my mk2 177 started to throw velocity variations between mags.
It was shooting a 6fps spread; now 20-25.
Tried another tin of JSB 10.3s and two different brands- no change.
Barrel pull through was clean, hammer was clear of grease.
Put reg on the tester- slow recharge with a little creep.
Bloody Ebay job that I'd thought had been sorted the last time.
Spec- shortcore 0.5mm discs doubled ))(())(()) 0.45mm endfloat
Stripped the reg and hmm ..the core nose had a fair dimple in it with a hint of mushrooming .
Drilled out and replaced the nose and polished up the back of the push-pin disc on a fine stone..
Reassembled with the original endfloat- made one (lucky) adjustment to 95bar.
Recharge is erratic straight to 95 and holding but drops 5 bar on flipping the dump valve. 95-90-95. Leak tested the reg-tester...fine.
Same variation on the gun- 708fps-700-690-685.
Nipped up to 100bar- 720-715-710-690.
So it's not opening until the pressure drops further-
too stiff a belville stack? Singles ()()()()() struggle for 95 bar
ok, so I wasted another hour.
I have some new belvilles from Lane that I bought a few years ago, set up as singles 6x2.
80-85 bar absolutely crisp fast reset &-no creep.
At 95 bar-straight to 95 at first then tapping the bleed valve 90-95-90 and creeps to 100 after 30 mins.
Doesn't seem to be any difference whether (()) or ()() at 95-100 bar reset is slow, erratic and the damn thing creeps 5bar
Isn't creep usually caused by the sealing surface? On my FXs it'd be the equivalent of nose I think.
Quote from: SiegeA on April 03, 2024, 05:44:30 PMIsn't creep usually caused by the sealing surface? On my FXs it'd be the equivalent of nose I think.
yes, as per previous post- absolutely spot on at 80 bar it just won't settle over that.
The core runs true in the lathe, possible that the inlet disc is rolling out when screwed in, not sure if it is the cause of the high-low variation at 95?
Not the first time that I've rebuilt this damned thing because of creep but it has/did reset quickly.
Quote from: Squinty on April 03, 2024, 06:40:47 PMQuote from: SiegeA on April 03, 2024, 05:44:30 PMIsn't creep usually caused by the sealing surface? On my FXs it'd be the equivalent of nose I think.
yes, as per previous post- absolutely spot on at 80 bar it just won't settle over that.
I'm right in thinking you mean the nozzle?
Perhaps try a few dabs of low strength thread sealer on it. Worst case is that it'd need cleaning up/off if it didn't work. At least it'd eliminate any roll if that's suspected.
The core runs true in the lathe, possible that the inlet disc is rolling out when screwed in, not sure if it is the cause of the high-low variation at 95?
Not the first time that I've rebuilt this damned thing because of creep but it has/did reset quickly.
Quote from: SiegeA on April 03, 2024, 07:53:05 PMI'm right in thinking you mean the nozzle?
Perhaps try a few dabs of low strength thread sealer on it. Worst case is that it'd need cleaning up/off if it didn't work. At least it'd eliminate any roll if that's suspected.
Possibly, not sure if there would be enough strength to fill any slop in the threads.
might not be seating square in the reg body thread which could explain why it keeps failing- pot luck positioning
is the reg body in good condition behind the push pin disc some times air can sneak through past the oring.
kevG
Quote from: KevG on April 03, 2024, 09:16:21 PMis the reg body in good condition behind the push pin disc some times air can sneak through past the oring.
kevG
couldn't see any scratches, whether it's perfectly centred or the thread is true- don't know.
This reg has tried my patience for over 2 years, works bang on then o-rings, creeps 3 out of 4 times its reassembled.
New nose sorted it last time but not this, may be peeing into the wind if the disc or body are the underlying cause.
Good job I'm not paying for the time thats gone into this :D