Riptide CPS Prototype

Homemade water gun threads that are notable.
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Drenchenator
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Riptide CPS Prototype

Post by Drenchenator » Thu Jul 09, 2009 11:02 pm

I've just finished my second homemade gun; I call it Riptide DR-4. I didn't want to jump the gun like 3 years ago, so I'm posting it now that it works completely.

I call it a prototype because it's imperfect and I used it to get the bugs out of the design. From all the pictures, you see that I drilled more holes than needed, and that many of the screws are too long. We're improving homemades, but it only happens step by step.

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Riptide leaps ahead. It sports a trigger, tracked pump, and casing. The casing contains all the parts and differs from the casing style I tried in DR-3. In DR-3, I tried to hard to copy the style of many Nerf designs, and forgot that those designs need not fit pressurized parts. Here, I returned to form with plates that sandwich the parts, like my water balloon launcher. I've yet to remove all the paper off the plastic, which comes with the paper attached and is compliments of Ben (thanks Ben). The plastic is clear. I didn't want to take the whole thing apart now, so I left the paper on.

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I used all brass parts. Brass weighs less than steel and occupies less space than PVC. I placed all the check valves at the end of the pump; and I admit I stole this directly from Hasbro's design. It's a nice convenience.

Plastic sheets with holes in them suspend the parts within the gun, keeping the parts from moving. The inside structures let me weave other parts (mostly the vinyl tubing) around them. I secured the plates with bolts, and spaced them with nylon spacers.

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The pump differs from my previous pump. I used two rubber grommets, screwed them into the end of a dowel. I don't have pictures of this, but will get some soon.

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After much thought, I realized that a rotary trigger results in more displacement for less space. This trigger pushes on the aluminum beam, pushing open the valve. Most valves you pull open; this one you push open. When you release the trigger, the rubber bands pull back on the aluminum rod, closing the valve and returning the trigger--a nice setup.

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The valve is a 3/8" brass ball valve. This valve opens with little force, and my longer torque arm opens it fully without hassle. The aluminum beam connects through a bolt to the arm, and pushes it forward to open the valve.

I ordered a special brass tee off McMaster, the one you see best in the overall internals picture. It has a square exterior, which means that since I cut a square whole for it to fit it, it won't rotate like circular parts. It also saves space.

The pipe nipple is aluminum.

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The gun is 28 inches long from nozzle to end. It weight roughly 7 pounds too, but that's only because I used 3" schedule 40 PVC for the pressure chamber casing. Once I switch to cellular-core pipe, it'll be less, likely around 6 pounds.

The trigger system works well. This video shows that you can do pulse shots easily. I apologize for the low quality and the big size (33 megs); I can't resize it.

I only used one nozzle, a sixteenth inch one, and it got about 36 feet in range. I haven't done any other testing yet, and I suspect that that nozzle range's was less than optimal.

Questions, criticisms, compliments, extra posts--all are welcome.
Last edited by Drenchenator on Fri Jul 10, 2009 2:53 am, edited 1 time in total.
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cantab
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Re: Riptide CPS Prototype

Post by cantab » Thu Jul 09, 2009 11:28 pm

I don't know what to say...this is just a cut above every other homemade out there.
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Silence
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Re: Riptide CPS Prototype

Post by Silence » Fri Jul 10, 2009 12:12 am

I'm impressed too.

From the first picture it looks like the plastic (or the paper, at least) had cracked radially around some of the drilled holes. Any idea how that happened? I suppose if it's just the paper, there's no issue.

The trigger system looks clean as always...one touch I especially like is the feed hose snaking between the trigger lever and the rubber bands in the fifth picture. The fact that the grip and trigger are only on the left plate could make holding the water gun awkward for right-handed users. (Looks like you might be a southpaw.)

I wonder if you'll be reworking the pump grip, too. My biggest complaint with tracked pumps, at least in commercial water guns, is that it can be hard to hold them in a way that lets you pull with a lot of force. At least there's a front edge to your handle.

