$2: Epoxy (not fast drying!)
$3: 5 gallon water jug
$4: 4 foot length of 1.5" ID Schd-40 PVC
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$10 + tax
My first large chamber improvised combustion cannon, as I had crushed (by accident) my first combustion cannon which was made from a 2-liter bottle & 2 feet of 1.5 inch Schd-40 PVC.
On a side note, when trying to make a spud gun safer by inserting the 2-liter bottle end into a large diameter cardboard shipping tube (super thick btw) & filling it with foam for stability, don't use triple expanding foam. It will crush the 2-liter bottle. Use the minimal expansion stuff for sealing around window frames. Much less crushing.
I built this by heating & widening the lip of the water jug to accept (very tight fit) the PVC barrel, & widening the lip a bit to give room for the epoxy. I then mixed the 1 hour epoxy (don't use fast set epoxy, it doesn't set into a hard resin, it crystallizes on the molecular level, providing a brittle bond).
With the epoxy resin mixed, I slathered it generously on the end of the barrel to be inserted into the jug after roughing it up with 80 grit sandpaper (better bond).
I inserted the barrel, most of it got squeegeed back out, but slowly crept back in. I then slathered more on the lip of the jug & onto the PVC to make a thicker ring like bond.
Once done I measured my grill lighter, drilled a pilot hole 3/4 of the diameter of the grill lighter's business end into the end of the water jug, as you can see in the pic & proceeded to heat the area up with said grill lighter.
Once it was hot enough to work with I inserted the gril lighter & twisted it around enough while it was cooling to provide just the right size entry hole for the lighter without being a mega tight squeeze on entry.
Loaded a prescription pill bottle in it (filled with sand), bottom first, cap pointing towards the open end of the barrel. (The prescription bottles I get are just the right diameter around the cap to provide a smooth sliding fit down this barrel)
I gave it a 2 second burst of propace from my torch tank, inserted my lighter... How's that song go?
Click. Click. BOOM!
I lost sight of the pill bottle (yes, I was smart enough to remove the label)
& realized it was waaaaaay louder than I thought it would be & proceeded to run inside my house as my neighbors laughed at how surprised I looked.
Here's the pic:
P.S. Don't be alarmed if this thing temporarily expands when you fire it. It does due to the indents in the walls & bottom. Also it is mega cool to fire at night, although the combustion is visible in daylight, at night it lights up everything around it, including you in a sppoky flashlight under the chin fashion.
The reason I chose this chamber was because one, it was cheap, two it was large & three because of the seams. Having seen chambers burst into jagged edges &/or shards, this is safer in case of an oops-overfuel. It is more likely to expand & crack at the seams causing a terrible scare, maybe a hot flash, few burnt hairs, but likely no shrapnel in your body.
Nice post! 8)
With a two liter, that would give almost exactly a 1.25:1 C:B ratio, still overkill a little!
