Loading ...
Sorry, an error occurred while loading the content.

Ridges on zinc cents

Expand Messages
  • Mike Diamond
    The latest Coin World (2/14/05) has an article on the frequently encountered ridges that parallel the rim in zinc cent (see Collector s Clearinghouse).
    Message 1 of 17 , Feb 4, 2005
    • 0 Attachment
      The latest Coin World (2/14/05) has an article on the frequently
      encountered ridges that parallel the rim in zinc cent (see
      Collector's Clearinghouse). Several hypotheses are presented. I am
      quite sure it's an unusual form of die fatigue or die deformation
      related to the material properties of zinc and the peculiar stresses
      it generates in the die face. For what it's worth, both the Mint and
      Arnie Margolis have also concluded that it's caused by die wear.

      Several other hypotheses are presented, but these are easily
      falsified. It's clear they are not bubbles beneath the copper
      plating, as they fail the "flex test". Copper plating is very thin
      and any bubbles this large should buckle with the slightest
      pressure. If, while looking through a microscope, you apply gentle
      pressure to any of these ridges with the tip of a toothpick, you'll
      see that they do not flex at all. They're solid throughout.

      The idea that the ridges are related to too tight a fit between die
      neck and collar is also easily falsified. Well-developed ridges can
      be seen in broadstrikes and off-center strikes.

      The notion that the metal experiences some kind of rebound effect
      upon withdrawal of the hammer die is not credible. Metal just does
      not behave this way. While heat warping does occasionally occur in
      some errors (e.g. reverse die caps; broadstrikes with full
      brockages), the affected metal is always very thin. A full-thickness
      zinc cent struck in-collar is far too thick, and besides, heat
      warping affects both faces. A rebound also fails to account for the
      manner in which peripheral elements are "swallowed up" by the ridge.

      Eric Von Klinger does report ridge development in some early die
      state cents. I have not seen this myself, but if his reports are
      accurate, this would indicate that the deformation can develop
      surprisingly quickly.
    • Grimaldon@yahoo.com
      Mike, I just had a thought about the ridges on zinc cents and thought you might like to hear it. Could those ridges be due, indirectly, to compression waves
      Message 2 of 17 , Feb 7, 2005
      • 0 Attachment
        Mike,

        I just had a thought about the ridges on zinc cents and thought you
        might like to hear it. Could those ridges be due, indirectly, to
        compression waves in the milling when the edges are turned up?

        When sufficient force is applied to metal to deform it, in front of
        the primary deformation compression waves form. (Like if you slide on
        a rug, the rug crumples up in front of your moving foot.) This all
        depends on the properties of the metal in question, but during the
        process of turning up the edges I would think it possible that a small
        compression wave might appear on the planchet just inside the rim.
        This would be pressed out in the minting chamber but would cause extra
        force on the die face along that wave. Over time the die face would
        then wear more along that line and allow a portion of the compression
        wave to remain after minting.

        What do you think, possible?

        Kevin


        --- In errorcoininformationexchange@yahoogroups.com, "Mike Diamond"
        <mdia1@a...> wrote:
        >
        > The latest Coin World (2/14/05) has an article on the frequently
        > encountered ridges that parallel the rim in zinc cent (see
        > Collector's Clearinghouse). Several hypotheses are presented. I am
        > quite sure it's an unusual form of die fatigue or die deformation
        > related to the material properties of zinc and the peculiar stresses
        > it generates in the die face. For what it's worth, both the Mint and
        > Arnie Margolis have also concluded that it's caused by die wear.
        >
        > Several other hypotheses are presented, but these are easily
        > falsified. It's clear they are not bubbles beneath the copper
        > plating, as they fail the "flex test". Copper plating is very thin
        > and any bubbles this large should buckle with the slightest
        > pressure. If, while looking through a microscope, you apply gentle
        > pressure to any of these ridges with the tip of a toothpick, you'll
        > see that they do not flex at all. They're solid throughout.
        >
        > The idea that the ridges are related to too tight a fit between die
        > neck and collar is also easily falsified. Well-developed ridges can
        > be seen in broadstrikes and off-center strikes.
        >
        > The notion that the metal experiences some kind of rebound effect
        > upon withdrawal of the hammer die is not credible. Metal just does
        > not behave this way. While heat warping does occasionally occur in
        > some errors (e.g. reverse die caps; broadstrikes with full
        > brockages), the affected metal is always very thin. A full-thickness
        > zinc cent struck in-collar is far too thick, and besides, heat
        > warping affects both faces. A rebound also fails to account for the
        > manner in which peripheral elements are "swallowed up" by the ridge.
        >
        > Eric Von Klinger does report ridge development in some early die
        > state cents. I have not seen this myself, but if his reports are
        > accurate, this would indicate that the deformation can develop
        > surprisingly quickly.
      • Mike Diamond
        ... Do compression waves even form in metal? Does the structure of metal permit this to happen? ... on ... small ... extra ... compression ... Again, I m
        Message 3 of 17 , Feb 7, 2005
        • 0 Attachment
          --- In errorcoininformationexchange@yahoogroups.com, Grimaldon@y...
          wrote:
          >
          > Mike,
          >
          > I just had a thought about the ridges on zinc cents and thought you
          > might like to hear it. Could those ridges be due, indirectly, to
          > compression waves in the milling when the edges are turned up?

