294 replies to this topic

[ompa]

Up to 30 pumps it hasn't popped any of mine yet... What are you pumping yours to Vintage, 50?

~ompa

[Arcanis]

I designed a inner tube cps the other day, quite simple. It can use teh rf20 mechanism also, but fit a small section of 3/4"pvc on either side of the bladder, endcapping one side. Clamp both sides. The do whatever you want with the other side, wether attaching it to a coupler, or sanding down the rf20 mech and shoving it in there.

Okay, will it matter if I cap up the other end? And you're sure it works, right? A cheap CPS would be great. I would need to drill a small hole in both ends.

Doh, now I realize that you need that end piece on it. I don't think that would matter, right? I just didn't know that you could use it like that.

[THIRST]

Okay, will it matter if I cap up the other end? And you're sure it works, right? A cheap CPS would be great. I would need to drill a small hole in both ends.

Doh, now I realize that you need that end piece on it. I don't think that would matter, right? I just didn't know that you could use it like that.

You need an endcaap on one end, obviously The other end can be connected to 3/4" couplers, elbows, hoever you want to ceonnect it to the gun.

THIRST

[ompa]

Or another endcap with tubes epoxyed into 2 holes into it. Hell, with some work, you MIGHT be able to make interchangable bladders.

~ompa

[Vintage]

Ompa, all I did was pump it 30 times, and then applied pressure with my hand to the bladder. I wanted to see if it would do anything for the range, but it blew the vinyl off one of the connections. Now, I am reinforcing all the connections, and removing the unwanted RF20 valve.

Concerning the CPS, you might want to adjust your design a bit. If you just try to clamp the layers of bike tube to 3/4" PVC, it just might slide off under pressure. You might want to try this which I posted over at Open::Nerf

The coupler halves provide support for the clamps. It helps the rubber from sliding off the PVC.

~Vintage

Edited by Vintage, 29 August 2004 - 09:11 PM.

[Hunter]

Perfect, Vintage.
You then must ensure that the couplers are secure. I would suggest PVC cement for that particular job, it melts both sides of the PVC to create a strong bond.
That design is on it's way to become interchangable, if you had enough patience.

[Jlego]

shit, pvc cement might not be enough. Try drilling pilot holes and then securing them togeather with screws.
-jlego

[Doom]

I tried to stay out of this, hoping that you'd eventually figure it out, but now it's just ignorant.

http://nerfhaven.com...?showtopic=2587
http://nerfhaven.com...?showtopic=2662

While you couldn't exactly find this topics using the search, they were recent enough for me to pull up without going crazy.

You can buy foam to make homemade darts. You can buy rubber tubing to make CPS bladders.

I'd suggest that all of you interested in this look at both of those topics. Also, read this PM I sent to someone.

http://nerfhaven.com/forums/index.php?showtopic=2587
http://nerfhaven.com...?showtopic=2662

Read the few topics on this and milk them for what they are worth. And if you've got anymore questions ask me or ask those on my forums. Actually, don't ask them, I really am the only one in the entier world who has used this stuff. I'm reuploading the images of my gun, which at this point needs work. The pump didn't last, needs a new one.

I get asked this a lot actually, but you're the first Nerfer to personally ask me. It doesn't matter what size you use. I am serious too. All the matters, power-wise, is total thickness. I will recommend that you buy the following however to make a good, powerful chamber. Be aware that these are two different sizes of LRT, one is to be put over the other and add resistance. This will produce a Super Soaker more powerful than the CPS 2000, please use caution. If you remember, a CPS 2500, weaker than the 2000, can shoot a Stefan over 250 feet.

ID: 3/8" Wall: 3/16"
ID: 1" Wall: 1/4"

Total thickness will be 7/16", and with some bike tubes you could get that up to like 9/16".

I only used about a foot of this stuff. I bought about 3, now I'm wishing I bought more. Buy a bunch of this stuff, if you get 25 feet or more of one type then it's cheaper. After that you can lie and say it's like PETG, only available in bulk and sell a ton. Or maybe I'm just giving you ideas.

If you look at my pictures, for this gun I closed the open end of the chamber, with a bolt and tubing clamps. That may not work very well on your very thick chamber. I would recommend getting a female threaded endcap, screwing in a tubing barb with teflon tape and then putting that on with a tubing clamp. DO NOT PUT IT ON TOO TIGHT! It will cut into the tubing, put some duct or electrical tape over where you are putting it if you want some protection from that.

Hopefully this helped.

[Vintage]

Doom, those rubber tubes have a max PSI of 30 at 70*F. We need something stronger than that. Layered bike tubing is something we can all get our hands on quickly, and will hold as much pressure as we want, just by adding layers.

