Water gun structures

Build a homemade water gun or water balloon launcher and tell us about it.
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SSCBen
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Water gun structures

Post by SSCBen » Wed Jan 16, 2008 6:53 pm

Most current designs use a PVC structure, i.e., PVC pipe is the gun's structure. While that is not bad in many designs, PVC structures do not allow for much flexibility in part placement unless parts are taped or glued on, which are sloppy. So, many designs with things like water reservoirs are harder to make or don't work well.

In my THR water gun, I used a mounting bracket to hold parts together. The mounting bracket offers structural stability and more flexibility in part placement than a PVC structure alone. Several years ago, Drenchenator used a structure in his first homemade water gun, which improved looks and offered a lot of flexibility in the placement of parts. He had a real handle, a pump handle, and an actual case for his water gun. I'd really like to see some more "structured" water guns because they offer a lot more. We can put things like reservoirs, handles, etc. wherever we want them. Looks are improved. Making triggered valves will be easier with some parts to mount stuff one. The water guns are structurally more stable.

The only disadvantages I can see are the increased cost, work, and possibly weight (if heavy plastics are used), but I think all those are of offset by the improvements after just starting to build THR.

The links below should be helpful to people who want to build more structured water guns. Some of these links are from Nerf forums because I've noticed Nerf is taking a similar direction.

Beginner's Guide To Machining Plastics
http://nerfhaven.com/forums/index.php?showtopic=8007

Drenchenator's water gun, DR-3
http://forums.sscentral.org/t3960/
http://www.sscentral.org/homemade/dr3.html

PlusBow construction guide
http://www.captainslug.com/plusbow.html

A few pages about my THR water gun
http://forums.sscentral.org/t4728/
http://www.isoaker.com/cgi-bin/Ikonboar ... =37;t=4318
http://www.isoaker.com/cgi-bin/Ikonboar ... =37;t=4298

Edit by Drenchenator--added link to my gun's write-up.
Last edited by Drenchenator on Fri May 09, 2008 12:07 am, edited 1 time in total.

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Specter
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Re: Water gun structures

Post by Specter » Wed Jan 16, 2008 11:00 pm

reading this gave me some ideas for a structured water gun. I'll have to read up more on homemade guns to get the gist of building one, but I have a feeling i can whip something up during the summer.
If i ever get the inspiration, money, and parts, you might see something nice for the summer. :)
My "arsenal": Customizable APH, Storm 600 pistol (still haven't finished fixing this), launcher- Model:AB1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future
My site Image My website/forum is back up and running, for the most part after it having been deleted in october

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SSCBen
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Re: Water gun structures

Post by SSCBen » Sat Jan 19, 2008 2:31 pm

I've been giving some ideas thought, and I'm thinking about getting some large pieces of plastic sheeting and tracing out a pattern on them to start building on. Of course, that idea comes as I am getting read to go back to college, so I probably won't be able to do anything neat like that for a while.

With two identical sides and enough space between them, some really neat things could be built. I'm thinking how easy it would be to attach handles and make a working trigger. My idea at the moment is to figure out how much torque is required to open up a lubricated metal ball valve and work from that figure. A triggered ball valve probably can be done with gears.

My THR water gun needs to be finished too... I think I'll cement it in a few days on a warmer day. That'll leave an LRT chamber and testing, which I suppose I'll do either on a weekend when I'm home or spring break. After that, it'd be time to start writing a guide.

This should be an interesting year because of the new possibilities in homemade water guns.
Last edited by SSCBen on Sat Jan 19, 2008 2:37 pm, edited 1 time in total.

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Silence
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Re: Water gun structures

Post by Silence » Sat Jan 19, 2008 5:24 pm

Gears are notoriously impractical in homemade devices. They're either cheap, unreliable, imprecise, and weak, or they're expensive, heavy, and hard to machine.

A wire pulley system seems to work well enough in Drenchenator's first homemade. And such a system can do anything that gears can, but in a much better way, as long as we're not talking about hundreds of foot-pounds of torque.

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SSCBen
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Re: Water gun structures

Post by SSCBen » Sat Jan 19, 2008 5:48 pm

Okay, thanks for the advice then. My second idea was a wire pulley system somewhat like this: http://www.sentex.net/~mwandel/cannon/air_gun.html

That'll will require some work to get the valve to turn easier, but it should work.

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Drenchenator
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Re: Water gun structures

Post by Drenchenator » Sat Jan 19, 2008 6:08 pm

The torque was not that bad; but it could get really bad in larger valves. Ben and I were talking last week about this actually. Hasbro's newest CPS guns all have riot blast and at least two firing valves. It begs the question--why two valves? Why couldn't one work? We think that we know why. The larger valve is used for the riot blast; the smaller one for the stream shot. The larger one must have much more torque, and so much more that Hasbro decided that the only way a kid can open it is with a handle on top, as it was made. Ben and I can actually invert his Arctic Blast and pull back the riot blast handle with one finger--but we're adults; young kids could have trouble trying that. So a second, smaller, triggered valve is needed.

