GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: lloyd-ss on January 26, 2018, 10:55:14 PM
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It took some arm twisting to get me to come out of hiding and do some pressure testing of the new Light Weight air tube for the Benjamin Marauder rifle. It’s being made by Jefferson State Air Rifles in Oregon. It was my first time talking to Jacob Ensign of JSA, but Travis Whitney was involved in the mix, and he and I go back a few years.
JSA was getting ready to produce an aircraft aluminum alloy (2024T3) air tube for the Benjamin Marauder. Most people love their Marauders (and if you don’t, start your own thread, LOL) but one of the main complaints about the gun is the weight. What if you could knock a pound and a half off your M-Rod without sacrificing any shot count or pressure capability. A drop-in replacement? Well, actually, you should also switch from the steel hammer to an MDS hammer, but no big deal.
But is the light weight tube strong enough for a standard 3,000 psi fill? All the calculations showed that it was strong enough, with the proper safety factors, but nothing like some real proof.
This video and test are for informational purposes only. No guarantee or warranty but the tests were performed as shown, and you can trust me on that.
So what is being tested?
The tube is designed with a 3,000 psi maximum fill pressure, just like the stock M-Rod tube, so first, safety factors are calculated for several possible modes of failure. Everybody thinks of a tube “blowing up”, but that is not the usual mode of failure. Also, safety factors are calculated at Yield, which means when the metal is just starting to permanently deform, and at Ultimate Tensile Strength (UTS), meaning when the metal actually breaks.
So let’s list the ways it might fail:
1. O-ring might leak or blow out. That is a good way to fail because there usually aren’t any flying metal parts.
2. Valve poppet might blow out.
3. The tube might separate (the end might pop off) at its thinnest section, usually where an end plug is threaded in. For this tube, the safety factor (SF) at Yield is 4.0 to 1, and at UTS is 5.6 to 1. So the end of the tube isn’t going to blow off.
4. The threads in the tube or the plug might strip out (shear off). For this tube, the SF for the tube threads is 6.9 to 1 and for the plug threads, is 4.5 to 1.
5. The tube might stretch (yield) or burst. The SF for Yield (stretch) is 2.7 to 1, and for UTS (burst) is 3.8 to 1. That means that the tube is going to stretch quite a bit before it breaks.
6. The bolts securing the valve might shear off. For this tube, the bolts are over 3 to 1.
7. The heads of the valve screws might crush the bearing surface of the holes in the tube. This tube has a SF of 2.7 to 1 for the bearing strength. This usually causes localized distortion, but then stops, unless severely overloaded.
8. The holes in the tube might rip out from the stress of the valve screw heads. The M-Rod tube is an odd case, because the 2 side screws have lots of material behind them, whereas the bottom screw at the bottom only has about .19” of material between it and the trigger sear slot. This SF is about 3 to 1.
Looking at these 8 factors listed above, the tube bursting doesn’t seem very likely. But maybe a problem with the valve attachment? O-Ring problem?, well, that has to do with the design, not the material.
Actually, in the first test, the o-ring on the valve body did blow out at 9,000 psi. That was the path of least resistance. That is a good thing, because nothing was damaged, and nobody got hurt. After that o-ring problem, I took the tube and valve apart and re-machined the -ring groove to a 90 duro o-ring with a back-up ring. This is often done for very high pressure applications, but it makes assembly fairly difficult. But that stopped the leak and it was time to find the next path of least resistance. This time, it was the holes in the tube for the valve screws. At 10,000 psi, the valve body had 8,800 pounds of force pushing on it, and the 3 screw heads just plowed right through the tube wall for about 3/4”. Movement stopped when additional screw holes were exposed and let the pressure drop.
The important thing here is that it took 10,000 psi to cause a serious failure (that is 3.3 times the rated pressure), but still, the tube did not explode.
I consider this a very successful test, and shows that the tube is worthy of its 3,000 psi pressure rating.
https://youtu.be/syT6yoT3TX8
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OK.
You made my head hurt!
;)
Great work Buddy!
(So, have you shot that air powered bell with the Big Gun yet?)
;D
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Hey Jeff,
Man, if I blew a big hole in that gas station bell, the grand kids would come after me! They love stompin' on that hose and making lots of ding, ding, dings.
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;D
I'm so happy you all are enjoying that thing!
I just brought it to Kentucky to shoot it!
8)
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If you would have used air instead of oil for failure test............there would have been bells ringing somewhere :o
Nice video ;D
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If you would have used air instead of oil for failure test............there would have been bells ringing somewhere :o
Nice video ;D
Right you are! At 10k, the pressure wasn't increasing much because the tube was expanding. It didn't exactly look like a python after a big lunch, but the growth was visible to the naked eye. And the growth was nicely uniform, not puffed out in one weak spot. Lloyd
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He has enuff Ding dings!!
https://youtu.be/cE9vudK4u18
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wow
bet you get more comments on the second video, than the first one ;D
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Many thanks Lloyd!!! Good to see the video and test results but GREAT to see you back!!!
:)
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Thanks Dez. Its good to be back!
