My CPH concept

[JLspacemarine]

Well, here is what it looks like so far:













I haven't ordered LRT yet but I tried layering a bunch of ballons (more than 50 of them I think) to make an experimental bladder. The power I get with this isn't that bad, actually it's about as powerful as a stock CPS 2100 with more shot time. But my goal with this gun is to make it shoot very thick streams of water at very long range, and right now it's not the case.

At least this experimental bladder made me discover that the pump leaks a lot and that the trigger has a tendency to not close completely, so I'll fix that first.

I'll return with more details of the building soon.

[aEx155]

Your design looks very good; it seems a lot more compact (to me, at least) than the SuperCPS, while keeping the same functionality. I can't wait till you get LRT, so you can get some range stats on it.

One thing I'd like to ask about is the trigger. Does it open the ball valve fully? I can't really tell from the pictures, but I think it does.

[cantab]

Good to hear that layered balloons work, even if power isn't great and it's not your long-term intention. How hard was it to layer them?

[Drenchenator]

Looks great! Can't wait 'til you get your LRT to test the thing out completely! This gun is more along the lines of what I want to see in a homemade; it's compact and functional. And the CPVC makes it look quite original, I gotta say. Good job!

the trigger has a tendency to not close completely, so I'll fix that first.

Same problem I ran into. I positioned the spring everywhere but the valve still would only close halfway at most. In retrospect, I used a weak spring, but regardless of the strength of the spring, you can always move it back more so that it's at least partially extended all the time. This would give it a more more force to close the valve. You can buy a stronger spring as I mentioned before too. Either method should give a bit more force to close it.

[JLspacemarine]

Originally Posted by aEx155

I can't wait till you get LRT, so you can get some range stats on it.

I managed to reach 35-40 feet with ballons, so according to what I know about LRT I should be able to reach more than that.

Originally Posted by aEx155

One thing I'd like to ask about is the trigger. Does it open the ball valve fully? I can't really tell from the pictures, but I think it does.

Yep, it opens the valve completely. But right now the closing feature isn't as great .

Originally Posted by cantab

Good to hear that layered balloons work, even if power isn't great and it's not your long-term intention. How hard was it to layer them?

Not that hard actually, layering the first ones might be tricky, but after 10 ballons it gets much easier. Also, starting with ballons of smaller size and finishing with bigger ones can help.

[Silence]

How did you attach the balloons? Just like you would attach the LRT? How many layers were under the clamp, and how many (if any) were over? How many (if any) did you cut the necks off of? Sorry about all the questions, but I'm curious about this - spherical bladders could come in handy in smaller designs.

While they'd be hard to mount, rotating constant force springs would be perfect.

[JLspacemarine]

Originally Posted by SilentGuy

How did you attach the balloons? Just like you would attach the LRT? How many layers were under the clamp, and how many (if any) were over? How many (if any) did you cut the necks off of? Sorry about all the questions, but I'm curious about this - spherical bladders could come in handy in smaller designs.

The ballons are attached just like LRT:



For some reason I totally forgot about counting the number of ballons when I made this bladder and I think 50 isn't the right total. The package I bought contained various shapes and sizes (to try those long shaped ballons, actually they were extremely hard to layer so I stopped). Then I started layering the normal ballons directly on a 1/2 hose barb, starting with the smaller ones without cutting the necks. I think there were at least 15-20 on them. I'm not sure. Thats where I added the tubing clamp over a 1 inch long strip of inner bike tube over the ballons just to protect them form ripping because of the clamp. Then I added
bigger ballons with their necks removed, just like k-modding (I just counted the necks afterwards to verify the number of ballons, there was fifteen of them).

Well, with about 30-35 ballons I'm not exactly sure why I'm getting good range stats but I'm going to check it again with more precision. If the range is as good as I first verified then its probably because of the laminator nozzle I'm using .

Edit: Rotating constant force springs? Never heard of. Could you explain what they are? Thanks!

[Silence]

This page shows an image of a constant force spring. Essentially, it's a strip of metal rolled around and around. Because it only unwinds a small amount compared to the total number of turns, the force applied is nearly constant. If you could mount one of these next to a ball valve with the two sharing the same axis of rotation, you'd have a flawless return spring. But mounting it would be hard.

Thanks for the information about spherical bladders. I always thought the hose clamps would cut the balloons, but that's a silly idea when you consider that LRT expands just as much right next to the clamp.

[Ben]

SilentGuy's link doesn't seem to be working.

This page links to a PDF with a bunch of engineering information about constant force springs. Smaller ones are available on McMaster-Carr for relatively cheap.

[Silence]

Hmm...you're right, the link doesn't work. Search for constant force springs at their website and click on the first link. I tried copying the URL of that link, but maybe it depends on sessions and cookies or something. Their website sucks for usability, at least as far as URLs go.

[swirlycurly]

looks cool

[CROC]

Did you ever finish making this gun JLspacemarine? It looks great!

If you are still worried about pump volume, a 3/4" CPVC pump works well, I think... It should be approximately the same volume as 1/2" PVC (I think)

Now, I'm full of questions...

What store do you get the plastic check valves at? Those look nice and compact, great for something I'm planning.

What material did you use for the ball valve pull arm, and how can it be made?

Does the wire go through the ABS(correct me if I'm wrong about material), or does it bend around it?

[JLspacemarine]

Originally Posted by CROC

Did you ever finish making this gun JLspacemarine? It looks great!

If you are still worried about pump volume, a 3/4" CPVC pump works well, I think... It should be approximately the same volume as 1/2" PVC (I think)

Now, I'm full of questions...

What store do you get the plastic check valves at? Those look nice and compact, great for something I'm planning.

What material did you use for the ball valve pull arm, and how can it be made?

Does the wire go through the ABS(correct me if I'm wrong about material), or does it bend around it?

Well, it isn't completed, but it works great, thanks. I'm still waiting for my prize (LRT) to arrive so that's why it isn't finished.

Actually, using test bladders such as ballons or even a hydroblitz bladder, I have been able to improve the pump and the trigger a lot. The trigger actuates the ball valve perfectly now. Yep, the wire travels trough the ABS, I've drilled holes in the casing for that purpose. I've took several pictures of the building process of the trigger so I should detail it's construction soon.

As for the pump, the orange handle snapped off but I'm planning to build some kind of tracked, properly positioned handle as a replacement. The original handle was a little bit too far from the grip, resulting in an unbalanced feel when combining pumping and shooting. I'm not worried anymore about the pump volume. Even if it is only about 40 mL, pumping is easy and smooth, allowing me to pump it faster without too much force. Any change to the gun's pump diameter would have forced me to change the trigger as well anyway, so I decided to keep it like it is.

I got those check valves at Réno Dépôt, but this hardware store isn't common outside the province of Québec. I belive they have a stock similar to RONA hardware, but I'm not sure though...

Also, after some work I attached my Powerpak rotating nozzle selector successfully to CPVC. Works great! . I should post pictures soon as well.

[CROC]

I only wish I knew where to look to get those parts. My Rona has swing valves I think.

Do you have recent pictures of the gun? I think Reno Depot may be a Home Depot in Quebec. Not sure though. Doesn't look like it. I saw one of these somewhere, but whatever.

Hope you get your LRT soon! I'd love to see how far it goes with LRT.

[JLspacemarine]

Just received the LRT today!

So, what would be the best length for maximum durability and power? 8 inches as Ben said?

The PC case (4" ABS drain pipe) on my CPH is 24 inches long, but has about 20 inches of space available for the expanded tubing. So, if LRT expands approximately 3 times it's length, 8 inches should work great, right?