What I have right now?

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
User avatar
Rudesill Ballistics
Private 3
Private 3
Posts: 57
Joined: Mon Jun 13, 2005 7:42 pm

Sat Sep 01, 2007 8:41 pm

but the problem: I pump the crap out of it then it launches whatver i want and goes 2 feet. The air pump dont be able to put enough pressure there for crap. how do I fix this? Air compressor?

How long is your barrel and how many PSI in the gun?
sniperx117
Private 2
Private 2
Posts: 38
Joined: Fri Aug 24, 2007 10:47 pm

Mon Sep 03, 2007 9:51 pm

its a 12"Barrel

I have no idea for the Psi
User avatar
frankrede
Sergeant Major 2
Sergeant Major 2
Posts: 3220
Joined: Thu Jul 20, 2006 9:47 pm
Has thanked: 1 time
Been thanked: 1 time

Mon Sep 03, 2007 10:02 pm

sniperx117 wrote:Ok. Teflon it is.


I did it. All wraped up no leaks. It pumps and holds air!

but the problem: I pump the crap out of it then it launches whatver i want and goes 2 feet. The air pump dont be able to put enough pressure there for crap. how do I fix this? Air compressor?

HELL NO! The cheapest 1 I ve ever found was like 100 bucks.

Plus i dont want to lug it around on a paintball feild.
\
Co2 looks like a must. Nut how? I need a steel hose, asa, and 1/8 connector. but thats gona cost me.

CRAP! :shock: :evil: :?:
Wan to know why you gun doesn't shoot good
Well heres a clue, go look at other launchers, and then look at yours.
(hint hint) the barrel(hint hint)
Current project: Afghanistan deployment
User avatar
Rudesill Ballistics
Private 3
Private 3
Posts: 57
Joined: Mon Jun 13, 2005 7:42 pm

Mon Sep 03, 2007 11:27 pm

Do you have a tire gauge you could use to test PSI?

You have a 12 inch barrel, unknown PSI and a ball valve. Not a good selection for optimum performance.
User avatar
noob of noobs
Specialist 3
Specialist 3
Posts: 320
Joined: Tue Jun 12, 2007 8:04 pm
Location: Illinois, Skokie

Tue Sep 04, 2007 6:37 am

Ball valves suck. I'd deffinitley upgrade. My friend's pneumatic used a ball valve, and he never got it to open successfully. Always went too slow to get any real performance. Deffinitley get a pressure gauge too. That's a definite must.
sniperx117
Private 2
Private 2
Posts: 38
Joined: Fri Aug 24, 2007 10:47 pm

Tue Sep 04, 2007 9:33 am

I think I can make the Ball Valve work, But the barrel has to be longer? It doesnt look like it will help.
User avatar
DYI
First Sergeant 5
First Sergeant 5
Antigua & Barbuda
Posts: 2862
Joined: Sat Jul 07, 2007 8:18 pm
Location: Here and there

Tue Sep 04, 2007 10:09 am

Ball valves open very slowly. Unless you are using really high pressures (400+ psi), you won't be able to get decent performance with a short barrel. Worse still, the length of barrel you would need to get decent power out of it would make it rather impractical.

My recommendation is that you get a faster valve, use at least 200 psi (because your chamber is so small), and make the barrel at least 2' long. If you insist on sticking with the ball valve, spring load it with a really strong spring, and use at least 300psi or more. I would definitely invest in a CO2 setup if I were you. It will make the cannon portable, easy to charge, and shouldn't cost more than $150 or so in total.
User avatar
Rudesill Ballistics
Private 3
Private 3
Posts: 57
Joined: Mon Jun 13, 2005 7:42 pm

Tue Sep 04, 2007 4:09 pm

When you open a ball valve, it releases the air SLLLLLOOOOOWWWWLLLYYYYYY.

Your projectile is already gone by the time it's fully open, with a 12 inch barrel, it's probably gone before the valve is a quarter of the way open.

That's constricted flow, and it's bad for cannon. You want the valve to open fast, so most of the air released is at full power.

Some have worked up a thinga-ma-jig to spring open ball valves quite fast.

A longer barrel will help, I used to use a 79" barrel and I got great performance out of it just using 40 PSI. It used more of the chamber's air to accelerate the projectile.
sniperx117
Private 2
Private 2
Posts: 38
Joined: Fri Aug 24, 2007 10:47 pm

Tue Sep 04, 2007 9:46 pm

Ok. Make the barrel longer and that will help. And as for the ball valve, its prety smooth. I can lube it and everything.

As for CO2, thats a definate. Il use a stell braided hose connecting to an asa with a 9 oz pb tank. The hose will go into a standard 1/8th straight fitting connetcting with the chamber and the chamber will fill. I ll use an on of co2 asa. After that, open up the ball valve and it will rip.

Will a 2' barrel be enough? personnaly id love to have it like 3-4 ft but my home depot doesnt carry that long unless you cut. Parents dont want to make it a big deal.
sniperx117
Private 2
Private 2
Posts: 38
Joined: Fri Aug 24, 2007 10:47 pm

Tue Sep 04, 2007 9:47 pm

and the psi of co2 is like 800 psi i think thats alot of pressure
User avatar
blind909
Corporal 4
Corporal 4
Posts: 828
Joined: Thu Aug 02, 2007 6:06 pm
Location: Las Vegas, NV
Contact:

Tue Sep 04, 2007 10:52 pm

but galvanized steel should be able to handle that, lots of people use unregulated Co2 in galvanized steel, just make sure your ball valve can handle that much pressure.
sniperx117
Private 2
Private 2
Posts: 38
Joined: Fri Aug 24, 2007 10:47 pm

Wed Sep 05, 2007 5:22 am

The ball valve is brass/metal
Orpackrat
Specialist 2
Specialist 2
Posts: 254
Joined: Mon Mar 19, 2007 4:11 pm
Location: Oregon Coast

Wed Sep 05, 2007 5:47 am

2' of barrel is more than enough when using unregulated Co2. I recommend a second ball valve before the chamber for better efficiancy. When it comes to cost, I have built a cannon for under $100. Even for how slowly the ball valve opens, with unregulated Co2 and a decent sized valve to fire, you should have no problems with range and power, just open the valve as fast as you can (spring assist not needed).
K.I.S.S. "Keep It Simple ******"
sniperx117
Private 2
Private 2
Posts: 38
Joined: Fri Aug 24, 2007 10:47 pm

Wed Sep 05, 2007 1:16 pm

on/off will work as the valve
Orpackrat
Specialist 2
Specialist 2
Posts: 254
Joined: Mon Mar 19, 2007 4:11 pm
Location: Oregon Coast

Wed Sep 05, 2007 1:57 pm

sniperx117 wrote:on/off will work as the valve
Is that on/off the twist down type or ball valve type, the twist downs bleed the pressure from the line (launchers chamber), the ball valve type will be fine.
K.I.S.S. "Keep It Simple ******"
Post Reply