Error Coin Essentials: Die Adjustment Myth

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Error Coin Essentials introduces the core concepts behind coins that didn’t come out quite right. These articles provide a practical foundation for collectors who want to understand how errors happen, how to identify them, and how to collect them. With strong collector demand and wide variety, error coins remain one of the hobby’s most engaging fields. 

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Several misconceptions riddle the error-coin collecting community. One misconception I constantly harp on is the misleading term “die adjustment strike.” Equally misleading synonyms include “die trial” and “set-up piece.” These terms are applied to coins that show a dramatically weak strike, like the undated dime shown below. Why not just use the term “weak strike?” It’s because grading services, dealers, and collectors are attached to the profitable myth that weak strikes arise from something other than spontaneous press malfunctions. In their view, a drastically weak strike owes its existence to one of two circumstances: either the coin was produced while adjusting the press settings and somehow escaped destruction, or the coin was produced while starting or shutting down the press, with the assumption that coining presses gradually raise or lower their striking pressure during these procedures.

The Reality

While modern mechanical presses are computer-controlled and ordinarily don’t require manual adjustments, it’s conceivable that a press might initially spit out weakly struck coins that might require tweaking of the press settings. The second scenario, however, doesn’t fly. Modern presses immediately start striking coins at full tonnage and immediately stop when power is shut off. These two scenarios were never verifiable to begin with, as they speak to ultimate causation, which, in this context, can neither be observed nor corroborated by physical evidence. At best, weak strikes can be assigned to two proximate causes. One is inadequate ram pressure (the tonnage applied to a planchet of normal thickness), and the other is minimum die clearance (the gap between the dies at their closest approach in the absence of a planchet).

The Causes of Weak Strikes

Behind these two proximate causes lie any number of ultimate causes. These may include: a cracked, bent, or weakened press frame; a loose or broken press linkage; an electrical interruption; a jam in the guts of the press; a pileup in an adjacent striking chamber; or dies falling out of adjustment. Numerous lines of evidence show that the vast majority of weak strikes are the product of spontaneous equipment malfunction. Excessive minimum die clearance is almost always the proximate cause. The evidence also shows that weak strikes are often short-lived and self-correcting.

First of all, weak strikes are far too common to represent rare escapees from the reject bin. Second, if weak strikes were the result of press adjustment or start-up/shut-down malfunctions, their abundance should track with mintage. In other words, weakly struck cents should be most numerous. In fact, it is dimes that are most commonly affected. This makes perfect sense if excessive minimum die clearance is responsible, as the tolerances are very tight for this thinnest of coins. Thicker denominations have more generous tolerances, so a slight increase in die clearance is not likely to alter a coin’s appearance.

Types of Weak Strikes

For every kind of striking error, there is a weak-strike version. In other words, you can find weakly struck off-center strikes, misaligned die errors, tilted die errors, double strikes, indents, brockages, and so on ad infinitum. Under the traditional scenarios, you wouldn’t expect anything beyond a simple, centered weak strike. Shown below is a 1983-D nickel that received a normal first strike and a very weak second strike with a major (35 percent) misalignment that was also rotated or pivoted 30 degrees.

This coin also shows an instantaneous change in striking pressure between strikes. I’ve documented other double-struck coins that show a strong first strike followed by a weak second strike or a weak second strike followed by a strong first strike. Shown below is a quarter with a normal first strike, a very weak 40-percent off-center second strike, and a very strong 75-percent off-center third strike. The same die pair delivered all strikes. Significant die wear (i.e., a late die state) shows that the malfunction occurred late in the press run.

Conclusion

Weak strikes are fascinating windows into the minting process and the malfunctions that contribute to inadequate striking pressure.  There’s no reason to muddy this corner of the error hobby with hoary myths that should have been discarded decades ago.

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Mike Diamond has been collecting, researching, and writing about error coins since 1997.  Since November 2009, he has written a weekly column for Coin World (“Collectors’ Clearinghouse”) that focuses on minting errors and die varieties.  Prior to that, he was responsible for dozens of articles that appeared in CONECA’s specialty journal Errorscope.  He created and contributed most of the content found in The Error-Variety Ready Reference.  Over the past 28 years, he has discovered or described well over 100 new error types.