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Old 02-24-2014, 09:33 PM   #41 (permalink)
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Ya, I occasionally peruse craigslist, but dont really come across much. Although I did stumble across a crossman air powered shotgun about a month ago that I almost jumped on. It was dirt cheap too.
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Old 02-24-2014, 11:08 PM   #42 (permalink)
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I have been doing some research on oring gland design and I think the problem is they were designed with too much squeeze.

I just I just finished up a stretch and squeeze calculator biased on formulas found in the parker oring handbook (section 3 pg 8 fig 3-3).

What it does is calculates the adjusted cross section of the oring biased on the gland OD. Then it calculates the OD baised on the gland od + (adjusted cross section x2)

so here is a quick example of what it does.

I know I want to use a 114 oring on 12gram plug

the oring chart here give me an actual od of 0.612 and a cross section of 0.103
O-ring Sizing Chart

the gland dia is 0.672

so the adjusted cross section is 0.096 so the adjusted oring od is 0.864

I measured the tube id at 0.842

So the squeeze on that particular seal is 2.54%

That is actually pretty low for a static oring seal but typical for a dynamic.

I have yet to measure any of the "difficult" seals but I would expect the squeeze to be somewhere in the 20-30% range (typical static industrial seal squeeze) This would also cause problems during install due to going past the threads. I think 90% of the problems would go away if that squeeze was more like 5-10% still very much in the well sealed range but much easier and more forgiving to install.
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Old 02-25-2014, 08:13 AM   #43 (permalink)
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Hmm... Well, damn your good.
That may be a reason why people have honed the tubes with success as well. Aside from cleaning up the rough spots, slightly increasing the bores at the same time, albeit minute.

If you would like to experiment, I can send you my spare valve body to tinker with.
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Old 03-06-2014, 07:23 AM   #44 (permalink)
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Quote:
Originally Posted by pghp8ntballer View Post
Hmm... Well, damn your good.
That may be a reason why people have honed the tubes with success as well. Aside from cleaning up the rough spots, slightly increasing the bores at the same time, albeit minute.

If you would like to experiment, I can send you my spare valve body to tinker with.
Definitely a problem. Interested to see where this goes.
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Dye says that they're going to make a 'Faultline Broomstick' soon, so wait for that, then you'll never be outshoot, unless the other guy has a full-auto ramping Boo-Ya frame on there Spider and a Dye Broomstick, then your screwed, you mite as well play Airsoft.
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Old 03-13-2014, 06:20 PM   #45 (permalink)
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pghp8ntballer I got your spare valve today. I have been taking some measurements and nothing was really working a 113 oring was not really fitting right (too tight according to my spread sheet) If you used a 112 but made the groove shallower it might work. It was making me scratch my head for a while until I switched my mics to metric. the valve body is 18.25 dia the gland is 14.3 and the width is 2.92 so if you assume that the valve is under size to the bore by the standard 0.010in (0.25mm) that gives you a bore of 18.5mm . That is really really close to what you would like to see for a M14x2.5 oring so if you take all that information and throw it into the chart what you end up with is when using a M14x2.5 oring it will have a stretch value of 2.06% perfect then you take the 18.5mm bore assumption and calculate the squeeze ends up being 3.8% that perfect. So I will have to at least try to put the valve together using the M14x2.5 orings to see if it leaks. I think that is the solution though.
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Old 03-13-2014, 06:29 PM   #46 (permalink)
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That is very interesting. I look forward to hearing your results. I wonder if the Oring info is all wrong about these guns.
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Old 04-02-2014, 05:37 PM   #47 (permalink)
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tjd10684 - Any updates as to whether the valve seals with the M14x2.5 orings?
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Old 04-02-2014, 08:26 PM   #48 (permalink)
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No not yet I have not worked up the guts to pull it apart yet.
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Old 04-02-2014, 09:01 PM   #49 (permalink)
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Lol. The lower tube comes apart a bit easier than the upper tube on mine. I polished that valve body and bolt up some. The pierce pin assembly is a bear with those Orings. It's VERY tight. A 5/8" wooden dowel and a hammer. Have at it. Don't forget the set screws!
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Old 04-03-2014, 10:08 AM   #50 (permalink)
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I just ordered a batch of 112 and 113 Buna-N orings to rebuild my aluminum LB Comp. I don't have a flex hone, but I will polish out the upper and lower tubes to ease the reassembly.
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