Know the difference: misaligned die errors vs. off-center strikes
Doing a little tutorial on the difference between a misaligned die error and an off-center strike, as the two have a similar appearance and can sometimes be incorrectly identified. Let’s review a few terms before we get started:

Planchet: the circular metal disk that is to be struck by the dies and turned into a coin. It differs from a bank, because a planchet has proto-rims (added when the blanks go through an upset mill), whereas a blank does not.

Striking chamber: The area where a coin is struck. Consists of 3 main parts; the anvil die, hammer die, and collar.

Anvil die: The “bottom” die, on which the planchet rests during striking. In Lincoln Cents, it is the reverse image (the memorial reverse, Union Shield, etc)

Hammer die: The “top” die, which comes down to strike the planchet with enough pressure to transfer the design. In Lincoln Cents, it is the obverse image of Lincoln’s Bust.

Collar: A circular piece of steel that the coin expands into upon strike, preventing the edges from over-expanding.

Now for the process.

First, we will look at a misaligned die error. These occur when (usually) the hammer die is not properly lined up with the anvil die, resulting in a slight offset on one side of the coin. This means that only one side will show the misalignment, and the reverse will appear normal. Misaligned errors are relatively common and do not command much of a premium unless extreme.
Here is an example of a 1991D misaligned die error I kept around. Notice that the obverse is offset, but the reverse is normal.

An off-center coin, on the other hand, does not have to do with the misalignment of the dies. These errors occur when the planchet is, for whatever reason, improperly fed into the striking chamber, and only sits partially on the collar. Since the collar is responsible for holding the planchet in place during striking, only part of the planchet (the part that is over the anvil die) gets struck. The coin is then ejected (providing it is not struck again). An off center strike will show an offsetting of the image on both sides of the coin, and may be misshapen and elongated. Off-center strikes are popular errors and do command a premium based on the percentage off center. Value for these errors increases if the date is intact as well.
Here is an example of an off-center strike, I would guess about 60% or so. Although the date is missing, inspection of the reverse design leads me to believe it is from the mid 1980s. Note the offsetting on both sides, as well as elongation of the coin.

I hope this little tutorial helps folks out and teaches the difference between these two errors.
Happy hunting!

Simon

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