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Spring Homemade

Posted: Tue May 24, 2011 1:01 am
by atvan
Edit: Spring as in metal object that creates force.

My idea was to build a homemade which had a single spring plunger as a PC, and a handle to pull it back in one stroke. Imagine, a water gun fully pressurized in half a pump!

For the design, I will post a pic.

My only concern would be trade-offs. You would have to balance ease of use and power- strength of spring, power and volume- size of plunger, etc. A question about springs- is the strength of a spring (e.g. 25 pounds) the springs strength fully compressed or something else?

Re: Spring Homemade

Posted: Tue May 24, 2011 1:11 am
by zeda.beta
Two things: The plunger design is really hard to hold water in the PC (at least reasonable amounts) and the springs rust if you get a single seal wrong.

The splat blaster and waterball launcher both tried this, and it doesnt work for a reasonable amount of water.

Re: Spring Homemade

Posted: Tue May 24, 2011 1:26 am
by atvan
Both those blaster tried to be fancy about it, with levers and fancy blasts. This would be much more simple, with a stronger spring, not intended of 5 year olds. This would have a linear pull on the plunger, making the charging much easier. I just realized that volume/shot time would not matter as much since you could re-pressurize so quickly. I pictured it using maybe plunger cups though from the SCII article, it seems that they have a lot of friction, but seal well. Just a developing idea thought up last August at Clifftop Music Festival.
:p

Re: Spring Homemade

Posted: Tue May 24, 2011 5:21 am
by DX
If you want to make a spring homemade, you should check out the Nerf community, for that is the mentality you need for the project - think of it like a Nerf homemade with a water intake. The idea has floated around before, and some of us have toyed with it.

I actually made a reasonably powerful proof-of-concept using a manufactured Nerf gun to provide the power - a Pump Action Shotgun (PAS) made by ERTL. Normally, water guns are converted to Nerf, you rarely hear about a Nerf gun being converted to water (actually, I've never heard of a Nerf gun being converted to a water gun before). Instead of a tight Nerf barrel, I put a 1" Tee on it and a reservoir that would feed into the plunger through that tee from above. The seal of the plunger in this gun is well-known for its quality, so the suction created by priming it could draw water through tubes if you wanted to use a backpack. I just put the reservoir above the gun for simplicity, as gravity did the work for me. The area of water you shoot is created when you draw the pump back. The gun primes and you let the pump return to its normal position. Pull the trigger and the water is fired, I don't know the potential range since I did this test indoors. I shot a wall about 20ft away with a 1" nozzleless riot blast, so it does have some kick. You can keep priming and firing in bursts, ejecting pulses of water as fast as you can prime and pull the trigger.

Now, some caveats about the experiment - you need a make a PERFECT seal in the plunger head in order to avoid being swamped. The PAS has such a tight seal that it will vacuum suck a dart right out of a CPVC barrel and into the plunger if you load before priming. If it's a slug dart and the barrel is really tight, the dart body will be separated from the felt and washer and it will be sucked into the plunger alone. Yet, water still easily managed to get past the seal and swamped the rest of the interior. I had to take the gun apart to get all the water out. Water came rushing out of the trigger opening, so this is not practical as a permanent conversion.

Additionally, since the PAS is a springer that was not designed to shoot water, there is no way to stop water from coming out of the nozzle if you put one on it, other than keeping the gun angled when you fill and fire. A check valve would solve that, but that would hamper flow, not to mention reduce the power. A stock PAS spring is not terribly powerful, a person of average strength can prime one very easily.

The final concern is that of power itself. Water requires a ton of energy to move - consider how much energy it takes to fire a dart 200ft vs how much it takes to fire a 5x stream of water 60ft. The former can be done in 10 pumps with a standard pump, the latter takes pushing a K-mod to the limits. Spring homemades probably can't fire water farther than 35ft, unless you use an extremely strong spring. As tempting is it would be, I am not willing to test the power of my K26-based RBP Nerf homemade to move water. It's the strongest spring-powered gun I own, but also my best Nerf gun and one not easily dis-assembled and dried. I don't know if the seal is watertight or whether the vital metal components are stainless. If you want to experiment with strong springs that you can prime with one hand, McMaster's offerings would be a good place to start. You'll have to essentially build a Nerf springer for that (or commission someone to build one for you), which is why I suggested gaining a background in Nerf homemade construction at the beginning of this post.

Other than those three problems, the concept has been proven operational. It's just a matter of solving the quirks and getting power that a player can handle. Really strong springs are really hard to prime. Don't forget about the law of diminishing returns, either. It takes vastly more effort to squeeze a little more power out of a gun as you go up in performance. I would not say don't do it, but a lot still has to be worked out.

