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Constant-pressure Mg


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#1 SirBlastalot

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Posted 05 June 2007 - 11:54 AM

So a friend and I are working on a project (several projects, actually) where we'll make a gun something like this:

Posted Image

It will be mounted on a tripod, with an electric pump. The pump we're using is designed to run off of a car's 12v battery, but we're going to use an adaptor to step down the 220v AC wall current to 12v DC. This design is really simple, as my friends and I are all newbies.

The way it works: We let the pump run untill the air resivoir is at an appropriate pressure. Then, just open the valve and air will continually stream out. We're going to pump up the pressure to something signicantly higher than the pressure nerf guns normally use, because we intend to lose alot via the feed mechanism. We'll either use a gravity-fed clip, or construct a chain with an electric motor to push darts in front of the stream of air. It'll obviously be very inefficent.

My question is this: What pressure do nerf guns normally fire at? I was remembering it as something around 15psi, but Capt. Slug mentioned 40psi in one of his recent posts. We had only planned on pumping up the tank to somewhere around 40-60 psi...
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#2 Prometheus

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Posted 05 June 2007 - 03:26 PM

70 psi max for nerf guns, or else you risk shredding darts. Also, this design looks very inefficient as per air output to shots fired, but if it's a turret, then okay. You may want to consider mount a couple of magstrikes on a tripod, and using a pump, pressure tank (like an airpig) and a regulator, like a scaled up version of CS's air tank. It would be way more efficient.
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#3 CaptainSlug

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Posted 06 June 2007 - 12:10 AM

Your tank is going to empty in less than a second unless you have some kind of regulation setup inbetween the tank and the valve. If the valve has a high enough flow rate to fire a dart then it also has a high enough flow rate to empty the entire tank really quickly.
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#4 SirBlastalot

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Posted 06 June 2007 - 01:27 PM

I see...any suggestions?
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#5 CaptainSlug

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Posted 06 June 2007 - 01:57 PM

You need a nonrelieving adjustable regulator
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6746K23 - Miniature Air Regulator Nonrelieving, 1/8" Pipe, 18 Max SCFM, 0 to 125 PSI = $22 ea

You also do not want a constant flow of air, that would be really wasteful. You should only deliver air when a dart is ready to fire, otherwise you're simply exhausting air for no reason.

It's really not that difficult to simply adapt an RF20 or a Magstrike to accomplish what you're trying to do. Much easier than engineering your own.
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