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Lloyd,
Thank you for the test & data ... always good to know ( or at least figure where ) a pending failure may happen.
being few have miens above 4500 psi it is good to know where the limits are.
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Many thanks Lloyd!!! Good to see the video and test results but GREAT to see you back!!!
:)
Amen. Definitely better here with your presence and of course skills.
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so after buying one of these I got wondering how strong they are and was glad to see how it does. but how does it compare with the factory tubes?
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Lloyd,
What about metal fatigue? Aluminum is notoriously poor in fatigue resistance when cyclically loaded well below yield stress, compared to steel:
https://www.asminternational.org/documents/10192/1849770/05224G_Chapter14.pdf (https://www.asminternational.org/documents/10192/1849770/05224G_Chapter14.pdf)
A comparison
of the S-N curves for steel and aluminum
is shown in Fig. 14.4. Note that steel not only has
a higher fatigue strength than aluminum, but it
also has an endurance limit. Below a certain
stress level, the steel alloy will never fail due
to cyclic loading alone. On the other hand,
aluminum does not have a true endurance limit.
It will always fail if tested to a sufficient number
of cycles.
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Lloyd,
What about metal fatigue? Aluminum is notoriously poor in fatigue resistance when cyclically loaded well below yield stress, compared to steel:
The 2024T3 alloy is one of the "aircraft alloys" and one of the properties it was developed for was its excellent fatigue resistance, along with 7075.
The fatigue question keeps popping up whenever aluminum tubes are mentioned, but that argument is misapplied in this case, for at least four reasons.
First, is the selection of the correct alloy, and 2024T3 is a fatigue resistant alloy.
Second is the low loading of the tube, with UTS being more than 3 times greater than the applied stress.
Third is the low cyclic rate of loading and unloading, specifically hundreds of cycles verses tens of thousands, or greater, cycles for the fatigue testing.
And fourth, although anecdotal, is the somewhat common use of aluminum pressure tubes in airguns, particularly more expensive airguns, without incident.
So again, I do not believe that fatigue in a properly designed, and used, 2024T3 air tube is a concern.
Lloyd
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Lloyd,
Thank you for the test & data ... always good to know ( or at least figure where ) a pending failure may happen.
being few have miens above 4500 psi it is good to know where the limits are.
Thanks Scott. Sometimes we just have to trust the physics and our calculations, but it is always nice to have a real-world test to prove that our calculations are correct. I've tested steel and aluminum tubes, and every time, the tubes were as good, or better, than predicted by the material specifications.
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When I saw the 1st video, I was wondering if there was any distortion in the tube near the three valve screws. I appreciate JSA having the tests done and for Lloyd performing them. Lloyd has been GTA's defacto expert on this subject. Thx again, and ordered a Gen 2 tube w/gauge hole this AM. :)
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Lloyd,
Thank you for these tube tests. I watched the first and only today viewed the second. I have often thought about "work-hardening" of tubes when being exhausted of all pressure and re-pressurizing. Appreciate the comments on fatigue and parameters that effect tube fatigue.
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One thing about material testing is that you are only testing a single sample of the material, so the results you get aren't really exact, but you hope they fall into an "average" range. In a way, its a little like a one-shot group. ;) Even when looking up the actual material specifications, you can find variations. There can be variations in the spec for material shape and size, and also what is listed as the minimum and the typical, so there is some judgement involved. Also, knowing what the material will be used for has some bearing on how the specifications should be applied.
But as I always say, the purpose of these destructive tests is NOT to find out at what pressure the part fails, but rather to prove that your calculations were correct. And again, the calculations were correct.
An interesting thing about the 2024T3 aluminum alloy is its elongation, or how much it will stretch before it breaks. For this alloy it is about 10% stretch, or more.
During this testing, I measured the diameter of the tube several times as I pressurized and depressurized the tube. The 5 minute video is actually edited from about 4 hours of testing and video. The tube started at about 1.245" dia. I say "about", because the diameter varied slightly along the length of the tube and it was not exactly straight or round, but it was well within the manufacturing specifications. So, starting at 1.245" dia, at 9,000 psi, the tube measured about 1.249". after releasing the pressure, the diameter was about 1.247". That is the text book definition of "yield." The material has stretched, and has not returned back to its original diameter. And that isn't necessarily a bad thing. During processing, metals are rolled and stretched and stress relived, etc, and it is a very exact science, specific to a particular material and shape. Sometimes, one of the final processing steps is stretching the material, usually to improve the strength. This is usually indicated by the temper designation of the material, the "T" at the end of the alloy number.
But back to the diameter measurements.
Started at 1.245" dia.
At 9,000 psi dia was about 1.249".
Dropped pressure to zero, and dia measured 1.247".
Raised pressure to 10,000 psi and dia was about 1.300".
Dropped pressure back to zero, and dia returned to about 1.280-1.290"
I find that interesting ;), but I know that some folks might not really care :P, and that is fine, too. ;D
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are the steel tubes able to go up to even higher pressures even? I have wondered how much of a safety factor guns like the huben have where they are filling to 4500 or are we pushing the metals more than should be done.
