Silver Bullet

[Silence]

Originally Posted by isoaker_com

The SS300 is probably too flimsy for most people which is why it seems undervalued.

I guess its flimsiness is a good thing to note, but it just occurred to me that most potential buyers probably wouldn't know a thing about its durability. I know I didn't. I also wouldn't be able to tell it's fun to use .

Joke: Why don't you buy the HydroBlitz instead if you want the minigun feel?

[Drenchenator]

The SS300 is my favorite stock gun. Overall it is a great gun but it does seem too be poorly built at times. One of the reasons could be that it feels so light empty and that the handle must be installed after it was bought (I bought my new-in-box and had to do that). The gun feels weak but performs extremely well.

[WaterWolf]

Ok people, lets get this thing rolling again.
I've let it sit for a few months so that it could have a rest, but I would like to work out the last bugs and details in this system, so that I might begin construction of the Silver-Bullet once I've finished my new line of water balloon launchers. (Which is now down to the one last component I am working on now.)

So, please list any problems you see in a constructive manner and give me some ideas as to how I should remedy these issues.

@Ben:
What are the expansion measurements for a piece of the thickest kind of LRT, approximately how much water can be stored per inch of tubing and had you used multiple layers of latex on your CPH?

Here is a V0.6.6 with supports now added:


The water is drawn from an underslung 4-liter reservoir made out of soda-bottles, which can be easily filled from the threaded cap just behind the first check-valve.
The check-valves will both be of my Homemade design, to keep the price down.
If the pressure-chamber works as well as Ben's CPH, then it should achieve ranges of 50 to 60 feet.
A conicle nozzle for more solid beams.
The cover for the LRT hart is a piece of 4-inch sewer-pipe PVC, which is lighter and can slide over the outside of a 3-inch female piece, as is shown in the above design.
Most of the body is 1-inch pvc, the pump however will be 1/2-inch diamiter pipe.

[Ben]

You will be disappointed if you build this design. Placing the pump on the top is a serious flaw. Using this water gun will be awkward. I know that DX said it would help balance, but I don't think that's true. That's speaking straight from experience. Balance never was a problem with any water guns I made, especially my CPS one which I thought was extremely well rounded. It was easy to build, definitely not awkward to hold, very powerful, and easy to service. I did use a strap and I would suggest this design uses a strap.

Bringing up the subject of gun service, be sure to include a way to remove the PC casing easily. With a homemade CPS gun, you will want to check the PC every once and a while. I've replaced my gun's PC once every year due to the wear and tear use applies. In this design you'll run into problems removing the casing with that pipe behind it and the others below it. If you make the handle easily removed this will be less of a problem, but you'll still have to give the casing enough room to be removed.

What are the expansion measurements for a piece of the thickest kind of LRT, approximately how much water can be stored per inch of tubing and had you used multiple layers of latex on your CPH?

I have used multiple layers of LRT in a CPH before. That's how I first achieved over 60 feet of range (which I think was the first time a water gun went over 60 feet of range). Read the thread you linked to for a little bit more information on how I did it.

As for the measurements, you can calculate that yourself. I haven't measured exactly, but you can approximate the diameter of the fully expanded tube with 2*wall+8*ID. The tubing expands about 3 times in length and 9 times in diameter (800%) from what I have read, but I've found it to expand a little less than 800% in diameter. The 3/16 inch ID 1/4 inch wall tube I've been using expands to a bit over 3 inches in diameter.

Approximate the volume with a 3 inch diameter cylinder. The formula for volume in mL per length would be length*16.387*1.5^2*pi or about length*115.829.

Remember, this is only an approximation and it only works on the parts of the tube that are mostly straight. When expanded the LRT is not in the shape of a perfect cylinder. The volume would be best approximated with an integral, but that's more effort than is needed for a simple approximation.

[WaterWolf]

As I build it, I'm leaving points where it can disassemble, each of the green pieces is threaded. The point in the pump where the elbow slides into the Tee is also going to be threaded, you just can't see it in this version.

Sections that it comes apart into are:
Both bottles.
Both check-valves.
The section just behind the first check-valve.
Handle.
The Tee between the two check-valves
The pump pipe and elbow.
Pump shaft.
Section just underneath the pump that includes the PC.
The barbed piece that the LRT is clamped onto.
The PC cover.
Valve.
Nozzle.

If I find that the upper pump design is unwieldily in battle, I can change it's configuration, but I would like to try this for now.

I'm sorry if I sound impatient, but I'm getting very tired of saying this.
The PC cover can be removed to preform repairs and maintenance.
I have had this in the design for several versions now and people keep telling me that I have to change it for this.

Thanks for the equations though. Its fine if their just approximate, I really don't need precise numbers at this time.

So you simply used the thickest piece of LRT you could get and then added 8 layers of bike-tire inner-tubing? Thanks for the pointer.

By the way, how long a piece of LRT did you use?
I saw that you seemed to get about 4 seconds of shot-time with your CPH and should I hazard a guess at the pictures, the LRT seemed to be about 6-inches long when unfilled.

