Minicannon

Build a homemade water gun or water balloon launcher and tell us about it.
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soakernerd
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Minicannon

Post by soakernerd » Thu Jan 28, 2010 7:12 pm

I have wanted to build a SuperCannon for a long time. What I have not wanted to do was spend $160 on one. Since I had 2 feet of PVC lying around, I decided to base my attempt on that. The big thing that was still going to cost was the piston. To solve this, I decided to use the Waterzooka's plunger, but without the plunger rod. Before I buy a bunch of o-rings and valves, I would like to know if anyone sees a problem with this plan.

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adronl
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Re: Minicannon

Post by adronl » Thu Jan 28, 2010 8:42 pm

You can build a supercannon for far cheaper than that I have actual figures for the cost of everything needed. A 2" piston gun costs me 32.95 to build and a 3" costs 52.07 so your prices shouldn't be far off that. There are some modifications that don't really cost much that are not listed in the SC2 instructions but they will prolong the life and efficiency of the gun.

These modifications are more that worth it first a second chamber for strictly air pressure. second a proper size bushing to re-enforce the piston. Last you need to modify the bushing on the firing side of the gun to allow the pipe for your nozzle to go through the bushing at the top of the firing chamber so that the pistons edges do not slam into the end of the firing chamber.

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C-A_99
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Re: Minicannon

Post by C-A_99 » Thu Jan 28, 2010 10:01 pm

You may have to use 2" instead of 3" to save money, but that will inhibit performance and capacity. However, O-rings will only go up to around 2"; I haven't seen any so large to fit 3" (and you still need something to hold it) I don't know if O-rings seal that well either, as any slight leak between air and water will be problematic.

At least one dedicated air chamber is probably a good idea. You just need some fittings and perhaps smaller pipe to facilitate the connection of the bend.

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soakernerd
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Re: Minicannon

Post by soakernerd » Thu Jan 28, 2010 10:58 pm

What do you mean by "dedicated air chamber"? I thought that the design of the Supercannon was just a LPD air chamber.

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adronl
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Re: Minicannon

Post by adronl » Fri Jan 29, 2010 12:11 am

Well as far as performance goes there is not much different in the performance of the gun from 2 and 3 to 4. In a SC design a lot of the performance is based on the air pressure and the ration of the volume of air to water. For my 2 and 3" piston guns I simply used a 3/4 output and the performance is pretty much the same as the SC2.

There are no O-rings necessary unless you plan to build an air pump or water pump into the design. The slight air leak occurs over time from the piston slamming into the end of the water chamber if you add the modification that keeps this from happening, use grease and re-enforce the piston with a plastic bushing then you can keep the wear down for a much longer time.

Dedicated air chamber is exactly that a seperate air chamber for the compressed air to be stored. You usually want at least a 50% or higher ration see the picture in the next post. The SC2 is an LPD if you only fill the chamber like 50%-66% or have it directly connected to an air compressor making it less mobile.

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adronl
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Re: Minicannon

Post by adronl » Fri Jan 29, 2010 12:16 am

Image

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soakernerd
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Re: Minicannon

Post by soakernerd » Fri Jan 29, 2010 12:36 am

I was going use the O-rings to make the seal between the pipe and the piston.

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adronl
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Re: Minicannon

Post by adronl » Fri Jan 29, 2010 12:52 am

I'd say just buy the piston cups from mcmaster carr they are at the bottom of the page.
here are the item # 's I suggest 9411K14, 9411K19, 9411K28
http://www.mcmaster.com/#piston-cups/=5kspth
Last edited by adronl on Fri Jan 29, 2010 1:08 am, edited 1 time in total.

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cantab
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Re: Minicannon

Post by cantab » Fri Jan 29, 2010 1:44 am

So in the gun you posted the photo of, when 'fully loaded' the piston will be at the rightmost end of the lower, white, pipe, and the upper black pipe will be full of compressed air, right? Meaning you get less pressure dropoff over the duration of the shot, and can fit the same amount of water and air in a shorter overall package than if you used a single pipe.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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adronl
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Re: Minicannon

Post by adronl » Fri Jan 29, 2010 2:30 am

Yes that is exactly correct.

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JuchTurtles
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Re: Minicannon

Post by JuchTurtles » Fri Jan 29, 2010 12:54 pm

Sweet, adronl! You're the king of cannons!

Now, soakernerd, what size is your pipe? You say you have 2 feet, but is it 4", 3", 2" or something else (that's diameter btw)? It's kind-of something you need to know.
The name's Juch, just Juch.
Also known as Commander JuchJawsTurtles, commander of the C0BALT TiDE team in The Ocean Volcano Union.
SPLASH! You're dead!

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soakernerd
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Re: Minicannon

Post by soakernerd » Fri Jan 29, 2010 9:08 pm

The Firing chamber is 2" wide, with a reducer on the firing end to 1".

Image

This is the design for my proposed water cannon. In replicating the design of supercannon, I have also found a way to get multiple shots off. Basically,you pump water into the front half of the firing chamber with the pump shown in the diagram. You then pressurize the back half of the firing chamber via a Schrader valve. After firing, you now only have to pump water in. this will move the piston back, compressing the trapped air. The only problem I have been able to see in this design is the possibility of disrupted flow because of the tee. I will be building one of these when I get the chance.

The small thing in the bottom left hand corner is supposed to be the piston. It is basically the piston from a Waterzooka, but with 2 O-rings, separated by a coupler.

The design for multiple shots is not affected by what kind of piston you use. I am just going to use O-rings because I already have them

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C-A_99
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Re: Minicannon

Post by C-A_99 » Fri Jan 29, 2010 10:34 pm

The flow should be fine because there are no bends from the PC to the valve and nozzle and the tee won't disrupt it significantly. The design is fairly similar to the LPD that Ben created a while ago, except without the 3 extra air chambers.

The most effortless way to fill it up the first time is to open the ball valve and ram-rod the piston down while keeping the schrader valve open, then filling it up from the muzzle. The trouble with this is that it does not prime the internals so some air will get into the shot later.

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cantab
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Re: Minicannon

Post by cantab » Sat Jan 30, 2010 4:09 am

It looks good, though I'd make tweaks to the ergonomics, by using a couple elbows either side of the pump 'out' check valve, bringing the pump shaft backwards and closer to the PC.
I work on Windows. My toolbox is Linux.
Arsenal:
Super Soaker: XP215, 2xXP220, Liquidator, Aquashock Secret Strike M(odded), Arctic Blast M, CPS1200, CPS2100, SC Power Pak, 3l aquapack, 1.5l aquapack
Water Warriors: Jet, Sting Ray M, Shark, Argon M, Tiger Shark, PulseMaster
Others: Waterbolt, The Blaster, Storm 500, Shield Blaster 2000, generic PR gun, generic backpack piston pumper (broken), 3l garden sprayer M, 10l water carrier:

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JuchTurtles
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Re: Minicannon

Post by JuchTurtles » Sat Jan 30, 2010 9:41 pm

Looks decent soakernerd. Are you going to build a backpack with it? Or are you just going to use a tap.

I'd fill for first times like C-A_99 said. Eventually, the piston will probably automatically move back with the flow of water and push forward from the air, creating pressure without having to move it to a certain spot.

Again, your egronomics don't look that great.

Also, are you going to use a different nozzle or just a 1" riot?
The name's Juch, just Juch.
Also known as Commander JuchJawsTurtles, commander of the C0BALT TiDE team in The Ocean Volcano Union.
SPLASH! You're dead!

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