How to create a powerful air powered gun from copper pipe and fittings, for very little in the way of cash.
this is a idea i had off a friend and the results are surprisingly good, in fact, Amazing
Step 1: Materials
1.5m (5ft) of copper pipe
Two 15mm stop ends
One 15mm Ball valve One Solder Equal tee
One tire valve
All pipe in this project can be any diameter, however, as the pipe size increases, so does the bill. A good chamber to barrel ratio by volume 1:2, however you can change this to suit your needs. A gun with a barrel which is either too long or too short will not be more powerful, but rather less powerful. As a UK based user getting copper is simple. Many plumbing and hardware stores stock it. I suspect the situation is similar in the U.S. Ball valves are very common, and can be bought from most plumbing stores.
Flux and solder will more than likely be available in the same store.
A vice (and bench)
A power drill
A file or deburring tool
A pipe cutter
A blowtorch and lighter
Old gloves, these will need to insulate you from hot pipe
Wet + Dry paper (a fine form of sandpaper)
A drill bit (for a standard schrader valve you will need a 5/16)
A fairly large adjustable spanner A bike pump, for your valve.
Step 2: Preparation
A good chamber to barrel ratio is by volume 1:2, however you can change this to suit your needs. A gun with a barrel which is either too long or too short will not be more powerful, but rather less powerful. Don't forget to include all the pipe including the stabilizers in your volume estimation.
After you have cut the pipe to the size you want, you must remove the burrs, as these will hinder your soldering. The cut needs to be clean and straight.
Step 3: The Valve
For the valve I cut a hole a little bigger than the diameter of the valve and put the valve through with the Schrader rings I found, on both sides of the copper end feed cap. I also added glue to create a very strong seal.
Step 4: Soldering
This is the hardest part.
Solder works best if both the pipe and the fitting are really clean. Use fine wet and dry or wire wool to get all the surfaces shining.
Flux should be applied to both the end of the pipe and to the inside of the fitting. Use a brush, flux is nasty stuff it rots skin and once it’s on your hands you will get it everywhere and that’s how you pipe starts to go green. All you need is a thin coating – as thick as a layer of lipstick.
Assemble the parts to be soldered. Remember for really strong joints you want to solder all of them at once. You may need to rig up a bit of a jig to hold everything straight and true but stay calm you can take ages over this bit the flux won’t go off. Soldering this is fine even if the valve is not straight because you can always adjust it later.
Heat the pipe first, do this until you just see it change color. Now heat the area just beyond the joint. Again wait for the color change and apply solder opposite where you are heating, you should see it melt and be draw into the joint. Don’t use too much solder you want to be aiming to use a similar length to the diameter of the pipe you are using as a maximum. I used Yorkshire solder end feed to make it easier. Now heat the other piece of pipe in you fitting and then back to the middle and again with the solder. Let it cool.
Clean your joints, if you can clean the inside as well. You don’t want the flux everywhere.
If in you don't feel confident try using solder ring or Yorkshire fittings, the flux bit is the same but you don’t need to add solder. Heat a little above the joint line until you see solder all round and then stop. However on mine which were Yorkshire fittings, I used some solder here and there because I ruined the solder ring on the inside.
Step 5: The Valve
The valve will be a compression fitting. Put the pipe into the correct valve port and tighten it. The olive (metal ring inside) will compress around the pipe meaning it won't move. This will form a seal.
Step 6: Done
My favourite ammunition for a 15mm barrel is a 12mm piece of glue for a hot glue gun. But you can use anything which fits in the barrel. Close the ball valve, pump it up and release the valve. Power will change depending on how big you made your gun. The faster you open your valve, the better your shot will be. Pumping your gun with the valve open results in cool compression condensation rings. I got my gun to reach 100psi and it has a range of over 50m.
i didn't have enough long pieces of copper pipe so i joined three pieces up with connectors. this included two connectors but this Instructable was the original plan.