Water gun structures

[wetmonkey442]

Alright, here is a rough render of a modified version of that design, with both the inlet and outlet accessing the bladder from the same end. At the other end of the bladder would be a solid dowel or pipe that would slide in and out of the PVC at the end, acting as a sort of guide along which the bladder can smoothly expand without bending down or twisting.



I look forward to seeing the design for the THR2.

[sbell25]

Looks good. The sliding pipe for the bladder is a good idea. I presume that the pipe is going to be blocked off so the water doesn't just pump back into the main tank? Also you'll need to plug up the pipe connecting the 2 tees that are sitting just behind the ball valve otherwise the gun won't be able to pump.

[Ben]

Remember that the LRT expands to about 3 times its length, so you might want to extend it. That's partially why I just put the LRT in a pipe. It's easy to make a pipe long. I use 10 inches of LRT with two feet of pipe, which doesn't expand fully, but I want to make sure that I don't pop the bladder too. Expanding 2 to 2.5 times the length is what I recommend.

You might want to extend it anyway so you could have a longer reservoir. I'd also recommend larger diameter pipe for the reservoir, like 4 inch drain pipe, which is nearly perfect for most water guns.

Also, will the gun have any sort of case or anything? I mean, it's not a good idea to have the LRT completely free like that, making it prone to damage. I assume you haven't drawn it yet.

Your aligner idea has me thinking. Previously I just left my LRT lying in the case, and it wouldn't really "stand up" until the gun was pumped up. I think I'll add a circle with a bold in the middle for alignment now so the chamber doesn't roll or bounce around in there. It also would help when making a PC gauge, which may or may not be necessary if I get some clear pipe.

Edit: Hey, wetmonkey, what program did you use to make that render? I'm experimenting with Google Sketchup and AutoCAD at the moment trying to make something, but I'd like to try another one.

[Drenchenator]

I have to agree with Ben that the design needs a lot of room to work with, along with a bladder casing and a disc to guide the bladder back within the casing. But the design is great in all other aspects--in particular, I love the tubing part where the pump connects to the chamber. I used this exact kind tubing setup to connect my pump and chamber, and it worked great. I kind of stole it from Larami since they used it on every CPS gun, but it really saves space and opens up more possibilities for design than before. If you want to save more space, use the small, brass check valves that are available on Mc-Master; they are many times smaller than "conventional" check valves you can get at home-improvement stores.

[wetmonkey442]

Also you'll need to plug up the pipe connecting the 2 tees that are sitting just behind the ball valve otherwise the gun won't be able to pump.

Those two tees would actually be sanded down on the inside to allow for the two pipes (both the pump and the nozzle) to fit through, so that water flowing through those pipes would still maintain a linear (and hopefully laminar) flow.

Remember that the LRT expands to about 3 times its length, so you might want to extend it. That's partially why I just put the LRT in a pipe. It's easy to make a pipe long. I use 10 inches of LRT with two feet of pipe, which doesn't expand fully, but I want to make sure that I don't pop the bladder too. Expanding 2 to 2.5 times the length is what I recommend.

I was worried about this. I really don't want this gun to start to become some gigantic monstrosity, but I suppose I'll have to find some balance between performance and usability.

I have to agree with Ben that the design needs a lot of room to work with, along with a bladder casing and a disc to guide the bladder back within the casing.

I'm still a bit confused about what you mean here. I'm going to need a case of some kind, to protect the bladder, but I don't know what your mean by "disc". The current design incorporates a sliding dowel in order to keep the bladder oriented as it expands.

Thanks for all the thoughts and comments.

Ben-I used the program Rhinoceros 3D. It's a much more powerful program than what is required to create something like this, you could achieve similar results with the products you listed. Another free program you might want to check out is MOI. It doesn't have an integrated render engine, but its simple to use, and pretty comprehensive.

[Ben]

I was worried about this. I really don't want this gun to start to become some gigantic monstrosity, but I suppose I'll have to find some balance between performance and usability.

I don't think the water gun will be gigantic by most standards. You can use a shorter piece about 6 inches long and a shorter housing if you want to keep it short. You'd still get really good PC capacity. I can pump over 1.5 liters into the PC of SuperCPS without problem and I likely could fill it to over 2 liters. You probably could get over a liter at maximum with 6 inches of tubing. Just be sure to give it about

Another thing to know is that the tubing expands to about 3 1/8 inches in diameter. You can house it in 3 inch PVC if you don't layer anything over it, but if you do, I recommend 3 1/2 inch or 4 inch pipe.

