Numismatic Coin Club World Internet Numismatic Society


Multiple Struck Error Coins
They Sometimes Escape the Mint
and End Up in Your Collection (Part 2 of 2)

By Ralph J. Huntzinger, WINS#158

Last month we discussed how certain misshapen error coins occur.  This month, we'll look at how these odd shaped coins can escape the Mint and end up in your hands.

The U.S. Mint makes every effort to catch its errors and to retrieve them before they escape the confines of the Mint.  Not unlike most other manufacturers, the Mint is proud of its product and the employees attempt to release only quality pieces.  But the sheer volume of their production – billions of coins per year – disallows for all of the errors to be caught.  Error coins produced by the Mint likely comprise a very tiny percentage of their overall production.  And then only a tiny fraction of those errors ever manage to escape.  That's primarily because the Mint utilizes a device known as a “riddler” to screen its product.  The riddler devices are in place at several stages of the production process.

The riddler devices are first used on the blanks which have been punched from the coin metal strip.  The second riddler-sifting is on the planchets after they've been through the upset mill (unstruck coins are "blanks" until they receive their raised edges in the upset mill, and then they're called "planchets").  The third use of the riddler is after the planchets have been annealed, washed and burnished and are ready for striking.  The riddlers are used a fourth time to screen/sift the struck coins just after they leave the coinage presses.  And finally, the riddlers are used one more time just before the coins are sealed into bags by weight.

What is a riddler, and how does it work?  It's a device that's composed of a system of elongated, vibrating screens or sifts that are intended to separate the errors from the non-errors.  These riddler screens/sifts are long, flat devices with various size holes which resemble a wide strip of coin metal after the planchets have been punched out.  The holes in these riddler screens vary in size depending on the size of the blanks, planchets or coins being screened or sifted at the time.  The riddlers resemble a conveyor belt with raised sides, but they don't move in conveyor fashion. The riddlers vibrate very strongly so as to cause the blanks, planchets or coins which pass over them to bounce around on the screen, and over the holes, to separate the good pieces from the errors.  The screens are angled/tilted downward so that the vibrating blanks, planchets or coins bounce along from one end of the screen to the other.  The riddler operation is entirely mechanical.  The blanks, planchets or coins are fed onto the riddler device at one end, and the separated products (errors and good pieces) are either retained at that screen level or they're dropped into bins at the other end.

The riddler screens are utilized in combination; that is to say, they're stacked on top of each other.  In other words, there are usually three levels of riddler screens which are used simultaneously.  The three levels are stacked, one above the other, and are each separated by several inches of height.  All three screens vibrate vigorously.  The blanks, planchets or coins are fed onto the top screen.

The holes in the top screen are sized to permit only proper sized pieces, or undersized pieces, to fall through the holes of the vibrating screen.  Thus, all oversized blanks, planchets or coins and larger pieces (maybe a piece of errant planchet strip) are retained on the top screen, allowing all of the proper sized pieces and undersized pieces to fall through to the second level.  The top riddler screen looks like a closed-end catch basin which holds all the pieces that are too large. These oversized pieces are eventually gathered from this top screen/box and sent back to be re-melted.

The second, or mid-level screen has holes which are slightly smaller than the proper size for the pieces being screened at the time.  Thus, as the coins or planchets vibrate along this middle screen, only the undersized pieces fall through the holes.  The proper size pieces are retained at the mid-level and eventually fall off the end of the tilted, mid-level screen into a bin or onto a conveyor belt.  In theory, only the perfectly shaped coins or planchets fall into the bin or onto the conveyor for further processing.

The lowest level screen is also a closed-end catch basin.  It, too, has holes, but the holes are fairly small and merely feed the vibrating, undersized pieces into boxes below the riddler device.  The undersized coins, planchets and pieces which are caught in these boxes below the riddler unit are then gathered and sent back to be re-melted.

Not to be redundant, but as an overview, try to visualize it this way.  Three long layers of screens or sifts - all are slightly tilted - all vibrate vigorously - all stacked a few inches above each other.  The top layer is boxed, closed on all four sides. It has holes the size of the coins being screened.  The proper size and undersize coins and pieces fall though to the middle layer screen.  The oversized coins and pieces are caught/trapped in this top layer to be re-melted. The middle layer screen has holes smaller than the coins or blanks being sized.  The vibration causes the undersize coins and pieces to fall through the holes to the lowest level/third level screen.  The proper size coins or planchets from the middle level vibrate off the open end of this mid-level screen and fall into a bin or onto a conveyor for further processing.  The lowest level of the riddler is also boxed/closed on all sides and has smaller holes yet.  It vibrates the undersize coins and pieces into catch bins below the riddler machine, where they're eventually gathered for re-melting.

With the blanks, planchets and coins going through the riddler devices an average of five times (each time catching errors that were previously missed - or catching new errors as a result of the next step in the coining process) it's really a wonder that any error coins whatsoever escape the Mint.  So, how do some of them escape?  Pretty simply, actually.  Some of the pieces float on top of each other and ride right over the holes!  And though the riddlers are designed to disallow for that, they can't prevent it.  So some tiny fraction of a percentage of error pieces escape the scrutiny and actually enter into commercial channels where they can eventually be had by the dealers and collectors.  How do they get into your hands?  Read on.

In today's world, the Mint weighs coins rather than counting them. The Mint hasn't utilized counting machines for more than two decades.  This would explain why some of the Mint-sealed dollar bags I've recently purchased have been short on the number of dollars in the bag.  Since we all know that the Mint has an acceptable +/- tolerance for coin weights, a few slightly underweight coins will cause a bag to have extra coins.  Conversely, a few slightly overweight coins will cause a bag to weigh properly but be short on the actual count.  The last $1000 bag of 1999 Susan B. Dollars I received from the Mint, as an example, had only 997 coins sealed in the bag.  But it weighed the correct amount.  I guess they figure the law of averages will come into play and that this ultimately balances out.

As the coins are minted and pass over the last riddler device, the struck coins fall into large bins.  The bins are weighed to determine the proper number of coins.  Some of the bins are sealed and shipped, just as they are, to the Federal Reserve Banks.  Coins from other bins are weighed into smaller mint bags which are sealed, stored on pallets, and then, too, are shipped to the Federal Reserve Banks.  The Mint has recently begun utilizing super-size bags that can only be lifted by forklifts.  These large reusable bags are apparently intended to eventually take the place of the bins and smaller canvas bags to ship coins.

As The Fed receives orders for coins from private banks and armored car carriers all over the country, they ship these bags and bins to them.  The larger banks receive the bulk shipments at their counting rooms and they roll the coins to supply their branches.  The armored carriers, such as Brinks, Wells Fargo and Metropolitan Armored Car also receive in bulk to supply coin rolls contractually to major retailers such as large food store chains.

Though counting/rolling machines aren't utilized by the Mint, they are still widely used by these private counting rooms.  When the counting rooms receive the large, sealed bins or bags from the Federal Reserve Banks, they dump the coins into the counting machine hoppers and start the automated rolling/wrapping process.  But, the machines tend to jam when a misshapen error coin is encountered.  An operator has to locate the jam, remove the misshapen coin and restart the machine.  The error coin is then set aside and the counting machine continues until it encounters another jamming error.  This is where many of the major error coin dealers across the country acquire the majority of their error coins.  They have a deal with the counting room personnel to purchase those errors.  Once the error coins are in the hands of the error dealers, the rest, as they say, is history.  The error coins wind up in dealer display cases and on the Internet in auctions – and eventually in YOUR collections.


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