41 replies to this topic

[SHADOW HUNTER ALPHA]

Seal off the bottom of the T-pipe that connects the tank, legs, and barrel at the part connecting the legs. Leave the legs off while you charge the tank so you can make sure the seal holds, but keep the open/sealed end POINTED IN THE OPPOSITE DIRECTION FROM YOU. This way you won't get hurt or knocked over if the seal blows out. Seal it with either a scrap section of PVC or some other pressure-resistant material, and use krazy glue, epoxy and/or PVC cement, and use a LOT of it. Check to make sure the valve is not leaking by pouring some water over the joints there and watching for bubbles as you charge it. If that doesn't work, PM me or post what still did/didn't happen.

[CaptainSlug]

If you are filling the tank of the gun with a compressor you will need a gauge on the tank of the gun, and a check valve inbetween the compressor and the gun tank.
I'm bringing this up because it wasn't mentioned anywhere else.

Edited by CaptainSlug, 29 October 2006 - 07:38 PM.

[Dr Nerf]

I know I have said similar things to other people (mostly about PVC primer though), but it appears (based on the pictures) that you did not solvent weld it together or at least not use PVC primer. If it is not cemented, it will never hold pressure. And if PVC primer is not used, it will eventually leak.

Quote

I took of the legs but still the thing just wont get to any pressure.

Again, did you PVC cement it? If it was cemented, the legs couldn't be removed. It will just leak if it is not cemented.

If you did PVC cement it but did it cleanly, did you leave the valve open by accident while filling it with air? It could also be a bad input valve. The only way to fix that is to use a check valve and put the other input valve after it as CaptainSlug recommended.

[ShadowSniper]

Also probably would have been wise to use the purple pvc primer too, it makes a much better seal.

[Sponge Nerfer]

Dr. Nerf, yeah I found the problem, the thing leaks. I did use pvc cement but I did not use it well enough. The joints are sealed just enough so I cant get the off but not well enough so they leak. How can I fix this?

-sponge

[SHADOW HUNTER ALPHA]

It might be wise to coat all of the joints in the tank area and near the barrel and ball valve with some of the purple PVC primer, and then seal it up with a second coat once dry. The second coat is not necessary, but it will act like insurance to make sure nothing leaks for a while. Once the primer is dry, then charge the tank again while pouring water over all the joints. Look for any bubbles, and mark any joints where bubbles are coming from. Then go back and seal those again with more primer. If this doesn't work, then you might have an even worse problem that I thought.

[Flaming Hilt]

Put the thing in a bathtub.

Otherwise if you wanted to make the tank smaller, I'd just reduce the current tank to a few inches. Then if you still want it to look big and cool, just glue the remnants of your tank onto the back (use a coupler that's the size of your endcaps).

[Dr Nerf]

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It might be wise to coat all of the joints in the tank area and near the barrel and ball valve with some of the purple PVC primer, and then seal it up with a second coat once dry.

Right now the primer would do nothing. The primer is supposed to go on first before the cement, so putting it on now would do nothing. It is probably leaking because it doesn't appear as if primer was used before (or possibly because not enough cement was used). I don't know how many times I have to say this: primer is needed. It cleans the pipe and also (as a plumber once told me) removes a special "glazing" that was put on to protect it during shipping. If you don't put on primer, you are literally bonding the pipe to the "glazing", dirt and grime, and not the pipe.

Flaming Hilt basically told you what you need to do. Fill it up and put it in a tub (with water of course). The leaks would bubble to the surface. Mark where they are. If it is too large, just get a water bottle. Spray water on areas that could leak while it is filled with air. If water bubbles to the surface, mark it as having a leak there.

Next, you should try to fix the leaks. The only guaranteed way to fix this is through fillet welding. Putting epoxy or PVC cement on the effected areas may not work well. I made a post over at Super Soaker Central about fillet welding a while ago. Basically, it is literally melting the pipe with a torch to close all leaks. This scan from a plumbing book describes fillet welding throughly.

Edit: If you ever get the chance to repair it, be careful. I would never use unrated sewer pipe as a pressure chamber; it's just like asking for trouble.

Edited by Dr. Nerf, 01 November 2006 - 05:59 PM.

[ledzepp2994]

Ok I see the pictures.
But the real reason that I’m posting is to tell you that I would suggest getting something bigger than your air tank and wrapping the air tank in it. This is so that if it does go boom you will not get shot full of PVC shrapnel then. Something as simple as a wood box or if you have a big Kevlar blanket that would do the trick also… but I think that you are right that could be very cool if it worked. But I know you might be responsible and not point it at some one but it’s the other few idiots in this world who might think that it would be funny or something. So I would watch out for how many in-depth instructions you post on here. But that’s just me. Good luck dot get your self killed. And have fun.

[SHADOW HUNTER ALPHA]

Alright, Dr. Nerf, Flaming Hilt, and I all agree on one thing: submerge the joints in water to find out where the leaks are. Then mark those areas. Dr. Nerf has a good point, though. My idea to smother the joints with primer and PVC cement was based on the assumption that at least part of the joints could be exposed by sliding them apart. Since it looks like you can't do that, listen to Dr. Nerf and "fillet weld" the pipes. Since you may not have a blowtorch available to you, a lighter might do the same thing, but it will take longer if it works at all. Then again, I have never actually gone out and done a fillet weld, so I could be completely wrong with the lighter bit. Nonetheless, you should try it and seal everything up, and then go back and put more water on the joints once they cool off enough for you to fill the tank up again. If you did the welds right, there shouldn't be any more leaks. If there are, then you either didn't weld all the joints, or you tried to pressurize the tank while a joint was still hot and "molten" and blew it out again.

[Sponge Nerfer]

Ok, fillet welding does not seem like the best option for me right now. I do not have a blowtorch and if I went out, got a lighter, and started welding plastic my parents would kill me. I am going to try harder to pull apart the connections using a screwdriver or something. If thatd doesnt work then I will have to think of something else.

-sponge

[SHADOW HUNTER ALPHA]

Be careful with that screwdriver, sponge. If you notice that it's taking too much effort to pull the pipes apart, then stop trying before you jerk it too hard and break a joint. I didn't think you had a blowtorch, so I started thinking of some other options after I signed off last night. What if you put some primer around the joint and then super glued some rubber strips around the pipe connections. Chances are this won't work, but it was a last-ditch effort to do something before a major screw-up could occur.

Seeing as you can't fillet weld, I guess you'll probably just have to keep trying to pull the pipes apart.

P.S.: What did you use to glue the pipes together, and how much of it. This could be affecting what choices you have to fix this problem.

[Sponge Nerfer]

Whew! just got back from trick-or-treating (yay holloween)!

Ok, as far as rubber goes, turns out I have some tire repair kits that I might be able to use!

I am going to try all of these things tommorow but now im going back out to get some more loot

happy halloween!

[One Man Clan]

Why has this topic gone on for 3 pages?

[Capt Crunch2319]

I think your cannon is cool for the bigger wars when you have lots of people.

[ledzepp2994]

Use more goop that’s all there is to it fill the seal and make it so that there is no leaking just lather the pvc cement on and do it thick.

[Sponge Nerfer]

Ok, I gave up on this project and did this, I have learned a good leson from this failure and have now managed a success. Thanks for all your advice, and help.

-sponge