Having murders.
The stock valve-assembly, so far I’ve had delivered and tried a 12mm x 2.0 tap & die set and ditto a 14mm x 2.0 set and neither fit the brass inserts (spring-retainer at one end, collar at the other). The chaps at the die company tell me they’d fall over if it was a 13mm. The 12mm tap will go down into the valve-body (14mm is way too big), but there’s a fair bit of play in there.
So, does anyone have any idea what the thread is? My pitch-gauge and theirs both indicate 2.0 pitch.
TIA to anyone who knows. 🙂
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the valve is made as nnoying to thread as possible…well allmost, they could have used a different thread for the spring retainer also LOL
½”-13 is the inside threads of the valve
bottle threads are 18×1.5mm (european standart)
and the frame threads are 7/8th-XX i cant remember the pitch
and then there dump valve threads…arghhhhh
if your maning your own valve body’s dont forget to make the middle part if the inside smooth, your can even increase the ID somewhat to accomodate a bit more air in the valve, and shorten the spring retainer increase volume too…it can give you ½-1 fpe more if it matters
So one presumes the valve-assembly was supplied and fitted by AF then.
the bottle is M18 x 1.5
I’m going to make new brass valve inserts and I’ll be cutting the thread on them with a die. 🙂
Most folks over here could have told you the thread size. But you got a lathe so the outer thread part can’t really be the problem in brass!
If your not confident at screw cutting try a peace of delrin first to try. Don’t forget the thread runout.
Regards,
Marc
This gets weirder. He reckons the brass bits are 1/2″ x 13TPI UNC, but he can’t get the die to go on, at least not without force (which he doesn’t want to apply).
Just rang him back, he said the tap sailed in sweet as a nut (har har 😆 ), so it looks like it’s 1/2″ 13TPI UNC then. So much for the bottle being “metric”. 🙄
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I’ve got a 5mm bore in a 6mm stem with a 6.75mm seal diameter. Can’t get it to seal properly yet, but I’ve just taken delivery of some acetal which will machine more precisely than the nylon I’ve been using. Sean’s also sent me a stronger spring to try (bless you Sean 😀 ), which I will try first on my original prototype (which seals just fine but is a bit on the big side).
Best I’ve seen so far is 890fps on a fill of approx 1500psi (while the seal was leaking). I’ve had a few tank-dumps along the way, but it’s all instructional stuff. 😆