BTW speaking of O-rings, hey phil...

BTW speaking of O-rings, hey phil...

Joined: December 14th, 2010, 5:08 am

March 26th, 2012, 4:55 pm #1

if youre reading this, i got around to trying out the o-ring on the 392 transfer port. i did some testing on it and everything. i ended up gaining about 25 fps. i think i could get more if i had done a better job fitting the oring. it's a bit loose. i need more practice to work up some courage to do it to my brass valves

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3rd o-ring transfer port o-ring oring




dnadnnoid


Last edited by Dnadnnoid on January 1st, 2015, 9:04 pm, edited 1 time in total.
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Joined: April 28th, 2010, 12:23 am

March 26th, 2012, 5:13 pm #2

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Joined: March 1st, 2002, 12:22 am

March 26th, 2012, 5:42 pm #3

if youre reading this, i got around to trying out the o-ring on the 392 transfer port. i did some testing on it and everything. i ended up gaining about 25 fps. i think i could get more if i had done a better job fitting the oring. it's a bit loose. i need more practice to work up some courage to do it to my brass valves

[/IMG]

3rd o-ring transfer port o-ring oring




dnadnnoid

I hvae Phil's explanation (Thank you Sir!) but would like to see how some one actually did it, since it figures large in a current build and in a repair..... 


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
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Joined: April 1st, 2009, 3:18 am

March 26th, 2012, 5:47 pm #4

if youre reading this, i got around to trying out the o-ring on the 392 transfer port. i did some testing on it and everything. i ended up gaining about 25 fps. i think i could get more if i had done a better job fitting the oring. it's a bit loose. i need more practice to work up some courage to do it to my brass valves

[/IMG]

3rd o-ring transfer port o-ring oring




dnadnnoid

Far greater gains to be had doing such an o-ring mod versus the traditional o-ring gland addition, ala Benji Airsource. Such an addition is a direct flow seal. The other method, an o-ring forward of the hole placed radially, like the rear, still presents a 'void' to be filled with air/pressure.

Fantastic! You got it, without me having to tear down my 392 to show people.

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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Joined: December 14th, 2010, 5:08 am

March 26th, 2012, 6:19 pm #5

"The other method, an o-ring forward of the hole placed radially, like the rear, still presents a 'void' to be filled with air/pressure. "

you also need a lathe to make the groove for that oring to fit in. I did this with just a drill press.


i ended up using a 5/16 pilot tip drill bit. home depot doesnt have end mill bits so i went with this. its a lot like an end mill only it has a 5/32 tip on it, which fits perfectly into the hole on the valve and makes alignment a cinch. a #008 oring has a 5/16 OD and i cant remember its ID but its also perfect size

the only problem a ran into was turning the valve slightly to grind the sides of the groove down so the oring conforms to the curve of the valve and tube. also when you turn it, the piloted tip starts drilling out the side of the transfer port and enlarging it a bit

to make it easier on my next try im going to get an actual 5/16 end mill for making the main part and use a smaller mill bit to grind the the sides a bit
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Joined: March 1st, 2002, 12:22 am

March 26th, 2012, 7:13 pm #6

to a flat tip?

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Joined: April 1st, 2009, 3:18 am

March 26th, 2012, 9:18 pm #7



"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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