Re: Spring Homemade

Posted: Tue May 24, 2011 12:44 pm
by isoaker_com
atvan wrote:Both those blaster tried to be fancy about it, with levers and fancy blasts. This would be much more simple, with a stronger spring, not intended of 5 year olds. This would have a linear pull on the plunger, making the charging much easier.
Levers and fancy blasts make the Water Ball and original Splat Blaster fancy? Hardly. The Water Ball function pretty much by catapulting a small plastic cup of water forward quickly enough, then stopping the cup suddenly and letting the water fly which resulted in the ball-shaped blast. The actual firing mechanism was fairly simple; only the opening was more complicated to prevent water dribbling out during the priming stage. As for the Splat Blaster, the lever-based-pump was used to try to make pumping easier since smaller kids may find directly pulling on the spring to be too difficult. Aside from that, the firing mechanisms is extremely simple.

Seems like the newer Splat Blaster II is along the lines of the sort of blaster you'd like to build, but adding in a trigger and better nozzle. That blaster using a single stroke pull-back spring-based mechanism, but lacks a laminating nozzle and trigger, firing upon every full pull and releasing a *splat* of water.

DX already pointed out many problems facing spring-based water guns. Single-pull-back triggered spring-based water guns have been made before, but older ones shot roughly as well as a basic water pistol. Finding good springs and creating good seals and structures make spring-based water blasters a little trickier to mass-manufacture.

Of course, for homemade building, sky's the limit! Good luck with this project and looking forward to hearing about your progress with it!

:cool:

Re: Spring Homemade

Posted: Tue May 24, 2011 7:48 pm
by C-A_99
From what I know, any spring that's weak enough for you to be able to compress by hand is too weak to shoot water effectively, but perhaps volume is the real issue. At low diameters, it should be possible to get much better shot results with a spring that's weak enough to be compressed by hand, but then you have to deal with extremely constricted volumes.

The Pulse series blasters already have low diameters and very low PC capacities, yet their springs are too strong to charge by hand (which is why they have pumps), and if they made the firing chambers any larger, it would require far too many materials and resources; they have to create a frame that's strong enough to handle the spring, use "better" springs, create larger chamber, etc.

Seals are indeed another likely concern, but we have to deal with this same issues constantly in pumps, piston valves, and piston-separated air pressure homemades. I don't see how sealing a spring powered piston is any more difficult than getting a piston seal in a SuperCannon II to work, or getting a pump to seal.

Nonetheless, spring-powered is not a preferred methodology for building homemades. Even stock blaster manufacturers don't like it unless they're making blasters with extremely low pressure chamber capacities or triggerless blasters. The Pulse series was cancelled due to the costs, low PC volume, and other issues. At the moment, bladder and and air pressure based systems remain the best methods.

Re: Spring Homemade

Posted: Tue May 24, 2011 10:11 pm
by atvan
Volume wouldn't matter much to me because this would be ready to fire in a half a pump, so if the shot time is a half of a second, thats the same as pump time, making it faster than all blasters I can think of.

On DX's comment, I might try a SNAP or the link below, except with solvent welding and small diameters, plus a backpack resivoir.
http://nerfhaven.com/forums/index.php?s ... ntry297283

Re: Spring Homemade

Posted: Wed May 25, 2011 1:32 am
by C-A_99
^ The same argument could be applied to a CPS 2000 with a 2" long bladder that can push out far less water. At the power level of most decent blasters however, it is impossible to pump fast enough to keep up with the shot. A single pump stroke can only push about 37mL at most, and without the assistance of a pressure chamber (or perhaps hydraulics), the shot will be a weak, average piston pumper shot.

Fact is, you can only pump so much at once, and that pumping can be directed only to higher shot volume or to higher power. The point of pressurizing a blaster is to get both by taking time to do it, and this pressurization, in some form or another, is required for decent performance.

Re: Spring Homemade

Posted: Wed May 25, 2011 3:03 am
by mysterio
I've actually played around with this idea, using some of my existing nerf blasters (not ending well) but I plan to procure a PVAT soon, which would solve the problem of water leaking out of the PC, and using a large amount of washers to ensure the seal is perfect. Having a little bit of a background in nerf does help, as zeda said. Won't be as quick to prime, but its the same concept as the pulse series.

Re: Spring Homemade

Posted: Wed May 25, 2011 4:08 am
by DX
Don't go any weaker than a K26 spring - the gun has to kick the water out hard and fast. Also, do it with pump action, never make a pull-back springer anymore. The pump action greatly increases the rate at which you can spit out shots. It won't match tapping the trigger on a pressurized water gun, but it's still fast enough to be practical.

