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Once we have a satisfactory master die for a given year, it is time to use that master die to produce working hubs. Those working hubs will then be used to produce the working dies which will then be used to strike the coins.
The process for producing the working hubs for a given year is identical to the process already discussed for making the master die. The master die is placed in the hubbing press. In the older multiple-squeeze hubbing presses it was clamped into the top of the hubbing chamber and a hub blank was placed directly below it. In the single-squeeze hubbing presses it rests on the top of the hub blank in a collar at the bottom of the hubbing press. When the press is activated hundreds of tons of pressure squeeze the face of the master die into the face of the blank steel rod that will become the working hub.
In the older multiple-squeeze hubbing presses it would require more than one hubbing to create a satisfactory impression in the working hub. The working hub had to be removed from the hubbing press and heated in an annealing oven to soften the steel for the next impression in the hubbing press. As with the production of the master die, if there was any kind of misalignment between the image on the master die and the incomplete image on the working hub, the result would be a doubled image where the misalignment of images occurred.
0December 30, 2018 8:47PM