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CONECA (pronounced: CŌ´NECA) is a national numismatic organization devoted to the education of error and variety coin collectors. CONECA focuses on many error and variety specialties, including doubled dies, Repunched mintmarks, multiple errors, clips, double strikes, off-metals and off-centers—just to name a few. In addition to its website, CONECA publishes an educational journal, The Errorscope, which is printed and mailed to members bimonthly. CONECA offers a lending library, examination, listing and attribution services; it holds annual meetings at major conventions (referred to as Errorama) around the country.

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The size of incomplete planchets..

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  • The size of incomplete planchets..

    Is there an easy way to calculate exactly how much of a coin is missing, in %?

  • #2
    Sure, weigh it to the nearest tenth of a gram and see how much is missing relative to a coin of normal weight.
    Mike Diamond. Error coin writer and researcher.

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    • #3
      Thank you.

      Is there other ways to calculate it or is weight the way to go?
      I`m thinking slabbed coins for example could be hard to weigh
      like that. And coins you have pics of, but you dont have the
      coin itself.

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      • #4
        You're never going to get an accurate percentage weight loss from a photo or from inside a slab. Metal expands under the force of the strike, and this often reduces the size of the original clip. Inaccuracy is greatest when the coin is struck out-of-collar, when there are multiple clips involved, when the clip is extremely small or extremely large, or when the clip is irregular.
        Mike Diamond. Error coin writer and researcher.

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        • #5
          Ok, thanks, had a feeling it could be hard to get done but started wondering if there could be some math formula to figure it out with.

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          • #6
            Try this: To find the area of a curved clip, use the following formula: pi X w X d / 4 with w = maximum width and d = diameter.

            All I'm saying is that any answer you get provides precision without accuracy.
            Mike Diamond. Error coin writer and researcher.

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            • #7
              Originally posted by diamond View Post
              Try this: To find the area of a curved clip, use the following formula: pi X w X d / 4 with w = maximum width and d = diameter.

              All I'm saying is that any answer you get provides precision without accuracy.
              I've been wondering about this for a long time Mike and now wish I hadn't failed basic Algebra!
              Lee Lydston

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