Ben-I used the program Rhinoceros 3D. It's a much more powerful program than what is required to create something like this, you could achieve similar results with the products you listed. Another free program you might want to check out is MOI. It doesn't have an integrated render engine, but its simple to use, and pretty comprehensive.

Okay, well I've been messing around with Sketchup for a few hours and I have something made. I checked out Rhinoceros 3D, and it's a paid program, so I'd rather not buy it anyway.

[Drenchenator]

I'm still a bit confused about what you mean here. I'm going to need a case of some kind, to protect the bladder, but I don't know what your mean by "disc". The current design incorporates a sliding dowel in order to keep the bladder oriented as it expands.

I'm referring to literally a plastic or wooden disc that you mount at the end of the bladder. Consult the photo below for further explanation--it should basically explain what it is; you've probably seen it before.

[Ben]

Here's a very rough render of some of my current THR2 plans. Basically, I'm tightening up THR while using a box-like structure to hold it together. I didn't complete the box, the handle, or even most of the water gun's parts themselves for this because I figured it doesn't matter.



It looks a little bulky from this image, but I plan on cutting off some parts of the box/layers to make it lighter anyway, but I didn't cut them off the picture. I'd like to cut off most of the plastic around the PC and hold the PC down with pipe clamps. Perhaps I'll do that in a future render. I think this was good work for having no prior experience with SketchUp.

The handle is part of the case on the side. I didn't draw the second part of it or the parts keeping it together. I plan on doing something similar to the PlusBow link I posted in the first post of the thread. The handle should be on the side to make it easier to have the wire leading up to the firing valve run along the side. Having the handle on the side also moves the handle closer to your hand, making probably more comfortable holding, though I don't know how balance will factor into this, but I don't expect it will much because it leans against the user and has a strap.

I'd appreciate any suggestions or comments. Right now I think the biggest problem is that it appears bulky due to the box structure, but that should be helped a lot by removing some of the structure where it is not needed.

I'm going to hold off another render until I get this in AutoCAD or ProE because they seem more flexible than SketchUp, but SketchUp is a great program for free. I'd recommend it to anyone who wants to draw anything 3D because it's pretty easy to use.

Edit: Okay, scrap most of this idea. I took a shower and thought of an even better way to hold everything together. It still involves a plastic structure, but this one is smaller. I'll have to render it. This is why you plan things out I guess!

If you have any comments about this design still, feel free to post them anyway. I'm not scraping everything, and I might like my original idea better with some suggestions to it.

[Silence]

Originally Posted by Ben

Though, it depends on several factors. I've noticed that the ones with the red handles are harder to turn than the ones with the black handles. I don't know which company manufactures which, but that rule has held true for all the ball valves I've used. The black ones are closer to as easy to turn as brass valves, but not quite there. The valves seem easier to turn after some use too.

My local Lowes marks the red ball valves as "industrial", "heavy duty", "durable", or something like that. I agree they're harder to turn. You might as well just get brass valves if you want something stronger and easier to turn.

Originally Posted by Ben

I didn't know they had online services for rapid prototyping. I thought you had to generally pay a company to make the prototype, but I'll admit I know little about the subject, just that they have several CNC machines at the University of Maryland.

I've forgotten the name of the service I read about, but I'll find it. Tell me if I forget.

Nice design, wetmonkey442! I really wish I had the talent or patience of you or Ben to actually create a 3D diagram. But I can draw well enough by hand, so I'm not really complaining.

Originally Posted by Ben

Your aligner idea has me thinking. Previously I just left my LRT lying in the case, and it wouldn't really "stand up" until the gun was pumped up. I think I'll add a circle with a bold in the middle for alignment now so the chamber doesn't roll or bounce around in there. It also would help when making a PC gauge, which may or may not be necessary if I get some clear pipe.

Yep, I've thought about sliding discs to keep the free end of the bladder centered in the case. I stole the idea directly from my CPS 4100.

