### Plastic Cannon??

Hi, I'm currently in Year 10 and we have been assigned to make a USB lamp. Now, I'm fine with the assignment only I cannot think of how to shape my idea realistically. I wanted to make a cannon shape, with a sphere like bottom before it curves into a thin neck. However, I don't know how to make the plastic bend into the sphere like shape. It's really difficult and I'll include a picture of my idea if it helps!

Question by Hodiernald   |  last reply

My friend and I are considering building a spring loaded cannon. The idea right now is to have a pvc pipe for the cannon chamber, and pvc pipes flanking it to hold springs in parallel. A cross-bar will go through all 3 pipes through slits cut long ways in the pipe. The springs will be attached to some point forward in the flanking pipes and to the cross bar, which will be used to pull the springs back and, once released, will launch the dart/ball in the center tube. My research so far - the spring rates of springs loaded in parallel are additive. With 5x 10-in*lb springs, we can produce 667 newtons of force when pulled back 3 inches (springs in question are 5.5 in long) . That will produce an acceleration of 303 m*s^2 on a 1 lb (2.2 kg) albeit for only a fraction of a second. http://www.amazon.com/Extension-Spring-5-625-Long-080-count/dp/B001292S08/ref=sr_1_1?ie=UTF8&s;=industrial&qid;=1257718057&sr;=1-1 These are the springs we're looking at. We'll need to use an even number of springs, so either 4 or 6 (or 8 or 10). So, what do you guys think? Practical? Will we be able to get any distance? Any suggestions? A ROUGH picture is shown below. === are spring tubes, | are handles, and left arrows indicate direction in which springs will be stretched, and the right arrow is a dart flying out of the center launch tube. <----| ===== XXXXXXXXX     ------> ===== <----|

Topic by chs9   |  last reply

### What is the best potato cannon?

Ok, I have seen a lot of variants on potato cannons (here on instructables as well as all over the internet) and have a few questions: 1. What is the best best cannon design? 2. What is the best propellant? 3. What is the best ammo? 4. What is the best barrel size?

Topic by Valkyrie103   |  last reply

### Pump pressured confetti cannon

I am hoping to build a football pump (or similar) pressured confetti gun, it would fire by pumping air thus making pressure for when you fire it will fire into the air, maybe 1-2 metres perhaps. Any help. Also it needs to be built by october 25

Question by Michaelgoode   |  last reply

### Could I get some advice when building a very strong vortex cannon?

I want to make something like this but without a shotgun. http://www.dispatch.com/content/graphics/2012/03/18/sci-votex-gun-art-gqigfas4-10318gfx-sci-vortex-gun-eps.jpg My question is, would hooking up an air cannon to the vortex cone work? If so, how or would there be a better way? If not, how else could i do it? The goal is to make an automated strong vortex cannon. I'd rather not use the normal "airzooka" type of vortex cannon.

Question by KhanSupreme.   |  last reply

### how many psi can a 5 gallon plastic bucket (found in home depot) can take?

So im doing this for a chemistry project. My plan: to create a cannon with buckets and tubes with ping pong ball. I use dry ice and water to compress gas in the bucket and release the air through the valve. i realized that when i puff air into it and conceal it, (3 to 4 times) the bucket starts to deform.

Question by punch2dface   |  last reply

### I'm making a pnuematic potato cannon and I need help on what is the best piston release method?

I know of two ways, but am looking for advice from veterans. I am not a novice at this, and cost is not a problem, so give all and any ideas. (illogical ones are accepted!)

Question by caspar97   |  last reply

### does anyone know where to find free (or very cheap) sheet rubber? Answered

I'm currently in an engineering class, and our goal is to build an improved potato cannon. we need sheet rubber for a couple parts of our project (1/16 inch thick), but we don't have money to make it. does anyone know a good place to get free (or very cheap) sheet rubber?

Question by codongolev   |  last reply

### So you wanna make Samus Aran's arm cannon eh?

Alright so I've decided this year for Halloween I want to be glorious Samus in her original suit glory. I'm just in the planning and blue print phase now. The bulk of the costume is going to be Eva foam. A stationary arm canon is cool and all, but what if I could get it to open up on the ends when i push a button? How cool would that be?I won't need a really beefy motor to move foam, and hopefully that motor wont require a huge power source, something that will fit inside the arm cannon somewhere.I can't find any video of HOW exactly the arm cannon opens up and functions but from this picture it could either A. opens up where the 4 outside plates separate from the main cannon to better reveal the pew pew part, this would require something to push out all four plates at the same time from the main cannon at a fixed distance. Not very much maybe half inch to an inch and be able to retract back flush against the cannon.B. the four plates simply rotate on a fixed axis.Ive crudely drawn what I would like the arm to do so you can see what I'm talking about.I've never dealt with motors before but I've seen amazing cosplays that have moving parts so I know it's possible. I'm more than willing to learn I just need to be pointed in the right direction.Any help with how to go about this would be greatly appreciated! :)

Question by MeonahH   |  last reply

### where do you get a 6mm steel tube?

I was wondering where you could buy a 6mm steel tube for the 6mm mini cannon.

