12 replies to this topic

[Sponge Nerfer]

I have been working on a project involving a triggered burst valve. I just got to home depot yesterday and put togethor most of the valve today. All thats left to do for it is put on the shrader and im done with the valve. Here is what it looks like.



This is a decent description of how the valve works that I put up earlier today.

The idea is to use an extremely powerful valve + large and high power tank to get a very powerfull shot. The catch is that in order to get all of this power it GREATLY lowers the rof of the gun. Many people I am sure will say that the terrible rof of the gun makes it a terrible weapon. This only the first stage of my project. After making this gun I have plans to creat a semi-automatic side arm that will compensate for the terrible rof of this gun and make it very usefull.

Questions, comments

-Sponge

[Brass]

If you used a stronger material than tinfoil you could have a much stronger gun.
Maybe try a rubber membrane?
I am very curious as to what this will be developed into.

[badger]

I learned that 3 layers of a heavy duty trash bag works best. I had a burst disk gun awhile ago and that worked best. Tinfoil will not give the burst effect that you are looking for (it will tear open a much wider breech, causing the air to be more diffused) and rubber will hold back too much pressure. The PVC will explode before the rubber is breached.

[The Crackerjack Man]

You look like you know what your doing. And if you want a good burst disk try useing somthing such as pieces of cut out milk jugs. They hold plenty of pressure before popping.

And off topic: are you part of a spud gun site too?

[LastManAlive]

Aside from what the materials you chose and how it will (or SHOULD) work, it's good engineering. Maybe a better design and the research stage could have taken longer to know for sure how much each burst disc can take and when they would give. Numerous trials however will cure that though.



If you are into making a Nerf Milsim movie, this would be cool to use as an intro airtillery type gun. Have 3 people loading it and getting it ready to fire with the background of someone receiving firing coordinates...could be something fun to waste a precious 15 minutes of space on your memory card and a good hour to waste throwing in music. Have fun with your contraption.

[Sponge Nerfer]

Well thanks for all of your quick responces. Most of it seemed positive which is always nice, here are my answers to some of you questions and comments.

1. Rubber membranes and cut out milk jugs seem like they would require far too much power to burst. Im not looking to kill bulls at 2000 yards. However badger's advice of using heavy duty trash bags seems possible. I plan to just have fun with trial and error for a little while until I find something perfect.

2. Last man alive, not too sure what you were talking about with your video plan. Dunno what a Nerf milsim movie is, if you want to try to explain it to me that would be fine.

From all of your posts I got the idea that you all wanted to have a better idea of what the gun might look like in the end. So I decided to put a little more meat on its bones (make the tank and put it on the valve) to give you a better idea of what im shooting at.

Here she is!



Next to a titan rocket for size comparison:



It clearly still has some work do be done, I need shrader valves for both the tank and the tiny burst chamber. Also it needs a barrel. None the less this project is well on its way.

Questions, comments?

-sponge

[The Crackerjack Man]

What size pipe are you using for the airtank?

[Torque]

What size pipe are you using for the airtank?

He's using 1 1/2" SCH 40 pipe going into a coupling and then a reducer bushing that converts from 1 1/2" to 1" pipe i believe. You can see the label on the air tank in the second picture of this thread.

Also Sponge_Nerfer, the piece of metal at the end of your blow gun can actually unscrew from the rest of it. (The small piece of threaded pipe with 2 holes in it right below the hook that you cut off) It might be worth taking this off as it could improve airflow as it increases the ID of the air outlet. If it does improve airflow then the pilot air will leave your union chamber faster, the burst discs will take less time to over pressurize and rupture, and there may be a slight increase in overall actuating time and performance from your valve. Or you could take it off just to make the handle more compact, I was just informing you that it was removable as i did not know that piece was removable on my blow gun and after i removed it, i found many uses for the threads that were exposed.

[Sponge Nerfer]

So today I sawed out a breach for the gun and got the whole barrel assembly working.

Here is most of the gun put togethor:



Things are going well, but I need a surefire way to get a shrader valve to seal onto 1" pvc pipe. If anybody knows of a good way to attach shardervalves to pvc, and get a nice seal, PLEASE let me know. One leak could really mess up this gun.

-sponge

[The Crackerjack Man]

If you are using a pre-cut one were out of a box it has threads just drill a hole, the size of the sharder valve, teflon the screws, and then screw it in. If your using one that you cut out of a bike tire, ect., just do pretty much the same thing. Drill a hole the size of the valve and slide it in from the back end of the end cap. Either way I find it easy to just use an end cap. I have used it on all my home mades and its worked fine.

[Torque]

If you are using a pre-cut one were out of a box it has threads just drill a hole, the size of the sharder valve, teflon the screws, and then screw it in. If your using one that you cut out of a bike tire, ect., just do pretty much the same thing. Drill a hole the size of the valve and slide it in from the back end of the end cap. Either way I find it easy to just use an end cap. I have used it on all my home mades and its worked fine.

You could also go to a shop and buy or get free valves for car tires, thats what i did. I went to a repair shop and the guy just gave me several for free, as they have them lying around usually. To install those kinds of valves you simple drill a hole and push them in to create a seal, no sealant/glue etc. is required at all.

[Sponge Nerfer]

Alright, I got a lot of work done over that past couple of days and pretty much finished the gun. I just finished off a few easy seals and now the gun is fully operational. I decided to take testing slow, today I only looked into which materials burst well and at which psi they did so. After having a lot of fun setting off different combinations of materials (4 sheets of tinfoil goes off at 100 psi, BANG, pretty much shook the whole neighborhood ) I discovered that two sheets of tinfoil goes off around 40 psi, just what I wanted it to be. Here are some pictures of my "test station" and the busted pieces of tinfoil.





I will start messing with the triggering system soon enough.

Questions? Comments?

-sponge

[The Crackerjack Man]

The gun looks great. Any kick back?