What a DUMBASS!!!
All this time I’ve been thinking the OD of the seal-rod passing through the aperture in the bottom of the valve-body affected the vacuum force.
ARGHHHHHHHHHH!!!
All it fecking affects is the amount of air that gets through. So, I can reduce my rod OD to 3mm from 4mm and get an extra 5 square MM of air through. I reckon that’ll put my .25 max up to 1100+ from 1080.
Ho hum.
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Some may find this hard to believe (yeah… 😆 ) but when I made the delrin plug I drilled it through to take the 7.5mm stem and completely neglected to provide a smaller 5.5mm hole at the bottom (the inlet-hole from the bottle to the valve). I’m somewhat baffled the valve could open at all with a 7.5mm aperture, but it did, and gave stonking FPS results. Unfortunately they proved wildly inconsistent, and when I reduced the spacers I could get no more than 550fps. Basically the 7.5mm aperture was all or very little, no fine-tuning to be had. So that’s where the extra 200fps was coming from. 😳 😆
But it was a fortuitous feckup as it allowed me to know the very upper limit for the spring, hammer and spacer combos I use. I’ve now fitted a plug with a 6mm aperture and I’m getting 950fps without putting the removed spacer back (and my chrony isn’t going into orbit anymore either, which is nice).
The reason all this fecking around started in the first place is I modded one of my last two valves with a stem o-ring, for Pablo’s new .25 setup. For some reason it led to seven tank-dumps (o-ring gripping the stem too tightly under pressure I guess). Without the o-ring the valve was blowing too much air, so I let him have mine which is pretty tight through closer tolerances. I then set about rescuing this one. The other good discovery is a close-tolerance delrin stem-shaft seals the valve tighter than a duck’s arse, removes a lot of the friction to be found between steel-on-brass and makes an o-ring unneccesary. Pretty much how AF went with their stock valves in the first place.
Sealing my design with an o-ring was the last hurdle and it appears I’ve found a far sweeter solution. And 950fps with 31-grain .25 Kodiaks from 3000psi with only 10mm of spacer (very easy cocking) is the cherry on the cake. I need to run some strings next to see how the consistency fares. 🙂
The force required to open a valve given a specific psi vs a specific size of hole vs all the bits trying to open the valve.
Eg, with my spring, hammer and pre-load vs 3000psi I can open a 5.5mm hole and get a useful pellet velocity, whereas with a 10mm hole I can’t get so much as a sniff of air.
I use the area of the hole to represent my ‘vacuum force’. It’s just a made-up number I find useful.
a ‘made-up’ term no less?
BTW how is your kick ass valve an improvement over a Condor valve?
Do you have a shot string to show say 10 or so shots?
Did I say it was an improvement over a Condor valve? I don’t have any idea what a Condor valve does anyway. Mine’s still kick-ass regardless. 😛
I was working on a 20-shot string, unfortunately the chrony won’t stay on either of the silencers or directly on the barrel. I’ve launched it into the air three times and across the yard three times too. Somehow it’s survived all that. I have a feeling that as the valve shoots in it’s producing more and more power. Highest fps so far is 1179. I’m going to remove a spacer next and see if I can tame the beast a little.
ARGHHHHHHHHHH!!!
All it fecking affects is the amount of air that gets through. So, I can reduce my rod OD to 3mm from 4mm and get an extra 5 square MM of air through. I reckon that’ll put my .25 max up to 1100+ from 1080.
Ho hum.
vacuum force? that’s a new one
The force required to open a valve given a specific psi vs a specific size of hole vs all the bits trying to open the valve.
Eg, with my spring, hammer and pre-load vs 3000psi I can open a 5.5mm hole and get a useful pellet velocity, whereas with a 10mm hole I can’t get so much as a sniff of air.
I use the area of the hole to represent my ‘vacuum force’. It’s just a made-up number I find useful.
a ‘made-up’ term no less?
BTW how is your kick ass valve an improvement over a Condor valve?
Do you have a shot string to show say 10 or so shots?
ARGHHHHHHHHHH!!!
All it fecking affects is the amount of air that gets through. So, I can reduce my rod OD to 3mm from 4mm and get an extra 5 square MM of air through. I reckon that’ll put my .25 max up to 1100+ from 1080.
Ho hum.
vacuum force? that’s a new one
The force required to open a valve given a specific psi vs a specific size of hole vs all the bits trying to open the valve.
Eg, with my spring, hammer and pre-load vs 3000psi I can open a 5.5mm hole and get a useful pellet velocity, whereas with a 10mm hole I can’t get so much as a sniff of air.
I use the area of the hole to represent my ‘vacuum force’. It’s just a made-up number I find useful.
Dumbass and lucky. I’ve just been firing 31-grain .25 Kodiaks at 1146fps and a six-ring Jerry-slug went at 921fps (105fpe). This is from a valve I ‘rescued’ from yesterday’s abortive 10mm-shaft experiment by making a delrin plug so I could use it again with the original shaft (stem). It seems to like it. Bearing in mind that I’m using the same spring, hammer and spacers, that previously gave me 950fps. So I’ve gained 200fps simply by inserting a delrin plug into the valve and lapping the stem to a perfect tolerance-fit within it. And the valve-spring is under 3mm of pre-load, whereas before it had zero.
Weird shit, but I ain’t complaining. My valve kicks serious ass. 😆
Just taken a bottle-reading, six Kodiaks and two Jerry-slugs used approx 400psi of air from a 3000psi fill.
ARGHHHHHHHHHH!!!
All it fecking affects is the amount of air that gets through. So, I can reduce my rod OD to 3mm from 4mm and get an extra 5 square MM of air through. I reckon that’ll put my .25 max up to 1100+ from 1080.
Ho hum.
You think you’re a dumb azz….
I have no idea what any of that means.
Who’s the dumb azz now?
ARGHHHHHHHHHH!!!
All it fecking affects is the amount of air that gets through. So, I can reduce my rod OD to 3mm from 4mm and get an extra 5 square MM of air through. I reckon that’ll put my .25 max up to 1100+ from 1080.
Ho hum.
vacuum force? that’s a new one
ARGHHHHHHHHHH!!!
.
Sounds like Doug Owen describing his first time 😀
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Bump. Any news?