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Over the past several years there have been various reports by collectors of having found Lincoln cents with raised concentric lines (marks) on the obverse or reverse face of US coinage. First identified on 1996-D Lincoln cents, what was frequently observed were soft concentric lines that became stronger toward the perimeter of the coin, yet did not go into the devices. On the reverses of various dated Lincoln cents, the lines are thinner, tend to be stronger in the middle and do go into the devices. While the the Jefferson nickels have thicker lines which resemble the appearance of the 1996-D lines yet go into the devices.
Ken Potter, of CONECA, has stated that he had a conversation with a Philadelphia Mint spokesmen about the occurrence of these coins (K. Potter CONECA), the Mint Spokesman suspected that they probably had not polished the die blanks sufficiently to remove all the lathe lines. The lines were created when the die blank was machined from a cylinder of steel according to him and we can presume that if this is accurate, that the hubbing process did not eliminate them completely.
To clarify, dies are made from steel rods called Blanks, in the process of preparation the rods they are lathed into a conical shape of approximately 22 degrees. Apparently, after reaching the desired shape, they are furthered polished to remove evidence of their formation. As hypothesized, the lines were inadequately removed from a number of different dies. After being hubbed, some of the lines remained. Below is a drawing of a die-blank.
Having been cataloging various coins with Lathe Lines for about four years, I have seen over 50 examples and documented 40 different dies. Most have been on Lincoln cents, a few have been on Jefferson nickels and a couple of Kennedy half dollars. The oldest is a 1959-D LMC with lines on the revere, in the memorial bays, the oldest obverse is a 1964-D LMC. On eBay one can sometimes find a cheap example of a 1996-D and recently a few Kennedy's from 1990 have been offered. Prices range from .99ยข to about $15. My files are located on errorvariety(dot)com
The lines very in size
Jefferson nickel
Lincoln cent obverse
Lincoln cent reverse
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