Hellow, new to Forum

rflach5 · Post by **rflach5** » Thu Jun 22, 2006 12:51 am

I did use cleaner, I did not use primer, and I regret it. I have a small pinhole leak to contend with. I didn't want the primer to ugly up my gun, so I didn't use it.
Thanks for the compliments. I was going to use 4" thinwall PVC for the tank, but the added cost of the reducers and the check valve was too much for what I have already spent. I am having second thoughts about the bag and thinking of leaving it like it is.

Silence · Post by **Silence** » Thu Jun 22, 2006 7:15 pm

Maybe epoxy is your solution now, especially if the hole is really as small as you imply. If it's any bigger, though, then I doubt the epoxy plug will stay in. For your next homemade soaker, you could just use the primer and then rub/wipe it off and then paint the soaker--that's what I'm thinking about doing.

However, I can certainly understand the financial problem--but cheapness is one of the nice things about Ben's backpack, if you ever decide to make a backpack gun. Nice solution for now, though...

rflach5 · Post by **rflach5** » Thu Jun 22, 2006 7:49 pm

I fixed the leak by first applying PVC glue around the joint where the leak was. Then I went around it with a liquid plastic repair kit and let that dry. I tried it this morning and it did not leak! It shot at least 40 feet no problem. I am now leaning again towards the backpack, but it means I will have to change the position of my water hookup on the gun to be at the bottom where the elbow for pump is right now. And that means another trip to Home Depot!

Silence · Post by **Silence** » Thu Jun 22, 2006 8:16 pm

Well then, congratulations! 40 feet of range isn't amazing for a homemade, but chances are excellent that you'll get good range with the ideal nozzle size. However, you can keep most of the gun's parts; just replace the only elbow in your design with a tee and add the correct fittings, and you'll be set to use both an onboard reservoir and a backpack one (just a note, though: if you use the backpack, filling the onboard reservoir as well will just increase the weight on your hands without a dramatic increase in capacity).

However, you might run into a few problems: adding a tee and a check valve at the bottom might have weird results, although you could put in a tee above the top check valve; that would be nice, although slightly awkward. You could also use a ball valve-barb for the hose for the backpack or even the bottle to switch everything on or off.

EDIT: I like your signature ("Cheesy Australian accent: That's not a gun, this is a gun!"), but in a few months, this thread will be buried and nobody will see the reference. Maybe a hyperlink would do the trick?

rflach5 · Post by **rflach5** » Thu Jun 22, 2006 9:06 pm

Yeah, my plan was to add a Tee with a hose fitting at the position where the elbow is right now. I would leave the attachment for the bottle up top and cap it off when not in use. That way I could use the gun either way, with a backpack or a bottle.

So does range increase or decrease with a smaller nozzle?

SSCBen · Post by **SSCBen** » Fri Jun 23, 2006 12:03 am

So does range increase or decrease with a smaller nozzle?

Distance varies with nozzle size. There is a nozzle orifice size optimized for total distance as SilentGuy said. An orifice that is too small will break up due to drag too early. An orifice that is too large will not have enough velocity to go very far. Moderate-sized orifices are the best, and you can find the right nozzle orifice size through trial-and-error and math.

More on this subject: http://www.sscentral.org/tech/articles/streams.php

That article is due for a rewrite and needs updating, but everything said in it is correct.

Silence · Post by **Silence** » Fri Jun 23, 2006 12:36 am

The purpose of the removable nozzles is to be able to create various sizes for selection--and have the option for a riot blast. As you can see in the Streams article, all you need are two different sizes in order to calculate the optimum one--though the riot blast probably isn't the best size to use for testing. Even though the method might not be perfect, it's pretty darn good. Also, if you don't have a TI graphing calculator, post the data and I can do the calculations for you.

For a more recent article (or an older one, depending on how you look at it), check out "My Next Mod Project, Inspired by XN." xN helps end the large-small nozzle debate by stating that larger nozzles allow for streams with greater momentum (though not too large--then, there wouldn't be enough velocity, so it's all about balance). I'm still thinking that the front-end area of the stream (dependent on the width) varies directly with both the mass/momentum and the friction, and that a smaller nozzle produces greater velocity/range but with the same output; but experimentation clearly shows that it isn't true. Much of this might be due to the improportionally increased resistance due to the increased speed and friction on the sides of the stream; also, quicker streams are less laminated.

