My CPH concept

[JLspacemarine]

Hi! I'ts been a while since I've showed up in the forums.

Well, I was thinking about building a homemade water gun this year and I was wondering what the online soaker community would think of my concept.

Basically it's superCPS in a more compact way, with a trigger activating the ball valve like on my Powerpak replacement gun. (http://forums.sscentral.org/t4007/2.html)





(note that some parts might not be to perfect scale, the actual size of the weapon will be measured when it will be assembled)

Actually I don't know what length of LRT I would be using and what size of PVC would act as a PC case. All of the PVC is 1/2" and the blue parts are 3/4 check valves. All of the parts represented are actual parts that I can easily buy at my local hardware store (of course the LRT would be ordered via McMaster-carr but hey, do they ship to Canada?). The trigger part is a virtual prototype, but it should be similar on the completed gun.

[SSCBen]

Glad to see you back with such a well thought out project. Wow. There's not much to say really. It should work great as is.

8 inches of LRT works well for me. 8 inches expands to about 24 inches. Read my LRT article for more information.

McMaster-Carr does not ship to Canada. Your best bet would be to ask a manufacturer like Primeline Industries or Kent Elastomer about more local distributors. You also could buy some from someone here if that doesn't work out.

For some reason I completely missed your trigger replacement thread. I actually hadn't thought anyone had that much success with a triggered ball valve. I should get to adding that to the repairs page pronto.

Edit: If you wouldn't mind detailing at least your trigger mechanism in an article or post that would be great. Some people really want triggers and this one looks like it works very well.

[JLspacemarine]

Oh, I didn't know LRT would be harder to get in Canada, it might be more complicated than I thought to complete the project....I'll gather some info about LRT in my local hardware stores to see if some tubing would be available. Otherwise I'll be forced to ask here to buy some, as you said.

As a last resort option I could try to use something else to make the bladder....such as ballons....but I dont think I would get the same overall performance and I would be forced to rethink the design of the gun by building a spherical pressure chamber.

As for detailing the trigger mechanism, I will be able do so, but the parts I've used in my power pack replacement gun are rather unconventional and it took some work to make it functional. So some kind of guide about this will be better when it will be made of parts that are common in hardware stores, which is exactly what I will be doing for the homemade.

[SSCBen]

Hardware stores are extremely unlikely to have any LRT worth using. You can find some but it's internal diameter is going to be 1/4 inch and it's wall thickness will be 1/16 inch (most likely). They usually only carry one variety and it's the tube I described. It'll work but it won't hold much water and it will be weak. A package forwarding service might be your best bet if you can't find a local distributor.

[Specter]

I know it might sound a bit weird, but try using condoms. Layered of course.
Condoms are extremely strong latex. (have you ever seen one blown up like a balloon?) And i would think that if you layer a bunch of them they might work like the LRT would.

Just a suggestion.

edit: Might be not as strong but you could also try the long balloons with a bunch layered.

[aEx155]

That definitely is weird...

I guess that would work for a spherical bladder; it might not be as large or powerful as a cylindrical, but you wouldn't have to order anything.

Just try not to attract attention when your buying a bunch of c_ _doms in the store...

[SSCBen]

I remember discussing use of condoms in water guns few weeks ago actually. Let me pull that up... We discussed it in the K-modding the HydraPak thread. It looks reasonable actually. A little weird, yes, but they're latex, easy to layer, and relatively cheap. No one's experimented with it yet so it's worth considering.

Edit: Let me say that you should try to find LRT locally first. Condoms are a little too weird for water guns. Email Primeline Industries or Kent Elastomer about it and if you can't find anything more locally try the package forwarding service.

[Silence]

Welcome back, JLspacemarine!

I'd suggest cutting a slot in the side of the PC cover. Then put the reducer that goes to the case between the nozzle and the ball valve, instead of between the tee and the hose barb. When you slide the PC cover into place, the slot should envelope the vertical pipe that goes to the second check valve. Ben did it with SuperCPS, giving a much cleaner look.

For the trigger, use a sliding piece (say, a ring cut from a 1/2" coupler) on the horizontal pipe attached to the elbow. It should be easy to attach a wire to the ball valve from there. You should also be able to attach a separate wire to the trigger, which should be attached to another sliding piece but closer to the handle. Having a piece tracked in the middle should help navigate the corner of the case.

Of course, that's just one way to do it. A wire bent in the right place should do the job just fine.

[Drenchenator]

Welcome back!

Your design is very solid, well-planned, and quite aesthetically pleasing. It should work without issue and perform well.

Judging by your previous work, I'm assuming you got the the trigger down. BBT's trigger system is pretty easy to copy.

A pump-guided trigger is the right thing to do in this case. I suggest you make sure it's strong; the one in my homemade broke twice. Just reinforce everything and it should hold together.

[JLspacemarine]

Thanks for the feedback guys!

I think I'll email Primeline Industries about buying some LRT, they seem to be open with providing some tubing for special needs.

Before I contact them, what size(s) of LRT should I ask them for? (O.D, I.D, Wall thickness....)

[Silence]

By the way, they'll probably ask you to order at least 50 or 100 feet of tubing, since it's not cost effective to manufacture just a few feet of each kind. That said, if you bought it, you could definitely resell it to builders of CPS homemades.

In SuperCPS, Ben used two layers. The inner tube had 3/8" ID and 3/4" OD, and the outer tube had 1" ID and 3/2" OD. (I don't know if Primeline will accept metric units. At any rate, onlineconversion.com has some useful conversion calculators.) I would ask for 1/2" ID and 3/2" OD, or failing that, 1/2" ID and the largest OD possible. If they offer really large ODs, you could even get 5/8" ID, so you'd be able to use larger, high-flow hose barbs. At any rate, you'd have trouble sliding the rubber onto the barb if the rubber was only 3/8" and the barb 1/2" or larger.

Ben, in the SuperCPS article, it says you used a 5/8" hose barb. Is that true?

[SSCBen]

Before I contact them, what size(s) of LRT should I ask them for? (O.D, I.D, Wall thickness....)

I'd suggest following the suggestions in Killer 7's guide. Use the same inner tube I used but change the outer tube to be one that has an ID that matches the OD of the inner tube. This worked out better for Killer 7 than does using tubing that slides over easily. He used a different more challenging method to layer that's worthwhile in my opinion.

Ben, in the SuperCPS article, it says you used a 5/8" hose barb. Is that true?

You can get the tubing over a 5/8 inch tubing barb if you try enough. Anything larger is extremely difficult. 1/2 inch is relatively easy.

[JLspacemarine]

I was wondering, is 1/2 inch PVC larger in diameter than 1/2 inch CPVC? CPVC is the only type of tubing that I can buy locally.

[SSCBen]

CPVC seems to be slightly smaller in general, but fairly close: http://www.harvel.com/pipecpvc-sch40-dim.asp

There shouldn't be a significant difference.

[Silence]

CPVC is usually very close in diameter to what's advertised, but according to that chart, it's still off at 1/2". (Also, PVC evens out at 3", then becomes smaller than advertised beyond that. CPVC apparently becomes larger and larger than advertised.) So you'll be able to get higher pressure but with most pumps.

You may want to check another chart, too, as I've heard CPVC can be very close to advertised. The Engineering Toolbox doesn't differentiate between PVC and CPVC sizes. Maybe CPVC is usually sold as Schedule 80; that would make sense if it has a lower pressure rating normally.