need advice for making a very custom water gun

[cantab]

CPS pressure chambers operate, as the name implies, at a fairly constant pressure. Which is probably less than 65 psi in the case of the Flash Flood and most blasters. Keep pumping at that pressure and you could well burst it.

To prevent bursting, put the PC inside a rigid plastic case rated for pressure. (You can probably go somewhat larger than the original PC case, but don't overdo it).

[neogeo]

So I should cut the current case off of the PC and make a PVC one then? I'd probably make it just about the same size as the current one. I did some preliminary tests with the sprayer and the FF internals, and interestingly enough, out of the small nozzle, I was able to get a really consistant stream for around 15 seconds straight. It seems that although the sprayer output is high pressure, low volume, it's perfect for the FF because it gives just enough volume to keep it spraying.

[neogeo]

I had an idea today. The FF's regular nozzle has a valve that's either fully opened or fully closed. It's operated via a small twisting knob that's attached to the trigger with a small bit of metal. I could totally use one of those and a servo for the water flow control valves. Obviously, I can't salvage the one off of the FF, so I'm wondering what, if any guns have a similar valve. Hopefully there's some really cheap water guns that I can just buy for that purpose out there.

[soakernerd]

those are called Max-D valves. They are generally hated because of their complexity and low durability. Valves off of stock soakers usually have a very low flow, because the pipe size is very small. If you have your mind set on using one, try to get one from the flood nozzle of a FF. The Flood nozzle has the same valve, but it is bigger, meaning a higher flow rate.

[neogeo]

Actually, that's not a bad idea. I tested out the smaller nozzle, and it actually flows just fone for my purposes. Remember, I'm not trying to make something that will shoot over a house or hit the kid down the street... yet. I'm just trying to make something that I can use when my regular gun goes empty or if I get ambushed when my gun isnt pressurized. The stock FF parts go across the yard, which is pretty good for a short range surprise attack.

[wetmonkey442]

@SoakerNerd: Max-D valves are simply production ball valves. They operate on the exact same principle.

The level of power you get from a Flash Flood is limited mostly by the size of the nozzle, not the valve. The valve, while still being a lot smaller than a PVC ball valve you could buy at Home Depot, still has a larger opening than the nozzle orifice.

On another note, how do you plan on increasing stream lamination? The Flash Flood nozzle has some low-tech mechanisms for making the stream smoother; wire mesh and narrow tubes help to focus the stream and decrease in-stream turbulence. Do you plan on removing the trigger valve from the flash flood nozzle before using it, or using it with the nozzle still attached?

[soakernerd]

Wetmonkey: Max-D valves have some extra parts that let it snap open instantly, rather than slowly moving open. this can be helpful, but the parts needed for that mechanism are notorious for breaking easily.
Here is a homemade laminator that works perfectly with the FF flood nozzle.

[C-A_99]

The wire mesh on the FF actually reduces its range and would only be helpful if you added a nozzle past the mesh.

Max-D valves require a bit more force to open and thus cannot be tap-fired as quickly. Most of their reliability problems are actually the same as with any ball valve mechanism; the ball valve needs lubrication over time but without it the spring will not be able to operate it quickly enough, thus it will tend not to close properly which results in leaks. Nonetheless, some Max-D triggers' plastic parts that hold the spring together may break, or the spring itself may snap.

[cantab]

The wire mesh is I believe there simply to stop dirt getting in the valve.

[neogeo]

On another note, how do you plan on increasing stream lamination? The Flash Flood nozzle has some low-tech mechanisms for making the stream smoother; wire mesh and narrow tubes help to focus the stream and decrease in-stream turbulence. Do you plan on removing the trigger valve from the flash flood nozzle before using it, or using it with the nozzle still attached?

Well, I was planning on attaching and running a very small fuel line from the valve to my hand. The fuel line is... IIRC, 1/4th in. OD and 1/8th in. ID. Coincidentally, the stock regular nozzle on the FF is exactly the same ID as the line. All I have to do is somehow modify the flash flood nozzle on the FF to have that same ID.

[martianshark]

I thought the screen was there to help the blast break up and spread out.

[C-A_99]

That's only true for other blasters; it serves no good purpose on the FF. Laminators only work when the water is going to go to a nozzle with a smaller diameter than the tubing/valve it's behind.

[cantab]

Well, I was planning on attaching and running a very small fuel line from the valve to my hand. The fuel line is... IIRC, 1/4th in. OD and 1/8th in. ID.

Ah right. That's quite narrow. It is on the order of what's used in many stock guns though, so it shouldn't be too bad. The length will cause a greater pressure drop than you'd get with a short piece.
Using a big valve like the FF's flood valve would thus be silly. The valve should be no smaller than the tubing, but same size or a little larger is good.
I'd also say the nozzle should be about half the ID of the tubing, so 1/16 inch or so. That's not big, but it will give you a decent stream that is going to get people wet and should shoot between 30 and 40 feet angled.

[neogeo]

As a bit of an update, work has slowed to a stop because today's my only day off between this past Teusday and this coming Thursday. I got around to cracking open my PC case to take a look at it, and I'm wondering if it's necessary to have that big plastic ring clamp on the end of it. I mean, obviously it needs some sort of clamp so the end doesn't blow out, but it looks like it's restricting the end of the PC from expanding all the way.

Also, apparently the PC case is about 2 1/4th in. in diameter, which means that finding a piece of PVC pipe to replace it with will be a huge pain in the neck. I think I could go up to a 3 in. diameter and possibly just run a a 2 in.-3 in. adapter between the base of the case and the PVC, but that means taking off the bit of the yellow case that remains there. For refference, I'd be talking about the blue bit of plastic in this picture. My question is what's the best way to do that without harming the white plastic underneath? The glue doesn't look all that solid, so maybe I could just pry it off with a screwdriver?

[cantab]

The big plastic clamp on the end seals the end of the bladder. The flat 'disc' part helps keep the bladder centred in the casing, otherwise it would drop down and that might affect the expansion.

The case does not need to be airtight - in fact it has to NOT be airtight. So I wouldn't worry about adapters. Just get a length of 3 inch pipe, put an endcap on one end, and fix the other end to the PC opening however.