Mid-Sized CPH

[mr. dude]

I'm considering building a CPH with an on board reservoir that's no bigger than a CPS 1200. However, I only have one size of LRT, and that's ~2' of 3/8"ID 3/16"Wall, so is that able to provide enough power to be worth it? Keep in mind that I do have quite a few pretty good mid-sized weapons. Also, ordering more LRT is out of the question, so I'm stuck with bike tubes and other guns' PCs to colossus.

[Ben]

The standard sized stuff you have is perfectly fine. You can get high end CPS performance from that with a few bike tubes.

The tube itself has 10 PSI more pressure than most CPS water guns (as reported at least), so it should be slightly more powerful than most. 23 PSI is a CPS 1000, 40 PSI is a CPS 2000, and this tube is 35 PSI. Now, the flow is reduced due to the 3/8 inch ID, but once we figure out a good way to stick a larger tubing barb in that's not a problem.

For on-board reservoirs I have a suggestion. Buy some metal strips, fold the sides over so there are no sharp edges, and wrap that around the pipe with a little overlap. A few of these can be a tubing clamp. Buy an aluminum bar to use as some sort of frame and mount the pressure chamber, reservoir, etc. in a THR like shape. This is what I planned for THR2. If you need any more of an explanation I can give you one tomorrow... I'm going to bed now.

[CROC]

Wait... The LRT he talks of is the same strength of LRT that is used to fix the CPS 2000 when the bladder ruptures.

Anyhow, I think that this could be easily done, and would be a great CPH building experience. Maybe I should make one too.

[mr. dude]

So should I expect range in the forties or fifties? I believe CROC's CPS2000 with that LRT gets something in the forties, but it was a pretty windy day when we tested it so it might be higher.
Anyway, I'm going to give it a 4" reservoir, possibly with a similar fill cap idea to the fast-fill caps of recent soakers, in other words a large check valve.
I haven't thought of an actual design yet though, so more to come later.

[Silence]

The problem with fill caps is that you need a fill "nozzle." That does make sense if all your water guns are equipped with a quick-fill cap or if the filler can fill regular reservoirs too. Otherwise you just limit the number of water sources for each type of cap.

If you do go with that idea, you should use a system similar to the 2 Liter Homemade's one.

On a sidenote, Ben, why isn't the 2 Liter homemade on SSC anymore? It may have been primitive (relatively) but it was popular. Now it can only be accessed through archive.org.

[mr. dude]

It'll be threaded, so I can take it off, but it's much more convenient than having a hole in an endcap, because the leaks are irritating. I might end up using an encap if money is tight, but I would prefer to use a check valve.
As for the frame, I was thinking of using a wooden case, similar to Drenchenator's, except that this wouldn't have a trigger, the ball valve, pump handle, and reservoir cap would simply stick out. Nothing's final yet, but that's one of the options.

[Drenchenator]

I added the 2L homemade to the site. I don't know why we didn't have it before, but we got it now and that's all that matters.

The whole point of the casing on my homemade (DR-3) was to provide an adequate housing for the moving parts--the trigger and pump--while putting it all in a good looking, small package. I don't really see any benefit having a case with no trigger, but I guess I won't complain; it'd look much better anyway.

If you want the reservoir to not leak, don't use an end cap--use a bushing. They may not be available in the right sizes though, but look out for them anyway.

[Ben]

Originally Posted by CROC

Wait... The LRT he talks of is the same strength of LRT that is used to fix the CPS 2000 when the bladder ruptures.

The CPS 2000 repair (at least on our website) uses two different tubes. The inner one has a pressure rating of 30 PSI. That's different than the 35 PSI of the tube mr. dude mentioned. Did you use a different tube in your repair?

Originally Posted by mr. dude

So should I expect range in the forties or fifties?

Leftovers got into the 40s from what I remember and that was nothing but an old thinned CPS tube in a chamber with pretty small tubing leading to a nozzle. I'd imagine at least 40s in range, and more should be easily achieved with the right nozzle diameter and layering bike tubes.

