I talked about train horns with my son and his friends. Looked into them on the internet and saw the total cost could exceed $1,200.00. I watched a couple of videos of folks tearing apart "real" train horns, and pictures of pvc horns and decided to attempt to build my own.
The materials are easy to obtain at the big box or corner hardware store. I made three for my CJ-7.
What you need: 4" to 2", or 4" to 1 1/2" reducer, which is the main body of the horn.
a 2" to 1" or 1 1/2" to 1" reducer (depending on what you purchased above).
threaded nipples to thread into the body, and the manifold you will build (I bought 7)
a foot or two of 4" PVC pipe
a 5' section of 1" PVC pipe
a couple of 1" caps to cap off the manifold
some plastic for the horn diaphram (i used dollar store plastic food container lids) trimmed to fit the 4" end of the body
plastic transmission funnel for each train horn's "flare"
reinforced tubing to run from the horns to the manifold and from the manifold to your air source/on/off valve
light PVC cement (for reducer to 1" pipe and inner diaphram ring)
screws to secure back diaphram retaining ring and to secure flare
an image of some materials
a completed horn with flare
two horns under hood with a view of the air distribution manifold
To build, take the body and the reducer to the 1" pipe.
You will need to use a file or dremel to cut down the stop inside the 1" reducer to allow the 1" pipe to go all the way through the reducer. Just grind or file enough to allow the pipe to pass.
The reducer is on the right in the picture above, and another is shown in place in the horn body on the left.
After the pipe stop is ground or filed away, you can cement it into the body.
Next you will have to cut small slivers of the 4" pipe to serve as diaphram rests. The small was about 1/2 inch wide and the larger was about 1".
above picture shows the cut pieces. I cut with my chop saw. They need to be square.
The smaller piece gets glued in with a very light coat of pvc cement.
next, drill a hole slightly smaller than the threaded nipple. Screw the nipple into the body of the horn at the location in the picture(s)
cut the plastic 4" in diameter to fit into the end of the body. should fit without slop or being too tight. Then put the larger 4" piece into the end and drill on the edge and secure the larger piece of 4" with the screws. I used larger sheet metal screws. This is screwed in so the outer diaphram retainer can be removed if the diaphram breaks or needs to be replaced.
Next, the 1" pipe gets tapped in from the top down to the diaphram. Before you tap it in, make sure the end cut is totally flush and square. Once again, I used a chop saw to cut. I tried to use the hand PVC cutters but could not get a totally square cut. This is very important because the horn sound is created when the air pushes out on the end of the daiphram and comes back up the 1" pipe and out the flare. If the cut is not totally flush, the air will "leak" through without the necessary vibrations.
Tap the 1" pipe down. It will be tight. If it is not going past the stop you grinded away, you may have to undo the diaphram retainer and grind a little more away.
once the 1" pipe touches the diaphram, tap a little more to create some tension on the diaphram. At this point, you can try to blow air through with your mouth to see if there is any resistance. Should not blow easily. (Blow through the brass fitting)
This tension on the diaphram is one part of tuning the horns. I just kept tapping on the diaphram to see how tight it was and stopped when I felt tension and it was difficult to blow through.
The picture above shows the inside of the body with the inner diaphram seat in place.
These are the dollar store food containers I bought for the diaphram material. I have heard you can also use very light gauge metal, but I did not try.
The different notes are achieved with different length 1" tubes coming out of the body.
I have three different lengths, all with the cut off black plastic transmission funnel on the end for a flare. The flare does increase to tone volume.
I made three horns and a manifold for air distribution
The manifold is a pience of 1" pipe (about 8 inches) with caps on both ends. I drilled one end and three holes in the side for the threaded nipples
As you can see, I zip tied my horns to the radiator support rods. I ran the air line from my 10 gallon tank behind the rear seat, with a valve at the front of my console/radio cb holder.
[FONT="Arial Black"][SIZE="5"][COLOR="Red"]RED JEEP CLUB # 621[/COLOR][/SIZE][/FONT]
It's not much, but check out my build thread;
[QUOTE=krashnpa;12397572] I know kev was riding his tank skid and belly pretty good on some of the blacks up at RC, but he doesn't back down from the line either.[/QUOTE]
[QUOTE=squazz;13612008]so I use my original nuts?[/QUOTE]
You should, in no way, take any of this personally. It's just business. So to recap, I come in peace, I mean you no harm, and you all will die. Gallaxhar out.
I really like the sound of them. They are fun, and I really like the "I did it factor". I have tried my best to not use them to try to scare anyone (other than my dad one time at a train crossing). As with anything, the best part of the project was the time with my son trying various combinations and going back and forth to the store to buy and look for parts.