          Do "compression waves" even form in metal? Does the structure of
          metal permit this to happen?

          > When sufficient force is applied to metal to deform it, in front of
          > the primary deformation compression waves form. (Like if you slide
          on
          > a rug, the rug crumples up in front of your moving foot.) This all
          > depends on the properties of the metal in question, but during the
          > process of turning up the edges I would think it possible that a
          small
          > compression wave might appear on the planchet just inside the rim.
          > This would be pressed out in the minting chamber but would cause
          extra
          > force on the die face along that wave. Over time the die face would
          > then wear more along that line and allow a portion of the
          compression
          > wave to remain after minting.
          >
          > What do you think, possible?

          Again, I'm not a metallurgist, so I don't have any familiarity with
          the concept of compression waves in metals. I would wonder why the
          same effect doesn't develop with other metals and alloys.

          Something is causing profound, and possibly rapid deformation.
          Oddly, this sort of deformation has not been reported in zinc coins
          from other countries. Perhaps there's a unique interaction between
          zinc's material properties, the hardness of the die, the force of the
          strike, and the velocity of the strike.
        • Kevin L. Stewart
          ... I m sure some metals have this ridges from force being applied. Try to find a coin struck on its edge and look to see if there are any ridges paralleling
          Message 4 of 17 , Feb 7, 2005
          • 0 Attachment
            --- Mike Diamond <mdia1@...> wrote:

            >
            > --- In errorcoininformationexchange@yahoogroups.com, Grimaldon@y...
            > wrote:
            > >
            > > Mike,
            > >
            > > I just had a thought about the ridges on zinc cents and thought you
            > > might like to hear it. Could those ridges be due, indirectly, to
            > > compression waves in the milling when the edges are turned up?
            >
            > Do "compression waves" even form in metal? Does the structure of
            > metal permit this to happen?

            I'm sure some metals have this ridges from force being applied. Try to find a
            coin struck on its edge and look to see if there are any ridges paralleling the
            impact. Another test would be to take a worthless zinc penny, put it in a vice
            and hit it with a hammer to see if it forms waves.

            >
            > > When sufficient force is applied to metal to deform it, in front of
            > > the primary deformation compression waves form. (Like if you slide
            > on
            > > a rug, the rug crumples up in front of your moving foot.) This all
            > > depends on the properties of the metal in question, but during the
            > > process of turning up the edges I would think it possible that a
            > small
            > > compression wave might appear on the planchet just inside the rim.
            > > This would be pressed out in the minting chamber but would cause
            > extra
            > > force on the die face along that wave. Over time the die face would
            > > then wear more along that line and allow a portion of the
            > compression
            > > wave to remain after minting.
            > >
            > > What do you think, possible?
            >
            > Again, I'm not a metallurgist, so I don't have any familiarity with
            > the concept of compression waves in metals. I would wonder why the
            > same effect doesn't develop with other metals and alloys.
            >
            > Something is causing profound, and possibly rapid deformation.
            > Oddly, this sort of deformation has not been reported in zinc coins
            > from other countries. Perhaps there's a unique interaction between
            > zinc's material properties, the hardness of the die, the force of the
            > strike, and the velocity of the strike.