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Thanks Lloyd... I'll be grabbing one for the Gen2 w/gauge hole as well. I fill from my 3300psi scuba tanks so I'll probably not be concerned with safety anyhow.
My only complaint with my synrod was weight. That's what has kept it restricted to the shooting bench. Hopefully the 1 1/2 pounds will bring the gun within the limits of my bum shoulder.
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are the steel tubes able to go up to even higher pressures even? I have wondered how much of a safety factor guns like the huben have where they are filling to 4500 or are we pushing the metals more than should be done.
I tested a steel tube I made for the Discovery. Same size as a Disco tube: 7/8" O.D. x .065" wall. It was A513Type5 DOM mild steel welded hydraulic tubing. Same 13/16-28 threads in the end as the disco. I threaded and plugged both ends because I knew the valve screws would break long before the tube. Anyway, that tube split open at 16,000 psi, so the material is capable of the task. Hopefully, the design is up to the task, too, and you have to trust the manufacturer on that. Like I stated in the first post in this thread, there are a multitude of ways the pressure system can fail, and they all need to be addressed.
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Thanks Lloyd... I'll be grabbing one for the Gen2 w/gauge hole as well. I fill from my 3300psi scuba tanks so I'll probably not be concerned with safety anyhow.
My only complaint with my synrod was weight. That's what has kept it restricted to the shooting bench. Hopefully the 1 1/2 pounds will bring the gun within the limits of my bum shoulder.
Shoulder your gun and imagine setting two full 12 oz cans of soda on top of it. Then toss the cans off. That is the difference in weight. Nice! ;)
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But back to the diameter measurements.
Started at 1.245" dia.
At 9,000 psi dia was about 1.249".
Dropped pressure to zero, and dia measured 1.247".
Raised pressure to 10,000 psi and dia was about 1.300".
Dropped pressure back to zero, and dia returned to about 1.280-1.290"
I find that interesting ;),
So it permanently deformed by taking it to its limits. I would expect that taking it to just 3k, it may expand slightly, but should return to the original at zero, within measuring capability. Would that be correct?
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But back to the diameter measurements.
Started at 1.245" dia.
At 9,000 psi dia was about 1.249".
Dropped pressure to zero, and dia measured 1.247".
Raised pressure to 10,000 psi and dia was about 1.300".
Dropped pressure back to zero, and dia returned to about 1.280-1.290"
I find that interesting ;),
So it permanently deformed by taking it to its limits. I would expect that taking it to just 3k, it may expand slightly, but should return to the original at zero, within measuring capability. Would that be correct?
You are correct, it would expand very slightly (less than one thou), but would return to its original size. Permanent deformation starts at something over 8,000 psi. Think of stretching the elastic in your shorts. Pull it a little and it returns to original size. Pull it till you hear the snappy noises (yield point), and you've messed up.
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I understand the sample of one and other factors. From JSA mfg side, I would think the quality and depth of the threads for the fill assy, to be one of the more critical items to check on each tube. I'd expect that if there was any valve screw hole size or position issue, that could be detected by the user.
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A bit off topic and I apologize but.... is there also a lighter weight barrel shroud available?
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A bit off topic and I apologize but.... is there also a lighter weight barrel shroud available?
Its already aluminum and think it only weighs around 4-5oz.
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K, thanks John.
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Does this mean that the aluminum anodized shroud will actually match the tube now? I dunno about anyone else, but my (original) tube is black, and the shroud is like a very very dark purple in full sunlight.
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I was concerned about fatigue, and I'm glad that the question came up and Lloyd addressed it. I appreciate the JS team working hard to prove and openly demonstrate the quality of this aftermarket part, that is really what sells it for me.
And I respect Lloyd's input because I believe he respects the potential dangers of HPA enough that I don't think he could sleep at night if it was misrepresented.
So...I got in on the gen1 pre-order. My favorite squirrel hunting rifle is going to be a little more bearable scrambling up the hills. :D
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Yep, just have to get the accounting department to release the funds.
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A bit off topic and I apologize but.... is there also a lighter weight barrel shroud available?
I don't believe you can make it much lighter. There pretty light as they are. I guess taking it off would make it lighter ;D
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I was concerned about fatigue, and I'm glad that the question came up and Lloyd addressed it. I appreciate the JS team working hard to prove and openly demonstrate the quality of this aftermarket part, that is really what sells it for me.
And I respect Lloyd's input because I believe he respects the potential dangers of HPA enough that I don't think he could sleep at night if it was misrepresented.
Thank you for the kind words, Mark. Even though my tests and opinions are offered for information only, I do take the safety aspect extremely seriously. The airgun parts should be such that I would be comfortable watching my grand kids use them. No exceptions.
Now, for my own personal stuff, I might bend the rules a tiny bit if there is a good reason to do so, and still remain safe.
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I was concerned about fatigue, and I'm glad that the question came up and Lloyd addressed it. I appreciate the JS team working hard to prove and openly demonstrate the quality of this aftermarket part, that is really what sells it for me.
And I respect Lloyd's input because I believe he respects the potential dangers of HPA enough that I don't think he could sleep at night if it was misrepresented.