Question by coatofarmsxl

### Explosions - How We Shook The World.

Anyone watching 'Explosions - How We Shook The World' on BBC4 (UK)? Jem Stansfield making various explosives and a very effective cannon! This is the kind of science program we want !!! - Memories of my younger days #;¬)

### Can someone help me with my fatal flaw in my spudgun design?

So i have built spudguns in the past and with every new gun i make it gets bigger and better. So i just found pressure rated 3" pvc and im going to use it for a new air chamber. Its a simple end around gun with a piloted sprinkler valve so yea the design is good. Except for one thing. I am enthusiastic enough of a spudgunner to use an air compressor to power it when im at home. but when im at a park or some open feild i bring along a bike pump to pump it up. But with each size up for the air chamber it takes longer and longer and longer to pump. Im not enthusiastic enough to buy a compressed air tank for \$60. so what should i do to power it up. i dont have enough room at my house for a distance or height shot and it will take forever to use a bike pump so what should i do. PLESE HELP ME  i will try to post pics of it soon  HELP ME

Question by ostomesto   |  last reply

### Could an O2 sensor from an automobile be used inside the combustion chamber of a potato gun?

So I was shooting my potato gun after talking about car repair today, when I got the idea. Could an O2 sensor from an automobile be used inside the combustion chamber of a potato gun to achieve optimal fuel/air ratio? Finding the chemistry of the aerosol fuel would be difficult, and I wouldn't know where to start with the computer stuff, but could it be done? If so, has anyone done it? I searched instructables and no one has even mentioned it. I found on a mazda forum that a wideband O2 sensor may detect the air/fuel ration when using propane, but what about aerosol? Propane in a plastic gun is just begging for injury. I use Right Guard sport deodorant (Without antiperspirant) as the fuel, I think it works the best. The primary ingredient is Denatured Alcohol.

Question by MistaStokes

### Whats a cheap and fun hobby that a teenager can enjoy?

Ive always enjoyed tinkering and building things in the garage and im always open to new things... because im a kid i dont have alot of money to spend on a hobby and id like to expand from the woodworking and cannon makeing hobbies i have already... just wondering what the instructables comunity had to offer!

Question by kdaviskid   |  last reply

### Why is the ball valve of my potato gun releasing the pressure? Answered

The ball valve of my air cannon releases the pressure once it climbs above 5 psi. Is there any way to fix this? Or am I stuck with a \$30 door stop I'd buy a new one but it just started to leak air, it was working, plus it's glued to my U joint, and really don't wanna rebuild it.

Question by monkhm   |  last reply

### Help! Thermo Electric Generator

Just wondering if any of you knowledgable folk can help me out. Of late I have experimenting with solar cells and energy production. I have been calculating some interesting results, many of which due to the use of lenses, magnification and mirrors etc. Alas this has led to more that on fried solar cell due to the temperatures im dealing with. Is there any practical way to obtain/construct a Thermo electric generator as pictured? I have spent some time with my friend Google, leaving me with little more than the notion that perhaps this technology is out of reach of the home experimentor. Think giant light cannon that can melt pennies. How can I harness this heat directly as apposed to, going the boiler/steam powered engine method?

Topic by Lftndbt   |  last reply

### Spring powered internal air compressor

Hello everyone, I've come here for some help on designing a PVC-based air tank. I'm planning on building a pneumatic cannon that I can charge once and use to fire multiple short bursts of air. To do I decided to have two tanks -one large tank acting as the main tank and a local tank with a much smaller volume fed by the main. My problem is that I want to squeeze out all the air I can from the main tank, and I'm not entirely sure what the best way to do that would be. My current design uses a spring behind a wooden plunger so that as the volume of compressed air drops, the spring can extend and restore the pressure. (Image attached for clarity) Can anyone spot potential problem areas or places that could be improved?

Topic by Ninja Togo   |  last reply

### best chamber to barrel ratio

Okay I have not built a cannon yet as such, as I am going to make my first one awesome but I've done some research and found the golden ratio for efficiency for chamber-barrel size, assuming the chamber is always the same volume a chamber is 1.6, now I'm guessing a bit from now on but it seems that that maximum efficiency is approximately 1.61803399 or the golden ratio that keeps appearing in our world, I just thought you guys would like to know for the design stage as this is what I'm going to be using when I make my gun. also is it worth spending extra for a high flow blowgun over a normal one for the pilot valve to my 1" sprinkler or wont it make a noticeable difference P.S. if my calculations are wrong please, if you know more ( I'm only 13) please correct me. I have worked this out from pneumatics, not combustion's or hybrids. expect to see my gun soon!

Topic by cheeseboy   |  last reply