            I'm not sure about other countries. Do they have turned up rims on their zinc
            coins like these pennies? I THINK I've seen similary ridges inside the rims of
            quarters too. I would think the amount of wave would be a function of the
            metal maliablity(sp?), the coin diameter vs. thickness and the amount of
            turning up of the rim. Anyway, it's all speculation on my part. Anyone have a
            picture of a zinc planchet?

            Kevin




            __________________________________
            Do you Yahoo!?
            Take Yahoo! Mail with you! Get it on your mobile phone.
            http://mobile.yahoo.com/maildemo
          • Mike Diamond
            ... Why such certainty? This does not seem obvious to me. ... paralleling the ... On edge strikes and saddle strikes, all you get is bulging of the metal
            Message 5 of 17 , Feb 8, 2005
            • 0 Attachment
              --- In errorcoininformationexchange@yahoogroups.com, "Kevin L.
              Stewart" <Grimaldon@y...> wrote:

              > I'm sure some metals have this ridges from force being applied.

              Why such certainty? This does not seem obvious to me.

              > Try to find a
              > coin struck on its edge and look to see if there are any ridges
              paralleling the
              > impact.

              On edge strikes and saddle strikes, all you get is bulging of the
              metal right next to the site of impact, strictly as the result of
              compressive forces acting parallel to the plane of the planchet.
              There are no ripples, waves, or ridges.

              The closest thing in appearance to what you're suggesting
              are "expansion ripples" seen in a small percentage of capped die
              strikes. In these errors you do have one or two sets of ripples
              emanating from large, central design elements, e.g., busts. However,
              I do not really know what causes them.

              In cases of progressive, indirect design transfer, the design of one
              die is slowly transferred to the opposite die through the medium of
              hundreds of thousands of planchets. It kind of looks like a "wavy"
              design. But this is simply a sub-category of die deterioration.

              > Another test would be to take a worthless zinc penny, put it in a
              vice
              > and hit it with a hammer to see if it forms waves.

              Considering that edge strikes show no ripples, I doubt this will
              yield results.

              I don't see how any ripples can form as the result of a die's impact,
              since the pressure of the die face itself will completely damp the
              formation of even an incipient ripple.

              > I'm not sure about other countries. Do they have turned up rims on
              their zinc
              > coins like these pennies?

              They have a design rim, just like our coins.

              > I THINK I've seen similary ridges inside the rims of
              > quarters too.

              Narrower "ridge rings" can be found on other denominations. I've
              seen them most often on half dollars. They appear to be due simply
              to die deterioration.

              > I would think the amount of wave would be a function of the
              > metal maliablity(sp?), the coin diameter vs. thickness and the
              amount of
              > turning up of the rim. Anyway, it's all speculation on my part.
              Anyone have a
              > picture of a zinc planchet?

              As you say, this is all speculation. We haven't even established
              that "waves" can even form in metal. A zinc planchet looks like any
              other planchet.
            • Kevin L. Stewart
              ... Why such certainty, because I have seen it in metals outside the coin world. It s just physics at work. In fact, I still where my highschool class ring
              Message 6 of 17 , Feb 8, 2005
              • 0 Attachment
                --- Mike Diamond <mdia1@...> wrote:

                >
                > --- In errorcoininformationexchange@yahoogroups.com, "Kevin L.
                > Stewart" <Grimaldon@y...> wrote:
                >
                > > I'm sure some metals have this ridges from force being applied.
                >
                > Why such certainty? This does not seem obvious to me.
                >

                Why such certainty, because I have seen it in metals outside the coin world.
                It's just physics at work. In fact, I still where my highschool class ring and
                I once accidentally flung it into the sidewalk. To this day I can see ripples
                and bulges nearly a quarter of an inch in from the point of impact. When you
                apply enough force to metal it moves. It wants to move in the direction of the
                force but if something is there to stop it then the metal will turn away from
                the force, this causes the turned up edges. But in this case the something
                there that stops the metal from moving is also metal and by stopping the rim
                metal it has force applied to it to. This would then mean that it too would
                want to move (if it was soft enough compared to the force applied). And since
                it too is prevented from moving in the direction of the force, it will instead
                move outward into bulges.

                > I don't see how any ripples can form as the result of a die's impact,
                > since the pressure of the die face itself will completely damp the
                > formation of even an incipient ripple.

