SpudFiles

barrel sealer/chamber sealer gives the same results.... and lighter piston won't help much.... possibly 3 m/s

It is still very powerfull.... hope you'll build it...

well i'm still thinking it over but if i do decide to build it i will probably buy the parts this weekend.

It is just a suggestion you know but If I were you I would use a pipe with larger bore (for example 2 cm ID ) that would fit more types of ammo...

anyway GGDT shows that paintbals would 'waste' the power/energy of the gun, if you can get some heavier ammo really cheap, for example 3/4" marbles, it will 'use' its potential better...

POLAND_SPUD wrote:It is just a suggestion you know but If I were you I would use a pipe with larger bore (for example 2 cm ID ) that would fit more types of ammo...

anyway GGDT shows that paintbals would 'waste' the power/energy of the gun, if you can get some heavier ammo really cheap, for example 3/4" marbles, it will 'use' its potential better...

11/16" steel bbs and the problem with making it a 22mm porting is that my piston is 25mm which is not much difference

Just thought i'd let you know I've just test fired my 3/4" QEV at 850psi.
Did just over ten shots, nothing special happened and the piston is fine.

al-xg wrote:Just thought i'd let you know I've just test fired my 3/4" QEV at 850psi.
Did just over ten shots, nothing special happened and the piston is fine.

ok looks like a 400psi qev cannon not really, if i ever do build it i will make a piston because i haven't made one yet.

al-xg wrote:Just thought i'd let you know I've just test fired my 3/4" QEV at 850psi.
Did just over ten shots, nothing special happened and the piston is fine.

I want some of whatever you were on when you did that.

Then again, maybe not

Given that the manufacturers operating pressure says 150psi, I'd say almost 6x that is getting close to the wrong end of the safety margin.

However it's nice to know the pressure I'm going to use in a day or so is perfectly safe by comparison

Yeah but thats probably just because people tend not to use over 150psi in air systems, they turn to hydrolics (i guess one could wonder why though and realise that they were right).
The point being its obviously nothing to do with the 3 times higher burst pressure rule in this case and that 400psi should be fine.

I didn't put myself at risk testing the valve, although i might have felt some regret if it had blown up...
I'd still trust a QEV over a homemade valve, unless it was machined out of steel...

Oh by the way this is a european QEV using a piston, i'm guessing diaphrames probably aren't as tough.

what size qev was it? that could have an effect on the maximum working pressure

He said 3/4" then you quoted it, then I quoted it... and then you asked what size it was

I think the ID is 37.9mm at its widest the wall thickness seems to be 1.5mm at its thinest. (the machined part around the piston also has a threaded ouside, the thickness around the chamber part is 1.9mm)

Hotwired wrote:He said 3/4" then you quoted it, then I quoted it... and then you asked what size it was

oh yeah another case of completely missing something blatantly obvious

hey could you post a pic of this piston QEV?

I think that the operating pressure of QEVs is as much a factor of the safety of venting high pressure gas from them as it is about what they can physically take.
Like blowguns are rated to 10 bar, but only recommended for use at around 2, QEVs will have similar considerations.

I took some pictures of the QEV a while back, i think I still have them.
They were taken with a camera phone though :/