Props Promo Tee-shirt Delivery Unit

[Loess]

Hey Loess, do you think a spudzooka could fire a shirt? I have a few lying around somewhere...

It probably could, but I always had some sticky residue build up from the hairspray that might cause problems for the shirts. I'd also be a bit worried about the velocity that the shirt would come out at, we don't want it going into the crowd too fast.

 

[Achille]

lol, death by flying T-shirt. If nothing else, it'd be a unique way to die.

 

[Samuray]

With that kind of set up for a spud gun (with the sprinkler valve release) you can totally use PVC for the holding tank. Even if you don't have a pressure safety release, a piece of schedule 40 2-inch PVC can hold pressures up to 240 PSI, I believe. The valve is only rated to 125-150. The valve will release air before it got to a high enough pressure to burst the PVC.

Using schedule 40 PVC is the key.

 

[Loess]

With that kind of set up for a spud gun (with the sprinkler valve release) you can totally use PVC for the holding tank. Even if you don't have a pressure safety release, a piece of schedule 40 2-inch PVC can hold pressures up to 240 PSI, I believe. The valve is only rated to 125-150. The valve will release air before it got to a high enough pressure to burst the PVC.

Using schedule 40 PVC is the key.

Yes, sch40 pipe is rated to 240 psi, but that's with water. There's a reason that "NOT FOR USE WITH COMPRESSED GASSES" is printed on the side of the pipe right next to the pressure rating stamp.

PVC breaks into sharp shards, and I don't want to be holding something that could turn into very sharp bits of high-velocity death with a safety factor of 2, when it's just as easy to get parts to build a pressure chamber with a much higher safety factor, and a more resilient material.


I've built air cannons with PVC pressure chambers, then I went to school to be a Mechanical Engineer. Now, I know not to do that.

 

[Samuray]

Yes, sch40 pipe is rated to 240 psi, but that's with water. There's a reason that "NOT FOR USE WITH COMPRESSED GASSES" is printed on the side of the pipe right next to the pressure rating stamp.

PVC breaks into sharp shards, and I don't want to be holding something that could turn into very sharp bits of high-velocity death with a safety factor of 2, when it's just as easy to get parts to build a pressure chamber with a much higher safety factor, and a more resilient material.
I've built air cannons with PVC pressure chambers, then I went to school to be a Mechanical Engineer. Now, I know not to do that.

I guess it would be unwise to say that it's unconditionally safe, depending on how much you think the pipe is going to be beaten up. I'm not going to go and change my cannon's pressure chambers, though. I just make sure to check for cracks and dents between filling it. Steel is readily available, but it has a tendency to be more expensive. Another alternative for air cannons, if you don't mind paying a little more for a lower weight than steel, is ABS plastic (which does have ratings for compressed air and comes in the same sizes as normal PVC). The difference between ABS and PVC is that ABS is made to split instead of splinter in the case of failures.

And like I said, I don't know about your sprinkler valve, but mine starts to let air out long before I get it up to the 125 PSI that the valve is rated for.

Also, I didn't make my cannon for parades and public events. How's yours coming along anyway?

 

[GremlinLord]

Since I only seem to get around to replying when someone is making things that go boom I'll recommend someone look up what the sch40 rating really means. It isn't a measure of the pipe's psi rating, its a measure of pipe wall thickness. Your pipe should have this on it if it's relatively safe: NSF-PW Sch 40 (or 80,120, etc) XXXPSI @73F. The key is the NSF-PW. All the fittings you use should have NSF-PW too. Just for good measure since cannons are much more fun when they shoot rather than blow up, here's a link, enjoy.

http://www.spudfiles.com/spud_wiki/index.p...ssure_Rated_PVC

 

[Loess]

Since I only seem to get around to replying when someone is making things that go boom I'll recommend someone look up what the sch40 rating really means. It isn't a measure of the pipe's psi rating, its a measure of pipe wall thickness. Your pipe should have this on it if it's relatively safe: NSF-PW Sch 40 (or 80,120, etc) XXXPSI @73F. The key is the NSF-PW. All the fittings you use should have NSF-PW too. Just for good measure since cannons are much more fun when they shoot rather than blow up, here's a link, enjoy.

http://www.spudfiles.com/spud_wiki/index.p...ssure_Rated_PVC

That's a really good point, Gremlin. That wiki page also had an important tip. Make sure you use pressure rated fittings!

Samuray, ABS is a good bit safer than PVC, but I still can't recommend it. (We have to be careful about Lawyers )

I'm going to get a bit of time off work next week, so I should be able to finally get some armor and weapon builds done, and then I can put time back into this project.

 

[Samuray]

That's a really good point, Gremlin. That wiki page also had an important tip. Make sure you use pressure rated fittings!

Samuray, ABS is a good bit safer than PVC, but I still can't recommend it. (We have to be careful about Lawyers )

I'm going to get a bit of time off work next week, so I should be able to finally get some armor and weapon builds done, and then I can put time back into this project.

Yeah. I wouldn't want to recommend this type of stuff to everyone. I guess I should have realized that this was more of a tut for everyone. I hope you didn't take my comments as being too argumentative.

gremlin - That's a good point. Sch40 3" PVC is rated lower than 2" PVC because the thickness of the wall is the same and has less structural integrity because of that.

 

[Soul Drinker]

That is pretty freaking awesome Loess...but you scared the crap out of your poor cat. Or whoever's cat that was..lol. Can't wait to see it work in a SPNKER!!

 

[Loess]

<div class='quotetop'>QUOTE(Loess @ Jun 23 2009, 09:18 AM) <{POST_SNAPBACK}></div><div class='quotemain'>That's a really good point, Gremlin. That wiki page also had an important tip. Make sure you use pressure rated fittings!



@Samuray, ABS is a good bit safer than PVC, but I still can't recommend it. (We have to be careful about Lawyers



I'm going to get a bit of time off work next week, so I should be able to finally get some armor and weapon builds done, and then I can put time back into this project.



Yeah. I wouldn't want to recommend this type of stuff to everyone. I guess I should have realized that this was more of a tut for everyone. I hope you didn't take my comments as being too argumentative.



@Gremlin - That's a good point. Sch40 3" PVC is rated lower than 2" PVC because the thickness of the wall is the same and has less structural integrity because of that.

I didn't see those as argumentative, I was mostly trying to limit liability for myself and the 405th (I really don't want to get anyone sued).

That is pretty freaking awesome Loess...but you scared the crap out of your poor cat. Or whoever's cat that was..lol. Can't wait to see it work in a SPNKER!!

Yeah, Guy didn't like the valve squeal at all, he didn't stop running 'till he got into the barn.



I haven't left this project completely, even though I haven't posted in a while I've still worked on it on and off. I think I found a fill valve to use in the next cannon I'm going to build to test scale factors.

 

[bevbor]

[media]http://www.youtube.c...h?v=0fgEu7mQKhY[/media]​

 

[Loess]

Hahaha, great vid.



Did anyone else cringe every time the kid looked down the bore of that gun?