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Will this piston valve work?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: watto » Tue Oct 23, 2007 7:35 am

A 32mm or 40mm tee would be fine for a 20mm barrel, the way I see it the smaller the tee, the smaller the piston, the easier it will be to make.
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Last edited by watto on Tue Oct 23, 2007 10:21 pm, edited 2 times in total.
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Unread postAuthor: jackssmirkingrevenge » Tue Oct 23, 2007 7:36 am

watto wrote:
chaos wrote:
Don't drill an equalization hole


not so true


Unless your machining a piston with o-rings, which this guy isn't, your not going to need an equalization hole...


Chaos, the man has a point ;)
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Unread postAuthor: watto » Tue Oct 23, 2007 7:47 am

jackssmirkingrevenge wrote:
watto wrote:
chaos wrote:
Don't drill an equalization hole


not so true


Unless your machining a piston with o-rings, which this guy isn't, your not going to need an equalization hole...


Chaos, the man has a point ;)


In your face Chaos! jackssmirkingrevenvge's word is final! (Nah just jokes :lol: :lol: :lol: )
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Last edited by watto on Tue Oct 23, 2007 10:22 pm, edited 1 time in total.
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Unread postAuthor: Gunner » Tue Oct 23, 2007 7:50 am

OK,well what is a good material for the piston because it wont be a very big (something 22-30mm I think)?
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Unread postAuthor: watto » Tue Oct 23, 2007 7:59 am

Well for mine I used a pvc coupler which joins 2 bits of pipe the same size together. If you find one thats a little to big (which they usually are) you can make it smaller by attaching it to a drill somehow and using it like a lathe by pushing sandpaper against it while its spinning. Some other popular choices are hot glue molded into the size of pipe that your using, which will make the piston fit perfectly, pieces of dowel, which are easily sanded to size or you could find some kind of household item like a skinny deoderent can and reinforce it with hot glue, making the piston is probably the most important part so take your time.

EDIT: My rank just changed! All hail staff sergeant WATTO!!
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Unread postAuthor: Gunner » Tue Oct 23, 2007 8:06 am

OK,By the way,what is usually the maximum pressure that ball valve can hold? :wink:
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Unread postAuthor: watto » Tue Oct 23, 2007 8:27 am

well in Australia pvc ball valves are class 18 which is 18 bar which is 260psi, thats the operating pressure, so obviously the burst pressure would be much higher (x3 I think) As for metal ball valves you won't find a compressor strong enough to break a metal ball valve. I would worry more about the pressure rating of the chamber and barrel than any of the fittings as they are usually rated to very high pressures (in Aus anyways)
Hope this helps
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Unread postAuthor: Gunner » Tue Oct 23, 2007 8:31 am

How about schrader valves? :D
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Unread postAuthor: watto » Tue Oct 23, 2007 8:37 am

Gunner wrote:How about schrader valves? :D


Shrader valves are metal inside and their sole purpose is to handle pressure, just make sure they are epoxy'd in tight, get screw in ones if you can, but If like me you couldn't find one just make sure theres a big bulge stopping the valve shooting out if the epoxy fails. I don't know what they are rated to but I'm sure jackssmirkingrevenge or mrcrowley can tell you.
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Unread postAuthor: jackssmirkingrevenge » Tue Oct 23, 2007 9:14 am

Gunner wrote:How about schrader valves?


I take schraders from car or bicycle inner tubes and have been using them at 400 psi for years now, never had one fail on me.
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Unread postAuthor: chaos » Tue Oct 23, 2007 4:35 pm

ok... this topic really took off, wasn't trying to burn you man soz, just pointing out that everything can be different when it comes to piston valves.

my point was having a big pilot valve, is not aways better, and that yer as you said EQ holes are not always needed but in some cases they are, like mine for example.

lol soz i was just saying this so that no1 would see your post and think thats exactly how its gotta be.

peace man
soz for the troubles earlier

~chaos
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Unread postAuthor: spudgunnerwryyyyy » Tue Oct 23, 2007 6:08 pm

Put it in a tee that houses a pipe that is atleast 15mm larger than the sealing pipe/ barrel. or else the piston will not actuate as well as you want. PM Mr. Crowley as he lives in New Zealand and can help you more with metric than I, but have made piston valves and i know that you need at least a 15mm larger tee than the sealing face.
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Unread postAuthor: watto » Tue Oct 23, 2007 10:20 pm

chaos wrote:ok... this topic really took off, wasn't trying to burn you man soz, just pointing out that everything can be different when it comes to piston valves.

my point was having a big pilot valve, is not aways better, and that yer as you said EQ holes are not always needed but in some cases they are, like mine for example.

lol soz i was just saying this so that no1 would see your post and think thats exactly how its gotta be.

peace man
soz for the troubles earlier

~chaos


When I said no equalization hole I was referring to his specific piston not every piston but I see what you mean, as for pilot valves with a gun like his I don't know how a big one couldn't be better, but I imagine you would know a lot more than me on the subject.

chaos wrote:soz for the troubles earlier


No troubles man I was just joking around :lol: :lol: :lol:

(BTW Pics of my first piston cannon coming within days: 50mm chamber 15mm barrel ~Sch80pipe = carnage)

WATTO
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