SpudFiles

So as you guys know I have been making PVC train horns for a while now...

Latest video if you so desire:
[youtube][/youtube]

Anyways I was wondering what you guys think of this idea:
I want to make a big ship horn, but to do that I can't use regular fittings/pipe. So my plan is to construct the horn body using multiple layers of wood. Epoxy coating would probably be part of the build too, for added strength and to keep it airtight. Attached is a CAD drawing to give you an idea what I mean... The layers from left to right are a front plate, two spacing plates that form the chamber and nozzle, and then the polycarbonate diaphragm. Not shown is the clamping ring which is just like rings 2 and 3 without the inside part. You'll also notice 8 holes around the plates; those are for 1/4" bolts that hold the layers together.


The horn itself doesn't actually hold pressure because the air goes out the bell tube almost immediately... but in the worse case I imagine the internal pressure reaches something not beyond 20 psi.

Assuming a good quality wood and epoxy coating, do you guys think the horn would hold up, or explode under pressure?

in my opinion it might workif you use alot of epoxy and fiberglass

Actually I had not thought about using fiberglass.

That's another possibility... something I'll think about. Thanks!

yea, this is just a side project for me but i realy want to build a boat out of wood so i kina know som things. also if you are gonna use wood make sure that you realy dry out the wood or else you will have it crack

You know there is special wood for making boats, this is a really great video worth watching if you want to build one. There are some good tips.
[youtube][/youtube]

How should I dry it out? Put it in the sun?

Gun Freak wrote:So as you guys know I have been making PVC train horns for a while now...

Nice!

I had considered this same exact design in my head years ago - after getting a small lung-powered air horn that uses the same coaxial diaphragm principle. It's nice to know it would have worked (and pretty well!).

Good luck - looks like you just need a beast of a volume flow air source. Make something that's ridiculously gigantic!

The plan was to make the internal volume of the horn very little. Since I have total control over this aspect, the volume should actually be less than my 3" PVC horns, in theory... But in any case, I'm not expecting the flow orifice to have to be any greater than 3/8" considering two of my 3" horns can be powered by a 1/4" line under high pressure.

The key to these is high flow, not necessarily high pressure as most people think. I run a 1/4" line to my horns, but with 300 psi. If I had a 1/2" line I could probably get away with using 60 psi...

But you're right- for those long cruise-ship style blasts that I'm going for I'll need to use my 33 gallon shop compressors or my scuba on very high pressure, assuming the wood can handle it... We'll see! I also have some ~1/16" aluminum that I could use for the front plate and I'd just use wood for the sides.

I watched that video but i would rather build something different like a sailboat.Drying it out would take about a week of drying with almost perfectly dry wood. In other words garage wood that hasnt made contact with water in a while but be cautious.

Bear in mind that 0.1psi on a normal door is enough for it to slam open with great force, so 20psi on a large surface area is nothing to sneeze at. I think it'll work, but I wouldn't stand next to it when you try it. (Come to think of it, I wouldn't stand next to it anytime, I value my hearing more than that, and that comes from the bloke who shoots his shotgun indoors a fair bit.)

Fair point, I should use metal for at least the front plate. Ive been pondering other materials lately like pvc flanges and coffee cans to think of stronger ways, but it's hard to use common materials to make complex parts.