2001-P 25c NC Wdoubled Die Obverse / DDO -003 - Page 2

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Author	Replies: 19 / Views: 1,943	Page: of 2

Tanman2001 Pillar of the Community United States 4404 Posts	Posted 10/03/2023 11:22 am Quote: Why would the clash marks be mostly visible in the central area? Dies are slightly convex. With a weak clash, only the very center of the dies touch. Quote: the airplane struts above are going to be recessed in Washington's bust? Yes, you got it. Report this Post to the Staff
Brandmeister Pillar of the Community United States 6535 Posts	Posted 10/03/2023 12:05 pm I took some pictures in different lighting conditions. First two are night, LED lamp, one filtered and one no filter. Last ones are daytime, indirect sunlight. I feel like maybe the indirect sunlight captures the full coin more accurately, but it is less useful for identifying small features on the coin under magnification. Report this Post to the Staff
Brandmeister Pillar of the Community United States 6535 Posts	Posted 10/03/2023 12:14 pm Separately, a convex die question. I know the dies are low cones when they are hubbed. That's to reduce friction and ensure good engagement of the hub details into the die face. It's also what generates pop doubling from the center on single squeeze dies. People have sometimes mentioned that the final working dies are also convex. But I have not been able to find anything online (yet) that indicates the actual curve of a working die. I assume the curvature must be small, but at those speeds and pressures, a small variation can produce big differences. Just how curved is a convex working die? Report this Post to the Staff
Tanman2001 Pillar of the Community United States 4404 Posts	Posted 10/03/2023 6:02 pm Quote: Just how curved is a convex working die? Not sure if it's ever been explicitly stated by the US mint. But we do know that the curve of dies is "spherical" (at least before c. 2020) and they have been experimenting with "exponential" curvature in recent years because of page 13 on this 2022 mint report: https://www.usmint.gov/wordpress/wp...P5_FINAL.pdf It maybe helpful to visualize this with a few images made by Shawn Tew in his recent book about the 1909 cent reverse dies where he had a 3D cross-section made of a few cents to examine die curvature. See pages 63-65: https://nnp.wustl.edu/library/book/629442 Report this Post to the Staff
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2001-P 25c NC WDDO-003