Thank you for the kind words, Mark. Even though my tests and opinions are offered for information only, I do take the safety aspect extremely seriously. The airgun parts should be such that I would be comfortable watching my grand kids use them. No exceptions.
Now, for my own personal stuff, I might bend the rules a tiny bit if there is a good reason to do so, and still remain safe.
LOL.... Careful Lloyd... you know Bob Sterne is watching.
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I was concerned about fatigue, and I'm glad that the question came up and Lloyd addressed it. I appreciate the JS team working hard to prove and openly demonstrate the quality of this aftermarket part, that is really what sells it for me.
And I respect Lloyd's input because I believe he respects the potential dangers of HPA enough that I don't think he could sleep at night if it was misrepresented.
So...I got in on the gen1 pre-order. My favorite squirrel hunting rifle is going to be a little more bearable scrambling up the hills. :D
If I am not mistaken fatigue tests on an air tube such as this would be done 0 to 3000 psi not 2000-3000 psi, which no one does on a gun that is not leaking. Most of us don't shock the tube with an instant 3000psi either.
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I get mine today!!
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I get mine today!!
mine also and a package from USPS...
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I get mine today!!
mine also and a package from USPS...
Yes sir perfect timing!
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Sweet, that is great news guys!!
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Here is the first video. I think its important to know the tube would fail in the manner in this video long before the valve would fail in original post. The tube would swell at 9000psi and the oring would fail. Lloyd used a urethane 90d oring and a backer to keep it from extruding(failing like in this video) to force the tank to rupture. The tank actually never did rupture.
https://youtu.be/cuShgXYktq0
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I get mine today!!
Where did you order it from?
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I get mine today!!
Where did you order it from?
www.jsairrifles.com (http://www.jsairrifles.com)
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So the 1 1/2 lb weight saving figure gets quoted...
But I would like to know real numbers because I am a precision type of guy, HaHA. { Millwright, Gas turbine A&P n ex-machinist so live and breath exactness }
What is the weight of a GenII steel stock tube vs the weight of the Jefferson aluminum tube.
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double post...
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www.jsairrifles.com (http://www.jsairrifles.com)
Thanks. Direct link for your product here:
http://www.jsairrifles.com/Marauder-Aluminum-Air-Cylinder-Gen-2_p_25.html (http://www.jsairrifles.com/Marauder-Aluminum-Air-Cylinder-Gen-2_p_25.html)
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So the 1 1/2 lb weight saving figure gets quoted...
But I would like to know real numbers because I am a precision type of guy, HaHA. { Millwright, Gas turbine A&P n ex-machinist so live and breath exactness }
What is the weight of a GenII steel stock tube vs the weight of the Jefferson aluminum tube.
Well, I try to use the amount of precision that the job requires 8), and the one and a half pound figure in the video was a statement, not a quote ;).
From a sample of one of each tube, rounded to the hundreth of a pound, actual weight measurements:
Marauder stock steel Gen2 tube 2.27 pounds
JSA Light Weight Gen2 tube 0.77 pounds
Weight savings = 1.50 pounds ;D
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The JSA statement on the website "This new air cylinder weighs 4.6 ounces," might have been just an estimate before the tubes were completed, or a typo. I did use that number in some of my comments in other threads, though. A Gen 1 air tube that I have sitting on the shelf weighs 35oz or 2.19lbs. The Gen 2 air tube is slightly longer, so Lloyd's numbers look right on, as you would expect.
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You guys are making it impossible for me to ever just be done with my Mrod. The good thing losing the weight... The bad thing having a stock tube just sitting around is only going to lead to some sort of project in the future... Which translates to I'll be ordering one soon.
Which leads to my asking maybe a dumb question, but if I use one without a gauge port, would that be best for going all in most power tune? I can see the benefit of the gauge with regulation but if I go all in max fpe for 8 tune I'm thinking I can ditch the gauge just use gauge from my tank...
I'm probably going to end up with one of each...
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well I ordered friday or saturday and it was already in the mail this morning. I don't even know how thats possible. Anyway I am a very patient person so I put it on the gun today already and shot it. wow is all I can say, feels like a different gun completely. Infact its lighter than my streamline(laminate) with the marauder synthetic stock and with the boyds jacardnia thumb hole stock. As for the color some were wondering about, it is black so it doesn't match the purple hued shroud :D, infact its a little more black than the marauder tube so the contrast is a little more. oh well I don't' care anyway just letting others know.
Now not sure if it was an overlooked detail or intentional but the hole for the transfer port adjustment screw is not there so unless you drill one you won't be using that anymore. For me it doesn't matter anyway I always leave it fully open so I don't need to access it.
I would post a picture of my gun but honestly not sure how. Had a relative put my avatar picture on for me and help me post some pics in nuah once but I can't figure it out. Doesn't matter though, others were just wondering about the weight and yeah it feels much lighter.
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I think I figured out how to attach a picture again.
