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600 psi 3/4" QEV Launcher

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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600 psi 3/4" QEV Launcher

Unread postAuthor: Dave_424 » Tue Feb 03, 2009 8:29 am

Hey, this is my new launcher and here are the specs

Barrel: 15mm copper 1.3m long
Chamber: 22mm copper 1m long (I know they are a little small for the size of valve
Valve: 3/4" QEV
Pilot Line: 30cm of 8mm copper
Pilot Valve: Blowgun
Operating Pressure: 100-600 psi
Ammo: 11.1mm steel ballbearings
Damage: Have been able to shoot the 11.1mm ballbearing through the 2" part of a 2x6 at 500 psi from about 20 yards away (Long range in spudgun terms with no sights, for me anyway)

This launcher is VERY close in FPS and FT/LBS to a .38 special :P

The 600psi reached is from my fridge compressor
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The ammo
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The Launcher
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And the destruction to the 2x6 at 500 psi
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The 2 holes in the centre of the pic
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Unread postAuthor: Ragnarok » Tue Feb 03, 2009 8:39 am

Nice, but I'm going to reiterate a point that's going around a lot currently. UK copper is not as thick walled as US copper, so my personal recommendation is that using any bore size past 500 psi is unwise.

So for those reasons, I suggest you stick to 500 psi - at least, if you want your launcher to remain in one usable piece.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: CpTn_lAw » Tue Feb 03, 2009 8:43 am

I personnaly wouldn't push it to 600 psi...still, simple design, well made, effective placement of the required parts...a very nice job ^^ congrats Dave ;)
.38 special is almost equivalent to a .45 black-powder revolver (I know it by experience), so i bet you get considerable power ;)
moar damage, moar pics, moar vids !!!!
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Unread postAuthor: sniper hero » Tue Feb 03, 2009 10:23 am

cool simple design :D
wow high pressure
and a vid would be o great:D:D
good work
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coming: semi auto pellet sniper:D
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Unread postAuthor: Hotwired » Tue Feb 03, 2009 10:54 am

Hmm, just noticed something.

Are you using hydraulic hose and couplings to connect your compressor? I couldn't say about the quick connect but the hose looks like the black, wire reinforced stuff I'm thinking of.
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Unread postAuthor: psycix » Tue Feb 03, 2009 11:22 am

That looks powerful. You should look into that big pilot volume though.
Do you keep the hose connected when firing?
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Unread postAuthor: maggotman » Tue Feb 03, 2009 1:25 pm

Would you put any more psi in it only thing i wouldn't trust the the compression joint on the chamber blowing out but but you can het 3/4 solder on ones anyway.
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Unread postAuthor: Dave_424 » Tue Feb 03, 2009 1:44 pm

Personally, I have only used it at 600psi once and since reading your posts rag, I ony use it at 500psi. Plus the climb from 500 to 600 is a bit too much for me to wait.

The hose is a 5800 psi hydraulic hose, The quick connect it a standard one for an airline, however it is only presurised when filling, when I dissconnect it, it leaks alot so I just push it back onto the male quick connect without pulling back the collar which releases the pressure in the hose.

I would not put any more pressure in it, end of. Have you got a fetish for high pressre maggotman?

Pilot volume is reduced as much as I want it. it is only about 9 cubic cm

Will definatley get some more damage pics and vids, any target ideas?

Dave

Any more questions?
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Unread postAuthor: Fnord » Tue Feb 03, 2009 1:53 pm

I don't think I'd trust a blowgun to 600 psi. If the blowgun fails, the gun fires. If you don't want to change it, I'd suggest putting a 3/8 or 1/2" ball valve between the QEV and the barrel as a safety. Good work other than that.

Also, I swear that's the same type of 1/4" ballvalve I just bought from ebay a while back. Nickle plated brass? I got like 10 of 'em for $20.
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 03, 2009 1:58 pm

Excellent stuff, always nice to see people pushing the envelope :)

How about visiting here for target ideas, you'll know how your launcher compares to powder burners ;)
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Unread postAuthor: Dave_424 » Tue Feb 03, 2009 2:15 pm

Cheers guys for the good responses.
Since the photos were taken, I have added a 1/4" ball valve above the blowgun. I got the ball valve from ebay aswel, they seem really common.

I have some 4-5mm thick aluminium that I will shoot, I think that some 1mm or 2mm steel might be a better test of power.

Dave

Edit: I might have to build myself Box o' truth using some 1/2" plywood and 1" spacers inbetween the sheets.
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Unread postAuthor: spudamine » Tue Feb 03, 2009 2:25 pm

Assuming this is the more commom, thinner walled table X copper pipe, you are a good 100psi below the max. working pressure (~750psi) and significantly below the burst pressure. But don't take my word for it or anybody elses, work it out for yourself, the link below (page 6) shows how to calculate the maximum working pressure for copper pipe, you just need the condition (usually half-hard) and the dimensions.
http://www.cda.org.uk/megab2/build/pub-33-copper-tube-in-domestic-water-services.pdf

As mentioned by others I would be much more worried about the fittings or blowgun failing, not to mention making sure whatever you fire out of the thing doesn't end up going through you or somebody else.
Nice cannon though :)
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Unread postAuthor: jackssmirkingrevenge » Tue Feb 03, 2009 2:38 pm

spudamine wrote:not to mention making sure whatever you fire out of the thing doesn't end up going through you or somebody else.


Valid advice, at these power levels one needs to be extremely sure that one has a good backstop that doesn't allow ricochets.

This was a ball bearing ricochet at just 110 psi, f'r chrissakes be careful.
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Unread postAuthor: frankrede » Tue Feb 03, 2009 6:21 pm

jackssmirkingrevenge wrote:
spudamine wrote:not to mention making sure whatever you fire out of the thing doesn't end up going through you or somebody else.


Valid advice, at these power levels one needs to be extremely sure that one has a good backstop that doesn't allow ricochets.

This was a ball bearing ricochet at just 110 psi, f'r chrissakes be careful.
I had a ricochet off the sidewalk from a co2 bb pistol shatter my sliding glass door. Its really ridiculous, cost me $300 to replace.
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Unread postAuthor: sputnick » Tue Feb 03, 2009 7:10 pm

I like it! it looks just like HOTWIRED's cannon, very simple yet still aesthetically pleasing, and with 600 psi you are going to knock the socks off of any target (not to suggest that the target wears socks, IE is human...)

Great work mate!
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