7 replies to this topic

[CROW]

A while back I posted a topic in the Homemade forum which basically showed off my homemade rifle. The gun itself was a simple design, using a large tank, an unmodded sprinkler valve, and a long barrel. Its only flaw was that it could only get one shot before it had to be re-pumped, which made it useless in a war. After a while, I finally decided to get off my lazy ass and mod the sprinkler valve. (Really only took 20 minutes ) I primed the tank the moment I finished to test it out, but was dissapointed to see that I STILL only got one shot. I have no clue why its not getting more shots (Already checked for possible leaks) so I figured that someone here might know what the problem was. Below are pics:

Before the mod (The scope is just for show)
http://i85.photobuck.../000_0063-1.jpg

http://i85.photobuck...21/000_0064.jpg

After the mod-
http://i85.photobuck...21/000_0121.jpg

http://i85.photobuck...21/000_0122.jpg

Thanks for any help

[CaptainSlug]

You only have one valve, which means you are dumping the entire volume of your tank every time you press the trigger. In order to get multiple shots from a tank you have to only release a consistent volume of air from a secondary chamber. You basically need a valve and pipe section inbetween your trigger valve and your tank.
See Zero's design for reference.

After each shot you have to open and close the valve inbetween the secondary chamber and tank to equalize the pressure between the two.

To accomplish this with a single valve it would have to be a directional control valve. However that type of valve is rather small and cannot be socket welded to PVC pipe. I'm still researching if they have a flow rate that would allow them to be used as the basis for a nerf gun.

Edited by CaptainSlug, 06 May 2007 - 02:27 AM.

[CROW]

Sorry if the pictures weren't detailed enough for you to see, but I do have a ball valve before the sprinkler valve. The reason I haven't gotten multiple shots by using that valve is because of this: What I'll do is fill up the entire tank with the ball valve open and the sprinker valve closed. Then, I'll close off the ball valve, and take my shot. Finally, I'll open the ball valve to equalize pressure again, but instead of the air being contained in by the sprinkler valve, it simply seeps through it. This is the question I should've asked in the first place: Why isn't the sprinkler valve holding the second round of air. Hope that clears that up.

[CaptainSlug]

I don't think your sprinkler valve is functioning properly and should be replaced. It sounds like the spring return isn't working..

[CROW]

Ouch...That is the last thing I wanted to hear, mainly because the sprinkler is locked in place. Guess I could put a shotgun style barrel to replace the single shot one, which might make it possbile to use in a war. Ah well. Thanks for the help CaptainSlug.

[Newbie]

I am not sure, but you may be using the wrong button or switch on the sprinkler valve. If the valve is a soloniod (sorry if spelled wrong), you may have to attach batteries to make it close again.

Hope this helps.

[Prometheus]

CS has the right idea, the diaphragm isn't closing properly, which allows air to seep out. I would recommend converting it to a pneumatic valve, and perhaps trying to replace the valve spring if you can find an adequate substitute.

[King Of Butt Land]

Make yourself a new diaphragm.

-Butt