30 PSI is probably fine for a water homemade, as it has a small nozzle to propel the water. 30 PSI is also fine for a homemade nerf gun that is single shot with a larger tank and longer barrel. We are working on an AirTech 2000 which has a tiny airtank that operates at a high pressure. I really don't know how much PSI it uses for optimum performance, but 30 sounds low for it.

If those rubber tubes could be bought for higher pressure, they should work great. The only high pressure ones on that site are 200 PSI, which is too much.

If any of my statements are incorrect, please correct me, and I would gladly buy rubber from that site if it will work.

~Vintage

[Doom]

Believe me, I know more than most anyone on this stuff. I'm as close to an expert as you'll get. Pressure does not matter, force does.

Think of this: My air pressure water gun has a pressure of about 100-110 PSI, and my CPS homemade has at most 60 PSI. The CPS one beats it in range by several feet. Why? Because pressure doesn't matter with CPS stuff. It's a well established fact at the water gun sites that CPS is lower pressure for equivilant power. Wasn't it Gaebo who modded a CPS 2500 and it shot like 250 feet? On the package, it lists the PSI as 22. The mighty CPS 2000's was listed as 26.

Plus, I don't think that the PSI listing is how much pressure is created. I think it's more like how much pressure is needed to make the tubing expand. It doesn't matter though, what ultimately matters most is total thickness.

Also, it will take 30+ bike tubes to make something as thick as what I said in that PM. And your RF20 bladder probably is a about as thick as the 3/16" thick tubes.

As I said (or meant), you all could learn a thing or two about CPS systems. The best way to get experience with the stuff is the buy it, so go and buy what I said to (buy it in black, I think the amber stuff might be different).

Edit:

If you want to get technical, technically CPS systems don't need to create any pressure at all. The collapsing of the tubing will force air out just like a chamber decompressing. No pressure is needed.

Edited by Doom, 30 August 2004 - 05:06 PM.

[THIRST]

This thread is not about competition. If you want to teach us a thing or two about cps, then please do so, no need to say it like that.
Also, I never saw/knew Tex's topic existed, as I was on vacation those days.

Believe me, I know more than most anyone on this stuff. I'm as close to an expert as you'll get. Pressure does not matter, force does.

We know that, as your "The water gun guy", we could use all the help we could get, and we would apprecicate if you helped us, but this thread isnt elevating onesself, were just trying to make one kickass gun.


THIRST

[Crankymonky]

If you want to get technical, technically CPS systems don't need to create any pressure at all.  The collapsing of the tubing will force air out just like a chamber decompressing.  No pressure is needed.

No, pumping air into it increases pressure...Half the stuff you talked about, well.

The bladder isn't creating pressure. Pressure is a type of force exherted on a gas. As you increase the number of molecules in the bladder(pumping), it increases the volume, and keeps the pressure constant. Eventually this rate will slow, since the bladder can't expand more, and the pressure increases. There were a few other iffy things in that last post.

Also, it will take 30+ bike tubes to make something as thick as what I said in that PM. And your RF20 bladder probably is a about as thick as the 3/16" thick tubes.

I think you have measurements wrong? I just measured the width of one side of an inner tube. 1 MM. 30x1mm=3 cm=over one inch. Now look at it because it is a circle, and it is almost 3 inches big, before even pumping. Look at a ruler. You'll be surprised at the size of 3 inches.

Pressure does not matter, force does.

So to speak, volume is the air outputted, and pressure is the "force" behind it.

I am not sure how all of this works in water guns, but in nerf, I think it may be a bit different after hearing you. Also, you do know much more than us in CPS, considering we have never really worked with it like water gun guys have.

Sorry, if this post comes out at all derogatory, it isn't meant to be.

Crank'

Edited by crankymonky, 31 August 2004 - 06:14 AM.

[Vintage]

Doom, as I tried to explain earlier, we are not dealing with a gun that will let out a massive amount of air all at once (like your CPS 2500). Our gun doesn't even use the CPS tank to fire the gun! All the CPS tank is there for is to provide tank refills for the standard 2K tank.

That is why we need the pressure high. If the CPS rubber inflates at 50 PSI, then it will refill the 2K tank to 50 PSI. Then the shot will be made using the air from the 2K tank, allowing another refill.

We NEED high power CPS, because it refills a small airtank. I think you are assuming we are trying to launch a continuous large blast of air all at once (like the CPS 2500). We just want tiny bursts of high pressure air from the small plastic airtank.

I wish I didn't have to explain this:



This is essentially what we are doing in it's most basic form. The one large tank is used to fill the small. The small tank is fired. The process repeats until all the air is used up. Only what we are doing is replacing the large hard tank with a large CPS tank to give each shot equal power.

I hope you can understand now why we need high pressure.

~Vintage

Edit: Now, concerning my progress, I had to redo most of the vinyl, because I removed the RF valve. But I accidently didn't goop enough vinyl to give the crimp I needed. Now I just finished gooping the right size tubing onto the assembly, and I will have results tomorrow night.