This picture shows the front end of the light weight tube after the 10,000 psi test. As stated previously, the tube grew about .050" in diameter and the volume increased about 20ccs. I think you can see the swelling in this picture. The swelling stops in the vicinity of the o-ring. That's another good reason to keep the o-ring inboard of the threads.
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10,000psi?? Most of us have a problem finding a dive shop that fills our tank to 4500.....
That said, I don't plan on exceeding 3000psi, have no reason to.
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Ok, ok. So if you can't do 10k, how about 9k? ;)
Here are two pictures of the valve screw areas after the 9,000 psi test (o-ring failure).
Periodically check your airgun for this type of distortion, particularly if it is over-pressurized.
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Thats some serious tension stress applied there. Im scared when I fill these high fill guns to 4500 not sure if I could keep my pants clean testing a tube to 10000PSI!!!
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Ok, ok. So if you can't do 10k, how about 9k? ;)
Here are two pictures of the valve screw areas after the 9,000 psi test (o-ring failure).
Periodically check your airgun for this type of distortion, particularly if it is over-pressurized.
Knurling ... COOL :o
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Surprisingly, the 3 screws easily threaded out after the 9k test, even though the valve body had puckers about .008 tall at each screw counterbore.
I didn't try to take the screws out after the 10k test :(, and this tube should be back in the hands of JSA tomorrow.
Here is a pic after the 10k test. Click on the picture to expand it to see the detail. Scary. But it was more than 3 times the recommended fill pressure. :o
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well I ordered friday or saturday and it was already in the mail this morning. I don't even know how thats possible.
I was in the shop Friday and shipped it right after you ordered... 8)
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Lloyd,
The valves retaining screws appear to be SS and not the OEM Black oxide.
Unless it is just a lighting thing ???
Reason of inquire has a few issues that I make note of.
1st being the screws in use have the striated head that clearly indented into tube at retention holes in the 9K test & inspection.
Sharp corners made as such would become stress risers and create a point of fracture ... where as a SMOOTH head socket head screw would not.
Any thoughts on this ?
Scott
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Hmm, Scott, I never gave it much thought. In fact, I have never really looked for socket head screws with a smooth head. I would think that at normal loadings it wouldn't be an issue.
I looked thru my boxes of SS and blk ox standard and high strength socket heads, and have to say that I only found a couple of odd screws that had a smooth O.D. Pretty much everything had the lightly straight knurled heads. However, all of the low profile socket heads are smooth.
Also, during these tests, the tubes failed at the holes for the screw heads just about as calculated. And yes, they are SS screws.
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Hmm, Scott, I never gave it much thought. In fact, I have never really looked for socket head screws with a smooth head. I would think that at normal loadings it wouldn't be an issue.
I looked thru my boxes of SS and blk ox standard and high strength socket heads, and have to say that I only found a couple of odd screws that had a smooth O.D. Pretty much everything had the lightly straight knurled heads. However, all of the low profile socket heads are smooth.
Also, during these tests, the tubes failed at the holes for the screw heads just about as calculated. And yes, they are SS screws.
Thanks ... just had a thought seeing the sharp indents .. "AH' stress points for a fracture to start from ???
As we were ;)
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Aaaaaaaaand ordered! My MROD has gained a few pounds over her life. She is my primary Night Snipe rifle currently and to take 1.5 pounds off, no brainer.
(https://i.imgur.com/muvbWBP.jpg)
Here she is with all her night ops gear on.
I will be producing an installation video of the process for sure.
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Getting that 1-1/2 pounds off your gun will make it so it doesn't need wheels, LOL. ;)
I hadn't seen your youtube channel before; you've got some great stuff. And it really shows me how much I need to upgrade my video capabilities. I am so far behind in that technology.:-\
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I noticed you were using SS screws or at least that's what it looks like. Do you think there would have been a difference in the results with using OEM screws if so?
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I noticed you were using SS screws or at least that's what it looks like. Do you think there would have been a difference in the results with using OEM screws if so?
I don't think there would have been any difference. SS socket heads are usually softer than standard steel socket heads, but often more ductile, unless you specifically get expensive high strength stainless fasteners. The screws bent a little bit, but the holes in the valve distorted and the tube wall sheared. When things start twisting and bending, the failure can either be accelerated or delayed, and that is very hard to predict.
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I noticed you were using SS screws or at least that's what it looks like. Do you think there would have been a difference in the results with using OEM screws if so?
I don't think there would have been any difference. SS socket heads are usually softer than standard steel socket heads, but often more ductile, unless you specifically get expensive high strength stainless fasteners. The screws bent a little bit, but the holes in the valve distorted and the tube wall sheared. When things start twisting and bending, the failure can either be accelerated or delayed, and that is very hard to predict.
I do appreciate your input and your testing efforts on this tube. Nice to see 9000lbs before trouble is noticed.
I do/may tend to bend the rules ever so slightly at times as my gauges can differ depending on the pressure when comparing them. From your results, this looks like a very safe tube or just as safe as OEM especially if one sticks with the 3000psi limit or very close to it.
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Aaaaaaaaand ordered! My MROD has gained a few pounds over her life. She is my primary Night Snipe rifle currently and to take 1.5 pounds off, no brainer.
