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Please Post Your Coins Which Have A Hemispherical Depression

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Pillar of the Community
United States
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 Posted 08/11/2015  3:07 pm Show Profile   Bookmark this topic Add Pete2226 to your friends list Get a Link to this Message
I know that this might be a strange request! I want to do a little more research into this question. I am looking for photos of coins which have a hemispherical depression in them in order to compare. The depression should have no pressure ridge around it and have a smooth floor. The circular design might be distorted into a slight oval. This is basically the definition of a Rockwell Test Mark http://www.error-ref.com/?s=rockwell ).

I recently started a thread with what I thought was a "Rockwell Test Mark in Planchet." (https://www.coincommunity.com/forum...35115#235115 )
As you can see, if you read the thread, some who commented thought it was not!

I am still not convinced that I was wrong! However, I have now found a coin with two identical hemispherical shaped depressions! I am posting both coins here for comparison. This newer coin with 2 depressions shows a smooth floor in each of them, a hemispherical shape, and no pressure ridge. I would like to find out if anyone else finds something like this and ask it to be posted in this thread so they can be compared.

It seems to me that any differences in the diameter and depth of the depressions might be explained by the variance in the hardness of the Planchet.

These depressions may not be from a Rockwell Test. However, if enough examples can be gathered and compared, then it might lead to an understanding of their origin. The similarity between these depressions is striking! Something is causing them! I would like to find the source.
Thanks for any help on this! (I know we have a propensity to dismiss features such as this as PMD very quickly - however I would like to encourage some creative thinking about this question before such dismissal!)

This 2000-D appeared in the earlier post I mentioned:





This is 1995-D with two depressions:




Edited by Pete2226
08/11/2015 5:13 pm
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54589 Posts
 Posted 08/11/2015  3:26 pm  Show Profile   Bookmark this reply Add coop to your friends list Get a Link to this Reply
Here is the information from Mike Diamond's web site:
http://www.error-ref.com/?s=rockwell
Richard S. Cooper
Some have asked about my images I use and I'm glad to say, you can now you can see the DVD in sections on youtube:
1. Intro, older coins, toned coins 2. Doubled dies 3. Die events, One of a kind errors 4. So called errors, Coin information 5. Coin information Types and Varieties, Overlays
Jefferson nickel doubled dies Wexler/Rebar complete listings

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Pillar of the Community
United States
4053 Posts
 Posted 08/11/2015  3:43 pm  Show Profile   Bookmark this reply Add bpoc1 to your friends list Get a Link to this Reply
Very interesting.
Thanks for posting Pete2226 and Coop.
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 Posted 08/11/2015  3:49 pm  Show Profile   Bookmark this reply Add koinpro to your friends list Get a Link to this Reply
Over the years I've seen a number of coins touted as being struck on planchets containing a Rockwell Test Mark. Most notably those offered for sale by Bill Fivaz in JoJa Jems and shown by Lonesome John.

I have operated a Rockwell and must say that I'm unconvinced that any of the coins shown so far anywhere in the numismatic community can be proven to contain a RTM.

It might be a good idea for somebody to go to their local stamping plant and get a few planchets marked as such and have them struck to see what happens.
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United States
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 Posted 08/11/2015  5:11 pm  Show Profile   Bookmark this reply Add Pete2226 to your friends list Get a Link to this Reply

Quote:
I have operated a Rockwell and must say that I'm unconvinced that any of the coins shown so far anywhere in the numismatic community can be proven to contain a RTM.


What would it take to prove it? Is that even possible?

What insights can you give us from having operated a Rockwell?
Valued Member
United States
85 Posts
 Posted 08/11/2015  5:14 pm  Show Profile   Bookmark this reply Add Craftworker to your friends list Get a Link to this Reply
I don't know if this is the same but I have this 1891 Morgan dollar with some type of depressions (two). I thought that maybe someone had jabbed the coin with a screwdriver or an awl.

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3124 Posts
 Posted 08/11/2015  5:38 pm  Show Profile   Bookmark this reply Add Pete2226 to your friends list Get a Link to this Reply

Quote:
I don't know if this is the same but I have this 1891 Morgan dollar with some type of depressions (two). I thought that maybe someone had jabbed the coin with a screwdriver or an awl.


