RustyBolt.Info/wordpress

Long ago there were ads in the back of magazines (especially hunting and gun mags) that offered a ‘toy’ called a Bangsite Cannon (these are still available today).  What I’m describing is the way I remember it, but I don’t know if it’s the same today (it looked like the 10FC model). It’s made out of sheet metal and cast metal, and comes in various sizes, one having a barrel about a foot (30 cm) long. There is a cavity low in the breech behind the barrel, which holds a small amount of water.  You buy a tube of Bangsite, which is granules of calcium carbonate.  When Bangsite contacts water, it turns to a white powder and releases acetylene, which is what is used in welding torches, and also miner’s lanterns.  When mixed with air, acetylene is explosive, hence the name Bangsite.

My high school buddy and his brothers bought one, and we had a lot of fun with it.  I decided that I wanted one, too, but I decided to make mine (see the photo).  The bangsite cannon has a flint and wheel just like a cigarette lighter, and it is on a removable cover that fits in the hole over the water cavity.  You can remove the cover and drop a few granules of Bangsite into the water, then screw the cover back on, and shen you spin the wheel, the resulting sparkes ignite the acetylene and the cannon makes a loud bang, and smoke comes out of the barrel.  When you remove the cover to p[ut more Bangsite in, you blow in the cavity to give it fresh air.

Mine was made of regular galvanized pipe and plumbing fittings with the result that it was much heavier.  But its advantage was that it didn’t use a flint, which wore out, and the switch made it more like a regular cannon in that it fired whenever the “trigger” or pushbutton switch was pressed and released.

The transformer was out of an old five tube AM radio and it was for a 50C5 tube, which uses a transformer with a 2.5k primary and a 4 ohm speaker winding (Today, the battery, transformer and pushbutton could be replaced with the spark generator out of a barbecue lighter).  Since today this transformer has become very rare, I think a 120VAC to 12VAC power transformer might work okay.

Today, in addition to the changes I mentioned above, the plumbing fittings could be heavy plastic pipe.    But if plastic pipe is used, the nipple and cap, which creates the cavity, must have threads so they can be removed for cleaning out the water and spent carbide.    It is very bad for the water to get on the spark plug contacts; it will cause the porcelain to conduct and there will no longer be a spark.

We quickly got really tired of spending a lot of money on the Bangsite, so we found a place where we could buy a tin of calcium carbide that is used for a miner’s lamp.  The granules are larger so when they get wet, they don’t disappear so fast and will bubble and sizzle for awhile, so one can then blow some fresh air into the cannon and get another bang out of it.  You might think that you can just crush the larger granules with a hammer or something, but calcium carbide ranks in hardness high up there with silicon carbide, which is used for making grinding wheels.

One other thought: this could be misconstrued to be a forbidden explosive device, such as a pipe bomb.  The commercially made ones are purposely made to look like a toy cannon, so they don’t have the chance of being misconstrued.  My disclaimers really do apply here (see my website).