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<p>[QUOTE=&quot;physics-fan3.14, post: 2311381, member: 19165&quot;]To clarify some of the confusion in this thread: </p><p><br /></p><p>In 1986, the mint reported using the single squeeze method of producing hubs on cent dies. They experimented with this process over the next decade. In the traditional method of making dies, a hub was used to make an impression in a die. After this, the die was annealed, and then the hub was reapplied to the die. If the primary and secondary image weren&#039;t exactly aligned, you would get a secondary image. This is true hub doubling (there are a number of different &quot;classes&quot; of doubling, based on how the appearance differs - that is, what caused the shift and how it appears on the final coin). </p><p><br /></p><p>Over the next decade, the single squeeze was gradually phased in at various mints and on various denominations. </p><p><br /></p><p>The mint went to the single squeeze process for all denominations and all mints in 1997. In the single squeeze process, the die is only hubbed once. It is possible for the die to slightly shift or slip during this process. However, the die is slightly conical: the center of the die makes contact with the hub first. If the die is going to slip or shift, it will do it at the beginning of the hubbing (when only the center has made contact with the hub). Thus, most doubling made with the single squeeze process will appear at the center of the coin. (Recent discoveries have shown that the die may slip later in the process as well, but these are much less common). </p><p><br /></p><p>Thus, any doubling on the Massachusetts quarter would be from a single squeeze hubbing, and would show at the center of the coin. </p><p><br /></p><p>All that being said: the OP&#039;s coin exhibits very minor machine doubling, not hub doubling.[/QUOTE]</p><p><br /></p>

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