2011 05 21

Machine parts above
collar can impede expanding coins

By Mike Diamond | 05-21-11

Article first published in May-2011, Expert Advice section of Coin World

As a coin is struck, its expansion
is abruptly halted by the surrounding collar.

When the collar fails to deploy, a
coin expands in all directions. As a result, all off-center strikes and
broadstrikes are wider than a normal coin, to varying degrees.

On some occasions a coin’s expansion
is impeded, and the edge damaged, by machine parts positioned above the collar
plate.

The most familiar obstacle to
unfettered expansion is the neck of an adjacent hammer die. In a dual or quad
Bliss press (the last of which was retired in 2005), the close proximity of
adjacent die pairs results in the occasional production of a “sideneck strike,”
also referred to as an “almost saddle strike” or a “one-die saddle strike.”

A typical example is shown here in
an off-center Lincoln cent. At the pole opposite the 1 o’clock position of the
obverse face, we see a deep, concave notch and an associated pressure ridge.
The planchet represented by this coin lay partly within one striking chamber
and almost managed to encroach on the adjacent striking chamber. In other
words, the coin fell just short of becoming a “saddle strike.” When struck, the
expanding die-struck area pushed the unstruck portion toward the adjacent
striking chamber. It collided with the side of the hammer (obverse) die neck as
the latter was striking its own coin.

Sideneck strikes are always concave
and always closest to the adjacent striking chamber. In most years, this
chamber would lie along a line drawn from the 1 o’clock position in Lincoln
cents, or the 11 o’clock position in Jefferson 5-cent coins and Roosevelt
dimes.

Strike-related edge damage of
another kind is seen in an undated Jefferson 5-cent coin. The pole opposite the
off-center strike has a flat, vertically oriented contact facet. It appears
that the facet was produced when the unstruck portion of the planchet was
pushed south by the expanding die-struck area and collided with a machine part.
Another possibility is that the coin was hit while momentarily immobilized by
the two dies.

In either case, we can’t be sure
what machine part was responsible, although I suspect a feeder finger. I’ve
encountered these flat facets on quite a few off-center and double-struck cents
and 5-cent coins. In each case, the strike is about 70 percent off-center and
the contact facet lies opposite the base of the bust.

The introduction of the Schuler
press introduced new types of strike-related edge damage. This press uses a
single die pair, with the reverse die operating as the hammer die. The damage
is primarily associated with multi-struck coins. A representative example is
provided by a quadruple-struck 5-cent coin. The first strike was normal. The
other strikes were delivered about 20 percent off-center and are closely
spaced. Edge damage is present on both the right and left sides. The contact
facet on the right side is convex, slightly beveled, and extends from 12
o’clock to 2:30.

The dies evidently struck whatever
machine part rested against the coin. On the left side the coin buckled when it
collided with a hard object. The contact facet here is quite compact and lies
next to the w of we. It’s possible that the coin was pushed laterally into an
obstruction by expansion produced by the off-center strikes. It’s also possible
that an object hit the coin as the latter was temporarily immobilized between
the dies.

This type of edge damage can be
found on numerous multi-struck cents, 5-cent coins, and Washington quarter
dollars struck by Schuler presses. The pattern is consistent, although the long
facet and the short facet can be located on either the right or the left side.

The affected coins all show a sequence
of strikes involving a normal (or at least centered) first strike, and one or
more closely spaced off-center strikes. Coins in which the off-center strikes
are widely spaced or erratically positioned typically do not show this edge
damage. The long facet that hugs the edge of the off-center strikes is almost
certainly caused by contact with a feeder finger. I’m not sure about the short
facet.

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