The 1/2" brass ball valve I used wasn't too bad. The torque arm's length was very short (less than 1/2" an inch if I remember correctly), so it can be much easier to open with a longer arm length. But the greater the length, the more trigger pull is needed. It's just a trade-off that we have to find a solution too. If I remember correctly again, I measured my CPS 2100's trigger pull at about 1" and redesigned the gun with that in mind (the first time I just winged it and it didn't open the valve all the way). In retrospect, 1 1/2" is probably better for our purposes though.

Back on topic--the wire system works very well provided the valve, torque arm, and trigger pull are designed well. Plus, it's been used before and is simple, effective, and cheap. But it has its share of problems that I've noticed too. One of the reasons I had trouble pulling the trigger at first was because the wire in fact designed poorly on my part: the wire's attachment to the valve's torque arm couldn't transfer all the force I used pulling the trigger. It's clear why in the following picture:

Image

As you can see, the wire attaches to the handle at an angle. It needs to actually be attached in the direction of motion, horizontally in most cases, to fully use the provided force. Look at the CPS Internals. The majority of them have a horizontal wire right before the valve's torque arm (the exception is the CPS 2700, which is nearly horizontal yet still angled, just proving that it's not always needed but just may be recommended in most cases). The CPS 2100 has a large angled section but doesn't connect angled; it connects horizontally, albeit for a short distance. It may seem silly but this tiny tip messed me up for a while. In the future, it would likely be best to avoid the problem through the system that the CPS 1000, 1500, and 1700 use, a plastic plate visible in the following photo at iSoaker.com (full internals picture at Aqua-Nexus).

Image

Really, when I was designing and building my first homemade, I had CPS soaker internals in front of me constantly--that's what I was trying to imitate, and there's certainly no harm in copying what has already worked!
The Drenchenator, also known as Lt. Col. Drench.

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SSCBen
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Re: Water gun structures

Post by SSCBen » Sat Jan 19, 2008 6:22 pm

I think the easiest solution to the angle problem is using a small wire that can curve like in the link I posted earlier. Then we can just put some pulleys in the right spots and get linear pull.

Of course, all this is made easier with more structure than simply PVC pipe. ;)

sbell25
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Re: Water gun structures

Post by sbell25 » Sat Jan 19, 2008 10:35 pm

This is quite interesting. I'd say you're right about the reason for Hasbro having a separate riot blast trigger. Still, they can use larger valves that can be finger-triggered. The Triple Shot is a good example. It's largest nozzle is around 5.5mm (7/32") yet it still shoots with good distance and pressure. The nozzle behind the selector is around 8mm (5/16") so the valve it uses must be larger than normal, yet it is just as easy to pull as any other.

As for getting the trigger wire right, couldn't you just have it horizontal then have a 90-degree bend in it rather than worrying about a plastic plate? I must be missing something.

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Drenchenator
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Re: Water gun structures

Post by Drenchenator » Sat Jan 19, 2008 10:57 pm

As for getting the trigger wire right, couldn't you just have it horizontal then have a 90-degree bend in it rather than worrying about a plastic plate? I must be missing something.
Yes, you could do that if you wanted to. What I was saying was that the wire before the valve should be approximately horizontal. What happens in the middle of things doesn't matter much except in saving materials and lowering costs. The 90-degree bend could work, but would waste more materials than a slight angle and then a horizontal part (like in the CPS 2100). But, hey, if space within the gun warrants a 90-degree bend, use it. An example eludes me right now, but it may be necessary in oddly shaped projects.

Space in another big problem when using actual PVC pipes as a structure. I based my structure off what other have done in Nerf homemades, but in homemade water guns, we have to use larger diameter pipes to accommodate the valves and fittings; most Nerf homemades with structured designs are spring-based and don't need valves--space really isn't a problem. While building my homemade I measured everything precisely to make sure it fit within the pipes; and some stuff didn't fit, prompting me to cut holes to make it fit.

