First, let's get our air cylinder together. You can see the hardware fittings are laid out here how you will want to connect them.  Later this assembly will be attached to the inlet of the water valve closest to the outlet nozzle. Be sure to use teflon plumber's tape on all the threads of our fittings and make sure all of your connections are very tight, as this will be under high pressure. Attach the end cap to one end of the pipe and the reducer to the other. Then once you assemble the two close 1/2" threaded fittings to each end of the T fitting, install the air nipple and 1/4" to 1/2" reducer to the right angle of the same. Screw this in tight to the 2" to 1/2" reducer.

   Now we will do a little surgery to the water valve. As you can see, the outlet of our valve is a 3/8" nipple that was meant to be attached to a water hose. For three reasons we will need to remove this nipple and I have found the easiest way to do that is drill directly into the nipple from the end using a 3/4" forstner bit which will stop with a flush cut just below the plastic, where you will find hiding, a black washer with a small hole in it. This I believe is some sort of anti surge to regulate the flow of water should there be a change in pressure. However this is one of a few things keeping our valve from discharging a large enough blast of air to make a serious report. Remove this and give it a toss. 

   Using your 3/8" drill bit, drill out the small port hole behind the washer as shown here in a photo where we were converting an N-51 valve for a cannon. You will need to drill this back past the inlet port inside the valve that is coming up from the cylinder . On the same valve I show doing the same thing to the inlet port. Note that this is the closest inlet port to the exhaust port as mentioned earlier. The brass cap you see to the right of this shot is a steel lawn hose end cap that I recommend using if you have a choice between the plastic one I used on my first prototype which you will see later. Okay! Now your valve will actually dump out enough air to make a startling sound.

   The plastic hose end cap shown here can be found in the garden section of your hardware store. The steel one above will be found in the hose fittings section next to the black and galvanized pipe as will the Female Hose-to-FIP fitting shown on the left side of the valve. Since these both seat against rubber washers, you will not need to use teflon tape on the threads of the water valve. Now to attach your power cord to the same solenoid as you are using for the release valve, chop off the female end of your extension cord and fit your 1/4" quick slide fittings using a crimp tool. Not shown in the photos here are the heat shrink tubes I put over these connections after I attach to the prongs on the water valve to prevent an electrical shock. Once completed, thread the entire assembly into the top end cap of your cylinder tightly. Remember to use teflon tape on the threads going into the bottom of the FIP fitting. I also recommend zip tying the electrical cord to the T fitting nice and tight to prevent the power cord from becoming unplugged to the valve.

   In this shot you can see where I have taken a  2" x 1/2" threaded fitting and inserted one end into a T fitting to use as a handle as I prepare to make a thread tap. Then the end remaining I used a die grinder to slot the sides in 4 places, about 1/2" up. When I make the cuts I keep the grinder on a angle to the fitting so that the slots will create sharp front edges to the threads which I will need to cut into plastic as well at route the shavings to the inside of the fitting and away from our new threads. Prior to this, I also ground down the threads of the fitting back about 1/2" on a taper. The very end threads are ground off, making it small enough to insert into a 3/4" hole such as we now have in the exhaust of our water valve. We will be using this thread tap to cut in threads into the exhaust port of the valve so we can insert a 1/2" short threaded fitting. Once that is done simply screw your 1/2" to 1 1/2" reducer fitting onto it for a megaphone. This was the result of quite and array of ideas tested in order to bring more of a Bang! sound to this cannon, and it certainly makes a decided difference! Not only that, but the new extension away from the body of the cannon means we can now drill a hole in the wall of our haunt, mount this cannon on the back side of it with the exhaust bell just sticking out, allowing us to hide this in plain sight down halls and in rooms where ever we desire!

   In the next section we look at adding a little safety to our noisemaker.