Posted 11/01/2012 8:34 pm
I hope its ok but it was such a good read, I have to share this from Coin World:
Machine, mechanical or Strike Doubling: Machine Doubling is often mistaken by nonspecialists as die doubling although the two forms of errors are unrelated. Machine Doubling occurs at the end of the strike and is usually attributed to a loose die or a vibrating die assembly, although other proposed explanations may have validity, notes researcher Diamond. Specialists recognize two forms of machine doublingâ€""push doubling" and "slide doubling."
Diamond describes the appearances and causes of the two forms: "Push doubling leaves flat, marginal shelving along the edge of the design and rounded doubling on interior design elements. Push doubling develops when the die (hammer or anvil) bounces up after impact, shifts slightly to one side and lands lightly on the newly-struck design.
"Slide doubling smears the design. It occurs when a die shifts laterally without a bounce and, as a consequence, drags itself through the newly-struck details."
While many specialists find Machine Doubling uninteresting, some very interesting and collectible pieces have been found. Collectors should be wary of paying a premium for routine examples of machine-doubled coins, although the more exotic pieces may carry collector premiums.
Machine, mechanical or Strike Doubling: Machine Doubling is often mistaken by nonspecialists as die doubling although the two forms of errors are unrelated. Machine Doubling occurs at the end of the strike and is usually attributed to a loose die or a vibrating die assembly, although other proposed explanations may have validity, notes researcher Diamond. Specialists recognize two forms of machine doublingâ€""push doubling" and "slide doubling."
Diamond describes the appearances and causes of the two forms: "Push doubling leaves flat, marginal shelving along the edge of the design and rounded doubling on interior design elements. Push doubling develops when the die (hammer or anvil) bounces up after impact, shifts slightly to one side and lands lightly on the newly-struck design.
"Slide doubling smears the design. It occurs when a die shifts laterally without a bounce and, as a consequence, drags itself through the newly-struck details."
While many specialists find Machine Doubling uninteresting, some very interesting and collectible pieces have been found. Collectors should be wary of paying a premium for routine examples of machine-doubled coins, although the more exotic pieces may carry collector premiums.
