My second pneumatic (This one didnt blow up)

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.
GrafixBoy
Private 2
Private 2
Posts: 25
Joined: Fri Sep 21, 2007 5:55 pm

Sat Sep 29, 2007 6:32 pm

This is my second try at a pneumatic. This one is all steel. I had a bucket of pipe fitting parts so it was like putting together a puzzle without knowing if all the pieces are there. I wish I could say there was a "plan" when I built it but there wasnt. This is what I had available. The barrel is 1"X24"

It shot a 6 inch nipple wrapped in tape about 50 or 60 yards at about 50psi. There are some leaks but i dont know where they are coming from because i cant hear them. When you put the air in, when its full will it stop or keep compressing it in there? I have a pressure gauge on it and when it gets to about 100 psi i stop. I dont know how much I can put in there. Ever since that death trap I made last time blew apart on me (it wasnt steel) Ive been kinda "gun shy".

I know a ball valve isnt the best thing to be using but its what I had. Please give me your thoughts.
Attachments
allsteel3.jpg
User avatar
iPaintball
Corporal 2
Corporal 2
Posts: 695
Joined: Sun Mar 04, 2007 8:37 pm

Sat Sep 29, 2007 6:37 pm

Sweet cannon dude. I love it when you can make entire guns from spare parts! When using larger diameter pipe nipples like that, it works better to use pipe thread paste or silicone.
Summer Projects:
CO2 tank hybrid: Gotta fix the meter :(
Cane gun: Needs a pilot/fill setup
1.5" piston valve gun: Almost done
Novacastrian
Staff Sergeant 2
Staff Sergeant 2
Posts: 1603
Joined: Sat Aug 11, 2007 6:59 pm
Been thanked: 1 time

Sat Sep 29, 2007 6:40 pm

Use soapy water to detect leaks, mix some detergent with water and put it in a spray bottle, pressurise the gun and spray the water onto the joints, bubbles will tell you were your leaks are.
As for the gun it looks sick nuts :P I'm thinking that it would be a tad on the heavy side though! At least it will last forever.
Good luck with finding those pesky leaks.
America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.
e1337
Specialist
Specialist
Posts: 110
Joined: Mon May 28, 2007 8:00 pm
Location: Florida

Sat Sep 29, 2007 6:41 pm

Im not sure how you can have leaks on threads when you have teflon tape in them. Try submerging in water (aka pool) and retape the treads that have bubbles coming out. As for advice, I would make a barrel-sealing piston and take it up to 150psi.

Peace,
E1337
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

Sat Sep 29, 2007 6:43 pm

That looks fairly interesting, but if you insist on using a slow valve, you should use a longer barrel (preferably smoothbore, not steel). What is the chamber volume on it? If you have the means, you should take it up to about 300-500 psi if you want fairly decent performance with a short barrel. What is the point of that union on the end of the chamber? Is it used as a safety valve?

PVC guns can be safe, but in my opinion, they require a higher level of skill, and are always slightly more prone to disasters. Turbohacker's dad lost an eye to a relatively well made PVC pneumatic yesterday, when the regulator failed, or something.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
User avatar
SpudUke5
Sergeant
Sergeant
Posts: 1099
Joined: Tue Sep 04, 2007 10:16 pm

Sat Sep 29, 2007 6:47 pm

well first things first, if you have leaks try to fill it and then shut it of you compressor and listen closely. Then make sure you used teflon tape on each of your threads, and dont be shy on your threads, tape them good. then rescrew them once you apply tefon tape to them. There is also some kind of glue or something you can put on threads so they dont leak. I saw this at Ace hardware and my dad told me that it does the same thing as teflon tape. But just use teflon tape to be sure. And you can pump it enought to 300 psi +. So dont be shy. Once there are no more leaks, fill it up. You can get alot of power out of that. :wink:
User avatar
noob of noobs
Specialist 3
Specialist 3
Posts: 320
Joined: Tue Jun 12, 2007 8:04 pm
Location: Illinois, Skokie

Sat Sep 29, 2007 6:55 pm

Major improvement! Everything looks good, except that if I were you, I'd both replace the valve, and make all the parts larger or equal to the barrel's diameter, just since it's more efficient. Also, I'd recommend shortening the distance between the barrel and valve to cut down on dead space that'll probably decrease power. I'm not sure how galvanized steel reacts with water, so I'm not sure submerging it in water would be all that wise. A good ear can probably do the trick.
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

Sat Sep 29, 2007 7:00 pm

I have found that for 2" steel joints, you should use at least 60" of teflon tape for a good seal. Don't be shy with it. If you can, you could dunk the whole launcher in a tub of water or some other clear liquid to detect leaks easily.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
GrafixBoy
Private 2
Private 2
Posts: 25
Joined: Fri Sep 21, 2007 5:55 pm

Sat Sep 29, 2007 7:37 pm

DYI wrote:What is the chamber volume on it?

What is the point of that union on the end of the chamber? Is it used as a safety valve?
Haha. My brain cant calculate volume. but they are 3" in diameter. I cant remember the length. The union on the end of the chamber is what i had to use to cap off the end. There is a threaded cap piece screwed into that. Pardon me if I dont know the proper terminology of these parts.
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

Sat Sep 29, 2007 8:24 pm

Are you sure those parts aren't 2" and not 3"? They look awfully small for 3" pipe and fittings.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
GrafixBoy
Private 2
Private 2
Posts: 25
Joined: Fri Sep 21, 2007 5:55 pm

Sat Sep 29, 2007 8:51 pm

i think they are 2" my bad
iknowmy3tables
Staff Sergeant
Staff Sergeant
United States of America
Posts: 1596
Joined: Fri Dec 15, 2006 3:57 pm
Location: maryland
Has thanked: 3 times
Been thanked: 9 times

Sat Sep 29, 2007 9:01 pm

man that is crazy you got the coupler thats just there for no reason and the union used as an end cap,
heck I'd probably come with a similar result since I don't have any NPT taps n dies
GrafixBoy
Private 2
Private 2
Posts: 25
Joined: Fri Sep 21, 2007 5:55 pm

Sat Sep 29, 2007 9:23 pm

iknowmy3tables wrote:man that is crazy you got the coupler thats just there for no reason and the union used as an end cap,
heck I'd probably come with a similar result since I don't have any NPT taps n dies
i used what i had. didnt buy anything
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

Sat Sep 29, 2007 10:22 pm

Want any thing that resembles performance to come of it?
I say you throw in some dry ice and hot water into the chamber via the union and wait a while then blast away.
that should help with your dead space and short barrel.
Current project: Afghanistan deployment
nivekatoz
Specialist 2
Specialist 2
Posts: 237
Joined: Sat Nov 25, 2006 7:05 pm

Wed Oct 03, 2007 6:07 pm

That thing must weigh a ton.....Try to use sch 80 aluminum pipe
Post Reply