(https://i.imgur.com/muvbWBP.jpg)
Here she is with all her night ops gear on.
I will be producing an installation video of the process for sure.
You'll love it hajimoto! Big difference! Mine feels so much better but I don't have all kinds of stuff like you lol mine weighs 7.4lbs scoped now!
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Gotta get me one of these (gen 2). Main reason my Mrod sits unused is weight. Aluminum tube should be an option at the Crosman custom shop.
Anyone know what the weight of the gauge/block assy is? Might go without it.
I'd also like to know if the anodize is Type II or Type III.
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;D
I'm so happy you all are enjoying that thing!
I just brought it to Kentucky to shoot it!
8)
Those bells were the most fun thing to shoot at the FunShoot. A LOT of fun !
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Would the transfer port and forward breech screws have made any difference? I understand an oring will fail before the tube rips but would it have taken even more pressure with the rest of the pieces in place? I know it is impossible for 99%+ of us to reach these pressures but I’m just curious. Knowledge is power they say.
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Gotta get me one of these (gen 2). Main reason my Mrod sits unused is weight. Aluminum tube should be an option at the Crosman custom shop.
Anyone know what the weight of the gauge/block assy is? Might go without it.
I'd also like to know if the anodize is Type II or Type III.
If you add the gauge block, gauge adapter, and the gauge together, that's another 2.7 ounces.
The guys from JSA will have to chime in on the anodize, but I am 99.9% sure it is Type 2, in black. The type 2 has insignificant thickness build-up, whereas the harder type 3 (also called hard coat) can build up a couple of thou in thickness and that has to be compensated for (thread gauging for example) when the part is initially machined. Type 3 would make a nice wear surface for the hammer area inside the tube, but honestly, I forget how you mask a part that has both type 2 and type 3, but I do remember that it is an expensive pain in the rear.
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Would the transfer port and forward breech screws have made any difference? I understand an oring will fail before the tube rips but would it have taken even more pressure with the rest of the pieces in place? I know it is impossible for 99%+ of us to reach these pressures but I’m just curious. Knowledge is power they say.
Provocative question, Justin, keep thinking and asking. The pressure testing of finished production assemblies is a bit like a game of whack-a-mole. You keep finding the next weakest link. This valve was plugged and didn't have a poppet in it, so when do you think the poppet might have failed? How about the fill nipple? The pair of 4-40 breech screws might have added another 8% of shear strength, and the T-port some more % too. But when the tube did actually fail in this test, it was kind of stuck at 10k psi, and the tube was just stretching in diameter and taking on more and more hydraulic oil. The tube might have actually burst at 10,500, or maybe not till 12,000, I really don't know. The only way to know when the tube itself would actually burst would be to make a test fixture for it that prevented the ends from swelling at the O-rings (like a constrictor ring around the ends) so that you could actually force the aluminum tube to burst. But that really wouldn't have given the real life safety information we needed to know. Now I am wondering what pressure the valve poppet would fail at, LOL. ::)
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Hmmm what pressure would have forced the poppet to extrude into bore or throat? I’m not certain but it is and intriguing question.
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Hmmm what pressure would have forced the poppet to extrude into bore or throat? I’m not certain but it is and intriguing question.
Darn you Travis, you knew I'd take the bait.
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I’ll bet it’s long before a tube failure would happen. Should be fun watching fluid spray out of the exhaust port
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I've got a short piece of steel M-rod tube and a stock valve body. The throat is about .23 dia, so even at 9,000 psi, the punch-thru force on the poppet is only 374 pounds. I might have to test that just to know. The shear area in the poppet is about .11 sqin (circumference of .23 dia x .15 thickness), so if the plastic has a shear strength greater than 3400psi, there is a chance it might not punch thru at 9k. Hmmmmmm... ::)
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I'd also like to know if the anodize is Type II or Type III.
Type II
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Hmmm what pressure would have forced the poppet to extrude into bore or throat? I’m not certain but it is and intriguing question.
IMO a LOT lower !! especially in gen II valves with the raised and fairly sharp sealing surface. Likely the seats edge will create shear just as we see in used guns when doing valve service.
Just a WAG tho ...
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Shear strength of Delrin is about 8,500 - 9,500 psi.... Doubt it would shear quickly, but could eventually extrude if left under pressure long enough at 9,000 psi ? .... MRod poppets will start to extrude into a 0.281" throat (and the sides begin to bell out) at 3000 psi, but seem fine in a 0.266" throat at 3000....
Bob
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Thanks for the answer Lloyd. I’m smarter today than i was yesterday but of course now i have more questions. Staying tuned as i know they will be answered. Awesome work guys. I wouldn’t be a hardcore air gunner without the support of pioneers like we have here. Lucky me.
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Hey LLoyd!
I have ordered one of these and was bragging to the fact on another forum and was informed of the following. Can you read through it and educate me accordingly?