Also, what thickness and type of plastic did you use? It looks to be 1/4" (or less) and made of Plexiglas or Lexan...

Another materials question: how much did all the brass fittings cost, at least relative to PVC?

Also, if/when you publish this on the site, some specifics about the latex rubber tubing you used could help. For now I'll assuming it's the same configuration used in CPS.

If you've been reading the forums lately you may have noticed discussion about ABS. If you can find 3", cellular core ABS, that might be an even better option for the case. You'd have to be truly paranoid to spring for it if your local Lowes' doesn't carry it, though. Also, I'm trying to figure out how the PC case is fixed to the rest of the structure.

I really want to see the ranges with 1/8", 3/16", and 1/4" nozzles, and whether or not the small bore limits the performance with larger nozzles..."drooping," as Ben used to call it.

Anyway, great building. The Riptide prototype looks clean and is built like a tank, so I don't know how much of it can be improved...perhaps a larger bore and more attention to ergonomics? That's hard to say, of course, since this one could still feel comfortable and perform well. Keep us posted. :)

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captianfear
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Re: Riptide CPS Prototype

Post by captianfear » Fri Jul 10, 2009 12:25 am

Nice Job.
Recently in your gun and Jcspacemarine's guns there has been a massive step in homemade s: Effective triggers. I still would like to see one with a pull valve but If it works thats great. I am wondering what is up with the handle and pump. How thick is it? They look
pretty thin but I am sure you are adding on to them.

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Silence
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Re: Riptide CPS Prototype

Post by Silence » Fri Jul 10, 2009 1:43 am

Pull valves are great for small valves, but as soon as you up the pressure or the bore size...they stop opening, they stop closing, or theoretically even both. In the open and closed states different faces of the piston are exposed; the pressure acting on these faces can push the piston one way or another.
Last edited by SSCBen on Fri Jul 10, 2009 2:14 am, edited 1 time in total.

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captianfear
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Re: Riptide CPS Prototype

Post by captianfear » Fri Jul 10, 2009 1:45 am

I know a prototype of Dr-3 had a pull valve. Have any other homemades used them?

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Drenchenator
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Re: Riptide CPS Prototype

Post by Drenchenator » Fri Jul 10, 2009 2:32 am

Thanks for the quick replies.

I forgot to mention one good feature I included. The casing is made of two plates: a base plate and several small plates on the opposing side. The base plate is the largest plate, and everything attaches to it. But the small plates can be removed one at a time, so you can work on one section without having to take the entire gun apart. It was easier to make this because I didn't have to make some many long cuts; I could make smaller pieces instead.

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Silence wrote:From the first picture it looks like the plastic (or the paper, at least) had cracked radially around some of the drilled holes. Any idea how that happened? I suppose if it's just the paper, there's no issue.

Silence wrote:Also, what thickness and type of plastic did you use? It looks to be 1/4" (or less) and made of Plexiglas or Lexan...

The plastic hasn't cracked; the paper around the hole lifted and twisted while I drilled through it. In all, the plastic is what made the gun: If Ben didn't let me use it, I likely wouldn't have made it. It's 1/4" Lexan from what I remember, but any quality plastic works. It's only a structural component, so it receives little stress, but it still is strong and tough.


Silence wrote:The trigger system looks clean as always...one touch I especially like is the feed hose snaking between the trigger lever and the rubber bands in the fifth picture. The fact that the grip and trigger are only on the left plate could make holding the water gun awkward for right-handed users. (Looks like you might be a southpaw.)

I'm a lefty, and I guess this shows it. There is no reason why this gun can't work for both righties and lefties. It's just that I didn't have time to place the handle in the center of the gun, or to build up the trigger so that part is on the base plate, and the other part, the trigger itself, is spaced out to the center.


Silence wrote:Another materials question: how much did all the brass fittings cost, at least relative to PVC?

The check valves cost 9 USD each, and each fitting was at least another 2 USD, if not 3 USD. Considering all parts, I believe the price is about one and a half to two times the price of comparable PVC parts. But I paid more to save--save space that it. PVC check valves are much larger, and both brass tees I had were the ideal size of their needed location. I deem highly the brass.


