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 Replies: 26 / Views: 1,577 |
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Pillar of the Community
United States
3199 Posts |
I am especially interested in hearing your critique of these ideas/observations and conclusions! Could the answer be that both mints produce minor doubled dies but more of them appear on a minted coin from Philadelphia because of a more thorough and complete die fill during striking? The mint is clear that crown height and design relief height differ between the two mints and that completeness of die fill IS affected and that the differences of die fill between the two mints is measurable. We know that Master Dies are cut in Philadelphia on a Digitally Controlled Milling Machine and that this is likely the initial place in the die making process where die camber is introduced, if not already present on the original sculpted design. (The Milling Machine's predecessor, the Pantograph, was responsible for the application of die camber). Some of those Master Dies are sent to Denver and somewhere in the subsequent process in Denver the crown and design relief heights were modified. We do not know whether Denver or Philadelphia exhibited higher crown and design relief features. I theorize that the only other place in the die production process for that modification to appear is during die polishing. (We know that original sculpted designs rendered both radius plates and basining obsolete, since the models as submitted already included the desired curvature, although the Mint's own staff sometimes had to modify this radius in the hub reduction stage). I also theorize that the camber is modified by slightly changing the radius of the polishing device so that it is different from the radius used for the Master Die. A smaller radius should produce a higher crown/relief. I further theorize that a higher crown/relief is more likely to produce more complete die fill, resulting in an increase of a minor number of doubled dies appearing. This therefore means that Denver would have increased the die radius. The Mint does not claim to understand where or how the modification happens and simply indicates that it requires more study. The mint is clear that crown height and design relief height differ between the two mints and that completeness of die fill IS affected and that the differences of die fill between the two mints is measurable.   Edited by Pete2226
09/29/2025 2:39 pm
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Valued Member
United States
409 Posts |
Certainly seems that, if nothing else, quality control protocols in Denver are much stricter (and better followed) than at the Philadelphia mint
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Moderator
 United States
171012 Posts |
Very interesting. Thank you for sharing.  |
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Bedrock of the Community
United States
63514 Posts |
Great information. Thank you for sharing. Errers and Varietys.
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Bedrock of the Community
United States
18070 Posts |
Long ago a coin show curmudgeon told me that he thought quality control processes were better executed in Denver than Philly.
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Moderator
United States
77073 Posts |
My dogs would love that 50" ball (or be intimidated by it)
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Pillar of the Community
United States
3202 Posts |
The number of dies used by each mint in a year is also an issue. When Philadelphia made all of the dies, the branch mints were sometimes treated with something approaching disdain. They had hand-me-down coining presses, and far fewer of them. They were also provided fewer die pairs each year. The sheer number of dies could account for much of the disparity in that era. The more modern era is a different discussion.
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Moderator
United States
33739 Posts |
Quote:
The number of dies used by each mint in a year is also an issue. This is where my first thought was too: of the roughly 12B cents minted in 2021, two thirds left the Philly mint compared to one third from Denver. More coins equals more chances for minor issues, almost regardless of QC efforts, right?
"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz
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Pillar of the Community
 United States
5212 Posts |
Having examined lots of modern nickels under magnification, I have wondered this same thing. One difference I have noticed is that Denver nickels often exhibit far more severe Die Deterioration. That could suggest that Philadelphia produces more working dies than Denver for the same number of strikings. The simplest explanation would be that whatever single squeeze hubbing process is used in Denver, the working die isn't allowed to move as much as the Philadelphia process. There is no guarantee that their equipment or procedure are identical, and even identical machines can have different settings. |
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Valued Member
United States
228 Posts |
Thanks for the very good informative information! |
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Moderator
United States
171012 Posts |
Quote:
Long ago a coin show curmudgeon told me that he thought quality control processes were better executed in Denver than Philly. My Eisenhower dollars tend to agree, at least that being the case during their run. 
