SpudFiles

I would certainly consider a cast epoxy piston assuming the pipe is smooth enough internally to cast it. As to pressure, I'm sure the galvanised pipe can take whatever the fridge compressor can put out.

With a QEV as a pilot you should be fine, looking forward to seeing this built

jackssmirkingrevenge wrote:I would certainly consider a cast epoxy piston assuming the pipe is smooth enough internally to cast it. As to pressure, I'm sure the galvanised pipe can take whatever the fridge compressor can put out.

With a QEV as a pilot you should be fine, looking forward to seeing this built

I thought about a cast epoxy piston, but im having a hard time figuring out how to hold a sealing face on to it at pressures a bit over the usual (right? ). also, i dont think the inside of the pipe is smooth enough, probably not even seamless, so i think im gonna sleeve it with some sort of pipe, probably copper.
About the pressure, yea, im pretty confident that the pipe can hold whatever im capeable of putting in there, its the fittings im worried about. as far as i know, the fittings arent made of steel, and are generally rated much lower than the pipe. Here in Denmark pressure ratings isnt really something you see, so im having a hard time finding out what ½" galvanized fittings are rated at, as i guess they will be the weak link.

.. Im looking forward to seeing this built too :headbang:

Edit: the qev might be a problem with higher pressures, I have seen them been used at up to 320psi, but it isnt even close to being rated at that. The qev im ordering is the kind they have in the UK. Anyone has any experience on how high you can take a 3/8" UK qev?

ahhh the UK type of qevs... just let me find the thread.... http://www.spudfiles.com/forums/400psi- ... rt,75.html
al-xg tested his to 850psi... i'm not sure how long the diaphgram would last at those pressures tho.....

Alasdair.

@ali... to be precise it is a piston not a diaphgram valve and they are availale all around europe... and my qev it still works well after several hundreds shots at pressures above 300 psi...

I mostly use galvanized fittings and they work fine and I know there are no pressure ratings printed on them... Most people who build steel guns use them and they work well even at higher pressures ( 30 bar )

I am having the same problem as you - seamless pipe is very rare - sometimes you can find seamless larger diameter pipes (5" or bigger )

Nice to know that the qev can hold a bit more than the 150psi its rated to
and POLAND_SPUD, thanks for the info on the fittings, that calms me down a bit too, but also inspires me to go get a high pressure gauge and use 30 bar

update:
waiting for parts in the mail:
3x 3/8" qev
4x ½" > 3/8" bell reducers
2x 3/8" > 8mm compression fittings
1050x 6mm steel ball bearings
1x 40bar pressure gauge
5m of 8mm copper pipe

Now im just waiting or the parts to arrive so i can get to it. I planned on making two of these if the first one comes out well, ive always wanted a small handheld gun

hyldgaard wrote:I've always wanted a smell handheld gun

You could easily stick a pipe up your arse and hold it

--

I have absolutely no idea what youre talking about

i THINK he is saying: it is equal to fart under water

"det er som og fise under vann"

hyldgaard wrote:I have absolutely no idea what youre talking about

Is that so?

Last edited by hyldgaard on Wednesday, 02 April 2008, 16:47; edited 1 time in total

must be technical difficulties

Spudfarm > I made a typo i edited, joke is on that

@ali... to be precise it is a piston not a diaphgram valve and they are availale all around europe... and my qev it still works well after several hundreds shots at pressures above 300 psi...

well its a piston diaphgramy thingy

Alasdair.

I think you should have ordered 1/2" qev instead... they are not much more expensive than 3/8"... a bigger qev might be useful for your future projects... but hey that's just my experience... (I bought a 1/2" QEV but now I realized that a 3/4" one would be better)

in my country qevs are not available to the ordinary person, i have ordered these on ebay from germay, which has very limited supply too. ould have bought bigger if i had the opportunity