GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: milo on April 11, 2014, 05:14:51 PM
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I have been following the $200 pcp article by rsterne, and have enjoyed it enough to try it myself. I bought a qb79 and the ninja regulated tank. Its a lovely little gun, feels good, smooth operation, very nice and a excellent value. I did the stage one mods, drilled out the bolt, and the barrel port, polished the inside of the air tube, and cleaned up the trigger and installed a softer trigger spring. I read the stage two mods and decided to give them a look over. I decided to take a different approach to increasing the inlet side volume, instead of milling away the aluminum can, I cut it off and just left a 3/8 sleeve. I notched the back so I can still compress the o ring with a tool I have made. I had read in the discussion that someone had reversed the spring and secured it with an e clip. After a little measuring I cut 3mmx.5mm threads on the poppet stem. I machined a shallow recess in the brass body to keep the spring from walking around, and installed the spring at a height of .54 inches. A small washer and some blue loctite hold it all together. I had to enlarge the hole in the spacer to 5/16 to fit over the spring. It worked out nicely, I am up to about 780-790 fps, and am looking forward to some more fine tuning. Thanks so much to rsterne for all the good background and clear explanations.
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that's an elegantly simple solution,nice work-- is the stem hard to thread?
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Its threaded easily, it did not seem to be hardened at all. The thread also allows you to adjust the spring pressure as well. I will shoot a couple of strings, then tighten up the spring a bit, and see what happens...
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Nicely done...good solution. Certainly maximized the amount of "on deck" air available for a shot.
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Really nice!!
I have one question though did you use the old poppet and if not what did you do to ensure the new one won't come off????
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been gone for a few days, so just getting back. I do not understand your question, I`m calling the poppet the brass piece with the seal and the stem on it. Maybe I am not using the right terms here. I cut off the aluminum tube to 3/8" to retain the O ring, and put the spring on the other side, retained by a washer and nut on the newly threaded stem.
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been gone for a few days, so just getting back. I do not understand your question, I`m calling the poppet the brass piece with the seal and the stem on it. Maybe I am not using the right terms here. I cut off the aluminum tube to 3/8" to retain the O ring, and put the spring on the other side, retained by a washer and nut on the newly threaded stem.
Terminology? I'm still learning also.
You used the OEM (original) poppet (the brass part on the stem) plus valve stem then threaded the the striker stem end for the reversal of valve spring. I'm just pondering how I can keep the poppet on with the reversal of force.
Thanks, your response is enlightening.
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the poppet and stem are one single piece, in fact I carefully chucked up the stem in the lathe and tapered the brass so as to allow better airflow into the valve. I also opened up the inside of brass valve body a bit to improve airflow. What you are doing here is instead of pushing the poppet against the seat from the inlet side, you are pulling the poppet against the seat from the outlet side. I think Archer sells a replacement poppet for about $15, and there is a picture of it on their website. You may be interested to know that I just finished making a .260 breech riser, cut 3 inches off the barrel, and put a full length shroud on the gun. Nice and quiet now, it really barked before.
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the poppet and stem are one single piece, in fact I carefully chucked up the stem in the lathe and tapered the brass so as to allow better airflow into the valve. I also opened up the inside of brass valve body a bit to improve airflow. What you are doing here is instead of pushing the poppet against the seat from the inlet side, you are pulling the poppet against the seat from the outlet side.
In my mind I'm trying to make sure my poppet will not pull off the stem with the reversal of force. i.e. The valve spring has been moved to the stem end and will the staking of the stem to the poppet keep the poppet from pulling off? I'm a curious mind to say the least. ;D
I think @=S+S%^$# sells a replacement poppet for about $15, and there is a picture of it on their website. You may be interested to know that I just finished making a .260 breech riser, cut 3 inches off the barrel, and put a full length shroud on the gun. Nice and quiet now, it really barked before.
Thanks for the Man With No Name replacement poppet but I think I'll turn me a new one.