Don't use too many things to make the seal - if the seal is too tight, it will create a lot of friction and slow down the plunger. You want the spring to slam down the plunger tube as fast as possible. The seal has to be perfect, yet light and able to slide. That's the main challenge.
I don't see how sealing a spring powered piston is any more difficult than getting a piston seal in a SuperCannon II to work, or getting a pump to seal.
It is totally different, because the "pump" in a springer is not a real pump, it is just a handhold for pushing the spring back to be cocked. A piston in a water cannon is propelled by the air pumped in from the back, there is no spring. And a pump seal also has no spring, it does not have to slide nearly as fast as the head of a plunger rod. The plunger head seal is not powered by air or hand, but spring compression. Thus, it's not just that the seal has to be airtight, the seal has to be slid faster than you blink. That makes the difference between crap range and usable range, how fast can the spring eject the water outta there.
From what I know, any spring that's weak enough for you to be able to compress by hand is too weak to shoot water effectively, but perhaps volume is the real issue. At low diameters, it should be possible to get much better shot results with a spring that's weak enough to be compressed by hand, but then you have to deal with extremely constricted volumes.
I personally don't think the volume matters too much, what matters is how fast you can eject the water. If a PAS spring can clear the room at 1" with no nozzle, I am willing to bet it can hit 25' with a 1/2" (conservative guess) or 30' on that 1/2" (more of a stretch guess). A K26 would then have 30'-35' range. That won't compete with top stock guns, any modded gun, or any pressurized homemade, but it would be in the mix with a mid-range CPS and surpass some modern air pressure. I'm not sure if it's possible to get more range with springs that can be handled. It's not just being able to handle it with one hand, the cocking mech has to be able to handle the power, too.

A springer misses out on the one thing that separates water guns from all others, the ability to shoot a continuous stream. But, it has a trigger, and can be more compact than any other homemade. It is interesting enough to be worth building if the quirks can be worked out.

Re: Spring Homemade

Posted: Wed May 25, 2011 4:35 am
by C-A_99
Plungers in water based spring PC's don't seem to slide that fast; nowhere near the speed at which air plungers (found in Nerf and Airsoft guns) have to slide, and reducing friction as much as possible is important in all three setups, though perhaps more important in the spring plunger due to how little power is going in the first place compared to air pressure.

Pressurized reservoir and reservoir-embedded CPS's just as easily have the same potential to be as compact as springers but with better capacity. The former is constantly seen on the shelves, while the latter has not yet been experimented with and only came about with BBT's Vindicator and vanquisher, but I see potential with it given better ways to allow higher air intake for bladder contraction while keeping water from spilling out.

Re: Spring Homemade

Posted: Wed May 25, 2011 5:37 am
by DX
I was under the assumption that a springer for water would use an air springer setup like in a typical Nerf homemade, just with a better seal. In my PAS experiment, the only difference from normal operation was that it drew and ejected water. The spring obviously did not pop back as fast as it would with air, but it was still designed to. I don't know how the companies manufactured springers as I have never owned one of those.

What could help push springers over is some kind of two stage spring system. While compressing the main spring, a second spring behind the plunger tube is compressed, so that the plunger head is propelled through the tube even faster when fired. I don't know how that would be set up, though.

If you put the reservoir in a backpack, a springer gun can be as narrow as 1.5" wide if you don't count the trigger handle. Find me a gun other than a piston pumper that is so small. The thing is long as hell, but you could slide the whole gun minus the handle through an opening the size of a glass of water. No other homemade can ever be that compact, minus piston pumpers.

Re: Spring Homemade

Posted: Wed May 25, 2011 2:07 pm
by C-A_99
Most CPS cases are close to that width. Without regard to internals, trigger valve, pistol grip, etc. it's not a far stretch to design something in the same form factor that hooks to a backpack and/or that contains the reservoir water in the space of the cylinder not used by the bladder. Same idea as putting LRT into a pipe as a casing, sealing it, and using the remaining space in the pipe as the reservoir.

Re: Spring Homemade

Posted: Wed May 25, 2011 11:53 pm
by strato_2r5
Well, you could take a nitefinder or any direct plunger nerf gun. It has to be direct. Then you take a tee and put it in front of the plunger. The tee would be connected to a ball valve straight. The 90 degree part of the tee would have a check valve connected to a reservoir. Then just get rid of the catch, trigger, and electronics. It just has to have a good seal.

P.s. Sorry if someone said this already, didn't feel like reading long posts.

Re: Spring Homemade

Posted: Thu May 26, 2011 3:26 am
by C-A_99
^ It has to be able to stand a much stronger spring too for any reasonable performance.