richard cero: and how the valve moves in the original position? Does it have a spring that is pushed back to its original position to seal the high pressure air?a retainer spring? plss reply plss.
timothy svec: Would there be any value in lapping the two mating surfaces together this maybe JB bore paste?
kawivloger: PCP = Pre-Charged Pneumatic
ulanbatorgator: Thanks for your comment! There are few things I regret in life..., but one of them is that I didn't get a lathe until I turned 30!
Nick R: Ok thank you, it is leaking less and less.
Hopefully after one more fill its 100% seated.
Otherwise i try to make the sealing surface smaller or valve spring heavyer.
If they all fail i go with the flat head valve.
What dimentions did you use for it? Like a 6mm valve head and 5mm hole so 0.5mm sealing surface?
Thanks again for sharing your information and skills with us !!
ulanbatorgator: I still haven't managed to wear out a valve! I have put somewhere around 10000 pellets through the barrel of one of my guns - and it has a flat face valve, brass body, delrin head. Somehow i find the all metal pin/soft valve body design easier to make and easier to get to seal at first fill, so most of my recent guns have that type of valve.
Nick R: By the way. do the Delrin valve/valvehead wear out quick if made correct without burrs or whatever?
Which ones wear out quicker, your dezign here or the oposite hard body soft valve head?
Did you ever had to replace a valve due to wear?
ulanbatorgator: Generally speaking; the lower the pressure, the thinner the sealing surface of the valve/seat in order to get it to seal properly. Most of the time a width of .5 - .75mm works well. If you gun is safe for higher pressures you might try some shots at lets say 200bar, just to slam the valve shut more forcefully and thereby aid in forming the valve and seat to match each other.
Don't spend your money on valves - buy tools instead!
ulanbatorgator: Sounds like you are on the right track! When I have difficulties to get a valve to seal @ first fill I try to "shock fill" from a scuba bottle or similar. At times it's almost impossible to get new valves to seal when filling from empty by means of a hand pump. Once pressurized and fired a couple of times i seldom get any problems from my valves... But as you said I normally go with higher pressure. Out of letters!
Nick R: Sealing surface is to your recommendations around 0.75mm.
What did you mean by cut the sealing surface to proper width?
You mean that the valve head is like 1mm bigger then the hole?
Or what do you recommend for that?
And that is just flat valve head to flat body right? I can't emagine how that could seal haha but i will try everything to make a good valve.
I refuse to order a 60 euro valve ( 35 shipping + 21% dutch taxes) from US and have a crappy chinese valve.
Nick R: Since im shooting at a regulated 100 bar and you i guess 200?
I think a heavier valve spring would do the trick.
Already put a heavier one in it and is leaking just a little bit right now.
I polished the seat and valve too, just put some polish paste on the valve head and turn it for a while in the valve seat so they kinda wear in to eachother.
Im supprised how little pressure 100 bar gives on the valve.
Since im still using the same hammer spring.
I hope it will seal good when i shoot a while
ulanbatorgator: Sorry to hear that your valves are leaking! Anyway, is there any signs of wear on either valve head or seat? The fact that the valve seals for 50 shots indicates that the desing is right, but the parts (material) might not be up to the strains. What type of aluminium did you cut the seat from? Debris in your system? Bent valve pin? Width of sealing surface? I have never tried 45deg, but have use flat valve seats - should work, just cut the sealing surface to proper width.
Nick R: Im afraid i have to order a new valve..
I made 3 none of them sealed.
Nick R: Hey,
I am modding an QB79 CO2 gun to HPA and made this valve too.
With the body from aluminium and the halve head of delrin.
But i can't get it sealed well.
First try was with a 7,5mm hole and second valve with a 6mm hole.
First one worked well but after like 50 shots it starterd leaking.
Second valve didn't make 10 shots.
Should i try a 45 degree angle on the valve and seat or just a flat valve face and a rim in the body of the valve?
I don't know.
gliping1: yes a return spring can be fitted to the end that the hammer hits this will make the airflow around the valve head much better because there is no restriction from the spring and spring retainer
gliping1: yes it will and it will be better because it will not require a end cap to hold the spring in place i often use that method on my high powered airguns for .22 i use a 6.5 hole and a 7 mm valve the 6.5 hole leads to a 5mm hole in the breach this set up will give me over 50ftlbs
ulanbatorgator: Thanks Marcus! I totally agree regarding insert tooling and acetal turning... HSS is the way to go!
Marcus Jenkins: Another great vid. Love Acetal. My local supplier only has it in white :-(. Nylon only in black. Reminds me that BSA made a bad batch of Hornet internals with Nylon instead of Acetal. Swelled in rain & rifle stopped working ;-) Nylon horrid to machine by comparison. I need to grind a tool like yours for plastics - insert tooling not sharp enough for precision cuts on plastics.
ulanbatorgator: Hi! I'm not sure i get the idea.. that should work,,, but you need toadd some extra lenght to the valve pin, un-supported lenght that is.. will make the valve pin more prone to bending, and also adding extra weight = more inertia.. Valve should be keept as light as possible IMHO..