Introduction, First Question, and APH Design

Build a homemade water gun or water balloon launcher and tell us about it.
all_washed_up
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Introduction, First Question, and APH Design

Post by all_washed_up » Fri Jun 15, 2007 3:50 am

Hi, all,
I enjoyed a neighborhood water fight the other day and came away thinking about homemade guns. The reason: four of the neighbors had the same gun (a SS XP70). Only one worked right, the others having been damaged in one way or another. I was thinking about the wasted money and the plastic that would head soon to a landfill and I wondered about homemades.

I'm surprised there are so few really explicit tutorials on the web about building these things. I've found a couple, and a few more that are quite general. I've worked with PVC before, have a workshop and am generally handy, but I much prefer to have detailed plans to follow, rather than mucking my way along, running the risk that I'll end up with garbage in the end.

So, in that spirit, I've decided to ask some questions before I begin and get some feedback on the design I develop before starting construction. Here's my first question. If I am going to build an APH, are there two possibilities for locating the pressure chamber (pc)--on the gun or in a backpack? It seem so. These links show guns of each design: pc on gun
pc in backpack

Is it practical to use a bike pump and the backpack pc, rather than having a pump on the gun? In some ways, I am more comfortable with the construction of the backpack system. I can tap the threads and I am familiar with the valve system. And just as we had to stop to refill the water chambers during our water fight, I suppose I can stop to pump up the pc with air. But I don't know; I guess it would depend on how often I had to do it, whereas I could pump the gun as I moved and shot. What do you think?

Thanks,
a_w_u

PS: Once I settle on this I'll start working up some construction plans and ask for feedback.

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SSCBen
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Post by SSCBen » Fri Jun 15, 2007 12:38 pm

Welcome to Super Soaker Central!

Our website is horribly out of date, so if you want to see anything from 2004 until today you have to check the forums. Until we make a substantial update, the website should remain this way. I've made a lot of water guns that sadly haven't made their way onto the website.

I suppose you are correct in saying that there are two places a pressurized chamber can be put. On a backpack or on your body is one and in a gun is the other. With that beind said, realize that there are many different positions within each of those positions the chamber can be put and the types of pressure chambers that can be used. Typically a chamber in a backpack presents several problems. It is good practice for the water to flow in as straight of a path as possible to reduce turbulence. Tubes from the backpack don't allow for that too much, but they won't be terrible. Tubes also can limit flow if they are not wide enough in diameter, and limited flow of course means limited performance.

Of course, most of the problems with backpacks can be avoided with the right design. In fact, I would call that water gun too powerful. I'm a fan of backpack based water guns, so I'm designing something similar at the moment. ;)

There are many advantages to putting a pressure chamber in the gun aside from flow benefits. I usually make water guns with both a gun part and a backpack. This helps divide the weight among muscles, reducing fatigue. Just a though I think some people don't realize... it will be hard on you to put all the weight on one place. This is on my mind because I just recently got an email from someone who wanted to make a water gun that wrapped around an arm. This guy wouldn't hear me when I said it will tire his arm out.

As for what problems a bike pump on a backpack water gun present, you have to consider that to pressurize the water gun, you will have to remove the backpack and get the pump out. That will take time and will be annoying. As you noted however, this will occur when refilling, so it may not be too bad.

Some backpack water guns, such as the one I linked to above, have their own air and air regulator systems to last for many refills without refilling air. I would suggest something similar if you don't want to have a pump on the gun.

Sounds like you have a lot of thoughts and good ideas... in my experience, those are signs of a well planned water gun, so I think whatever you do you'll be satisfied with it.

:)

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Silence
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Post by Silence » Fri Jun 15, 2007 1:48 pm

Welcome to Super Soaker Central!

As Ben said, one of the problems with having the PC in the backpack is pumping. Admittedly, you wouldn't need to pump very often, but it could be an inconvenience. People have suggested having a pump with the trigger and nozzle and having two hose tubes - so you can pump on the fly. But that sounds a bit complicated.