Anyway, I'm going to give it a 4" reservoir, possibly with a similar fill cap idea to the fast-fill caps of recent soakers, in other words a large check valve.

I had been thinking about the easiest way to do that recently, but I haven't come up with anything cheap. Let us know if you figure anything out that's better than buying threaded check valves and using those as caps. I remember blaze discussing a backpack he made that did something like that before. That would be the easiest way to make a "quick fill cap" like the Super Soaker ones.

It might be most worthwhile to tap a hole in a cap and install a small cheaper check valve that way. You could also tap the pipe/other endcap itself and install the check valve that way. That would work if you used a ball valve for a cap, which I've found convenient, but maybe too bulky and expensive for a project like this.

Originally Posted by SilentGuy

On a sidenote, Ben, why isn't the 2 Liter homemade on SSC anymore? It may have been primitive (relatively) but it was popular. Now it can only be accessed through archive.org.

I think I wanted to rewrite it but we never got around to it. I'd like to redo it a little more professionally this year, but until then what we have is adequate.

Also, I'd like to note that the 74 PSI is actually most likely 60 PSI. That stands out to me as one atmosphere too high. I don't know if I did the math right back in 2003. I've correct that figure and some spelling mistakes I noticed.

Edit: Thinking about it, I'm not sure if the "freezing the PC" technique I described for improving range would even work as described. The air would have less pressure at lower temperatures, yes, but I suggested waiting for it to warm up before filling, which shouldn't change the final pressure because the hose pressure is fixed and the system just equalizes. If you keep the air cool while filling and then wait for it to heat up, that should increase pressure. I'll change that tomorrow. Right now I'm going to bed.

[mr. dude]

The CPS 2000 repair (at least on our website) uses two different tubes. The inner one has a pressure rating of 30 PSI. That's different than the 35 PSI of the tube mr. dude mentioned. Did you use a different tube in your repair?

Well, we went by Wayne Schmidtt's (sorry if I spelled that wrong) site, and I believe he used that size, so we used it as well.
Anyway, I'm hoping to get started on this sometime this week. I pretty much only have the LRT and some 4" pipe.
Still haven't decided on a good design, but I'll save that for tomorrow at school (I need something to do in class )

[mr. dude]

I just bought some parts, now I need check valves. I spent $55 CAD+tax on it, and I expect to spend at least $15 more on the check valves. But now I have a reservoir (but no cap yet), which is basically a 4" tee with some extentions. I have yet to make a case, or even decide whether I'll make a case or a frame, but for now, I'm happy.
One more question, I couldn't find some parts in PVC, so I had to buy ABS, and I don't want to spend $8 on the two glues required (ABS cement and PVC/ABS transition cement) for just two pieces, so would good ol' epoxy work well enough for the purposes of making an unpressurized reservoir?

[Silence]

Yep, epoxy should work. I guess that also means you're not using ABS for any pressurized areas...unless you're using it there and only PVC for the reservoir.

[CROC]

Actually, the PVC/ABS transition cement works on bonding either PVC-PVC, ABS-ABS, or PVC-ABS, but epoxy should work well

[mr. dude]

Well, I got check valves. I then conducted a reservoir-less test, and have concluded that the gun needs more work, because right now it can barely clear 35', although I was using a 3/4" nozzle threaded onto a 1/2"-3/4" bushing.
Originally, the LRT was about 8" long, but I replaced it with a 5" strip of LRT because the old one was too long for the design I'm thinking of.
Speaking of which, this is the current layout (minus the case):

Basically, the PC is located above the reservoir up until the tee. My only problem is that the pump sticks out too far, which can be solved, but I don't feel like doing that at the moment.

[aEx155]

What are your ideas for fixing the pump problem? You could always try the displacement pump method; if I remember correctly, it was hard to do but it worked. Or, you could reposition things a little to make it work better:



Oh, and what does the light blue represent?

[mr. dude]

The idea I'm probabably going with is to change the position of the pump. This picture can explain much better than I can:

Sure, that over complicates everything and has more damage prone parts, but it keeps the gun relatively short.
And the light blue represents vinyl tubing.