Originally Posted by wetmonkey442

Those two tees would actually be sanded down on the inside to allow for the two pipes (both the pump and the nozzle) to fit through, so that water flowing through those pipes would still maintain a linear (and hopefully laminar) flow.

It sounds like you're looking for "pipe saddles." They're designed to let you attach the end of a tube to another tube, but without actually creating an opening in the straight piece. Dremeling or sanding an actual tee could be grueling.

Ben: So far it looks like the layout of THR2's components is the same as the layout of THR. The main difference is the plane of the supporting sheets of Plexiglass. I do worry about balance and design with THR2 - at the moment, THR appears a good deal better to me. THR2 imitates more conventional designs, but with the size of all the parts, it's probably easier to hold the water gun in the style of THR or SuperCannon II than in the style of another water gun. I find it hard to picture a gigantic box under your arm.

[Ben]

It does look hard to hold, but my other idea is similar to the original THR, but still with plexiglass. It's an easier to build version of the original THR with some features of the original THR2. Essentially, it's a thin plexiglass plate between the top and bottom that uses pipe straps to hold the reservoir and PC on. It'll need some sort of casing over one part to add the handle, but other than that it's the same as THR.

Now that I looked at a render of it, it wasn't quite like what I wanted, so I thought of something better.

Edit: They're called pipe straps, not pipe clamps.

[wetmonkey442]

Thanks for the comments SilentGuy, those pipe saddles sound like just the thing to preserve my sanity during this build. I was NOT looking forward to all that sanding.

@Drenchenator: I wouldn't need a disc because of the aforementioned sliding aligner. Maybe its hard to see it from the render, I'll try to elaborate on it further, especially when I get actual numbers for length when I take into account Ben's estimation of bladder expansion.

@Ben: The design looks good, but perhaps a bit boxy, although I'm sure that's merely a product of the early stages of design.

[Drenchenator]

@Drenchenator: I wouldn't need a disc because of the aforementioned sliding aligner. Maybe its hard to see it from the render, I'll try to elaborate on it further, especially when I get actual numbers for length when I take into account Ben's estimation of bladder expansion.

Okay, good--as long as you have something to keep it straight. I guess I must've not seen it.

I was just wondering about the overall length of your design, but I'll just wait until you do some numbers first; I know it might take a while to take all the parts and the expansion of bladder into account for a length estimate-measuring parts sometimes can get just plain time consuming too.

[Silence]

I found several online fabricators/rapid prototypers:
eMachineShop
QuickParts
Ridout Plastics
ProtoCAM

They're all pretty much the same, but the first two look especially convenient. Some sell molds that could be used if you're selling homemades, and molds are probably cheaper than any other option.

Just a thought. I doubt you're going very deep, at least right now, but the point is there's no need to worry about lack of access to these services.

[Ben]

@Ben: The design looks good, but perhaps a bit boxy, although I'm sure that's merely a product of the early stages of design.

Yeah, that's why I made a render I guess. I'll change my mind so many times that whatever I plan early on doesn't resemble what I make.

I'm actually a little stuck because they don't make pipe straps in the size I want. I think I'll make my own pipe straps, which should save money as well. All I have to do is bend a metal bar in to the right shape, which isn't hard.

@SilentGuy: Thanks for those links. They'll definitely help someone out who doesn't have a university at their dispense.

Today I was working on a Nerf rotating barrel assembly. UMD has a Nerf club and I'd like to attend a war or two, so I'm fixing up my Max Shot. It's not completely unrelated to water guns because I intend on using a very similar design for a nozzle selector. It's mainly proof of concept right now, built sloppy with whatever was available. I've even designed a simple way to get the snap in place feature using a rounded screw head. I would take pictures as I was constructing it, but it's one of those things where you make it up as you go along, so one picture would show one thing, but the next would show something different.

[Ben]

Here's a photo of the partially completed rotating barrel assembly I wrote about earlier. It even has a locking mechanism like most Nerf rotating barrel assemblies and water gun rotating nozzle assembles.



I don't have all the brass tubing I need to make the barrels themselves, but the remainder is complete. I'm going to stick the barrels on with putty epoxy, which should stick pretty good. It won't stick great to the plexiglass, but plexiglass was what I had lying around so I used it without thinking ahead. If I sand it, I should get a pretty decent bond.

A similar assembly with an O-ring and different diameter orifices will make a rotating nozzle assembly.