ABRASIVE METERING VALVE

I made this based on a Depression era budget toy idea that my Dad showed me back in the 1960s.

My Dad and his brothers would get what they called a varnish can (basically a quart size (0.9 liter) paint can), and punch a nail hole near the base with a nail. They'd then spit a few times into the can near the hole, then put a pinch of calcium carbide in that and pound on the lid real quick. A match would be applied to the nail hole - but keep the face clear of the lid - and if they got it right the lid would fly off with a HUGE bang. A lid from a quart size can will easily clear a two story house with many feet to spare.

They said the calcium carbide was often obtained by sweet talking an auto repair shop owner with acetylene welding gear. Often a small general repair shop doing welding on only once or twice a week would use a calcium carbide acetylene generator rather than have to pay rent on an extra tank. Also, at that time, calcium carbide was used for carbide mining lights and generally available in Pennsylvania in hardware stores.

A variation on this idea was to snag a valve stem from a tire repair shop from an unrepairable tube that had "blown out." This was the 1930s, long before tubeless tires. A hole would be put into the side of the can to accommodate the valve, the valve installed from the inside with the stem on outside, and sealed with rubber cement. The lid would be put into place, and blown off with the aid of a bicycle pump on the valve stem. I made this variation, and while it works, is not as loud as the carbide version and a LOT more work per bang. But that was the Depression, and a cheap noisemaker when there was no money to buy a few penny packs of firecrackers, let alone carbide....

The pictured variation uses a gallon paint can with a good lid seal, and an igniter used for gasoline/propane mantle lanterns (and hair spray powered potato cannons B-} ). Spray in a bit of hair spray, press on the lid, make sure the handle and vital body parts are not in the line of fire, and twist the igniter to set it off. HELPFUL HINT: this thing refuses to fire with hair spray fuel if the air temperature is much below 85 degrees Fahrenheit (29.5 Celsius), which is fine for the 4th of July celebrations.

Rubbing alcohol, the 70% by volume stuff from the over-the-counter medicine section of many stores, works too. About 5 squirts from a medicine dropper seems to be about right, but YMMV. Roll the can around in your hands about 1 minute to get the alcohol to evaporate before firing. Again, the outside air temperature should be quite high for rubbing alcohol to work successfully, 85 to 90 F. (29.5 to 32.2 C.).

Even though this doesn't make a loud bang, one dog is terribly frightened by it.

I got the sidewalk wet when I shook out my large daypack, which had a puddle inside. The water came from my Platypus water bladder. It and the drinking tube were inside my pack with everything else. At the trailhead I planned to set up the drinking tube outside the pack for normal use.

Something in the pack had pinched the drinking tube's bite valve, causing water to flow out, creating a puddle at the bottom of the pack. Stuff at the bottom of the pack got wet: my rain parka was drenched. I discovered this mess when I pulled the drinking tube out of the pack to fasten it to a shoulder strap. What a bummer!

After emptying the pack, I turned it upside down and the water poured out. I went hiking with my smaller pack. During the hike I laid my soggy rain parka on the rock to dry out.

Photographed at the trailhead parking lot at Delicate Arch Viewpoint.

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