8 replies to this topic

[Jaffe]

I didn't found it with the search, so here a topic where you can place all the valve desgin's .
Greetings from the Dutch, Jaffe
PS: My first valve I had ever made.

[Flaming Hilt]

...I still don't get how that one works.

Anyways, here's my Pinch, and I'll draw up something for my pull trigger eventually.
[Thread]


With a clothespin:


EDIT: There is actually a trigger design thread but I suppose this one works for one-way valves, which are frickin' hard to make but necessary for a homemade air pump.

Edited by Flaming Hilt, 30 June 2007 - 10:50 AM.

[Torque]

Here is a QEV (Quick Exhaust Valve) I've designed. They simply work by using a diaphragm to block off the barrel until a pilot valve such as a blowgun is used to decrease the pressure on one side of the seal, forcing it to open and allow the remaining pressure to vent out of the barrel. Once the pilot valve is actuated the diaphragm seals the passage used to vent the pilot air so no compressed air is wasted. QEV valves can be used to make extremely high flow valves as well as compact overall designs as the air tank can actually shroud the barrel. This creates a simple looking overall design as you can see in the picture.



This bazooka looking design i have actually built completely but I'm still in the testing phase figuring out which diaphragm materials work best etc. I have had some successful firings but I've yet to have it set up reliably.

I also have a copper pipe homemade that uses a spring actuated ball valve. It uses a simple trigger mechanism to actuate it. I find that copper/brass ball valves work much better than pvc valves for this use because they are much easier to turn so a less powerful spring can be used. In addition to that they can handle much higher pressures that pvc pipe. I have pumped my copper homemade up to around 150 psi ( thats where my air compressor maxes out) and had it operate flawlessly. I chose this over a solenoid valve because it has the potential to be used for a high pressure CO2 or nitrogen design if needed.

[Sponge Nerfer]

A very crudely drawn, triggered burst valve. I am using this in a project im working on currently.



RED: Tinfoil burst plate

PURPLE: 1" union, to hold the tinfoil burst plate

BLACK: 1" PVC pipe

BLUE: Shrader valve, for input. (same kind of valve you see on a bike, or car tire)

GREEN: 1/4" blow gun valve used as a pilot

HOW IT WORKS:

1. Lets asume that the pressure at which the tinfoil burst plate breaks is 40 psi.

2. Pump up the chamber in between the two burst plates to 20 psi, the plates do not break.

3. Pump the main tank of the gun up to any pressure between 40 and 45 psi. Because of the 20 psi pushing back at the tanks pressure the psi that the burst plates have to endure is still only around 20 psi.

4. After loading a dart the gun is now ready to fire.

5. Pull the trigger of the blow gun valve. This will cause the pressure inside the small chamber between the burst plates to become nearly zero, thus alowing the 40 psi tank to press its entire force onto the burst plate. Both burst plates break and the dart you have in your barrel is gone to hell.

-sponge

[hard rockr]

This doesn't sound like it would be very reliable though, because you wouldn't know when it would shoot.

[Sponge Nerfer]

TRIGGERED burst valve, read it again.

-sponge

[Torque]

This is sort of off-topic, but Torque, can you give us a brief update on that "Boomstick" of yours?

I really stopped working on my boomstick homemade mainly because I was tired of spring/plunger designs and with school didn't have very much time. I basically became uninterested. I might be able to get up some pictures of my spring actuated ball valve and bazooka looking homemade sometime this weekend or next week though that way people can see real versions of what the valves look like incorporated into a nerf gun.

Sponge_Nerfer: I'm not sure that aluminum foil would be the best substance for a burst disc as it might tear when you're trying to put it into the union. You might be able to use layers of something like plastic wrap though, because that way you can adjust the pressure at which the valve fires. For instance if 1 layer of plastic wrap bursts at 10 psi and you needed a higher pressure, you could simply add more layers to get it to burst at your desired psi. Balloons also might be worth trying if they're stretched tight enough in the union. (only a section of material from the balloon, not the whole thing.) Both plastic wrap and balloons seem fairly air tight when used right, i have never tried aluminum foil though so it might be interesting to see if you can get it to work.

Burst discs are also used in hybrid spud guns but materials like the plastic from coke bottles are used which i have heard burst at around 150 psi. This of course is not made with pvc pipe but metal unions and threaded pipe from something like galvanized steal pipe. Also propane or another fuel is mixed with air inside the chamber and a spark plug or other spark gap between screws etc. is used to ignite the mixture. When the disc ruptures the desired projectile is forced out of the barrel. I have thought about making a similar device but using a disc that ruptures at a much lower pressure so it could be constructed from pvc pipe. I would then make multiple cannisters with a union/burst disc, spark plug, and pipe/end cap and use these as shells. The problem with this is they would really be too large to be used for normal stefans but might have a more practical use for a grenade launcher style gun or a grenade launcher attachment to another gun. It may not be the most practical thing ever but having a muzzle flash and a loud boom would definitely make a cool factor about it.

[telekinetic]

A very crudely drawn, triggered burst valve. I am using this in a project im working on currently.

-sponge

Awesome. Could you stack those in series to get up to ridiculous pressures? I was also thinking you could 'shell' your pressure chamber in a similar manner.

Probably more a topic for spud tech, but definitely got me thinking.

Edited by telekinetic, 12 July 2007 - 03:35 PM.