Previous Collectors’ Clearinghouse columns (Feb. 22, 2010; Aug. 22,
2011; Jan. 16, 2012) introduced an unusual form of machine doubling
designated “one-sided, rim-restricted design duplication.”
After reaching the lowest point of its downstroke, the hammer die
bounces up, shifts laterally and lands lightly on top of the coin’s
newly struck design rim. This second impact leaves a duplicate set of
peripheral design elements atop the design rim.
Specifying “one-sided” is essential because there are cases in
which a second set of design elements appears on both the obverse and
reverse design rims. One must sift through multiple working hypotheses
when evaluating such unusual cases. Furthermore, one shouldn’t assume
that the same explanation will apply to every case.
The illustrated 2005 Lincoln cent exhibits bifacial,
rim-restricted letters on the left side. Duplicated obverse design
elements include the L of LIBERTY and the upper half of IN GOD WE.
Duplicated reverse design elements include the bottom portions of ONE
C and the top portions of UN (from UNITED).
By 2005 nearly all cents were being struck by high-speed Schuler
presses employing inverted dies (reverse die as hammer die). I would
therefore assume that the reverse face of this 2005 cent was struck by
the hammer die.
While it’s impossible to be absolutely sure about the events
responsible for these extra letters, some scenarios are more likely
Double-sided machine doubling is uncommon but nevertheless
well-documented (Clearinghouse, March 15, 2010). The amount of offset
displayed by the extra letters of the 2005 Lincoln cent is well within
the range of die movements documented in severe cases of machine
doubling, but only in those cases generated by the hammer die. The
amount of lateral movement required of the anvil die to leave
lettering on the obverse rim of the 2005 cent is impossible if we
assume the anvil die neck was tightly confined by the collar. A second
problem with this scenario is that when machine doubling occurs on
both faces it almost always points in different directions.
The extra letters on each face of the 2005 cent are properly
aligned relative to each other and show the same degree and direction
of lateral offset. This strongly implies that it was the coin that
moved and not the dies. A double strike is therefore a much more
plausible explanation, leaving only the sequence of strikes to be determined.
Light off-center strike followed by strong in-collar strike:
It’s possible that the faint letters were produced by a very weak,
slightly off-center first strike, with the impact primarily felt on
the planchet’s proto-rim. This would have been followed by an
in-collar strike of normal strength. A planchet struck this weakly
would show no significant expansion and would be able to fit back into
the collar for a second strike. Planchets with design elements largely
or completely restricted to the proto-rim have been reported
(Clearinghouse, Oct. 10, 2011, and April 8, 2013). These elements
could conceivably persist on top of the coin’s design rim after a
normal second strike due to the lower effective striking pressure in
this area. However, I would expect the letters to be somewhat
flattened from contact with the roof of the rim gutter and this
doesn’t appear to be the case here.
Normal first strike followed by weak, slightly off-center second strike:
This appears to be the most convincing scenario. After a normal
first strike, the collar presumably failed to deploy and the coin
shifted ever so slightly in an east/northeast direction (as seen from
above). During the second strike, something prevented the dies from
approximating normally so that at their closest approach they only
managed to contact the points of highest relief, located on the
newly-struck design rim.
Another coin, another explanation:
An outlying crescent of die-struck design replaces much of the
design rim on the left side of a 1967 20-centavo coin from Brazil
illustrated here. In this case the extra elements are the product of a
weak, off-center first strike. The coin was properly centered during
the second strike although the collar was only partly deployed (making
it a partial collar error). The hammer (obverse) die was misaligned
toward the southeast during the second strike, allowing details of the
first strike to persist to a greater extent than they ordinarily would have.
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