Thanks for posting this, Craftworker, and to CCF. Those are interesting, but I think they may be different from the ones I posted. Please check to see if I am right: it looks like a pressure ridge around a portion of each one of them (think of something like ejecta from a meteor crater) and also they appear to be conical in shape rather than hemispherical in shape.
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 Posted 08/11/2015  6:19 pm  Show Profile   Bookmark this reply Add Craftworker to your friends list Get a Link to this Reply
I didn't think it was what you were looking for, but since I don't know exactly what caused the "depressions" I gave it a shot. Yes, the depressions are conical, reminds me of something a drill bit might make. Sorry I couldn't help ya.
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 Posted 08/11/2015  6:21 pm  Show Profile   Bookmark this reply Add mikediamond to your friends list Get a Link to this Reply
I'm not sure why anyone would apply a Rockwell tester to a zinc planchet. Their uniform composition and the fact that they're not annealed would seem to insure a consistent hardness. It is notoriously difficult to assign a cause to circular and oval depressions.
Error coin writer and researcher.
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3124 Posts
 Posted 08/11/2015  7:10 pm  Show Profile   Bookmark this reply Add Pete2226 to your friends list Get a Link to this Reply

Quote:
I'm not sure why anyone would apply a Rockwell tester to a zinc planchet. Their uniform composition and the fact that they're not annealed would seem to insure a consistent hardness.


That seems to me to be the best argument I have heard as to why these marks are not Rockwell!

What really puzzles me, then, is what could possibly be the origin of these marks on more than one coin? They are virtually identical!

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 Posted 08/11/2015  7:30 pm  Show Profile   Bookmark this reply Add Pete2226 to your friends list Get a Link to this Reply
I found this statement in a description of how the Royal Canadian Mint processes strips to be punched into planchets. I would assume a similar process in the US Mint.


Quote:
The flattened strip emerging from the strip leveler is gripped by the blanking press feed rolls and passed through the machine where the blanks are cut by punches moving up and down synchronous with the forward movement of the strip.


I am wondering how the flattened strip is gripped by the blanking press feed rolls? Might it be possible for these kind of marks to made there? Or made even somewhere else in the process?
Pillar of the Community
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3124 Posts
 Posted 08/11/2015  7:38 pm  Show Profile   Bookmark this reply Add Pete2226 to your friends list Get a Link to this Reply
I have also found this punched planchet strip image which contains some marks which might be similar to the ones in question. Unfortunately, it is too blurry to tell for sure and also it is 95% copper. However the principle should be the same for a zinc strip (?)

https://www.davidlawrence.com/produ...83-x-128mm-/

Still doesn't prove anything!! Just tantalizing food for thought!
Valued Member
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134 Posts
 Posted 08/11/2015  8:15 pm  Show Profile   Bookmark this reply Add SheltieGuy1966 to your friends list Get a Link to this Reply
As a relatively new collector and coin roll hunter, if I pulled a coin like that from a roll I would immediately think "Struck Through". But then there is struck through what? It would have to be something commonly found at the mint if it is occurring on multiple coins. My first thought was a small ball bearing that had fallen from some working part of the machinery. But then I realized how small it would have to be to fit between the columns of the memorial ...I've never seen a ball bearing that small. Anyway, through the eyes of a 50 year old child ...struck through something round. ?
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 Posted 08/11/2015  9:42 pm  Show Profile   Bookmark this reply Add Pete2226 to your friends list Get a Link to this Reply

Quote:
...I've never seen a ball bearing that small. Anyway, through the eyes of a 50 year old child ...struck through something round. ?


The similarity - almost congruence of these depressions - on two different coins do suggest to me that this was something that happened at the mint. I am having difficulty in thinking that a PMD event could leave such similar impressions!

Valued Member
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134 Posts
 Posted 08/11/2015  9:55 pm  Show Profile   Bookmark this reply Add SheltieGuy1966 to your friends list Get a Link to this Reply
If it were PMD the displaced metal would be there somewhere. It would not mysteriously vanish into thin air. Definitely happened during the strike or pre-strike.
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 Posted 08/11/2015  9:59 pm  Show Profile   Bookmark this reply Add cwb to your friends list Get a Link to this Reply
I would also like to learn more on this subject. Are the impressions all the same or close to the same distance from the edge of the coins?
Are there any machines that are commonly used that would create dents like these? Maybe coin machines at a bank, casino, vending machines, or even something at the mint after the coins are struck?
What does the floor look like at the mint? Could these be coins that were dropped then stepped on creating the dents? I know that is a far fetched theory but maybe if we think of all the possible ways this could happen, we will come up with the correct answer.
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