Grade this New Walker Pickup

Discussion in 'US Coins Forum' started by physics-fan3.14, Oct 18, 2010.

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  1. GDJMSP

    GDJMSP Numismatist Moderator

    The process is documented, that's how I found out about it. But you will find very few references to it. I had to search and search through many old books, old copies of The Numismatist, and old copies of the ANS Numismatic Notes and Monographs to find where the technique is documented.

    And Mike, I don't think those lines on the pics you posted are die polish lines.

    ldhair - if a die is still in the press the most that is ever done to it is that it is wiped off with a cloth or rag because that's about all that can be done to it while in the press. And while a cloth or rag may produce very fine hairlines in the surface of the die, it cannot produce anything even remotely like die polish lines. The die steel is just too hard. And those fine hairlines would be wiped out by metal flow in short order because they would be so shallow.
     
    GDJMSP, Oct 21, 2010
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  3. Leadfoot

    Leadfoot there is no spoon

    Thanks for the references.

    If they are not die polish, what are they?

    They are raised. They go right up to the edge of the devices and do not extend into the devices. The only conclusion I can fathom is that they are die polish lines.
     
    Leadfoot, Oct 21, 2010
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  4. rlm's cents

    rlm's cents Numismatist

    I have no idea your background, but I have some minor amount in polishing things. Believe me when I say you do not polish things with anything that coarse. Those look more like file marks. Files do not polish. But that does not help me determine what it is.
     
    rlm's cents, Oct 21, 2010
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  5. Duke Kavanaugh

    Duke Kavanaugh The Big Coin Hunter

    Do you think that the steel would be softer after it coined many coins then the press operator took the worn die out to polish it? I'm just thinking that it being worn would make it softer plus if it's still warm from the striking, maybe?
     
    Duke Kavanaugh, Oct 21, 2010
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  6. Leadfoot

    Leadfoot there is no spoon

    I'm a engineer/scientist by schooling, and a salesman by vocation.

    I suspect both polishing and filing are part of the die refreshing procedure, with filing first and polishing second, and the result being called "die polish lines" -- but really I'm not sure. That's part of why I asked the question ATS. :)
     
    Leadfoot, Oct 21, 2010
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  7. Lehigh96

    Lehigh96 Toning Enthusiast

    Actually, the exact opposite would occur. The coining process would cause an effect known as work hardening (strain hardening) whereby plastic deformation increases the number of dislocations in the crystal structure. This process increases strength and hardness and lowers ductility.
     
    Lehigh96, Oct 21, 2010
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  8. ldhair

    ldhair Clean Supporter

    That is correct.
     
    ldhair, Oct 21, 2010
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  9. richarrb

    richarrb Junior Member

    Just shooting from the hip on this question. What if the zinc plate was not properly secured and it wobbled? Does the mint use different sized polishing plates for different sized coins? Like I said just coming up with different ideas.
     
    richarrb, Oct 21, 2010
    #48 + Quote Reply
  10. rlm's cents

    rlm's cents Numismatist

    Wobble would make no difference. The problem with assigning those marks to any mechanical anything is that the lines would be both parallel and straight (or in a smooth arc). Those lines are not parallel, and not straight (or on a uniform arc). In stead, they are in random and erratic angles to each other and they are in parabolic arcs. That has to mean they were done by hand.
     
    rlm's cents, Oct 21, 2010
    #49 + Quote Reply
  11. Leadfoot

    Leadfoot there is no spoon

    Or hand application of a rotational plate that deforms.
     
    Leadfoot, Oct 22, 2010
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  12. tdec1000

    tdec1000 Coin Rich, Money Poor :D

    I used to own a 1941 S in MS66 that had the same luster and strike, except I don't think it was so much a matter of weak strikes rather it be a die that was overworked and overpolished.
     
    tdec1000, Oct 22, 2010
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  13. rlm's cents

    rlm's cents Numismatist

    Deforms on nearly every revolution? Does not make sense to me.

    Here is an interesting quote from a CU reference on your earlier post. http://www.allbusiness.com/economy-economic-indicators/money-currencies/11713589-1.html
     
    rlm's cents, Oct 22, 2010
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  14. GDJMSP

    GDJMSP Numismatist Moderator

    That diamond paste, it's placed on the zinc plates. It is mentioned several times in the articles. It is also mentioned that they use different grits for business strike and Proof dies - as one would expect them to do.

