Hey, I'm working on this page right now. I've got a lot of things to do...you should be thanking me that I even got this far...har har. Don't worry, I should have more info up by the end of today, March 3rd.
Are you tired of a short range, puny power, or just want to blow small rodents to pieces? Then, you've come to the right place! I will first (besides experimenting with tables) list the generic parts you will need for each gun, with great description for each one. Some parts are used for every gun, like all guns need PVC pipe, a valve, a tire stem...the list goes on. What? That confused expression on your face...I think I'll just start to explain now:
PVC Pipe - PVC (Poly Vynl Chloride) is a white plastic-like tubing that you would use for things like an automatic sprinkeler system. It's pressure pipe, which means it can hold pressurized air at abnormally high pressures. Sch 40 (that's just a rating of the pressure pipe, it's also the most common rating) is rated to something like 400 psi (psi stands for pounds per square inch, or ammount of force exerted per square inch). I would not recomend giving it this high of pressure, as if it bursts it will create a rather devestating sharapnel explosion. I would recomend only filling it to 100 psi MAX as that's all most valves can handle anyway.
But, what does the PVC pipe do in a homemade, anyway? For one thing, like in a lot of modifications, it acts as the barrel for a nerf gun. It's smooth interior provides good accuracy and
it's length lets you get the maximum projectile-accelleration at the end of the barrel(basically, you can cut the barrel to the right length for the ammount of air you have, and get maximum distance)
The other thing PVC will be is the airtank for your gun. It is pressure pipe, after all.
PVC can be bought at any hardware store, and is CHEAP! A local neighborhood store will sell it for over $2/10 feet, but a large chain store, like Home Depot, will sell the same pipe for around $1.50 for the same length. Of course, the price goes up depending on how large the inner diameter of the pipe is.
You can't just bend PVC or glue it at a right angle--you have to buy special attachments, like a 45 degree attachment for bends and a 90 degree attachment
for right angles. There are male and female adapters (Please, if you don't know what I'm talking about, ask your parents...)
Whatever of the zillions of attachments you use, almost all of them need to be glued in place. PVC glue is about $2 for a whole bunch of it, be careful not to inhale this stuff)
If they are threaded (this means they screw in), make sure you either use teflon thread tape or screw it in tight.
Valves, Valves, Valves - The valve keeps all of the air in the airtank, but releases it to fire the projectile. Keep in mind that a valve will get you better accuracy and distance the quicker it opens. Here are your options:
Ball Valves - These are the cheapest option, but give the poorest performance. You have to turn them to open them, which decreases accuracy when the gun jerks. Also, as far as valves go, these open very slowly. You can minimize this by making sure to buy the slickest valve possible.
If you want a cheaper, general use gun, buy a NON-threaded valve. This means it slips onto the PVC and is glued (these are usually white with a red handle).
If you want a slightly more expensive but modular valve, buy a threaded one; you can screw in new pieces for different 'jobs'. (Threaded ball valves are usually grey and have a red handle--mine says UPVC on the side)
Solenoid Sprinkeler Valves - This is an electric valve used for controlling an automatic sprinkeler system. We have different uses for this. They require batteries and electronic switches to opperate, but open quicker and more evenly than a ball valve. This means better performance and accuracy...woohoo. Now, when buying one, make sure you buy the one for the size you need, usually they come in 1" or 3/4". Also make sure that you note wether it's vertically operated or inline. Some valves take in the air from the bottom and let it open back down on the other side. The inline one takes the air in from one side and shoot it right out the other side. Solenoid sprinkeler valves are also always threaded, so make sure you have plenty of male adapters
Your valve choice has a serious effect on how your gun will be designed, so make sure you buy the right one(threaded/nonthreaded, or inline/vertical) when you go to the store.
Tire Stem - This is how the air gets into your gun. It's the little thing that sticks out of a tire or bike wheel and lets you fill the tire. You can buy them either as the valve itself, or an entire stem. For some reason, the entire rubber-pop in stems are cheaper (2 for like $1.50) but are harder to install because they need a bigger hole. The tire valve is much more compact, but costs more from my research. I dunno, I can't even find these, just the pop-in stems. You can find these crucial parts in the automotive section of any walmart or hardware store.
Usually, you will have to make a hole in a PVC endcap and install the tire stem.
But, for more complex guns, you're going to need the pieces below:
Believe it or not, but I always try to fix problems people spot on my site, or help people work out complications. So go ahead, my mailbox is so lonely...