It was just curios if you were in any way involved with the pressure test video? [/color][/size]Early in the video when tube diameter measurements were taken after the first pressure cycle and it was noted the change in diameter, the material had already yielded. When designing and working with high pressure materials to be used with a compressible fluid, we consider a yield of this magnitude to be a material failure. Any time an item is stressed to the point of exceeding the specified minimum yield strength of that material, the item has officially failed. Testing to ultimate catastrophic failure is certainly important, but it is not a point I would ever want to use in the real world safety design rating of a product. Hopefully those doing the video performed a calculated yield point to use for predicting material failure and fatigue related cycles.[/size]
Thank you in advance!
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That is a reasonable question and a material sheet with the data needs to be in the reply or it will yield even more questions I believe.
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Maybe. But your not using compressible fluids in real world application. And certainly not pressurizing that high!
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Maybe. But your not using compressible fluids in real world application. And certainly not pressurizing that high!
True but to inform people to the specs and material is important otherwise there are people out there whos opinion will be swayed by miss information.
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I'd be interested in what forum that was actually posted.
;)
I'd also like to see data and comparable tests on stock tubes and see their replies.
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I'd be interested in what forum that was actually posted.
;)
I'd also like to see data and comparable tests on stock tubes and see their replies.
I know what your saying but all I can do is provide the information and let them make up their own minds. JSAR has 3 engineers 1 Mechanical Engineer. we didnt need to do any failure tests to know it was plenty safe but we also knew it was the right thing to do. Ill have Matt post a material list and Lloyd can give his perspective on the questions. There will all ways be questions with new products or materials.
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Right Travis.
Haters gonna hate and all that when they didn't have a hand in it.
(Not to mention what forum that all may have been in)
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Right Travis.
Haters gonna hate and all that when they didn't have a hand in it.
(Not to mention what forum that all may have been in)
I know Jeff but what can I do? Ill just give the facts thats all I can do. The material used is 2024 T3 alloy .095 wall and specs are all the same as OEM.
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Yep. You all are doing good!
If I had any doubt? I'd have never pre-ordered the Gen 1 tube nor sent the Hatsan tube for your look see.
;)
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Hey LLoyd!
I have ordered one of these and was bragging to the fact on another forum and was informed of the following. Can you read through it and educate me accordingly?
It was just curios if you were in any way involved with the pressure test video? [/color][/size]Early in the video when tube diameter measurements were taken after the first pressure cycle and it was noted the change in diameter, the material had already yielded. When designing and working with high pressure materials to be used with a compressible fluid, we consider a yield of this magnitude to be a material failure. Any time an item is stressed to the point of exceeding the specified minimum yield strength of that material, the item has officially failed. Testing to ultimate catastrophic failure is certainly important, but it is not a point I would ever want to use in the real world safety design rating of a product. Hopefully those doing the video performed a calculated yield point to use for predicting material failure and fatigue related cycles.[/size]
Thank you in advance!
Sure, I will be happy to address that comment, and it is a good comment. A couple of hours of video was edited to produce the two videos of a few minutes each. Numerous measurements were taken throughout the testing that are not shown on the videos.
The yield calculation for the tube predict material yield to start at approximately 8500psi. Yield is normally taken as a 0.2 percent permanent deformation of the tube. After the 9,000 psi o-ring failure, the deformation was measured as being 0.002" on the diameter, or about 0.16 percent, so still barely below the yield definition. Based on that measurement, one could say that yield had started and that failure had occurred. However, as the pressurization continued, the growth remained rather insignificant, as determined by measurements, and also by observation of the minimal amount of oil that was pumped into the tube. The increase in oil volume did not really occur until about 10,000 psi, when yield and resulting elongation were fully underway. Full failure occurred at 10,000 psi.
You could say that yield had started at 9,000 psi, which would be a 3 to one safety factor for yield. Final failure was at 10,000psi, or a 3.3 to one safety factor.
Those two numbers represent good, solid safety factors for a small pressure vessel.
Required safety factors vary by certifying organization with the yield safety factor always being lower than the ultimate failure safety factor. Bob Sterne has researched the various trends in safety factors, and I hope he will chime in. As I said, suggested/required safety factors vary by organization, and even year to year within some organizations.
Again, a 3 to 1 safety factor for yield is, I believe, satisfactory and safe.
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And I suppose for anyone who is still nervous but still, inexplicably, finds one of these tubes overwhelmingly compelling....
A Marauder can be pretty easily tuned to a performance curve only requiring a 2600-2800psi fill, increasing the safety margin by a small factor.
Now...let the smart guys carry on..
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LLoyd,
I was asked to post the following from the gentleman that asked the question relative to the tube failure. Because he is new to GTA he was not able to respond directly.
"I just read the latest post by lloyd-ss on GTA and I appreciate his response. In addition, in no way was I trying to create trouble or ”hate” as another poster noted. My concern was only that of safety. Being a Mechanical Engineer and having spent a good part of my life working with the design of high pressure piping and support equipment, I only offered the post quoted for the concern of others. If it caused any problems or concerns, I sincerely apologize."
Thanks for everything Lloyd!
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It was a legitimate and good question from someone with knowledge of the standards used I hope it answers his questions. The material if he wants to know is 2024 T3. No such thing as a stupid question.
