16 replies to this topic

[gohavefun]

Okay here's the deal I'm making a homemade and I already went and got the stuff for it, i think I messed up. I bought plumbers putty when I ment to get goop. Is there a diffense and/or can putty be put under presser( it's an air gun with a tire nossle and pump)

[Broderick]

depends on what you're doing. Goop is good for sealing up leaks and creating a bond between things. I prefer it to JB weld due to the lack of mixing, which is good. Putty is good for adding on to things. (BBB catch for example.)

Edited by Broderick, 05 April 2010 - 10:33 PM.

[gohavefun]

It's going to look something like this http://nerfhaven.com.....iest homemade

[Draconis]

You definitely want to get something which is an adhesive, rather than a sealant. Plumbers putty is a sealant, and not a glue of any type. Take it back to the store.

[Lion]

You want PVC glue.

[Fome]

Holy fuck.

First off. PVC isn't meant to hold air pressure. It's important to understand that while it can, it's not meant to.

Second. If you're going to make it hold pressure, you NEED to solvent weld the connections.

Third. Maybe you should hold off on making a pressurized air gun until you fully understand the process and the materials you're working with. Doing this copycat bullshit while substituting materials willy-nilly is a recipe for disaster. I hope you'll forgive my lack of confidence in you, but your post quality doesn't lead me to believe otherwise.

[Lion]

I am dumb.

Edited by Lion, 06 April 2010 - 07:24 AM.

[Fome]

K. I'm not going to go into this because, honestly, I probably can't explain it as well as others could.

Water pressure and air pressure are different. Pressure ratings on PVC pipe do not apply to air pressure. In fact, it's ILLEGAL in many states for PVC pipe to hold pressurized air for construction purposes. You should really start researching things before blindly stating them on the internet, ESPECIALLY when it concerns safety.

Bottom line: 100 PSI of air stores far more energy than 100 PSI of water. Your PVC pipe is much more likely to explode violently if it's filled with air rather than water.
PVC isn't designed to hold pressurized air. It's not impact resistant, it gets brittle in the cold and malleable in the heat, and it shatters (think frag grenade) instead of splinters like ABS when it breaks.


Tangent: Everyone always talks about "the dangers of nerf", and some dumbass getting shot by a cop because he spray painted his maverick black. Unlikely. The biggest danger in this hobby is going to be some unsupervised child that either a.) fucks himself up on a bandsaw, b.) succumbs to the various noxious fumes involved in modding nerf guns, or c.) blows himself up by hooking his shitty PVC hard tank/homemade up to an air compressor.

Edited by Fome, 06 April 2010 - 04:00 AM.

[Lion]

I am dumb.

Edited by Lion, 06 April 2010 - 07:24 AM.

[zaphodB]

No. The difference between 100psi of air and 100 psi of water is that wader does not compress. A pipe full of water at 100 psi has pretty much the same volume of water in it as a pipe full of water at 0 psi. On the other hand, a pipe full of air at 100 psi has substantially more air in it than a pipe full of air at 0. That air will expand if the pipe is ruptured. Violently. Which is why you shouldn't fuck around with high pressure air systems unless you're very sure what you're doing.

Every single high-pressure air system is a fucking bomb, under the right circumstances.

[Lion]

zaphodB, on Apr 6 2010, 07:07 AM, said:

No. The difference between 100psi of air and 100 psi of water is that wader does not compress. A pipe full of water at 100 psi has pretty much the same volume of water in it as a pipe full of water at 0 psi. On the other hand, a pipe full of air at 100 psi has substantially more air in it than a pipe full of air at 0. That air will expand if the pipe is ruptured. Violently. Which is why you shouldn't fuck around with high pressure air systems unless you're very sure what you're doing.

Every single high-pressure air system is a fucking bomb, under the right circumstances.

Ok, you got me there, true water doesn't compress anywhere near as much as air.

[gohavefun]

Draconis, on Apr 5 2010, 08:38 PM, said:

You definitely want to get something which is an adhesive, rather than a sealant. Plumbers putty is a sealant, and not a glue of any type. Take it back to the store.

Thanks draconis that's what I needed to know. To every one else if these PVC guns are so dangerous then why do people make them all the time.
(And I'm not copying I said it would look LIKE)

[VACC]

Lion, we all deal with the fact that you are annoying, but I'm not going to put up with you poo-pooing relevant safety advice. When you don't know what you are talking about, just don't say anything.

Next time I see you doing this I'm just gonna get rid of you for good. I don't need the kind of liability created by dangerous and ignorant advice.

[Lion]

VACC, on Apr 6 2010, 08:18 AM, said:

Lion, we all deal with the fact that you are annoying, but I'm not going to put up with you poo-pooing relevant safety advice. When you don't know what you are talking about, just don't say anything.

Next time I see you doing this I'm just gonna get rid of you for good. I don't need the kind of liability created by dangerous and ignorant advice.

I am truly sorry.



I have found this manufacturers web site that explains how bad of an idea it is to use pvc for air pressure. http://www.lascofitt...mpressedAir.asp

Edited by Lion, 06 April 2010 - 07:46 AM.

[sistermol]

gohavefun, on Apr 6 2010, 03:18 AM, said:

To every one else if these PVC guns are so dangerous then why do people make them all the time.

It's not pvc guns that are dangerous.
It's pvc airtanks they are talking about. If you were to fill up a pvc airtank to much it would be like a frag grenade blowing up in your hand. (minus the fire)

And if you are wanting to make an airgun you will need PVC CEMENT not goop.

[Talio]

You know what? This thread details a lot of wild ass claims that get thrown around on this site. Specifically this one being that water pressure and air pressure are different. How about you show some fucking evidence of this? I'm no physicist, but I find it hard to believe that 100 PSI will make PVC "explode....violently." If you're gonna say some shit like that, you better back it up with something.

Oh and for the god damn record a high pressure air system is not something that's being created with a bicycle pump. If so, every bike tire in the world could potentially kill someone. What it all boils down to is that the original poster isn't going to pull this off with plumbers putty. Goop or PVC cement would probably be best. But lets stop the bullshitting.

[VACC]

Read the last two paragraphs on the page Lion linked. That's good enough for me. If you want some first hand proof I guess you could blow up a pvc pipe in your apartment; I don't have the blast shield for it.