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 Replies: 13 / Views: 339 |
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Pillar of the Community
United States
999 Posts |
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Pillar of the Community
United States
3071 Posts |
Compare and contrast was my history prof's favorite essay question. Hand punched mint marks are indeed all over the place, so it's only when they are far from the norm that collectors begin to have interest. I, too, find identifying RPMs difficult. To simplify things, I primarily look for split serifs on the mint mark, which means seeing two (or more) separate points on the left side of a D, That does not work well for S since its serifs are rounded. Bumps inside the curls of the S are not evidence of an RPM because most such bumps originate from a damaged mint mark punch. Then you have Machine Doubling which can yield a fake RPM. Learn how to distinguish Machine Doubling on other devices first, then you'll be prepared to spot it on a mint mark. Others will likely chime in with their own favorite RPM spotting techniques. |
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Pillar of the Community
Topic StarterUnited States
999 Posts |
I believe that both '69 nickels above have some light Machine Doubling on the numbers. I imagine that die polishing or wear can result in a chubby-D or filled-D, but then I see published examples where that is called RPM. The center of a D or P mint mark is basically just a tiny spike of metal on the die, so I imagine that wears down really quickly compared to the bigger devices. |
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Pillar of the Community
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3071 Posts |
I've also seen published RPMs that look ambiguous, but I defer to the experts. Most hand punched mint marks on nickels look imperfect under magnification. Given how difficult RPMs can be, and with my vision not getting better with time, I've decided to stop looking for them, even though the search can be fun.
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Bedrock of the Community
 United States
22375 Posts |
The mint mark location can vary from coin to coin (die to die actually) and year to year because they were hand punched onto the die. As long as the MM is below the date, it is within tolerances.
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Pillar of the Community
Topic StarterUnited States
999 Posts |
Manual variability is basically what causes RPM, right? The punch skips during the hammering process, and gets struck again in a slightly different position. It's different from an over punch like S/D where someone came back at a later date and hammered something different into the existing mint mark.
Tbh, I am a little puzzled why people seem to place such a high premium on RPM. I can understand the OPM interest—including corrections like X/Lazy X, X/Sideways X, X/Backwards X—because it captures a little story about the minting process. RPM is just a relatively tiny accident of bad aim or a shaky hand.
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Bedrock of the Community
United States
22375 Posts |
Quote:
Manual variability is basically what causes RPM, right? The punch skips during the hammering process, and gets struck again in a slightly different position That is exactly correct. but an OMM (over Mintmark) like a D over an S and such, happens when a die that already had a MM was sent to another Mint for them to use, and they place the new MM over the old one.
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Pillar of the Community
Topic StarterUnited States
999 Posts |
So with that in mind, are any of the above examples actually RPM? What causes the fat D, filled D, the ghost P, the weird little variations? The hammering process might be a little imprecise, but the punch is a correctly formed mint mark.
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Pillar of the Community
 United States
3939 Posts |
Brandmeister, it would appear that you have a very good understanding of mint marks, RPM's and how they occur, this is the first step but most definitely not the only one. You have been given good information and advice above, but here is a good read to look over. LINK http://doubleddie.com/58243.html There are a lot of things that come into play when searching for RPM's though. There can be things going on with the die and "whole" die, that will help you determine whether you have an RPM or something else. You need to pay attention to the die state, the condition of the die, possible movement in other devices on the coin itself and the condition of the coin. Machine Doubling can typically be seen elsewhere on the coin and will sometimes make it easier to rule out and RPM. Die wear (an older die), can greatly affect the look of a mint mark. Unintentional damage or intentional alterations to the die, after the mm has been placed can also happen. A damaged or over used mint mark punch can affect the look of it. And probably, most common, damage to the coin itself, because of circulation wear or intentional damage. All this being said, there is nothing that can replace time, patience and just plain old experience and even then, there will be questionable situations. The main thing, is have fun with it, because if you do not enjoy it, there is no point, in my opinion.  Quote:
So with that in mind, are any of the above examples actually RPM? The pics are a little fuzzy but I do not see any RPM's in the above pics, but some are quite minute at times, so could be overlooked. -makecents-
Edited by -makecents-
06/02/2023 08:55 am
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Pillar of the Community
Topic StarterUnited States
999 Posts |
Thanks for the link. I had read the Wexler stuff, but it's a good resource. I was interested in those books listed at the end of the article, but they are not available at any library to which I have access. The example images in the article are clear as a bell. However, many of the attributed RPM in Wexler's listings are nowhere near that cut and dried. Same with Variety Vista. I am entirely willing to accept that I did not photograph any RPM examples. The odds of finding one on seven coins seems slim. But two questions remain (among many more subtle points): 1. That 1977 nickel is basically a high AU coin. Minimal wear, decent strike, relatively sharp letters and numbers. So what is the mechanical cause of the D being almost filled completely? The 1979 has a similar problem, although that nickel has comparatively more circulation wear. 2. What is the cause of the little shelf inside the 1970 D mint mark, and the shelf outside-right of the 1984 P mint mark? In other threads people have discussed Machine Doubling and die polishing. Is that the cause here, and if so, how do you distinguish that from true RPM? It's easy to imagine that the second blow on the punch shifted slightly left as the tool dug into the die. |
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Pillar of the Community
United States
3071 Posts |
some RPMs are due to the mint mark punch bouncing on the die when hammered
missing interior sections of mint marks are due to that part of the die breaking off, some call it a broken post
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Pillar of the Community
Topic StarterUnited States
999 Posts |
Ok, so question #1 answer is a broken post. Which seems like a highly specific Cud. Question #2? |
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Pillar of the Community
United States
3071 Posts |
by defintion, Cuds involve the rim. so a broken post is a form of die chip you'll find anomalies like the 70D and 84P on lots of nickels, probably Machine Doubling, but I find those tough to determine for sure even with the coin in hand |
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Pillar of the Community
United States
3939 Posts |
So, for the 84P, this is why a full coin shot helps a lot, so we can see what's going on throughout. It could be "isolated MD", which is a thing where there is only MD on one particular device, but I'm leaning towards a deteriorated die, it looks like there is also deterioation towards the rim on the 8. As for the 70D, it looks like MD to me, as does the lower inside of the zero. In both cases, there could be lighting adding to what you are seeing. You need to turn your coin in quarter turns, without changing the lighting direction and see if it shows differently, you will be surprised at what you find when you do this. And yes, not a Cud, as nick10 said, it is nowhere near the rim. Here is another link to brouse and learn from. COC http://cuds-on-coins.com/cuds-on-u-s-coins/-makecents-
Edited by -makecents-
06/02/2023 9:29 pm
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Replies: 13 / Views: 339 |
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Posted 06/01/2023 12:17 pm
