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
ulanbatorgator: @pastorjavier65 Thanks for watching my stuff! The valve body is made of
Acetal, sometimes called POM. cheers
titop96: Thank you so much i appreciate it
zuludance1: Yes!! Thanks for the speedy reply. I am looking forward to building myself
one of these. You really got me excited!
ulanbatorgator: Probably... i think it's a bit on the soft side, but if nylon is what you
have; go for it! It will most likely give a good seal, but it might not
give as long service as a acetal valve body before it needs replacing.
Beschaulichkeit: This is great! You've renewed my interest in actually building something
zuludance1: Man, you sure have built some great PCP airguns compared to others!! I just
have a question; from the last video, the diagram shows what you call an
'air transfer port'. Is that drilled in to the top of this knock-open
valve? And how does that connect to the slider/loading chamber? Thanks!!
titop96: great video loved it what type of blade did you use to shave the steel to
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
alehax27: @ulanbatorgator The reason I was asking was because it looked a bit soft.
If you've used it before then I'm assuming it works fine.
Nick R: Hello, Will it seal good? I just got a cheap QB78 CO2 gun. Converting it to
PCP. But i want a other valve too couse original has too much distriction.
If i cut the brass valve head in a 60* angle with an inside tool and make a
like pvc kind of valve head wich later can be glued to a steel rod. Wil i
it seal if both cut to 60*? i first have to save up for a lathe anyway
Marc De Anda: @ulanbatorgator We call that Delrin/Acetal here in the States.
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
Jtag Sheep: nice :) im gona build one on a friends lathe also your english well you
trying to speak english i actualy understood you better than a fluent
english speaker thx man also you know the end of the pin that gets hit by
the hammer well how to i stop air leaking out of that bit when it opens ?
can i put an o ring on the valve pin its self just past the exit hole ?
inside the plastic housing so it stays air tight ? cheers
ulanbatorgator: Thanks Marcus! I totally agree regarding insert tooling and acetal
turning... HSS is the way to go! best regards
Nick R: Im afraid i have to order a new valve.. I made 3 none of them sealed.
alehax27: great video. What material are you using for the valve pin?
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! thanks
Nick R: Its getting EU screws on the pressure tube, Not chinese crap. Airtube is
rated for like 2000/2500 PSI. It will be running at a regulated pressure of
loke a 1000 PSI. For the valve head i think im going for PTFE rod. Yes no
need to glue indeed, in my head i had drilled it all the way trough haha
but littlebit past half way would be ok, pressure and spring will keep it
in place. I would like to get a Emco Maximat Mentor 10 lathe:) Or just a
Huvema lathe.... Its cheaper Emco is like 1600E :(
Jtag Sheep: @ulanbatorgator ill do that then as i will be using soda stream co2
canisters to power it and so on
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.
Jtag Sheep: @ulanbatorgator ahh right will do :) cheers i plan on making the stem like
6-8 mm so i can have room for an o ring if needed cheers :)
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! Take care
ulanbatorgator: @wyz2285 When i use a valve return spring i make a recess for it in the air
tube/bottle adaptor that screws into the same hole that the valve body sits
in... Hope you understand what i mean... would be a lot easier if i had a
picture of it! Thanks
ulanbatorgator: Yes, those machine tools are mine... I have actually five lathes... none of
the has cost me more than 300usd, but a lot of hours to rebuild. I prefer
to buy good quality second hand machines instead of new low end machines.
My oldest lathe is something like 70 y/o..
ulanbatorgator: @alehax27 Hi, the pin is cut from a piece taken from a scrapped printer.
miguelwieland: I will buy a lathe and mill as soon as I can afford it. These vids help and
inspire. I like your comment " buy tools not valves"
blackingkoo: hey bro, I'm very interested your DIY airgun. do u mine to email me the
drawing..? i wanna own one for myself..Thank you..
ulanbatorgator: @pyronathanpyro Thanks! You are right aboutthe air loss past the valve stem
during fireing.. I have built valves both with and with out o-ring on the
stem. The valve built in this video has a stem diam of 2,3mm so it doesn't
have enough material to cut a o-ring groove in. As long as you get a good
fit between valve stem and the hole the air loss is acceptable. thanks
alehax27: @pyronathanpyro I've read that adding an o-ring to the pin causes extra
friction. That extra friction affects the performance.
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. thanks
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.. Thanks
ulanbatorgator: Perfect! Thats what my vids are intended for...; inspire others to start
building their own airguns! thanks
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
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
stratmaninoff: Hello, Will Nylon work as the valve body?
Rosendo Javier Rodríguez: Great vid!! What is the material you used for the valve body? I couldn't
make the name out of the audio. Regards
kawivloger: PCP = Pre-Charged Pneumatic
Nick R: Emco and huvema is just all chinese too. For old machines, you still pay
for technology from 20 to 70 like years ago. And cheaper no brand machines
are almost just as wel at this time. And that old machines most of the time
need a lot of maintnence and parts are often not much available. And yes i
need to cut threads with it.
ulanbatorgator: @pyronathanpyro One thing to consider is that the force needed to knock
open the valve is proportional to the "sealed area".. it takes a lot more
hammer force to open a valve head with a diam of 10mm compared to a valve
head of 5 or 6mm.. Also a bigger diam valve stem means higher weight and
more inertia. If you go with a stem of 4,5mm you have enough material to
fit an oring, and if you use a 4,5-5mm inlet in the valve body and turn
down the stem just behind the head it's good for +900fps...
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? TY!
Jtag Sheep: @alehax27 ahh right i sea how would i go about sealing it or shoudl it be
ok ? if not i can make a deeper groove and oil it so it doesnt create
William Morozumi: PCP... is angel dust.
TheMrkylester101: Hej from Australia would a return spring be able to function on the end
that gets hit by the striker
ulanbatorgator: Where are you located? Maximat Is a nice machine.. but there are cheaper
alternatives depending on where you live..
sjm2inok: You do nice work, I enjoyed watching you. I too have an interest in
building my own pcp airguns, both rifle and pistol, you have inspired me. I
couldn't tell the accent, where are you from, I'm in the States, Oklahoma
to be precise. Keep the great videos coming!!
ulanbatorgator: Thank you for the kind words! Yes; the transferport hole is drilled in the
top of the valve body.. I prefer to mount the valvebody in the receiver and
then drill the transfer port through the receiver ( the metal part...) and
in to the valve body in one set up.. That ensures that everything lines up
perfectly.. Then it's just to drill a hole in "the bottom" of the barrel to
let the air enter the barrel. A bit short of space to write here! do you
get the idea? Thanks
wyz2285: Where you are going to mount the spring to keep the valve stem closed to
the valve body?
Nick R: You have any suggestions? i think Huvema has too much chinese parts in it,
Igor Popovic: great video, u should make more similar videos about hammer valve and pcp
greetings from Serbia 'KOSOVO IS SERBIA!'