1964 Kennedy Error ????

Discussion in 'Coin Chat' started by Marine1, Jan 27, 2017.

  1. mynamespat

    mynamespat Well-Known Member

    Cool backstory! Personally, I think that is neater than the coin in question (whether it turns out to be an error or not).
     
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  3. mynamespat

    mynamespat Well-Known Member

    You realize the mark in question is raised, not incuse, right?
     
  4. Insider

    Insider Talent on loan from...

    :facepalm: As the OP said:
    So if that's what made the mark, what piece used to make coins do you think was tested to produce a raised round mark on the coin?

    And I just changed my mind! The mark is NOT perfectly round so I'll say occluded gas + heat.
     
  5. mynamespat

    mynamespat Well-Known Member

    I don't even really have an opinion without better pics. I just feel it's safe to say it is not a hardness test mark on the die. From my understanding the hardness tests performed on dies in operation were done with tools more closely resembling the Mohs hardness test tools:
    [​IMG]
    Tests were performed on places in the design where a single divot would not be noticeable/blend-in with the surrounding features. It is a quick simple go/no-go test to ensure that the hardness still rests within the given tolerances as layers are polished off. Hence why I used the 1921 16/17 berry as an example.

    I guess it's always possible a die that utterly failed the Rockwell Test was still put into operation to produce the coin like above. I just think that it is highly unlikely and if it were the case there would be at least another handful of examples making it highly research-able.
     
  6. davidh

    davidh soloist gnomic

    I'm nowhere near an expert but to me the whole coin looks kind of funky. The ear, hair, fields, cheek near the mouth, hair near the lettering, etc.

    [​IMG]
     
  7. Insider

    Insider Talent on loan from...

    If memory serves (35 - 40 years ago) the mint used a piece of equipment like a very large seal press mounted about eye level. In any case, they did not use the tiny little "toys" you imaged!
     
  8. Paddy54

    Paddy54 Well-Known Member

    Due to the coins history and background add to that it has a strange look to it......I'm in the Chinese fake camp.
     
    TIF likes this.
  9. mynamespat

    mynamespat Well-Known Member

    You are correct as far as the tool used to test planchets and dies before operation would be this (or a more measuring intensive version from before the digital age):
    [​IMG]
    but you are completely off-base calling a simpler precision measuring instrument a "toy". I also said RESEMBLES because in a working machine shop these tools can easily be created by a toolmaster; however, a precision set-up will easily cost over $100 (getting even more expensive when you get into auto-punches and the like). I picked that photo in particular (which is actually a higher-grade gem/stone test kit) because of the shape of the tips compared to that of a Rockwell tester.

    One of the first things you learn in high volume machining is you don't use the $10k tool to do something that can be done more quickly with a tool at hand and satisfy the requirements to continue manufacturing. The two cardinal sins of machining are making bad parts and not making parts at all.
     
  10. Pickin and Grinin

    Pickin and Grinin Well-Known Member

    Some thing I found on Wexlers site
    Rockwell Hardness Test Marks
    On Lincoln Cents


    By Pete Apple

    The correct degree of hardness is a critical factor in the minting of coins. If an unstruck planchet is too hard the image pressed on the coin will not be clear. If it’s too soft, the coin will wear too quickly. The U S Mint uses a Rockwell Hardness Test on all raw coin material (including copper- plated zinc blanks). (US Mint, E-mail 8/24/2015, Diamond, 2006, Page 16).

    The test procedure involves pressing a 1/16” metal ball into the coin material with a known amount of pressure and measuring the depth of penetration. There are other Rockwell Scale Protocols for harder materials where either a different sized ball or a spheroconical diamond is used to make the indentation. The Scale Protocol currently used for coin material involves the lightest pressure that can be used by a Rockwell tester.

    This same source shows an image (shown beloSw with permission) of an alleged Rockwell Test Mark in planchet on a 1971- Lincoln Cent.

    [​IMG]Figure 1

    Read the full storyHERE
     
    green18 likes this.
  11. Insider

    Insider Talent on loan from...

    I know about these. I was told they tested the DIES also.
     
  12. Marine1

    Marine1 Active Member

    There is a die error that can cause this, " Die hole" rare but possible. A X Ray diffraction test is being done by a metallurgist this Friday to determine if the coin is fake and if the dimple is solid or hollow. I conducted a micro gauss test with a pin magnet and if it were hollow an anomaly would have registered which it did not So I am convinced the coin #1 is real and not cast and #2 the dimple was caused by a die with a hole in it however Ill know for sure Fri.PM
    M1
     
    paddyman98 likes this.
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