For many years the writers of this column have made a conscious
decision to avoid the term “die adjustment strike” when referring to
an exceedingly weak (low-pressure) strike. Synonyms include “die
trial,” “test strike,” “trial strike” and “setup piece.” All of these
terms assume that a profoundly weak strike represents a coin that was
struck as the settings of the coinage press were adjusted.
There is no doubt that die adjustment strikes have been produced
through much of the Mint’s history. The word “myth” is instead
directed at two common misconceptions; 1) that press adjustment is the
sole or primary source of very weak strikes, and 2) that die
adjustment strikes escape the Mint in numbers large enough to account
for their frequent presence in the marketplace.
Weak strikes arise from two proximate causes — inadequate ram
pressure and insufficient die approximation (excessive minimum die
clearance). Ram pressure is the tonnage applied to a planchet of
normal thickness. Die clearance refers to the closest approach the
dies make to each other in the absence of a planchet.
Determining proximate cause
Determining proximate cause is often difficult; assigning ultimate
cause is virtually impossible. A simple, centered weak strike could be
a die adjustment strike or the product of spontaneous equipment
malfunction. The latter category might encompass dies falling out of
adjustment, a jam-up in the guts of the press, a mistimed or broken
cam (upon which the anvil die rests), a mistimed hammer die, a slack
or cracked press frame, a loose or broken knuckle joint, or a broken
Numerous independent lines of evidence indicate that the vast
majority of weak strikes in the marketplace are the product of
spontaneous equipment malfunction, with most caused by an increase in
minimum die clearance.
Absolute abundance: If weak strikes were the product of die
adjustment, they should be very rare, as such test strikes are
ordinarily consigned to the furnace. In truth, weak strikes are
relatively common. They frequently pop up on the online auction site
eBay, and the prices they command are commensurate with their ready
availability. Most lower-denomination examples (cent to quarter
dollar), cost $50 or less. Shown here is a recently purchased 2007
Montana quarter dollar that cost a mere $35.
Distribution by denomination: If most simple, centered weak
strikes were die adjustment strikes, their relative abundance should
be proportional to the total number of coins struck and dies used.
Cents should therefore be the most common denomination affected by
In my experience, however, the most commonly affected denomination
is the dime, followed by the cent, quarter dollar and 5-cent coin.
This is exactly the pattern you’d expect from weakness caused by
spontaneous press malfunction resulting in insufficient die
approximation. Dime planchets are quite thin, enforcing a narrow
margin of error when setting the minimum die clearance. Only a slight
increase in this safety margin will result in a weak strike. A slight
decrease will result in a clash if a planchet is not positioned
between the dies — an error that occurs on dimes with great frequency.
A larger margin of error exists for thicker planchets.
This distribution pattern is also at odds with the once-popular
notion that weak strikes are generated when a press is first turned on
and when it’s shut off.
Occurrence with other striking errors: If weak strikes were lucky
escapees from a test run, then multi-error weak strikes should be
almost nonexistent. In fact, I have observed exceedingly weak strikes
in association with a wide range of striking errors: off-center
strike, brockaged off-center strike, double strike, triple strike,
saddle strike, misaligned die error, rotated die error, clashed dies,
indent, partial brockage, full brockage and struck-through. Shown here
is a 1983-D Jefferson 5-cent coin with a weak second strike delivered
by a rotated (30 degrees) and misaligned (35 percent) hammer die.
Multi-error weak strikes also provide a second argument against
the press start-up/shut-down
Instantaneous changes of striking pressure: The die adjustment
scenario is falsified by multiple strikes in which there are
instantaneous changes in striking pressure between strikes.
This phenomenon is beautifully illustrated by a Washington quarter
dollar struck three times by the same die pair.
The first strike was normal while the second was 40 percent
off-center and exceedingly weak. The third strike was 75 percent off
center and forcefully delivered. This example also illustrates the
self-correcting nature of some malfunctions responsible for weak strikes.
Coin World’s Collectors’ Clearinghouse department does
not accept coins or other items for examination without prior
permission from News Editor William T. Gibbs. Materials sent to
Clearinghouse without prior permission will be returned unexamined.
Please address all Clearinghouse inquiries to email@example.com or to
(800) 673-8311, Ext. 172.