Edited by Vintage, 30 August 2004 - 10:37 PM.

[cxwq]

Thanks for clarifying for him Vintage. I was about to come say more or less the same thing and found that you had done it for me.

[Doom]

Sorry about that, when topics get this long I tend to print them out and I did 3 days ago. Anyway, I am NOT assuming that you are shooting one large blast at once, the topic title with the words "semi-auto" explain that well enough. The CPS chamber actually will pressurize a smaller chamber like that very easily (that 9/16" chamber I described probably won't expand without having 80+ PSI on it). However, at this point you might just make a large air chamber and accept that there will be a performance drop-off because it will be easier to construct.

Anyhow, I myself had made a homemade that shoots a short burst of air with each shot. I was able to get 6 or 7 shots out with about 60-70 feet in range (the last shot had less because there was about half the amount of air as the other shots), all in about 40 pumps. The only thing that regulated that was the mechanism that opened and shut the valve.

I'd also like to know how this is going to be semi-auto, which to me is one trigger pull equals one dart shot, nothing special inbetween shots.

I think you have measurements wrong? I just measured the width of one side of an inner tube. 1 CM. 30x1cm=30 cm=over one inch. Now look at it because it is a circle, and it is almost 3 inches big, before even pumping. Look at a ruler. You'll be surprised at the size of 3 inches.

I believe that it was thickness I was measuring. Not the width of the tube. That depends on the ID of the tube, which doesn't matter much in this situation.

[Crankymonky]

I was measuring the width of one wall of the inner tube. If you stack 30 of them together, each wall is 3 cm. That is about 1.5inches, just for wall size.

[Vintage]

I'd also like to know how this is going to be semi-auto, which to me is one trigger pull equals one dart shot, nothing special inbetween shots.

Starting with Thirst, we all agreed that if you limited the airflow from the large reservoir tank to the small firing tank, the shots would be semi-auto. The air fills the tank slowly (I say slowly, but it takes under a second) and when you fire, not much extra air from the reservoir is lost (if you remember to let go of the trigger asap.)

So with two crimps in my vinyl tubing as the air restrictor between my two tanks, I can get 1 shot per second without using anything but the AT2K trigger. Of course you still have to rotate the turret for each shot, but we are going to try ShortShit's barrel setup to help the rate of fire.

~Vintage

Edited by Vintage, 31 August 2004 - 11:52 AM.

[BoltMasterZero]

I didn't exactly follow along with everyone else but heres my version.

With about 25 pumps I can pull off 3 really hard shots. I haven't measured distance but I will do so soon. The whole assembly is constructed of CPVC. A definate plus is that it doubles as a stock. Questions?

[cxwq]

Damn, you beat me to it. Oh well, I'll still find something interesting to contribute. Expect my entry soon.

[THIRST]

BMZ, on behalf of this group...we need a writeup! Nice man, Im glad that someone finally did something like that, and it gives us a better understanding of semi-auto and laws of diffusion. Also, you cleared up all too many rumors. Like I said, if you could give me a writerup with pcitures, I would love to put that in the project, seeing as its along the same lines, just appraached differently.


THIRST

Edited by THIRST, 31 August 2004 - 04:54 PM.

[ompa]

Considering the whole thing is made of cpvc... Wouldn't each shot be weaker than the shot before it? I'm probably wrong, but that's what I'm getting out of it.

~ompa

[Slicer]

fully semi auto

::love::

Edited by Slicer, 31 August 2004 - 06:06 PM.

[BoltMasterZero]

Yes, each shot gets weaker, but you don't notice any difference in shot power until the fourth shot. The 4th and 5th shots are lower power (probably around 55ft) but still might be of some use. Thrist, I would be more than happy to do a write up. When will it have to be finished by?

Edited by BoltMasterZero, 31 August 2004 - 09:21 PM.

[THIRST]

Whenver you feel like it. Slicer, I appreciate that, but lets keep this thread just for ideas.

THIRST

EDIT: Alright,I just finished makign my origional 2k a lot better, Ill post ranges and stats tomorrow because Im going to sleep, but I'll tell you this, its much better.

Edited by THIRST, 31 August 2004 - 07:17 PM.

[Jlego]

along the lines of repressureizing(sp) the valve, to keep it regular, couldn't you use a wf valve? You pull the wf trigger, it would send three shots of air to the valve, release that trigger, then pull the other. Repeat.
the line up of stuff, now that i think about it more woulnt fit in the case. so if we used an sm1500 as an almost equal example, just bigger, it would go

pump-> wf trigger -> wf bladder and wf valve.

then the wf vale -> sm1.5k valve, which is still connected to the original trigger.

I don't think this idea will work in this situation or this case (ohhh, that was bad) but it was an idea for a regulated air output per shot setup. do what you will with it.
my two cents.
-Jlego