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Pillar of the Community
 United States
3199 Posts |
I appreciate the responses! My thinking is always prodded to explore areas I have overlooked.
With regards to the question of Quality Control for Minor Doubled Dies:
I am inclined to think that it is not a factor that would be relevant for this discussion. My primary reason is because of a letter from the US Mint reported by Ken Potter. Here is what he had to say:
"Finding microscopic errors, in my opinion, is counterproductive since the mint sees them as inherent in the minting process and makes no attempt to keep them from distribution. Some folks search for tiny doubled dies, but some resources refuse to list minor doubling.
I am not ready to rule out a doubled die...just yet. If it is, it is quite minor and certainly within tolerance. Operators at the press in the Mint use low power magnification (3X to 7X) to inspect coins against a visual standard. Operators focus on problem areas such as crack propagation and areas known to have high wear. It is highly doubtful that this type of imperfection would be caught by an operator at the press. The Mint says: "Subtle imperfections on circulating quality coins...are inherent in the coin making process. Such slight imperfections do not affect the coin's use in commercial transactions."
"The Mint's Opinion on Minor Doubled Dies by Ken Potter
Reviewing an April 2005 letter from the United States Mint about the 2004-P Peace Nickel Doubled Die Obverse, I noted a couple interesting passages. Collectors should know that doubled dies like this are considered "inherent" and are of no concern to the US Mint. They don't even look for them. I pass this on because a person asked about this not too long ago.
Here are a couple passages from that Mint letter: "Subtle imperfections on circulating quality coins, such as the image found on the 2004 Peace Medal nickel that was examined, are inherent in the coin making process. Such slight imperfections do not affect the coin's use in commercial transactions."
"As a note on coin and die inspection, operators at the press use low power magnification (3X to 7X) to inspect coins against a visual standard. Operators focus on problem areas such as crack propagation and areas known to have high wear. It is highly doubtful that the type of imperfection found on the 2004 Peace Medal nickel would be caught by an operator at the press. The photographs published of the specimen were at much higher magnification, 30X-100X. The quality systems in place at the Mint are not designed nor intended to screen out these very small, subtle imperfections."
So there you have it folks - the Mint at least back in 2005 didn't care and made no attempts to catch doubled dies such as the one shown here."
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Pillar of the Community
United States
5212 Posts |
You can't fault the Mint for that attitude. They are correct—doubled dies, die clashes, rotated dies and other minor errors and varieties generally require strong magnification to identify. Such variations and imperfections do not even slightly impair the coin's usage in daily circulation.
It doesn't do much to explain why recent Philly coins have a profusion of minor doubled dies when compared to Denver, unless the conclusion is that the Denver branch cares about minor imperfections and Philly simply does not.
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Moderator
United States
171012 Posts |
That reads correct to me. |
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Pillar of the Community
United States
3199 Posts |
Kinds of Quality Control at the Mint: This Audit Report (see image) is more concerned with Quality Control as it relates to Coin Composition.  I also know that the Mint has a Press Die Vision System (PDVS), which is integrated with the coin press so that no striking can occur until the system inspects and approves the installed dies. This integration was created by a group in San Francisco. The system uses technology such as computer-controlled servo motors, infrared lights, special mirrors, and a camera to inspect the installed dies in the press. If the dies are not an appropriate pair, striking is interlocked and prevents the striking of mule coins (obverses and reverses not meant to be together) for all denominations, increasing efficiency and lowering production costs. 2013 Annual Report, US Mint, Page 9 I have already mentioned that Operators at the presses in the Mint use low power magnification (3X to 7X) to inspect coins against a visual standard. Of course this inspection is not intended to catch minor Doubled Dies. I know that dies are inspected before Hubbing, and there are also various quality control inspections through the process. |
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Moderator
United States
171012 Posts |
Very interesting! |
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Replies: 26 / Views: 1,577 |
Posted 09/29/2025 2:45 pm