                I didn't say the die would cause the ripples, I said the upsetting mill might
                cause them and then cause the die be affected. The force of the mill would be
                applied to the sides of the blank, most of which would cause the rim to be
                turned up but some small percentage would be absorbed by the blank and form a
                secondary ridge/bulge inside the rim of the planchet, theorectially. If so,
                this would make the planchet thicher there and cause disproportionate force on
                the die face along that ridge.

                > As you say, this is all speculation. We haven't even established
                > that "waves" can even form in metal. A zinc planchet looks like any
                > other planchet.
                >

                I was wondering about the zinc planchet because it might confirm or disprove
                what I'm saying. If you see no zinc planchets with secondary ridges then we'll
                know I'm wrong (or at least highly improbably) and that the ultimate cause of
                the ridges on the coins must purely be a minting phenomena. But if you see
                zinc planchets with ridges inside, then that will confirm what I am saying is
                possible. For that matter, seeing a similar ridge on any planchet with an
                upturned rim would confirm it as at least possible.

                Kevin


                __________________________________________________
                Do You Yahoo!?
                Tired of spam? Yahoo! Mail has the best spam protection around
                http://mail.yahoo.com
              • Mike Diamond
                ... coin world. ... class ring and ... see ripples ... That must have been some impact! ... mill might ... Ah, I completely misunderstood your original post,
                Message 7 of 17 , Feb 8, 2005
                • 0 Attachment
                  --- In errorcoininformationexchange@yahoogroups.com, "Kevin L.
                  Stewart" <Grimaldon@y...> wrote:

                  > Why such certainty, because I have seen it in metals outside the
                  coin world.
                  > It's just physics at work. In fact, I still wear my highschool
                  class ring and
                  > I once accidentally flung it into the sidewalk. To this day I can
                  see ripples
                  > and bulges nearly a quarter of an inch in from the point of impact.

                  That must have been some impact!

                  > I didn't say the die would cause the ripples, I said the upsetting
                  mill might
                  > cause them and then cause the die be affected.

                  Ah, I completely misunderstood your original post, then. Thanks for
                  clarifying

                  > The force of the mill would be
                  > applied to the sides of the blank, most of which would cause the
                  rim to be
                  > turned up but some small percentage would be absorbed by the blank
                  and form a
                  > secondary ridge/bulge inside the rim of the planchet,
                  theorectially. If so,
                  > this would make the planchet thicher there and cause
                  disproportionate force on
                  > the die face along that ridge.
                  >
                  > I was wondering about the zinc planchet because it might confirm or
                  disprove
                  > what I'm saying. If you see no zinc planchets with secondary
                  ridges then we'll
                  > know I'm wrong (or at least highly improbably) and that the
                  ultimate cause of
                  > the ridges on the coins must purely be a minting phenomena. But if
                  you see
                  > zinc planchets with ridges inside, then that will confirm what I am
                  saying is
                  > possible. For that matter, seeing a similar ridge on any planchet
                  with an
                  > upturned rim would confirm it as at least possible.

                  I have personally inspected only a handful of unstruck zinc planchets
                  (both plated and unplated). All showed only the expected upset rim
                  (a.k.a. "proto-rim"). There were no secondary ridges internal to
                  that. I have, however, inspected untold numbers of off-center zinc
                  cents. The unstruck portion of the planchet only shows the normal
                  upset rim. I have never seen secondary ridges, waves, or ripples on
                  any off-center coin or unstruck planchet I've inspected. This is
                  true of even strongly upset planchets (the extent up upset varies).
                  So it appears that your hypothesis has been "upset" (awful pun, I
                  know).

                  It was in interesting idea and I appreciate the thought you put into
                  it.
                • Kevin L. Stewart
                  I did a web search and MAY have found an image to back up what I am saying. It s at Ken Potter s website. The third planchet has appearant ridge in the upper
                  Message 8 of 17 , Feb 8, 2005
                  • 0 Attachment
                    I did a web search and MAY have found an image to back up what I am saying.
                    It's at Ken Potter's website. The third planchet has appearant ridge in the
                    upper left corner. Hard to tell from the pic for sure though.

                    http://koinpro.tripod.com/cgi-bin/Unplated.jpg

                    But looking at this following image another possibility crossed my mind.

                    http://iwork4coin.tripod.com/pics/qe004.jpg

                    Here the upturning is a broad raised area (a $.25 planchet). If that is normal
                    for pennies too then the there is more raised metal there than on the final
                    coin rim so when the coin is minted this extra raised metal has to be shoved
                    back into the body of the coin. This might cause extra force on the die just
                    inside of the rim and cause the wear you were suspecting. Alternately, the
                    extra metal might erode the die face as it is pushed back into the body of the
                    coin.

