CAP

Build a homemade water gun or water balloon launcher and tell us about it.
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Hunt_and_Annoy
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CAP

Post by Hunt_and_Annoy » Sun Jun 15, 2008 10:41 pm

So me and a friend built a relatively small CAP gun using 1 liter bottles. It was really only a prototype to test the concept, and doesn't work at anything larger than like 3x, but it works. Just though I'd let you guys know. Will post pictures eventually

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Silence
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Re: CAP

Post by Silence » Sun Jun 15, 2008 11:22 pm

Wow, sounds cool! I'd guess the regulator didn't have enough flow capacity to handle anything more than 3x, but at least there's potential there. :)

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Hunt_and_Annoy
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Re: CAP

Post by Hunt_and_Annoy » Sun Jun 15, 2008 11:31 pm

Yeah. We're buying a bigger regulator for our backpack version. In theory. We're also considering building a digital regulator.

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Drenchenator
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Re: CAP

Post by Drenchenator » Mon Jun 16, 2008 12:12 am

Good job on the prototype!
We're also considering building a digital regulator.
What do you mean by a digital regulator? A typically regulator works using springs, so I don't really see how it can be digital versus analog here. Could you elaborate on what you have in mind? Digital readout, maybe?
The Drenchenator, also known as Lt. Col. Drench.

aEx155
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Re: CAP

Post by aEx155 » Mon Jun 16, 2008 12:30 am

Drenchenator wrote:What do you mean by a digital regulator? A typically regulator works using springs, so I don't really see how it can be digital versus analog here. Could you elaborate on what you have in mind? Digital readout, maybe?
He might mean those pressure switches used in air compressors. I believe you can set them to a certain pressure and they control a switch (typically, it controls whether or not an air pump is on or not); it could be connected to a sprinkler valve. I saw someone using the same setup somewhere else, but I don't remember the link.

I wouldn't call this digital, but at least its electronic.

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SSCBen
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Re: CAP

Post by SSCBen » Mon Jun 16, 2008 9:24 pm

I don't understand what you mean by "digital regulator" either Hunt and Annoy? Could you explain? What aEx said makes sense but if it's something cool I'd like to know about it before I build my new CAP water gun. More options are good.

aEx155
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Re: CAP

Post by aEx155 » Mon Jun 16, 2008 10:42 pm

A quick search on Google brought up this, which might be what Hunt_and_Annoy was talking about.

I guess it's just a pressure sensor hooked up to a valve, which is basically what I said earlier.

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SSCBen
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Re: CAP

Post by SSCBen » Tue Jun 17, 2008 1:39 am

Interesting. I can't find any price figures but it's probably safe to assume it will cost more than an analog regulator. In my experience normal regulators have enough precision to make any differences in pressure negligible.

That might not be what he's planning though because he said he'll build it.

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Drenchenator
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Re: CAP

Post by Drenchenator » Tue Jun 17, 2008 3:33 pm

I agree. Given that that site has a page for getting a quote, I'm assuming it's pretty expensive.

Hunt_and_Annoy, could you elaborate on your plans? They seem interesting enough for some discussion.
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Hunt_and_Annoy
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Re: CAP

Post by Hunt_and_Annoy » Tue Jun 17, 2008 6:14 pm

I was thinking about having an electric pressure sensor which would turn on and off a solenoid valve very quickly to keep the pressure constant in the firing chamber.

aEx155
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Re: CAP

Post by aEx155 » Tue Jun 17, 2008 7:33 pm

Hunt_and_Annoy wrote:I was thinking about having an electric pressure sensor which would turn on and off a solenoid valve very quickly to keep the pressure constant in the firing chamber.
That sounds a lot like what I described earlier...

I would just go for an analog one, like Ben used on his SuperCAP. Using an electrical system would just make it more complex and less reliable.

EDIT: I found the link I had talked about earlier. Here is a picture from here about a potato cannon that used the setup.
Last edited by aEx155 on Tue Jun 17, 2008 7:39 pm, edited 1 time in total.

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Silence
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Re: CAP

Post by Silence » Tue Jun 17, 2008 8:25 pm

It probably depends on the application. As limited as flow is through solenoids, there's definitely a higher flow coefficient than with a mechanical regulator. With launchers or other devices that use up a lot of air and then need more soon, it makes more sense to use a large valve than a small one, so an electric regulator may be better. But with CAP water guns and the like, which use many short bursts of water with low flow, a mechanical regulator is more suitable - it can open and close more quickly than a solenoid and it provides sufficient flow.

Well, I see why you'd want an electric regulator, since the current mechanical one may have limited the flow. But first (as you implied you would do), it's probably better to compare the flow of your current regulator with the flow of one that Ben used.

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SSCBen
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Re: CAP

Post by SSCBen » Tue Jun 17, 2008 11:43 pm

EDIT: I found the link I had talked about earlier. Here is a picture from here about a potato cannon that used the setup.
Interesting. I wonder where he bought the pressure switch. I'm looking at McMaster-Carr and the most reasonable part is 3460K61 which cost $23, which is half the cost he reported. The picture on McMaster-Carr doesn't look like the one in that spudgun so it's a different switch.

1/4 inch regulators will have more air flow than you'll need. You don't need to spend money on anything complicated. You probably could get away with 1/8 inch regulators on pressures lower than a certain amount.

This would be a cheaper way to get higher flow regulated pressure than a simple larger mechanical regulator but for sizes that are reasonable for water guns it's more expensive than a simple regulator. The normal regulator I'm going to use in my new CAP water gun costs $18 on McMaster-Carr from what I remember and it's better than what you need Hunt and Annoy. If you haven't bought anything yet I'd suggest saving some money with a mechanical regulator. ;)

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Drenchenator
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Re: CAP

Post by Drenchenator » Tue Jun 17, 2008 11:56 pm

I understand now. I might be able to see some advantage from the flow perspective--I don't think that a regular regulator allows much flow; but then again a solenoid doesn't either. I guess it's just another viable option. Try it out.
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