The Big Bang Coins|
October 01, 2008
They said it couldn't be done. I said it couldn't be done. All of us were wrong, dead wrong. It is not only possible to reduce the diameter of a coin, it can be done without losing one iota of the metal or affecting the weight of the coin. I need to thank John Hoxie for the tip leading to this column.
Bah! Humbug! It's a trick! I'm sure the inventor of the process has heard from every Doubting Thomas that has seen one of his altered coins.
In the previous column I mentioned swedged coins made smaller by forcing them through a tapered tube. There are probably other methods, but we see so many coins altered by hammering them, squeezing them in a vice or some other, easily applied method, sometimes referred to as blacksmith jobs. Here we have high tech for a change.
I captioned this column, "The Big Bang Coins," with good reason.
If you go to www.capturedlightning.com/photos/shrinker5.pdf, you will be greeted with this headline: "Making Small Change… Quarter Shrinking."
I have permission from Bert Hickman of Stoneridge Engineering to quote some of the material he has issued. Under this headline, he says, "the Quarter Shrinker uses a technique called high-velocity metal forming to 'electromagically' shrink coins. This process creates an invisible, but extremely powerful, pulsed magnetic field which literally 'hammers' the coin with a powerful shock wave, forcing it to change its physical shape in the blink of an eye.
"Energy stored within a high voltage capacitor bank is suddenly discharged into an insulated wire work coil that is wrapped around the coin. Up to 100,000 amperes of current is forced through the coil, inducing perhaps as much as one million amperes of current to flow within the coin via transformer action. The instantaneous power going into the work coil is comparable to the electrical power consumed by a medium sized city."
Dimming the lights in a large city is not cheap, but the pieces have been on the market for a decade. I think I've had one or two of the coins to examine, but without this background information I didn't have a clue as to how they were made. The biggest mystery to me is that none of the experts picked up on tbis, despite the coins being sold on the Internet, and the information about them in plain public view.
It gets even more interesting when we learned that Hickman has taught several others the process, less the trade secrets of just how he enhances the beauty of the coins. In other words, this is not a project that you want your kids to work on in the basement. For us techie nerds, this is one of those impossible dreams.
"The resulting compressive forces on the coin easily overcome its mechanical yield strength, and the coin is evenly 'crushed' to a smaller diameter, becoming thicker in the process.
"The shrinking process is all over in instant - about 20-25 millionths of a second. At an energy level of 5,000 Joules, a quarter shrinks to a diameter a bit smaller than a dime, but, amazingly, it still retains all of its surface features!"
Remember what I said about not letting the kids play with this?
"For safety, the work coil must be confined within a bulletproof blast shield. Once the coil disintegrates, residual energy in the system is transformed into a blinding ball of blue-white plasma, accompanied by a loud explosion."
That would make one heck of a July Fourth fireworks, but it's not for kids. Fun to watch, certainly.
"The Quarter Shrinker works on most coins. It's particularly effective on US 'clad' coins, since these coins use a highly conductive pure copper core sandwiched between thin outer layers of a nickel copper alloy that has a higher melting temperature. Sacagawea and new Presidential Dollars ('Golden Dollars') also shrink quite well, since these utilize a pure copper core sandwiched between layers of a manganese/brass alloy.
"Bronze cents (those made before 1982) also shrink well. Cents made after 1982 use a thin copper layer plated over an easily melted zinc core during shrinking, the copper layer vaporizes, leaving an unrecognizable, and partially vaporized, glob of molten zinc."
Now that I have your attention, there's more, and there's lots for the kids at www.teslamania.com.
The theme of the site is that: "Physics can be fun!"
Hickman gave me a list of Web pages going deeper into the process. If you'd like to explore further, e-mail me at firstname.lastname@example.org.
Alan Herbert, "The Answerman," may be reached by e-mail at: email@example.com. Questions may also be directed to him via "Coin Clinic," which appears in each issue of Coins. See the mailing instructions at the end of that column for specifics.
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On October 1, 2008 navya
On December 9, 2010 ron warner
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