[Ben]

Threaded doesn't mean easily removable. When you turn one valve in one direction, it loosens one side while tightening the others if one part doesn't spin. That makes removal impossible. Try PVC unions. They are made for this purpose (i.e. removing parts without the entire thing spinning) and would work great.

So you simply used the thickest piece of LRT you could get and then added 8 layers of bike-tire inner-tubing? Thanks for the pointer.

When I got over 60 feet of range, I had two layers of LRT, and perhaps 10 or more layers of bike tubes. Right now I'm planning on redoing it with simply three layers of LRT.

The LRT in the picture of the internals is simply an example piece. Typically I use 12 inch long pieces.

As for the 4 seconds of shot time, that's not a full chamber. That was about 15 to 20 pumps from what I remember. A full chamber would have been over 40 pumps and I only wanted to get a video made. Lots of water volume.

[WaterWolf]

Ok, I'll experiment with the LRT when I get to that point.
Is 12-inches the length of LRT you used on that CPH?

I think that in order to stay lighter and more practical, I'd build the SB (Silver-Bullet abbreviated) with about 4 to 6 seconds of shot-time. If you pulse-fire and tap-shot that, it should be plenty.

I'm not building this gun for field stripping, since in the middle of a battle its going to be more practical to switch to another weapon than to stop and repair the SB there and then.
So the fact that you have to take it apart starting at one end and working your way up isn't too much of a problem. However, since the LRT is the thing you are most likely to want access too, I have built it so that the PC can be quickly removed by simply taking off the hose clamp holding the handle, then sliding the chamber-cover out.

[Ben]

12 inches is the length I use for the most part. In my first version the length was about 10 inches. The length for the most part doesn't matter. I would suggest anywhere from 8 to 14 inches for most LRT homemade water guns.

I left 12 inches on there to get a little more shot time and also to make a burst bladder repair very easy. While you might not find the ability to field strip a water gun to be of much value, I have had a CPS bladder pop before (the gun was being used by a friend) and you can cut the damaged part off and continue to use the remainder. The ability to field strip a homemade CPS gun therefore is a valuable feature. Switching guns works too, but why switch when you don't have to? I wouldn't say that it is more practical to switch because that makes the assumption that you can return to base safely, you have some supply line, or you carry more water guns than is necessary. To me, only requiring a pocket knife, an item I bring anyway, for a repair is very valuable. With a few changes your design can be as easily repaired as this.

With that being said, there are only two times I had LRT pop. The first time was a genuine accident by my friend who didn't listen to my warning that overpumping will pop the chamber (he REALLY liked that water gun). The second time was when I wanted to see for myself what a pop looks like when it happens. Sadly, it happened too quickly for me to get a good view, but I might make a video next year and use slow motion. You chamber will not pop if you make an effort to count pumps and make the chamber larger to begin with to avoid a complete fill.

[WaterWolf]

Another possible way to avoid bursting would be to cut a slit along the side of the cover (Like on most cylindrical CPS guns), or leave the end open.
Now you can watch and tell when you should stop pumping.

Could you please read this so that I do not have to say it again:
The pressure chamber can be easily field stripped simply by removing the hose-clamp on the handle and sliding the cover back. This can be done with a pocket-knife as you had talked about above.
People keep telling me I need to add this feature, BUT ITS ALREADY THERE!

[Ben]

I was under the impression that you didn't think such a feature was important. Sorry that I skipped one sentence. I should read more closely.

[WaterWolf]

Its ok, as long as that matter is cleared up.

For a test, I just tried holding some soda bottles of water strapped together in the same volume and configuration as the current design would be. It was quite comfortable to carry, even when I loaded it with more water than the SB would be able to hold. Though the level of mobility may vary from person to person.
I understand that the pvc structure and systems will add weight and affect the balance, but the water makes up most of the mass, so this was an still an interesting physical test.

[Drenchenator]

What size is the soaker going to be? To me, it looks gigantic but that might be due to the image size.

[WaterWolf]

Its current dimension approximations are:

30 inches long.
10 inches tall.
8 inches wide. (The two bottles side-by-side are the only spots where it is this size.)

To give you a comparison, the CPS 2500/2000 is:

34 X 11 X 5.

So as you can see, its a fairly sizable gun, though not overly large.

I could make the SB much more compact, but that would result in an imbalanced load.

[Drenchenator]

The cover for the LRT hart is a piece of 4-inch sewer-pipe PVC, which is lighter and can slide over the outside of a 3-inch female piece, as is shown in the above design.

A good "end cap" for that would be one of the 4" sewer grates. I bought one for my CPS homemade this week. It is fairly loose in 4" sewer pipe but I used 3 screws to hold it tightly in place. It also lets you watch it inflate.

[WaterWolf]

Yup, having an opening that would allow you to check the condition of the rubber was something I had been planning to work into it. Thanks for the tip Drench.

@Ben: I'm going to be buying some LRT for a different project right now, but what specifications (ID, OD, Wall) would you suggest for the SB? I saw your article on LRT, but I was wondering if you had any additional ideas for this specific design.

For instance, the McMaster site is telling me that the PSI rating for that size of LRT is only 35 PSI, is that enough? Should I order a narrower ID and thicker wall, or will layering solve the issue?