    And Dick, I agree that whatever caused those lines on the coin linked by Mike absolutely had to be caused by hand. But what does not make sense is that they only cover small portions of the coin so equally small portions of the die had to be affected. That is assuming they were all on the die.

    My point here is this - take any cent, put your index finger on it. Now how much of that coin is covered by your finger ? Now imagine moving your finger around a sif you were trying to polish it. How much more of the coin would then be affected ?

    We have to think of all these things when talk about what caused this or what caused that. It is all too easy to make assumptions and think that any lines on a coin were cause dby this or that just because we read about it once. And yes, even the experts do that.
     
    GDJMSP, Oct 22, 2010
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  15. Lehigh96

    Lehigh96 Toning Enthusiast

    So how do we explain the die polish lines on this Jefferson Nickel? They go in different directions and they are on the devices!

    [​IMG]
    [​IMG]

    The lines on Jefferson's coat are most certainly raised and look exactly like die polish lines to me.
     
    Lehigh96, Nov 4, 2010
    #54 + Quote Reply
  16. rlm's cents

    rlm's cents Numismatist

    I do not think those lines on the coat are the same as on the fields. The lines in the fields are similar/the same as the lines we have been talking about. However, the lines on Tom's coat are less abrupt and not all of them even look raised. As for a cause, I have no good answers. The only thing I have not been able to totally rule out are grease and inherent in the planchet and I would be very hard pressed to explain either.
     
    rlm's cents, Nov 4, 2010
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  17. mpcusa

    mpcusa "Official C.T. TROLL SWEEPER"

    What ever the case maybe die-polish lines or cleaned it,s still a very attractive coin :)
     
    mpcusa, Nov 4, 2010
    #56 + Quote Reply
  18. GDJMSP

    GDJMSP Numismatist Moderator


    As I have explained many times, you CANNOT have die polish lines on the devices - ever ! It is a physical impossibility.
     
    GDJMSP, Nov 4, 2010
    #57 + Quote Reply
  19. Lehigh96

    Lehigh96 Toning Enthusiast

    Doug,

    With all due respect you also explained that die polish lines can't go in different directions but we have seen evidence to the contrary. At this point, it seems logical to conclude that the mint used some other method in addition to the zinc plates when polishing dies. Based on the visual evidence, that method was most likely a hand held method capable of reaching the recessed devices of the dies.

    If those raised lines of Jeff's coat are not die polish lines, then what are they? If they are not raised lines, there is no way PCGS would assign the lofty grade of MS66 to that coin. The grade is evidence that PCGS believes that the lines were a result of a mint process and not PMD. To my knowledge, the only mint process that causes lines like that is die polishing.
     
    Lehigh96, Nov 4, 2010
    #58 + Quote Reply
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  20. ldhair

    ldhair Clean Supporter

    I thought the zinc disk is called a basining disk and was used to make large coins strike up better.
     
    ldhair, Nov 4, 2010
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  21. GDJMSP

    GDJMSP Numismatist Moderator

    Basining has two very different definitions. 1 - simply means polishing. 2 - is where the center of the die (for some large coins) is actually ground down making the face of the die somewhat concave in the center, but only very slightly. This makes the coin turn out thinner around the outer edges than it is towards the center. And because the outter edges of the die are the highest point of a basined die they push more metal into towards the center of the coin to fill the recesses of the devices.

    Now I don't know what exactly was used to grind down the central high points, or fields, of the die. But rather obviously it had to be something that was slightly convex. I would imagine they made a special tool just for doing this. And rather obviously that tool would have to have the ability to grind down the metal of the die and yet leave it as highly polished as the rest of the field areas on the coin. But yet not reach into the devices or recesses of the die and thus mess up the design.

    Now the evidence of what I am saying being true is the coins themselves. For I am saying was not true then every Morgan dollar there is would have raised lines running all over the central devices. But yet they don't. So what I am saying must therefore be true.

    And Paul, you are merely making assumptions. There are several other ways that the interior of the recess in a die could get marked like that. The most obvious of course is a tool mark. And given the countless examples of coins with die polish lines, where those lines stop at each and every device, letter, or numeral there is on a coin, and then pick back up on the other side and continue on - to even think that raised lines on the devices could be caused by die polishing is - well it's just foolish. It's somebody reaching for a way to explain something they don't understand.
     
    GDJMSP, Nov 4, 2010
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