Then there are CPS (constant pressure system) water guns that use rubber bladder for...well, constant pressure. Those could easily be filled using a homemade quick-fill device that attaches to the hose, so you don't need to pump.

And then there are CAP (constant air pressure) systems like the one pictured in Ben's link. However, those are generally expensive and probably excessively powerful for most purposes.

It's definitely possible to have the PC anywhere. You can do anything with homemades. However, unless you have a reason to put the PC in the backpack, I would just stick with the regular design for balance, power, and convenience. :cool:

all_washed_up
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Continuing Thread Elsewhere?

Post by all_washed_up » Sat Jun 16, 2007 1:31 am

Thanks for the replies. I am working up a design now and would like to continue the discussion, but maybe it'd be better if I continue the discussion in the homemades forum rather than here?

a_w_u

PS: I wish I could work up a drawing in 3d, but while I have sketchup and gmax on my computer, I am terrible at using both. I like the ease of the pvc designer, but it's pretty limiting to work only in 2D side view.

all_washed_up
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Seeking APH Design Review (pics included)

Post by all_washed_up » Sat Jun 16, 2007 3:30 am

Hi, all,
I'm working up an APH design. It's my first gun so I'd like to work out the design kinks before I start to cut and glue.
Here's a drawing, showing top and side views:
Image
PVC designer (used for making the pics) limited me in a few respects. There is a second check valve in the vertical segment behind the big reservoir. And the reservoir incorporates a "Y" piece, set at an angle, allowing water to drain completely out of the horizontal reservoir and allowing the upper half of the gun to sit alongside the lower half, as I hope the upper view shows.

I actually have a different idea for a trigger pull, but for now I'll ask for feedback on the general design, as shown here.

Thanks,
a_w_u

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Kalogagatya
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3D drawing

Post by Kalogagatya » Sat Jun 16, 2007 11:24 am

hey there

for that a good option would be using AutoDesk inventor 10 or 11 :) they're quite easy to use and already have an integrated mechanical library with hydraulic elements :)

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SSCBen
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Post by SSCBen » Sat Jun 16, 2007 11:29 am

Looks fine aside from the pressure chamber. Why is the pressure chamber at an angle? If you angle the water gun to increase range, your PC capacity would be extremely limited because eventually the water gun will shoot air instead of water. Keep the standard vertical pressure chamber unless you're going to use a piston. ;)

all_washed_up
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Post by all_washed_up » Sat Jun 16, 2007 3:06 pm

Ahhh...
I had the pc at an angle to allow a more direct line of flow from pc to nozzle--a 45 rather than 90 degree turn. But I see what you mean about what happens if I raise the nozzle. I'll have to give this aspect of the design some more thought. I'm glad to hear that it looks okay otherwise. I'll update it at some point as I figure out how to illustrate my trigger concept.

a_w_u

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Silence
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Post by Silence » Sat Jun 16, 2007 3:11 pm

Nice designs. As Ben pointed out, the PC shouldn't be angled like that though. People have suggested doing that for more linear flow, but I believe having large tubing is a better way to increase flow.

Similarly, with your reservoir, you might not want to use a wye that's angled like that. It isn't as much of a problem there because you don't need to angle the gun up when pumping; but still, there's the potential for problems.

Other than that, it's a very creative design, having the reservoir alongside the rest of the gun. I personally would make the reservoir a bit shorter so it could be inline with the rest of the gun, but that's just my personal preference...I like things symmetrical.

Anyway, good luck with building the homemade! :)

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Silence
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Post by Silence » Sat Jun 16, 2007 3:18 pm

Ben already moved the thread to the Homemades forum. So no worries. :)

In my limited experience, I've found that it's somewhat difficult and a bit pointless to excessively plan out what you're doing ahead of time. Even simple designs done on a piece of paper are usually off due to the proportions of the fittings and everything. You can make a drawing, but don't expect the result to be identical to what you wanted.