The three valves (two check valves and the firing valve) will take up the most space. I left the firing valve (ball valve) out in the open for the most part (until I used 4" drain pipe for the chamber casing, great stuff). I used swing check valves to save space, which, in retrospect, was not a good idea. First of all, they were very heavy; and second of all, they took up too much space too. On McMaster-Carr, they have small check valves, which should be used in these kind of homemades. When Ben bought one, I was so surprised how small it was: it could fit into a film cannister!
The Drenchenator, also known as Lt. Col. Drench.

sbell25
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Re: Water gun structures

Post by sbell25 » Sat Jan 19, 2008 11:15 pm

What I was saying was that the wire before the valve should be approximately horizontal.
That's what I was talking about too. I thought that having the wire at an angle was your problem, and that having it horizontal where it connects to the valve would fix that. You're right, a small horizontal part then a diagonal bend would be best. Having a look at that 2100 seems like the best way to do it.

About the problem with using larger valves, is the current trigger a finger one, or do you use your whole hand? I'm thinking if you made one that used the whole hand to pull, with another handle to place your palm around, you'd eliminate the torque problem as well. You'd be able to exert more force on the trigger, and have a longer trigger pull as well.

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Drenchenator
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Re: Water gun structures

Post by Drenchenator » Sun Jan 20, 2008 12:04 am

Image

I added a grip later made of 1" PVC but didn't post about it because it was months later and I forgot.

I only used a single finger to pull. The trigger was that long because I just made it that way; I didn't really think about it. But I never really solved one problem that left this gun "incomplete" in my mind: I couldn't get the firing valve to close all the way! I positioned springs all over the place to little effect, closing it partially but never all the way. I have a system in my head that should work, but I just don't know. The weather doesn't really agree with homemade projects as the moment (plus, I only have a week before I have to go back to college). This stuff is tricky--hopefully we can take it step by step until we figure it out. My first homemade is incomplete, but it did at least help me figure out somethings for the next one I'll hopefully build.
The Drenchenator, also known as Lt. Col. Drench.

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SSCBen
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Re: Water gun structures

Post by SSCBen » Sun Jan 20, 2008 1:47 am

Don't forget that slow progress is still progress. Right now I think we're combining the best we've seen and thinking of new stuff. Maybe we should change this thread into a new homemade water gun ideas thread?

One thing I'd like to tackle are rotating nozzle selectors. I think we could construct one much like the old ones by having a rotating cylinder. We'd have to figure out a method of construction, but once we do, I think rotating nozzle selectors would be standard additions in homemade water guns.

There's a few other ideas I'd like to consider like more comfortable handles, but I might add those on my current THR project.

Does anyone have any other ideas?

I'm going to do some more research into triggered ball valves... most of what I've seen has been similar to the link I posted above. We need to use larger diameter valves, which might have problems with torque as said. Lubrication might be in order, or figuring out what sort of trigger pull is acceptable.

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Silence
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Re: Water gun structures

Post by Silence » Sun Jan 20, 2008 2:34 am

What happened to all those plans about large pull valves? As you've written recently (or perhaps it was Drenchenator), flow is more important than linear design if you want lamination. And flow is just plain good. If it's easier to open a large pull valve than a large ball valve, then maybe we should reconsider pull valves.

I honestly don't think a rotating nozzle selector would be that hard to make. All you need for the seal is an O-ring epoxied onto the end of the barrel. A plastic disc can be screwed onto a nearby rod, and a rim on the other side of the barrel holds the plastic disc onto the O-ring.

Probably the worst assumption is that the rotating disc can only be held in place by the screw. If you support the disc at multiple points, then the torque caused by the pressure inside the barrel won't matter.

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SSCBen
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Re: Water gun structures

Post by SSCBen » Sun Jan 20, 2008 3:01 am

The thing about pull valves is that they're hard to seal right. I later figured out that you can buy some PVC repair couplings that would seal easily and work fairly well, but they'll be large. It's worth investigating, yes. I might just turn my old pull valve Nerf gun that I never worked on into a water gun valve now...

One thing I'm not sure about though is whether these valves will open at higher pressures. But, as I said, we don't know until someone tries it. That's pretty much how everything in homemade water guns has been. You build one gun, learn something from it, build another, etc.

As for the rotating nozzle selector, yeah, that's how I see it. All you need is the seal, and after that it should be relatively easy given your alignment is right.

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Silence
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Re: Water gun structures

Post by Silence » Sun Jan 20, 2008 3:37 am

Ben wrote:One thing I'm not sure about though is whether these valves will open at higher pressures. But, as I said, we don't know until someone tries it. That's pretty much how everything in homemade water guns has been. You build one gun, learn something from it, build another, etc.
Look at the attached images to see how to make the valves easier to open at higher pressures. With a thick pin/rod, there's less area for the pressure to act on and thus less force required to open the valve. On the other hand, a large valve with a thin rod might have 1 square inch of area. At 60 PSI, you'd need to pull the rod with 60 pounds of force to get it to open!

As for the building and learning process...yeah, I need to get back into that. I know I can do a much better job next time.
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