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Certainly no offense taken by me. Sharing of good technical information is always appreciated.
Lloyd
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If you add the gauge block, gauge adapter, and the gauge together, that's another 2.7 ounces.
Good to know. Thank you.
The guys from JSA will have to chime in on the anodize, but I am 99.9% sure it is Type 2, in black. The type 2 has insignificant thickness build-up, whereas the harder type 3 (also called hard coat) can build up a couple of thou in thickness and that has to be compensated for (thread gauging for example) when the part is initially machined.
True but generally speaking, one specifies the coating thickness required. This is standard practice (per MIL-A-8625) for all types of anodic aluminum coatings.
Side note - Sulfuric (Type II & III) anodize penetrates the material and builds up equally. If .001" thickness is specified, .0005 will be below the surface, .0005 will be on top of it. Important to know when designing anodized parts.
Type 3 would make a nice wear surface for the hammer area inside the tube...
Yes it would. Type III with a teflon seal (common practice for high wear parts) would be ideal for this application. Steel hammer (subject to side-loading during cocking) under a spring in an aluminum tube needs a little something to help prevent undue wear.
...but honestly, I forget how you mask a part that has both type 2 and type 3, but I do remember that it is an expensive pain in the rear.
PITA indeed. You never want to mask anything you don't have to. One plating house I dealt with for many years charged 50 cents each to mask blind holes, a buck for through holes. Slots? forget it. Often charged us $10 each. We specified the coating thickness on the print and dimensioned parts to allow for it.
I've never seen anything that required both II and III on the same part. If a part required Type III in even one small area, the entire part got it. Type II & III cost us the same (but we did a lot of business with plating houses).
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It was a legitimate and good question from someone with knowledge of the standards used I hope it answers his questions. The material if he wants to know is 2024 T3. No such thing as a stupid question.
I beg to differ Travis. I saw a stupid question on Youtube just today. LOL! ;D
Knife
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It was a legitimate and good question from someone with knowledge of the standards used I hope it answers his questions. The material if he wants to know is 2024 T3. No such thing as a stupid question.
I beg to differ Travis. I saw a stupid question on Youtube just today. LOL! ;D
Knife
Youtube doesnt count.....haha
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I just stumbled onto this thread. I have not read through the whole thing yet, but just wanted to say it is good to see you back Lloyd.
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I found him hiding in his doomsday cave trying to figure out if the stalagmites could be used as transistors. I talked him back to reality now we have him among us . Glad he’s here also
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A lotta good folks here. ;D This is a great place to be, especially after having met many of you at the Funshoots over the years. ;)
Lloyd
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It was a pleasure meeting you too Lloyd. I never did catch the name of that canon you brought with you though.
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Hi Keith,
Yes, I think that cannon should be called "The Awkward 51." Definitely heavy and awkward. After I got it back home, I sorted out the mechanics of it and got it shooting pretty well. Its in pieces now on my workbench, ready to be transformed into "The Ergonomic 51", LOL.
Here are a few pics: The Awkward 51, its balanced valve (which cocks very easy), a 5 shot 100 yd group with 250 gn .51 bullets. There are 3 shots in the hole at 11 o'clock.
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Yes it would. Type III with a teflon seal (common practice for high wear parts) would be ideal for this application. Steel hammer (subject to side-loading during cocking) under a spring in an aluminum tube needs a little something to help prevent undue wear.
That's why it's stated to NOT use the metal hammers with these tubes. The MDS work great and honestly there much better than the metal hammers
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Yes it would. Type III with a teflon seal (common practice for high wear parts) would be ideal for this application. Steel hammer (subject to side-loading during cocking) under a spring in an aluminum tube needs a little something to help prevent undue wear.
That's why it's stated to NOT use the metal hammers with these tubes. The MDS work great and honestly there much better than the metal hammers
That's correct. We would no longer be able to anodize them locally, so the price would go up due to shipping and the extra cost of the hard coat.
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Hi Keith,
Yes, I think that cannon should be called "The Awkward 51." Definitely heavy and awkward. After I got it back home, I sorted out the mechanics of it and got it shooting pretty well. Its in pieces now on my workbench, ready to be transformed into "The Ergonomic 51", LOL.
Here are a few pics: The Awkward 51, its balanced valve (which cocks very easy), a 5 shot 100 yd group with 250 gn .51 bullets. There are 3 shots in the hole at 11 o'clock.
That name is fitting. Never seen a butt stock plenum before. It just needs one of these LW tubes on it to lighten it up a bit. ;)
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Thanks for letting me shoot that awesome piece of work at the fun shoot Lloyd. Always fun shooting air rifles with recoil. Nothing like being aggravated and pulling out the big bores to blow some stuff up and get to a better mood without having to go to the range. Anxious to see the final product. Hope to see you again at the fun shoot this year.
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You got enough tubes on that thing, Lloyd?.... FOUR counting the barrel?.... Very unique design, look forward to more information on it.... and as I have said before, WELCOME BACK !!!
Bob
PS, did the Stagamites work?....
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PS, did the Stagamites work?....
Only if I wore a tinfoil hat. :o