A very nice job on the riser plate and shroud, but as I've heard before here on GTA; No pictures, it didn't happen. ;D
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You are right, the poppet is pressed onto the stem, and the seal is pressed into the poppet. I did not stake mine and have probably shot it 500 times at least. The spring does not apply that much pressure to the stem, so it seems ok. Good point though, I will check it out next time I take it apart, which will be soon as I have a small leak in the transfer port. I`m post i pic of the qb with shroud, though the shroud is still in the white.
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You are right, the poppet is pressed onto the stem, and the seal is pressed into the poppet. I did not stake mine and have probably shot it 500 times at least. The spring does not apply that much pressure to the stem, so it seems ok. Good point though, I will check it out next time I take it apart, which will be soon as I have a small leak in the transfer port. I`m post i pic of the qb with shroud, though the shroud is still in the white.
Nice job Milo!!
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Thanks Milo, I liked your valve so much I started on one myself and it will go into my .22 Bobcat upon its receipt.
I lapped the Delrin poppet to the valve seat and she shines like a new born babies butt with 100% contact and a nice small shiny seat area. I've still work on the valve seat end but that will be for another day. Not sure if I'm going to bore the valve body out to .475 but I did make the poppet O.D. smaller than the OEM and could still go a wee bit smaller. I think I'm going to do like rsterne and expoxy a piece of the shortened aluminum to the brass threads leaving enough o-ring gland to compress the o-ring correctly when installed.
Has anyone but me found this stuff fun?? ;D ;D ;D
(http://i202.photobucket.com/albums/aa86/madmike77_photos/Airgun%20Stuff/IMG_3686_zps5829b07e.jpg) (http://s202.photobucket.com/user/madmike77_photos/media/Airgun%20Stuff/IMG_3686_zps5829b07e.jpg.html)
(http://i202.photobucket.com/albums/aa86/madmike77_photos/Airgun%20Stuff/IMG_3682_zps8f83cf16.jpg) (http://s202.photobucket.com/user/madmike77_photos/media/Airgun%20Stuff/IMG_3682_zps8f83cf16.jpg.html)
(http://i202.photobucket.com/albums/aa86/madmike77_photos/Airgun%20Stuff/IMG_3684_zps83f5ddd5.jpg) (http://s202.photobucket.com/user/madmike77_photos/media/Airgun%20Stuff/IMG_3684_zps83f5ddd5.jpg.html)
(http://i202.photobucket.com/albums/aa86/madmike77_photos/Airgun%20Stuff/IMG_3685_zps574d9560.jpg) (http://s202.photobucket.com/user/madmike77_photos/media/Airgun%20Stuff/IMG_3685_zps574d9560.jpg.html)
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My aluminum ring on the front on my QB79 valve doesn't compress the O-ring at all, the gap is, if anything a couple of thou wider than the O-ring.... Air pressure alone causes the ring to seal in the corner between the valve and tube, like on a Disco....
Bob
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My aluminum ring on the front on my QB79 valve doesn't compress the O-ring at all, the gap is, if anything a couple of thou wider than the O-ring.... Air pressure alone causes the ring to seal in the corner between the valve and tube, like on a Disco....
Bob
Thanks for the input because I was thinking somewhere along 1.5 of the o-ring's cross section for the gap. A couple of thou it will be.
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More will probably be fine, it will depend on the OD of the section of valve where the O-ring fits.... The larger that is, the wider the groove needs to be to provide room for the O-ring.... particularly during installation since you will be sliding it in, in place, not tightening it in afterwards....
Bob
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More will probably be fine, it will depend on the OD of the section of valve where the O-ring fits.... The larger that is, the wider the groove needs to be to provide room for the O-ring.... particularly during installation since you will be sliding it in, in place, not tightening it in afterwards....
Bob
I'll check the O.D. of the area where the o-ring lies and adjust accordingly. Again, a big thanks for all you do.
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that looks really good, nice work you are doing over there. And yes, I really enjoy playing with these guns and experimenting with them. I have made about a dozen different air strippers for my various guns, working on a design with a circle of holes around the face to exhaust the air caught by the first baffle back into the shroud, but having trouble setting up the db meter to get comparative results, still messing with it.