araldite. ;)
As ever, it's not just "what" you use...it's largely about "how" you use it. I have my doubts that epoxy will stand up in this application where there WILL be some flexing and vibration...but one never knows until one tries hmm?
Worst case is that it leaks and you have a mess to clean up, it'll be an interesting experiment and I hope you post it.
Regards,
Al
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My only experience with JB Weld in a valve was replacing the seat area with a carefully machined plug that relied only on the epoxy for sealing, the mechanical loads taken by a shoulder.... Eventually the epoxy cracked and the valve leaked air.... slowly at first, then gradually more until it was obvious where the problem was.... That doesn't mean epoxy can't be made to work.... but I have worked with glues and composites for more than half my 70 years.... I didn't expect it to leak in that application.... but leak it did....
I lied, I did have one other experience sealing with JB Weld, on a threaded plug.... Careful cleaning and prep, the mechanical load taken by tightening the threads.... Lots of curing time.... and a telltale trail of bubbles when I applied soapy water to the outside of the plug when the leak occurred.... ::)
Bob