                    Just exploring possible causes for the die wear you hypothosized earlier.

                    Kevin


                    >
                    > I was wondering about the zinc planchet because it might confirm or disprove
                    > what I'm saying. If you see no zinc planchets with secondary ridges then
                    > we'll
                    > know I'm wrong (or at least highly improbably) and that the ultimate cause of
                    > the ridges on the coins must purely be a minting phenomena. But if you see
                    > zinc planchets with ridges inside, then that will confirm what I am saying is
                    > possible. For that matter, seeing a similar ridge on any planchet with an
                    > upturned rim would confirm it as at least possible.
                    >
                    > Kevin
                    >
                    >
                    > __________________________________________________
                    > Do You Yahoo!?
                    > Tired of spam? Yahoo! Mail has the best spam protection around
                    > http://mail.yahoo.com
                    >


                    __________________________________________________
                    Do You Yahoo!?
                    Tired of spam? Yahoo! Mail has the best spam protection around
                    http://mail.yahoo.com
                  • Kevin L. Stewart
                    Where are the pun police when you need them? bo} I know a lot about material science, but compared to you guys I know nothing about coins. So I can construct
                    Message 9 of 17 , Feb 8, 2005
                    • 0 Attachment
                      Where are the pun police when you need them? bo}

                      I know a lot about material science, but compared to you guys I know nothing
                      about coins. So I can construct some interesting hypotheses, but I have to
                      rely on your experience to know if anything I'm saying is realistic in this
                      domain. Thanks for at least giving my ideas consideration.

                      Kevin


                      --- Mike Diamond <mdia1@...> wrote:
                      >
                      > I have personally inspected only a handful of unstruck zinc planchets
                      > (both plated and unplated). All showed only the expected upset rim
                      > (a.k.a. "proto-rim"). There were no secondary ridges internal to
                      > that. I have, however, inspected untold numbers of off-center zinc
                      > cents. The unstruck portion of the planchet only shows the normal
                      > upset rim. I have never seen secondary ridges, waves, or ripples on
                      > any off-center coin or unstruck planchet I've inspected. This is
                      > true of even strongly upset planchets (the extent up upset varies).
                      > So it appears that your hypothesis has been "upset" (awful pun, I
                      > know).
                      >
                      > It was in interesting idea and I appreciate the thought you put into
                      > it.
                      >
                      >
                      >
                      >


                      __________________________________________________
                      Do You Yahoo!?
                      Tired of spam? Yahoo! Mail has the best spam protection around
                      http://mail.yahoo.com
                    • Mike Diamond
                      ... saying. ... ridge in the ... The image is too small to say. I rather doubt it. ... mind. ... that is normal ... the final ... be shoved ... the die just
                      Message 10 of 17 , Feb 8, 2005
                      • 0 Attachment
                        --- In errorcoininformationexchange@yahoogroups.com, "Kevin L.
                        Stewart" <Grimaldon@y...> wrote:
                        > I did a web search and MAY have found an image to back up what I am
                        saying.
                        > It's at Ken Potter's website. The third planchet has appearant
                        ridge in the
                        > upper left corner. Hard to tell from the pic for sure though.
                        >
                        > http://koinpro.tripod.com/cgi-bin/Unplated.jpg

                        The image is too small to say. I rather doubt it.
                        >
                        > But looking at this following image another possibility crossed my
                        mind.
                        >
                        > http://iwork4coin.tripod.com/pics/qe004.jpg
                        >
                        > Here the upturning is a broad raised area (a $.25 planchet). If
                        that is normal
                        > for pennies too then the there is more raised metal there than on
                        the final
                        > coin rim so when the coin is minted this extra raised metal has to
                        be shoved
                        > back into the body of the coin. This might cause extra force on
                        the die just
                        > inside of the rim and cause the wear you were suspecting.
                        Alternately, the
                        > extra metal might erode the die face as it is pushed back into the
                        body of the
                        > coin.
                        >
                        > Just exploring possible causes for the die wear you hypothosized
                        earlier.

