Just wondering

[Thumperrr]

Hi all,rather new here...I bought a CFX .22 I seen some pics where a fellow opened the piston side seal area of the breach and was wondering why he didn't use a round nose cutter so there would be more surface contact on the round "O" ring. I got a weird idea that I haven't tried yet...since the downfall of the breach seal seems to be the air getting by the outer edge of the "O" ring ...why not use a cup seal like you find on the axle of your trailer,this way the air would force up against the inside of the lip and actually force it out against the outer surface thereby sealing itself...as soon as I get my lathe up and running I may try these things...let me know if I'm all wet or what here OK? thx

[RedFeather]

Might want to be sure you can get a spare unit first. Someone has requested one from PA but hasn't heard on it yet. While the CFX's are nice, I think there's not a lot more you can do with the design. Probably optimum at their current power level (and why they shoot so well as a result). Just passed on one in .177 that was tuned and chronied at high 800's but the owner said it was shooting slower. Maybe it held up for the first few shots and then the seals began leaking?

Anyone tried turning a new roller tap for one of these? [Man, I'm gettin' old. Too many brain farts!] There's the post here from MZE (?) in South Africa who is making alternative taps. Also found a blog on the BSA Superstar (predecessor) and got a look at the rotating tap. Now I know what I'm dealing with. There's no small o-ring on the barrel side? That makes no sense. Unless the designers felt the outer ring would make up for any slop in aligning the tap with the breech.

Oddly enough, the guy's blog on the BSA stated he was in the 700's with an old Theoben ram conversion but went back to the 800's when he replaced the original spring.

[Thumperrr]

Yea,I guess I better order a half dozen.... the way I cut aluminum..there should be a law..lol I was just fasinated that he cut a square slot for a round  "O" ring..square peg..round hole..awww there I go wandering aimlessly in left field

[kiwi]

Thumperrr - 1/11/2010  5:23 AM

Yea,I guess I better order a half dozen.... the way I cut aluminum..there should be a law..lol I was just fasinated that he cut a square slot for a round  "O" ring..square peg..round hole..awww there I go wandering aimlessly in left field

I guess he's talking about me...LOL

Because it was cut to take a Z-ring....has not happened as yet
I will pull it apart one day....PS..it still leaks slightly"
Keep in mined you don't want to much fiction on the O-ring..
1... The breach has to beable to move fowards under compression to seal
the front/barrel O-ring..As after you have rotated the breech to load a
pellet  the breech is only sitting against the barrel with next to NO pressure
on the O-ring...
2... You have to beable to rotate the breech with that little
plastic handle...."I'm waiting for mine to snap of"

The seal you are talking about is called a exsternal lip seal...
You will fined a greatest range of them at a outlet for
hydraulic rams etc. they come with diffrent lip sizes & shapes.

The narrowest one I could fined in the correct DIA was to deep
and would mean the groove would be cut into the transfer port..
And it would also help if the breech was a bit longer so there was
 more overlap..3mm more would be heaps..
There maybe ones that arn't so deep... I just have not come across one...
You could make a new longer breech with the port angled towards the centre
to clear the lip seal groove...
So a Z-ring was the next option from a O-ring....
PS..If yer cut a Z-ring in half it has a cross section
that is some what Z shaped....


Peter

[RedFeather]

Don't be too quick to judge the design. Consider that the older style lever taps don't even have o-rings. I think they are simply friction-fit. Yes, too much pressure will make that roller a beast to shift. My CFX is kind of stiff, as is. Is a few more fps really worth all that re-engineering? And consider that the BSA was out a few years earlier. How much similar work has been done in the UK? Think I will ask over on AirgunBBS.

[Thumperrr]

OK thinking about the O-ring and it's cost and function,it's probably the best way to go.Thanks kiwi,obviously you'd already thought about doing the same thing,I printed those pics out for future reference...poof goes that idea..lol

[kiwi]

NO NO NO..Don't toss the idea out...
just fined a lip seal small enough.
its more than possable..

Pete

[TexasShooter72]

I can't comment much on the "insides" of things...   all I know is that the breech "O" ring is very easily thrashed which is very likely why I gifted my ex's son with mine...  I just didn't feel like putting up with it.  Accurate gun, nice power for the right applications..  the perfect gun for the right kid who loves to hunt and well, I know he wanted it!  Love you Jay!  Enjoy it, bud!  You've got a helluva shooter there!

Matt

[RedFeather]

Asked about BSA conversions on the UK AirgunBBS and got this reply:

"I built one that doesn't use an O ring.. it uses a piston style ring with stepped, overlapping ends. The breech 'plug' needs to be re grooved for this, then on the rear face of the groove a lightly milled "crowsfoot" design about .015" deep can be milled, converging to a radiused transfer port. RB"

Russ Best, perhaps? Anyway, thought Kiwi might benefit from this engineering gobblety-gook.

[Thumperrr]

Hmmmm,ok that sounds like he used a ring from an old 2 cycle bike piston...I'm guessing about a 50 cc piston compression ring,the japanese piston rings all overlapped,the only thing with that is inherent wear at the ring from metal on metal contact

[kiwi]

The term "crowsfoot" got me scratching my head....??
Have never concidered a piston ring...
26/26mm bore is a dam small motorbike..even a 50cc
chain saw / headge trimmer type engines around 20/30cc

Pete

[crackshot777]

what about air compressor rings i know there pretty small