a 3,000 psi cannon

Hubb · Sat Nov 03, 2007 4:41 am

grumpy wrote:yes i will be using hpa. from playing paintball i've got scuba tanks , scba tanks and paintball tanks along with a 5k psi compressor, also a couple of 20lb co2 tanks

Helium could get expensive, but grumpy plans on using HPA (high pressured air). It should be fairly cheap, especially since he has his own compressor.

Marco321 · Sat Nov 03, 2007 4:43 am

hubb017 wrote:
grumpy wrote:yes i will be using hpa. from playing paintball i've got scuba tanks , scba tanks and paintball tanks along with a 5k psi compressor, also a couple of 20lb co2 tanks
Helium could get expensive, but grumpy plans on using HPA (high pressured air). It should be fairly cheap, especially since he has his own compressor.

Ahh yes, i missed that part

. My bad

Then it will nice and cheap

grumpy · Sat Nov 03, 2007 5:48 am

the only cost will be the air fittings and pnumatic piston to operate the valve i already have everything else.
as for the noise , my neighbors are cool, i have several large calibre rifles that i shoot in my backyard. oh and the only thing behind my house is about 300 acres of swamp.

Marco321 · Sat Nov 03, 2007 6:25 am

grumpy wrote:the only cost will be the air fittings and pnumatic piston to operate the valve i already have everything else.
as for the noise , my neighbors are cool, i have several large calibre rifles that i shoot in my backyard. oh and the only thing behind my house is about 300 acres of swamp.

Ok cool, your lucky.

I hope to see it soon.

666lucky693 · Sun Nov 04, 2007 9:21 am

that thing is going to be ridiculous it will probably destroy the ammo

HaiThar · Sun Nov 04, 2007 9:53 am

Are the chamber and barrel going to be inline with each other? Using bends of any kind would be scary. :O

Where are you getting your materials from?

grumpy · Sun Nov 04, 2007 12:21 pm

666lucky693,
i was planning on making some steel darts out of some rebar, i have some 3/8" and 1/2" just not sure wich will work better.

HaiThar,
no, i did not consider making it inline, there will only be 2 tee fittings and the valve, as it will be all welded together i did not forsee any problems. i would like to here the reasons for your concern as you might have thought of something i didn't. all the materials except for the valve came from a local supplier called mine and mill supply , they supply all kinds of stuff mostly to the phosphate mines but they will also sell to the public .

DYI · Sun Nov 04, 2007 1:46 pm

For a given length, 3/8" darts would have better penetration, but may not be as sturdy as 1/2". As long as you are shooting at targets softer than steel, there won't be any problem. I shot a 1/4" steel dart at a piece of plate steel, and it looked like a candy cane afterwards, with no visible damage to the target.

Infernal Maveric · Sun Nov 04, 2007 3:18 pm

I don't know if you have considered some kind of stand (with shock absorbers) for this monster as 3000PSI will send the gun shooting backwards like a missile. The Mythbusters made a small 3000PSI (IIRC) grappling hook launcher for their "Super Heroes" special, and when they first tested the gun, they had it on a standard camera tripod and it shot backwards smashing stuff in its path. Might be useful to watch that episode mate. Watch episode (Not sure how Illegal it is to link that.

Good luck building it and I look forward to seeing it.

grumpy · Sun Nov 04, 2007 6:01 pm

yes i saw that episode when it aired on tv was quite interesting. and as i said in an earlier post , i'll be using some old motorcycle shocks to make a mount for it.

Solar · Mon Nov 05, 2007 2:59 am

Since I think you will be happy to still have anything left of your motorcycle shocks using these specifications, you should work your way up. I know the use of a projectile anywhere near 8 oz fired from a 40mm (1.575") bore launcher with a 1" valve port at around 600psi is enough to warrant the use of them. What is the cubic feet inside your barrel? I am getting 676fps with a 32 gram POW foam rocket at only 275psi from a 40mm using a 1" valve port.
An o-ring based piston valve is rated at 1200psi with buna-N. A true bonded stopper and milled air cavity could get you higher working pressures I'm sure. Welding pressure vessels poses a long term absolute danger for stress fracturing. Do yourself a favor and invest in a 6 cubic foot SCUBA PONY bottle to achieve airflow requirements while testing the valve. (they have 3/4" npt fittings and are around 1:1 mated to a 30" 1.5" barrel. Don't forget the safety air release on this beast. I hear that spool valves are useful as high pressure triggers.

Here is a picture of the latest valve design that goes into my launcher.

rory@eclipselauncher.com

DYI · Mon Nov 05, 2007 4:18 pm

In case anyone didn't notice, the reason that the Mythbusters' launcher recoiled at high speed into a wall was the fact that the 10 pound projectiles they were firing weighed as much, or more than the cannon itself. The high pressure is not the problem. Some firearms generate in excess of 60 000 psi, and their recoil isn't uncontrollable. Just don't get stupid with your projectiles, and you should be fine.

Solar, that's a great looking piston valve. I'm in the process of designing a piston valve to operate at 2400 psi, do you think you could PM me and take a look at my design?

a 3,000 psi cannon

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