Silence wrote:Also, if/when you publish this on the site, some specifics about the latex rubber tubing you used could help. For now I'll assuming it's the same configuration used in CPS.

The latex rubber tubing is the same as it's listed on Ben's SuperCPS. We got two drawers of the stuff within our shelves of parts; this morning I walked up, reached in, and walked out with a small piece of it. I didn't even cut it; I assume Ben did before. But it looked unused, so I'll use it.


Silence wrote:If you've been reading the forums lately you may have noticed discussion about ABS. If you can find 3", cellular core ABS, that might be an even better option for the case. You'd have to be truly paranoid to spring for it if your local Lowes' doesn't carry it, though. Also, I'm trying to figure out how the PC case is fixed to the rest of the structure.

I've been paying attention somewhat and remember reading that thread. The thing is that ABS isn't sold around where Ben and I live; our local Lowes and both our local Home Depots don't stock it. But McMaster must have it (I assume). I'm looking at all options for the chamber casing, so thank you Silence for the tip.


Silence wrote:Anyway, great building. The Riptide prototype looks clean and is built like a tank, so I don't know how much of it can be improved...perhaps a larger bore and more attention to ergonomics? That's hard to say, of course, since this one could still feel comfortable and perform well. Keep us posted.


captainfear wrote:I am wondering what is up with the handle and pump. How thick is it? They look pretty thin but I am sure you are adding on to them.


At the moment, Riptide lacks any ergonomics. It's so square. But I do have plans to attach 1" PVC to give the grip and the pump handle something to grip on. They are very thin, 1/2 inch each. I'm still thinking of how I want to do them.


captainfear wrote:Recently in your gun and Jcspacemarine's guns there has been a massive step in homemade s: Effective triggers.

Yes, JLspacemarine and I have kicked down a couple doors when it comes to triggers. I struggled with DR-3's trigger, but this one just came together so beautifully. I'm glad that homemades are finally catching and passing the old stock guns. It's past it's due. One of the main reasons I built this gun was that I couldn't use my CPS 1200 forever. It was going to break down one day. So I built something more permanent.



captainfear wrote:I know a prototype of Dr-3 had a pull valve. Have any other homemades used them?

I built a special kind of pull valve, but I don't recommend building it any more. It just wasn't worth the effect. Too much work in, too little function out.

I do remember someone else building a water gun with a pull valve sometime in 2007. I'm not sure who did it. Anyone remember?
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adronl
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Re: Riptide CPS Prototype

Post by adronl » Fri Jul 10, 2009 3:08 am

It looks good very complex design compared to most homemades probably cost a bit too. I wish it were more powerful though.

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Drenchenator
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Re: Riptide CPS Prototype

Post by Drenchenator » Fri Jul 10, 2009 11:59 am

I wish it were more powerful though.

There's little reason to believe this gun is weak: The nozzle I tested the shot with was 1/16 of an inch in diameter; if a more typical nozzle is around 3/16 inches, then that nozzle has 9 times less cross-sectional area, which makes the stream fast but liable to break up.

I suspect it would peak at around 45 feet in range with a good nozzle, and if I add another layer of latex rubber tubing, it would peak at around 55 feet in range.

Nothing in the design prevents the gun from performing poorly. I built it with a straight line from the chamber, through the valve, and out the nozzle. The straight line maximizes performance by minimizing turbulence. It's the same range-increasing concept the Ben's SuperCPS uses.

I'll do range testing later today, so we'll see how good it really does.

-----

Edit: I tried out some range testing and a problem popped up.

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This thin cable tie snapped and the firing valve assembly jumped forward an inch, preventing me from pulling the trigger to discharge the chamber. I got Ben out to help to hold the assembly in place while I pulled the trigger, and we learned quickly that it wasn't happening. Instead, I reached into the gun and pulled the aluminum beam forward, holding it at its center and at the valve arm, and opened the valve enough to discharge the gun.