                        You are probably right that the proto-rim of the planchet is
                        sometimes wider than the design rim of the finished coin. So some
                        metal from the inner part of the proto-rim would have to be pushed
                        laterally. Thing is, the "ridge ring" on zinc cents is often very
                        wide, much wider than the widest proto-rim. And there's often a
                        clear separation between the ridge ring and the design rim. So who
                        knows what's going on.
                        >
                        > Kevin
                      • Mike Diamond
                        ... know nothing ... have to ... in this ... We all acknowledge the value of the cross-fertilization that takes place when specialists in different disciplines
                        Message 11 of 17 , Feb 8, 2005
                        • 0 Attachment
                          --- In errorcoininformationexchange@yahoogroups.com, "Kevin L.
                          Stewart" <Grimaldon@y...> wrote:
                          > Where are the pun police when you need them? bo}
                          >
                          > I know a lot about material science, but compared to you guys I
                          know nothing
                          > about coins. So I can construct some interesting hypotheses, but I
                          have to
                          > rely on your experience to know if anything I'm saying is realistic
                          in this
                          > domain. Thanks for at least giving my ideas consideration.

                          We all acknowledge the value of the cross-fertilization that takes
                          place when specialists in different disciplines cooperate and share
                          their expertise. This hobby is a cooperative effort and I appreciate
                          your efforts tremendously.
                        • Kevin L. Stewart
                          If the extra metal of the proto-rim were moved laterally it would rub against the die face. With enough repetition this could erode the die face, potentially
                          Message 12 of 17 , Feb 8, 2005
                          • 0 Attachment
                            If the extra metal of the proto-rim were moved laterally it would rub against
                            the die face. With enough repetition this could erode the die face,
                            potentially to a much wider extent than the original proto-rim. Again, I think
                            your orginal idea is correct, just mentally exploring how it came to pass.

                            Kevin


                            --- Mike Diamond <mdia1@...> wrote:
                            > You are probably right that the proto-rim of the planchet is
                            > sometimes wider than the design rim of the finished coin. So some
                            > metal from the inner part of the proto-rim would have to be pushed
                            > laterally. Thing is, the "ridge ring" on zinc cents is often very
                            > wide, much wider than the widest proto-rim. And there's often a
                            > clear separation between the ridge ring and the design rim. So who
                            > knows what's going on.
                            >
                            >
                            >
                            >


                            __________________________________________________
                            Do You Yahoo!?
                            Tired of spam? Yahoo! Mail has the best spam protection around
                            http://mail.yahoo.com
                          • Mike Diamond
                            ... rub against ... Again, I think ... to pass. If this sort of erosion/deformation was going on, you d expect the internal border of the rim gutter to take
                            Message 13 of 17 , Feb 8, 2005
                            • 0 Attachment
                              --- In errorcoininformationexchange@yahoogroups.com, "Kevin L.
                              Stewart" <Grimaldon@y...> wrote:
                              > If the extra metal of the proto-rim were moved laterally it would
                              rub against
                              > the die face. With enough repetition this could erode the die face,
                              > potentially to a much wider extent than the original proto-rim.
                              Again, I think
                              > your orginal idea is correct, just mentally exploring how it came
                              to pass.

                              If this sort of erosion/deformation was going on, you'd expect the
                              internal border of the rim gutter to take the brunt of it. But the
                              junction between the field and rim appears only modestly affected.
                              The worst distortion occurs farther in.
                            • Kevin L. Stewart
                              Well, your no fun. BoP Got me then. Kevin ... __________________________________ Do you Yahoo!? Take Yahoo! Mail with you! Get it on your mobile phone.
                              Message 14 of 17 , Feb 8, 2005
                              • 0 Attachment
                                Well, your no fun. BoP Got me then.