So, in other words, you really only need three endcaps (although more wouldn't hurt) to get one of them perfect. From there, you can have ones designated to conserve water more or drench more, but make sure you keep tabs on the "magic" one. By the way (off topic), yesterday I went to Lowes again to finish up on the parts for my compact backpack APH. I got everything I needed except the aluminum pump shaft, but more relevantly, I got a metal ball valve that has female threaded (FIPT) sides; and I returned all the FIPT endcaps I had bought and replaced them with male threaded (MIPT) plugs. This removed the need of any MIPT couplers, and if all my homemades are like it, compatibility won't be an issue...

@ Ben: Off topic again, but do all 2"-3" reducers have a small, elliptical hole in the side? It seems like the indentation was made during manufacturing it, but when I went to look at the other at Lowes (both of mine had it), everything was the same.

SSCBen · Post by **SSCBen** » Fri Jun 23, 2006 12:43 am

Off topic again, but do all 2"-3" reducers have a small, elliptical hole in the side? It seems like the indentation was made during manufacturing it, but when I went to look at the other at Lowes (both of mine had it), everything was the same.

Those marks are on all large reducers and a lot of other large PVC pieces. It's definitely a mark from manufacturing - I bet that's where the molten plastic was put into a cast.

rflach5 · Post by **rflach5** » Fri Jun 23, 2006 2:18 am

Wow, that's a lot of good info there! I wish I had read the stream article before building my gun, I would have done things differently. I will play around with different nozzles and see what I come up with. Thanks. So why couldn't a guy build a gun with the PC (my first use of an acronym relating to water guns) that is inline with the source and with the nozzle? That would seem to make more sense to me.

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Nozzle (|||Gate Valve|| PC |||||Check Valve||||||
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                                              (|||||Pump||||||Check Valve|||||||Source

rflach5 · Post by **rflach5** » Fri Jun 23, 2006 2:19 am

Aw man, when I posted my message, my ASCII art got all messed up! Sorry about that!

SSCBen · Post by **SSCBen** » Fri Jun 23, 2006 2:32 am

I've fixed your ASCII drawing. Due to the way the forum handles messages, you have to put it in a

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 tag for the spaces to not be removed.

[quote]So why couldn't a guy build a gun with the PC (my first use of an acronym relating to water guns) that is inline with the source and with the nozzle? That would seem to make more sense to me.[/quote]

The air will float on top.  For that reason, having PCs oriented as most do is the easiest option.  However, there are other designs that will allow for straigter flow such as a piston or the "inverted-T" design.  The piston design uses a piston to separate the water and air so that the air will be below the water.  The inverted-T design gives the air a place to go so that it is nearly always on top as well (the pressure chamber is shaped like an upside-down T).

Another common question I believe there should be a more in-depth article on. ;)

DX · Post by DX » Fri Jun 23, 2006 2:35 am

You can't make a fully in-line pc in an air pressure gun. This is because the air must exit the pc last in order to have a good shot, yet the air floats on top. If you just turned a regular pc on its side, the air would come out with the water and cut up your stream.

However, you can come close to having an in-line pc with the inverted T design:

^Making the top area long enough will ensure that the air exits last. You could also use a 45 degree piece to bend the top in a manner that the air would exit last no matter what.

But if you still want a fully in-line pc, you'll have to make a CPH [Constant Pressure Homemade]. Those use latex rubber tubing as a pc, which works just like a CPS soaker. You would have to order the tubing at mcmaster-carr online, and have to adjust the design a bit, but you would have a great homemade.

rflach5 · Post by **rflach5** » Fri Jun 23, 2006 4:14 am

I see. I like the looks of your gun. Let me know how it works out for you. I also see you are using PVC for the tank. That is how my next gun will be. I thought of using 4" thinwall drainage pipe for a water tank. I want the main body of the gun to be a really long thinwall tank and where I reduce it at the fill end for a check valve to let air in, I will put in a sweep and screw cap for a fill hole. The tank will reduce down on the supply end and curve down and around like yours does back towards the draw check valve, but I was thinking about at a slight downward angle out to the side of the tank so that the pump and the PC part of the gun is almost besides the tank, but slightly lower. This would result in a gun that is not so tall as my current design. I hope I am describing it clearly enough?

Silence · Post by **Silence** » Fri Jun 23, 2006 6:18 pm

PCgHs are also excellent choices for linear flow; not only is the water always separated from the air, but by PreCharging the soaker, performance is made superior, too. However, is the drainage pipe you were considering made out of PVC or metal (I think metal)? If you're using PVC, it should be at least Schedule 40 throughout.

The picture portrays Duxburian's n00b Killer in a mostly complete stage (though it was completed long ago). In case you were confused, the reservoir top was moved back and the pump tube shortened for the final design; the performance was supposedly good, although I should be letting Duxburian talk about it more.