I need some help...

[k9turrent]

Well first off, I'm K9. I usually work on nerf guns, so I know some basics but I'm not sure how make an efficient water gun.

SO I'm deciding to convert one of my air guns to fire water...


so in this basic paint image, I have my air tank forcing the water into the barrel... but how effective is this?

[cantab]

Should work OK. There are four drawbacks I can think of. One is that you'll get some water trapped in the bottom of the bottle. But you may be able to get that out through where the air goes in.

The second is the bend in the water line. But virtually all water guns have some bends in their pipe, it's not a huge issue.

The third is that 1/4" tubing may be too small for a powerful water gun. Or did you get the pipes the wrong way round - ie do you actually mean that for the air line?

The fourth is that pop bottles have one neck. Getting two pipes in could be hard.

[k9turrent]

Should work OK. There are four drawbacks I can think of. One is that you'll get some water trapped in the bottom of the bottle. But you may be able to get that out through where the air goes in.

The second is the bend in the water line. But virtually all water guns have some bends in their pipe, it's not a huge issue.

The third is that 1/4" tubing may be too small for a powerful water gun. Or did you get the pipes the wrong way round - ie do you actually mean that for the air line?

The fourth is that pop bottles have one neck. Getting two pipes in could be hard.

1. I'll probably just fling the extra water at people
2. cool
3. the 1/4" tubing is the "barrel" so I might have to change that...
4. I was going to nest the 1/4" inside the cpvc because this would all be housed in a tee coupler

[cantab]

Ah, clever, running the tubing through the pipe. I'd never have thought of that.

[k9turrent]

Also, with this system, is it safe to just use a water bottle or will I have to use a pop bottle

[cantab]

You must use a bottle originally used to hold a fizzy drink. They're designed to hold reasonable pressure (around 80 psi). Other bottles aren't.

[Silence]

You'll need a ball valve in the barrel to, and a nozzle system. And as cantab said, a larger bore for the water is better.

Generally, we have the water outlet at the bottom to avoid issues with releasing air. That sometimes produces awkward designs, though.

How are you pressurizing the air tank?

[C-A_99]

Since its from a Nerf gun, it'll probably be pressurized by the Nerf gun's pump.

Interesting concept. The air tank as well as the part of the bottle thats not submerged will basically act as one air tank; the original air tank isn't really even necessary. However, you will definately want to use at least 3/8" for the water to nozzle tubing. Also, some of this will be difficult to fit together, you may have to cut out a large portion of the gun's casing to fit tubes through. Will you use the original Nerf gun's valve or attach your own? If you want to keep the trigger as it is you'll need to adjust a lot of stuff.

Or maybe I interpreted this design incorrectly; if you meant for the Nerf gun's trigger to open the air tank to push the water out, that will not work. There is simply not enough air volume to handle all the water, and its going to only get worse as the water drains out of the bottle. You want to keep the pressure on the water the whole time before pulling the trigger to let the water out. (this is true for pretty much all water pressurization concepts and systems)

[SSCBen]

In my experience, "feed tubes" don't work very well. Feed tubes can be avoided completely. Put the water outlet on the bottom and take advantage of gravity.

I'd also strongly suggest against using Nerf guns to build water guns. Using the pump might be a good idea if you have nothing else, but the two are nearly mutually exclusive in terms of part use otherwise. Some of the old valves are fairly similar to Nerf pneumatic valves too, but the Nerf valves have much smaller diameters and consequently won't perform as well as a water gun designed as a water gun. This does mean that water guns converted to Nerf will be very powerful though.

[k9turrent]

Ok thanks guys for the replies and all the good advice... so from the looks of it, you guys will be seeing a homemade from my work shop sooner or later.

But other fun facts:
-most converted Water guns are banned from nerf wars because of the safety issues.
-Also I have Two nerf gun mods to finish, plus an epic homemade that even you guys can appreciate.