Silver Bullet

[WaterWolf]

What would you suggest for the reservoirs then?

And I don't think you're understanding the PC quite the way I planned it.

There is a straight piece of LRT through the middle of the 12" PC.
Its just a simple cylindrical CPS PC, except than in my design the water enters at one end, the rubber expands, then the water is forced out the other end of the LRT when the trigger is opened.

I'll draw it into the design to clarify things.

@Ben:
With your CPH, what parts did you use to get the LRT connected with the PVC?

[DX]

I don't see how LRT can do that unless you've got something special. In conventional CPHs, the water has to enter and exit from the same end. That's my only concern, the rest seems sound.

Reservoirs using a gallon container or the such would be difficult to use in a gun with balance in mind. They are also much less sturdy than PVC, though there are ways to make them work.

[C-A_99]

That design limits the LRT to expanding by thickness and does not allow it to expand by length, though I'm unsure how that would affect the power and max PC volume.

For the reservoirs, it might be simpler to use 4" for now, but if a tank that's shaped similarly can be found (a tank that's relatively flat, etc) without too much trouble, such should probably be used instead.

Edit: Started posting this before seeing DX's post.

Off topic, but what's with the rule with animated avatars? Why can mods and admins use them and not regular members?

[DX]

Oh, I see how that would work. Not sure if it would work as well as an expanding chamber. 4" for dual reservoirs of the proposed length would make the gun hell to carry. Even 3" is pushing it. You do want them to be long, however, both for balance and capacity. Now you see why I haven't been able to come up with a true Silver Bullet design! It is really difficult to balance all the factors.

I am not aware that there is such a rule? I've been using this spinning x since this time back in 2004.

[C-A_99]

Well, whenever I link to my animated one, it says I'm not allowed to upload it. Looking at the spinning X, I thought you used mod powers to bypass the rule, but it seems like that rule was put in after you set your avatar.

I thought using 4" could shorten the gun, and it seems not to be a huge increase in diameter. While 2.77L is fairly standard for a medium CPS, the way it's distributed seems to be fairly poor considering it's throughout the gun. Though the idea is balance and avoiding any area being heavier than another, the cylinderical shape cuts out a lot of room that could be used to hold more water. The PVC alone also seems to add unecessary weight, but so far there doesn't seem to be a sturdy tank that's shaped well for such a design.

[Silence]

LRT expands both in length and width. You have to connect it only at one end so it can lengthen. Take a look at all the CPH designs out there.

Your avatar used to be animated until you changed it. Perhaps one of the settings is wrong? It looks like it was too big but was cropped instead of resized, or something like that, and lost the animation. Resize it in a photo editor and see.

[Ben]

This design is closer to what would be an improved single-piece CPS water gun. However, there are several things I would like to point out.

The way the PC is set up is completely wrong. I originally wanted to do something similar in my first homemade water gun. At the time I didn't realize an important property of the rubber tubing. The rubber tubing expands in length when filled. You really can't stop it either. If it won't expand in that direction but can move around in others, it'll squeeze up and you'll risk popping the rubber.

For that reason, any LRT PC designed with solid connections on both ends is asking for trouble. For the most part, filling the PC and shooting from it should come from the same end of the rubber. (I do suppose however that a piece of flexible rubber tubing could be used to remedy this problem, but there's nothing wrong with using the same end for both tasks.)

The PC container also needs to be set up like a container. The tube must be accessible easily because you will eventually want to replace the PC with a newer one (the rubber degrades due to the stretching). While not completely obvious in the image of my CPS water gun, I have the PC set up so that it can be opened when needed. I cut notches in the PVC caps to allow the pipes to go in and out as well as make the entire structure accessible later. Your design is made to attach like regular PVC fittings, and that makes it rather inaccessible and construction of something like that is more difficult (but not impossible).

As for how I attached the tubing, this image shows that I used simple tubing barbs and clamps. On one end I saved a little money by using a bolt as opposed to a tubing barb and a threaded endcap. The bolt works and I would suggest others try the cost-saving measure.

I think a design close to my CPS water gun with some reservoirs on the side would be better than this one. I would also make the reservoirs of larger and lighter pipe (like drain pipe in large diameters). Those pipes are rather cheap and strong enough to serve as a reservoir.

I personally would also suggest againsts the "tracked pump" idea because tracked pumps are hard for most to duplicate and don't really offer an advantage over simple solid rods. Simplicity wins in the end.

Also, large pipe diameter threaded plugs don't seal well even not under pressure. To fill the reservoir, I would suggest stepping down the pipe to a lower diameter and then using a threaded cap (which is cheap) or a ball valve (which is convenient, but costly and bulky).

Off topic, but what's with the rule with animated avatars? Why can mods and admins use them and not regular members?

There are no rules really when it comes to avatars other than the unspoken ones (no obscenity, etc.). I've checked the usergroup permissions and it seems that administrators and moderators have everything checked off, while the other user groups had things more close to the default settings. I've changed the settings so that everyone should be able to use animated avatars. Let me know if this doesn't work.

[C-A_99]

Meh, I definately should've used more threaded parts on my CPH (primarily the valves), but I'm a bit unsure on using a bolt, worried that it might not be good for the LRT and thought the hose barb would work better in general.

I still cannot use the animated version of my avatar, weird. Either way, thanks for having a look at it.

[WaterWolf]

Thank-you everybody for the comments.
I've drawn up a V0.2 design with the appropriate changes.



The reservoirs are slightly longer and the threaded cap has been reduced in size.
I've rearranged the trigger in accordance with your suggestions.
The pump is now a standard type.
You can now see the internals of the CPS PC.
I hadn't said anything on my reply with the first design, but I had been going to leave the PC unglued for exactly the reasons that were later stated.
This PC is also not glued in and can be taken apart to access the LRT.

Keep up the replies, the Silver-Bullet is taking shape.

[Silence]

As with the comments at the other forums, I would just advise turning the PC around and adding another reservoir cap. I personally would use a pull valve, if only to test the waters (look at how well commercial blasters do with pull valves), but it looks good.

[CROC]

Just a random thought, but why can't LRT be connected on both sides? One, connected to a check valve, to let water in, the other to the ball valve? Why would this not work?
By the Way, I would lengthen the resevoir to be the same length as the rest of the gun.
Hope I was helpful:
CROC

[Silence]

LRT likes to expand both in diameter and in length. Even if you hold both sides down, the rubber will try to elongate. The contortions will make something break.

Ben explained it in more detail a few posts above.

Somewhere here at SSC there was a discussion about having the second end of the tubing be attached to a piece that slides over PVC. Kinda complex though.

[WaterWolf]

Ok, Version 0.3 coming at ya.



Better flow with a more compact and lighter design.

You night-owls can toss some more ideas at me, but its nearly midnight here and I've got to get to bed.

I'll check up on this in the morning.

[CROC]

@Ben/Silence- What would happen if you stretched the LRT when you assembled the gun, to make the LRT be as long as it would be inflated? Would this not work?

Anyways, that design looks good, but personally, I think the pump is too high.
What happened to the tracked pump? I think that would work great, but I guess the pump may be too short to be able to do that now?
~CROC~

[WaterWolf]

Stretching the LRT would cause it to fray much faster (I'd imagine).

Ben mentioned that he had attempted track pumps before and that they never worked out well, so I ditched it for a more simple type.