Saturday, 17 March 2012

Elephant No. 167: Wire Coils

About a year ago, I bought a wire-coiling gadget to use to make coiled beads for jewellery. After I'd played with it for a day or so, it went the way of most gadgets in my house and ended up forgotten in a box. A jewellery toolbox, but a box nonetheless. Today, however, it occurred to me that it might be interesting to make some sort of elephant from joined-together wire coils.

The best-known type of wire coil is an electromagnetic coil, which is formed when a conductor such as copper wire is wound around a form to create an electromagnet. This is the principle we were being taught in elementary school when we wrapped nails in copper wire.

Knowing very little about electromagnetic principles, I was surprised to discover that there is a lexicon related to wire coils. The basic terms are as follows:

Turn: One loop of wire.
Coil: Multiple loops of wire.
Taps: Electrical terminals attached to coils to create an electronic circuit.
Winding: A completed coil with taps.
Transformer: An electromagnetic device with a primary winding and a secondary winding, able to transfer energy from one electrical circuit to another without moving parts.

There are many other, more complex terms. From my limited knowledge, however, the above appear to be the building blocks upon which all other coil assemblages are founded.

There is virtually no end to the uses for electromagnetic coils. Ignition coils provide the spark for any vehicle with an internal-combustion engine. Degaussing coils remove magnetism from an object—particularly ships that don't want magnetic mines glomming onto them. Garrett coils are found in metal detectors. Micro coils are used in security devices. Single coils are found in the pickups on electrical guitars, and voice coils are essential to microphones. One of the most eccentric coils is the spider coil, which is a flat coil used in crystal radio sets. There are even coilguns, which contain a series of electromagnetic coils that essentially ramp up the speed of cannon shells to exceedingly high velocity.

Modern spider coils by Geoff Roberts of Geoff's Crystal Radios
of Birmingham, England.

And then there's the Tesla coil. If I could figure out how to make one of these without fearing that I might fry myself to a crisp, I surely would. In a nutshell, a Tesla coil takes a standard 120-volt AC current to a multi-kilovolt transformer and a driver circuit, then pushes it to extremely high voltage. Voltages are normally above one million volts, and discharge in an electrical arc. Tesla was apparently able to achieve voltages of 100 million, but no one has since been able to duplicate that feat.

Nikola Tesla sitting beneath his eponymous coil in his Colorado Springs laboratory.

Tesla coils also create powerful electrical fields and can light up disconnected fluorescent tubes up to 15 metres (50 feet) away without any wiring. Even weirder, the electrical field goes directly into the tube, bypassing the electrodes, and can thus cause the gas to glow even in a burnt-out tube. To see a recent experiment with Tesla coils, click here. And to see performers from ArcAttack turn themselves into human lightning rods—and light up fluorescent tubes at the same time—click here.

For today's elephant, I made a simple form using a bunch of different coils. I pulled a sampling of coloured wire, not really sure what colour might appeal to me. Partly because it's St. Patrick's Day (even though I'm not even remotely Irish), and partly because it was the heaviest wire, I ultimately settled on the forest green wire on the far left. This is an 18-gauge copper wire coated in a thin layer of ceramic colour.

This is the tool I used, invented by a jeweller named LeRoy Goertz.

This is what it looks like out of the box. It comes with two diameters of crankshaft, so that you can make coils in two different sizes.

The principle is elegantly simple. To start, you wrap some wire around the loop in the crank handle.

Next, holding the wire against the flat side of the frame, you begin winding wire onto the crankshaft.

From this point on, you simply turn the hand, which winds wire onto the crankshaft until you have a coil that looks something like the springs you'd find inside a retractable ballpoint pen.

This is what a full-length finished single coil looks like. This one measures about 15 cm (6 inches) in length, but you can make them any length under that. I made this long because I wanted to turn it into a double coil, or even a triple coil.

To make a double coil, you feed wire through the centre of the single coil, and wind it the same way, being careful to hold the feeder wire tightly so that the coil actually winds onto the crankshaft.

This is what a finished double coil looks like.

To create a triple coil, which has a far more anarchic look, I fed a piece of wire through this double coil and repeated the process. The photograph below shows what a finished triple coil à la Sheila looks like. This one is not in the instruction booklet, so it may be wrong somehow, but I like this weird shape. This is what I decided to use for the elephant's body.

I made another, smaller, triple coil for the head. Then I made a full-length double coil that I chopped into four pieces for legs, and some single coils that I used for a tail, the trunk and these tripartite ears.

After this, I just wired everything together using the same green wire. This was somewhat challenging, as it's easy to deform the wire coils if you push them around too much. After things were more or less in place, I shaped the tail and the trunk. For the trunk, I'd used the larger diameter of shaft, which I thought would look better.

This didn't turn out quite how I'd originally pictured it before I started coiling, but I like the final result. It has a nice weight to it, and it's also really springy—which only makes sense, I guess, since it's essentially made of springs.

This took me about an hour to make, once I reminded myself how the coiling tool worked. It wasn't hard at all, although assembling was a bit challenging at times. I actually enjoyed it enough that I may play with this tool again soon—maybe even to make something electromagnetic.

Elephant Lore of the Day
Sadly, elephants are struck and killed by lightning all the time in the wild. There have even been instances of small family herds being killed by lightning conducted through the ground. Lightning is obviously a greater risk for elephants who live on open lands, such as Africa's desert and savannah elephants. Interestingly, lightning is thought to be far more destructive to four-legged animals than two-legged ones, because the lightning travels around the body to more devastating effect. 

The most famous captive elephant to be hit by lightning was Norma Jean, star attraction of the small Clark and Walters Circus. On July 17, 1972, a sudden bolt of lightning hit Norma Jean while she was standing in the town square of Oquakwa, Illinois. Norma Jean was killed instantly, and her nearby keeper was sent flying 9 metres (30 feet).

Norma Jean was buried where she fell, and it was expected that she would soon be forgotten. Instead, local druggist Wade Meloan began raising money for a memorial. He eventually raised enough money to commission a limestone tombstone 3.6 metres (12 feet) high, and convinced the town to allow him to erect it in the town square, above Norma Jean's grave.

Today, the town holds an annual festival in August celebrating Norma Jean, including an elephant walk, a white elephant sale, and a bake sale featuring elephant ears. Signs from various places in the town point visitors to Norma Jean's gravesite, which includes a small collection of Norma Jean memorabilia in a glass case, and a concrete elephant perched atop the tombstone.

Norma Jean's memorial in Oquakwa, Illinois.

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