CAD is probably an even bigger waste of time - and the best software is expensive. What you should do is just think about the ideal layout, and don't worry about finer details like proportions. A simple sketch in Paint is fine too. Just don't expect anything to be realistic.

At first I was also a bit frustrated with the limited design options in PVC designer. Then I realized that it wasn't supposed to be able to do exact blueprints - I just use graph paper to do that. And the lack of a precise positioning system actually helps because in practice, it's fairly hard to create precise homemades with flush fittings anyway. Things just don't work out perfectly.

(Note that the results will still be good, even if they're not what you planned.)

all_washed_up
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Post by all_washed_up » Sun Jun 17, 2007 12:17 pm

Thanks for the feedback. I'll figure out component lengths as I get a better sense of the size of the elements. You bring up an interesting point, though: pipe size. I was planning on 1/2 for the barrel and 3/4 for most of the rest of the pipe, but maybe I should plan on larger diameter for where the pc joins the gun? Also, are there any guidelines for the overall volume of the pc? The ones on retail guns are all pretty small.

a_w_u
Last edited by Silence on Sun Jun 17, 2007 2:13 pm, edited 1 time in total.

all_washed_up
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Post by all_washed_up » Sun Jun 17, 2007 12:28 pm

Thanks for the reply--sage advice, really. I spent a lot of time yesterday with 3D modeling programs. I'm working on a SimCity modeling project as well as the gun, and I have been working toward proficiency with several software packages. Unfortunately, no one package is well suited to both projects. I can tell that it'd be best to stop sketching the gun, but it's so doggone fun to try!

I really like the simplicity and ease of PVC designer--it was a terrific donation to this community--but I was hoping to impress with a truly accurate 3D model. :p

Anyway, I think I'm going to continue the modeling for my SimCity project but stop the drawing for the gun. I still have to work out the trigger system, but once I do I think it's time to start putting it together.

a_w_u

PS: Ben, I don't know if you can merge threads? I started one in this forum --Seeking APH Design Review--and then you moved my original thread over. Can they be combined?

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Silence
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Post by Silence » Sun Jun 17, 2007 2:12 pm

Just merged the threads. I don't know what name you wanted now, but that can be changed too. Note that everything's ordered chronologically, so it might be hard to track which messages were posted for which topic, and also it looks like there are double-posts now that were meant to be in different threads.

I agree it's fun to plan things out to the nth degree. I'm a bit of a perfectionist, so I try to get everything ironed out beforehand. And a nice 3D model is fine if you can make one. Just be prepared for it to be a bit difficult to get the final result exactly as you want it. :cool:

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DX
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Post by DX » Sun Jun 17, 2007 4:33 pm

Oh gosh - my homemades NEVER resemble what I draw beforehand! I can't even use PVC Designer anymore, because I build very strange designs. If you make drawings, only expect them to be guidelines so that you don't forget certain parts when you go to buy them. The best picture to have is the one in your head. That is the best place to shape and reshape the gun as it starts to physically come together.
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all_washed_up
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Post by all_washed_up » Tue Jun 19, 2007 4:16 pm

I've been to the store and made some discoveries that alter my design. The 3-inch PVC is SO big that it'll overwhelm the design and it's too hard to reduce for the smaller bits, so I'm going to use 2-inch for the water chamber and add a second chamber, in line. I'll have two parallel water chambers, with the pc above. I'm working on a 3-D drawing to show you.

UPDATE: I'll probably skip the 3-D drawing, or I'll make one to show construction after-the-fact, because I went shopping yesterday and I hope I now have everything I'll need.

I have one more questions at this point: I based my pump design on doom's pump article. But I don't know how long to make the pump chamber or how much longer to make the rod. I figure rod length should just exceed pump chamber length by enough to comfortably grab the rod. But how long to make the 1/2-inch ID pump chamber?

I hope someone can help. I'm going to do the rest of the dry fit today.

a_w_u
Last edited by all_washed_up on Wed Jun 20, 2007 4:20 pm, edited 1 time in total.
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