The Janvier Reduction Lathe was used to reduce the images that were found on the galvano transferring them onto the master die.

The large white disc at the center of this Janvier Reduction Lathe is a galvano for the 1999-S proof Kennedy half
dollars.  The device near the bottom of the galvano is tracing out the design in that area.

Here we see the Master Hub for the 1999-S proof Kennedy half dollars that is being carved in the same Janvier Reduction Lathe as seen in the previous photo.  The device at the bottom of the Master Hub is doing the engraving.

Images and text courtesy of John Wexler. To learn more concerning the Janvier reduction lathe, click HERE

PART VI. Striking Errors:

Design Ablation Error:On Second Strike

Definition: The die-struck design on the surface of a coin is scraped off by lateral (horizontal) die movement.  This can occur on a first or second strike.

This quadruple-struck 2000-D Lincoln cent was struck with inverted dies (reverse die acting as hammer die).  The first strike was normal.  The third and fourth strikes were received in tandem as the coin straddled two adjacent striking chambers (a saddle strike).  The second strike was off-center, uniface, and incorporates a design ablation error.

During the second strike, the impact of the hammer die on the reverse face was relatively weak, even though the aggregate thickness it confronted was doubled by the presence of an an underlying planchet.  After making light contact with the surface of the coin, the hammer die shifted a considerable distance toward 12:00 (reverse clock position).  As the die moved northward, it completely scraped off the first-strike design elements and whatever second strike design elements were generated during the initial impact.  All that is left is a series of fine parallel striations that expose a little bit of the zinc core.

This is the only known example of a design ablation error on the second strike.

PART VI. Striking Errors:

Abnormally Strong Strike:

Due to Stacked Coins or Planchets

 Definition: Effective striking pressure is always increased when the aggregate thickness between the dies is increased.  An extra planchet or coin inserted into the striking chamber will cause a significant increase in effective striking pressure.  If one or both coins are struck within the collar, those coins confined by the collar will show strong finning.  Finning occurs when coin metal squeezes into the narrow gap between die neck and collar. If one or both coins are struck outside the collar, they will expand enormously.