                                Kevin


                                --- Mike Diamond <mdia1@...> wrote:

                                >
                                > --- In errorcoininformationexchange@yahoogroups.com, "Kevin L.
                                > Stewart" <Grimaldon@y...> wrote:
                                > > If the extra metal of the proto-rim were moved laterally it would
                                > rub against
                                > > the die face. With enough repetition this could erode the die face,
                                > > potentially to a much wider extent than the original proto-rim.
                                > Again, I think
                                > > your orginal idea is correct, just mentally exploring how it came
                                > to pass.
                                >
                                > If this sort of erosion/deformation was going on, you'd expect the
                                > internal border of the rim gutter to take the brunt of it. But the
                                > junction between the field and rim appears only modestly affected.
                                > The worst distortion occurs farther in.
                                >
                                >
                                >
                                >




                                __________________________________
                                Do you Yahoo!?
                                Take Yahoo! Mail with you! Get it on your mobile phone.
                                http://mobile.yahoo.com/maildemo
                              • Grimaldon@yahoo.com
                                Mike, I saw something the other day that caught my eye. I was looking at my pocket change and found a zinc cent that didn t have the raised ridges but did
                                Message 15 of 17 , Mar 1, 2005
                                • 0 Attachment
                                  Mike,

                                  I saw something the other day that caught my eye. I was looking at my
                                  pocket change and found a zinc cent that didn't have the raised ridges
                                  but did have some intense flow lines in the same place that the ridges
                                  would be. Could this be an early state in the formation of a die that
                                  would produce the ridges? I didn't notice any raising of the metal
                                  there, but the flow lines were quite pronounced. Just thought I'd
                                  share that incase it is another clue for you.

                                  Kevin


                                  --- In errorcoininformationexchange@yahoogroups.com, "Mike Diamond"
                                  <mdia1@a...> wrote:
                                  >
                                  > If this sort of erosion/deformation was going on, you'd expect the
                                  > internal border of the rim gutter to take the brunt of it. But the
                                  > junction between the field and rim appears only modestly affected.
                                  > The worst distortion occurs farther in.
                                • Mike Diamond
                                  I wouldn t be surprised if there was some association between flow lines and ridge formation, as they re both expressions of die fatigue. I ve place in the
                                  Message 16 of 17 , Mar 1, 2005
                                  • 0 Attachment
                                    I wouldn't be surprised if there was some association between flow
                                    lines and ridge formation, as they're both expressions of die
                                    fatigue. I've place in the Default Album an image of a 1990
                                    broadstruck cent with a wide ridge on the reverse. The metal in and
                                    around the ridge has a bit of an orange-peel texture, which is yet
                                    another expression of die fatigue.

                                    I don't think the association is a particularly tight one, as I've
                                    seen ridges in cents with no appreciable orange peel texture or flow
                                    lines. It seems that the ridges can develop rather rapidly in some
                                    circumstances.

                                    --- In errorcoininformationexchange@yahoogroups.com, Grimaldon@y...
                                    wrote:
                                    >
                                    > Mike,
                                    >
                                    > I saw something the other day that caught my eye. I was looking at
                                    my
                                    > pocket change and found a zinc cent that didn't have the raised
                                    ridges
                                    > but did have some intense flow lines in the same place that the
                                    ridges
                                    > would be. Could this be an early state in the formation of a die
                                    that
                                    > would produce the ridges? I didn't notice any raising of the metal
                                    > there, but the flow lines were quite pronounced. Just thought I'd
                                    > share that incase it is another clue for you.
                                    >
                                    > Kevin
                                  • Kevin L. Stewart
                                    Ok. I was just wondering if the flow lines might be a first step in the ridges forming and if so would that help you piece together why. Kevin ...
                                    Message 17 of 17 , Mar 1, 2005
                                    • 0 Attachment
                                      Ok. I was just wondering if the flow lines might be a first step in the ridges
                                      forming and if so would that help you piece together why.

                                      Kevin


                                      --- Mike Diamond <mdia1@...> wrote:
                                      >
                                      > I wouldn't be surprised if there was some association between flow
                                      > lines and ridge formation, as they're both expressions of die
                                      > fatigue. I've place in the Default Album an image of a 1990
                                      > broadstruck cent with a wide ridge on the reverse. The metal in and
                                      > around the ridge has a bit of an orange-peel texture, which is yet
                                      > another expression of die fatigue.
                                      >
                                      > I don't think the association is a particularly tight one, as I've
                                      > seen ridges in cents with no appreciable orange peel texture or flow
                                      > lines. It seems that the ridges can develop rather rapidly in some
                                      > circumstances.
                                      >



                                      __________________________________
                                      Do you Yahoo!?
                                      Take Yahoo! Mail with you! Get it on your mobile phone.
                                      http://mobile.yahoo.com/maildemo
                                    Your message has been successfully submitted and would be delivered to recipients shortly.