The cable tie was thin, so I will replace it with a thick one, or perhaps two thick ties. I didn't anticipate this problem though, because I never knew that the LRT pushes the valve forward while it expands.
Last edited by Drenchenator on Mon Jul 13, 2009 11:09 pm, edited 1 time in total.
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adronl
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Re: Riptide CPS Prototype

Post by adronl » Tue Jul 21, 2009 4:28 am

Honestly the gun is pretty darn well engineered and Is easier to operate than mine I think in a water war you would get your shot off before me. Also like you said you can use another layer of latex or if you felt like it you could try gum rubber. You have put a lot more design time and work into that thing than I typically do with mine. I say awesome gun man all you have is one little kink to work out and it will be more functional than anybody's homemade I've seen yet.

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Drenchenator
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Re: Riptide CPS Prototype

Post by Drenchenator » Tue Jul 21, 2009 7:06 pm

Thanks.

I still haven't tested the range yet, because I'm still working on the feel and comfort of it. The grip and handle don't feel good at all, and I have to figure out how to attach pipes to them.
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adronl
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Re: Riptide CPS Prototype

Post by adronl » Tue Jul 21, 2009 9:37 pm

I was thinking you might be able to make ergonomic wooden handles if you need to. You would just have to use a decent hard wood and if you took some time they could be much more ergonomic than some pipes. Poplar is cheap and very hard FYI they use it is the construction of couches and other furniture to add strength with out adding much cost. Also that is Plexiglass or similar right are you going to peel off the protective white layer to show off the inner mechanics at some point.

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Re: Riptide CPS Prototype

Post by JLspacemarine » Thu Jul 23, 2009 3:41 am

Impressive!

I like how you always manage to build your homemades within a casing, just like commercial water guns. This one especially has a «commercial CPS» feel when you take a look at those internals alone : The check valves are stacked at the back of the pump rod and the firing chamber/trigger valve is separated from the pump via vinyl tubing. As well as the pump which is tracked.

It seems to be on the heavy side though,obviously because of all these bolts and brass pieces in there... my CPH weights the same and I found that too heavy to be comfortable, but at least Riptide looks more compact and dont have a 4 L onboard reservoir... so 6-7 pounds should be alright I think.

I'm currently building another homemade as well, and for the grip and pump handle I've come out with the solution of using some 1/2 PVC pipe wrapped in home pipe insulation. I found it great for building comfy handles. I usually add inner bike tubing over it just for more grip and durability.

Btw, great work on the trigger. Looks like it is better at closing than my system, and only with a rubber band! :p
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Drenchenator
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Re: Riptide CPS Prototype

Post by Drenchenator » Thu Jul 23, 2009 8:27 pm

Thanks for the positive comments, JLspacemarine.

Being Ben's brother, I always could shoot one of Ben's half dozen homemades when we fought, so I never needed to build a conventional homemade water gun. I shot for a much more commercial feel for this one, a feel that I plan to improve whenever I add a new handle and grip.

I'm still debating what to do. I appreciate what you said, adronl, because a wooden handle would be ideal; but I couldn't make one well at the moment because I lack the proper equipment, mostly sanders. And JLspacemarine, your idea is good too. Ben and I have the same foam you're talking about and have used it for other projects, so I don't need to buy any. I current grip and handle eat into my hands. I just need to figure out which system to use and how to attach it.

The trigger system took the most thought (the grip and handle are very much after-thoughts). The gun uses two natural-rubber rubber bands that are looped around the bolt to half their length, increasing the force to close the valve. If I didn't do it that way, the valve wouldn't close because the rubber bands wouldn't be stretched!

I look forward to any homemades you're building, JL.
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Re: Riptide CPS Prototype

Post by JuchTurtles » Thu Jul 23, 2009 8:57 pm

Very Impressive!!

I might have just missed this but what nozzle size are you using?

It looks great, but is it easy to handle in a water war? It seems like it could be unwieldy if not used in a proper way.
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