Machine doubling is a post-strike mechanical effect that happens when the coin die shifts slightly upon making contact with the planchet (the blank coin) but before the metal has a chance to fully settle into its final form. This can be due to several factors, including loose die, mechanical vibration, or an issue with the press itself. Unlike true doubled dies, where the doubling effect is a result of an error during the die’s creation leading to a doubled image on every coin struck from that die, machine doubling is a random occurrence.
Machine doubling
Machine doubling manifests in several ways on coins, depending on the specific circumstances of the striking process. Here are some common characteristics and situations:
- Shelf-like Appearance: Machine doubled features often appear as flat, shelf-like extensions of design elements. Unlike the rounded, sculpted appearance of true doubling, machine doubling lacks depth and dimension.
- Reduced Detail: In areas affected by machine doubling, you might notice a reduction in detail due to the secondary, shifted strike. This contrasts with doubled dies, where additional detail is created in the doubling process.
- Inconsistency Across Specimens: Since machine doubling is a result of mechanical error during the strike rather than a fault in the die itself, its presence and appearance can vary widely even among coins from the same batch.
- Location and Direction: Machine doubling can occur in any direction (not just towards the coin’s edge, which is a common misconception) and can affect any part of the design, depending on how the die moves at the moment of striking.