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 Replies: 19 / Views: 1,724 |
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Pillar of the Community
United States
978 Posts |
Right off the top - these crop circles are odd.... This one may help solve the mystery. There is more going on here than just rings, arc's and spirals. There appears to be evidence of design elements inside this ring on Lincoln's chest and left side of his head. Might be combination of over polishing and dropped die? More investigation of these UFO's is needed. https://www.error-ref.com/die-rings...and-spirals/https://doubleddie.com/2397300.html
"Definition: Tiny rings, semicircles, crescents, and spirals that usually appear in the center of the coin or nearby. Their origin is a mystery and it's likely that they have more than one cause."    "We are all flawed, some MD and some PMD." NYI Edited by NY Islander
09/29/2024 11:42 am
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Pillar of the Community
United States
1780 Posts |
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Moderator
 United States
56855 Posts |
 My theory is something to do with lathe lines. John1  |
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Pillar of the Community
 United States
978 Posts |
Don't think so John1. Lathe lines are very symmetrical in width, gap and depth. These are not.
"We are all flawed, some MD and some PMD." NYI |
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Pillar of the Community
United States
4395 Posts |
I don't believe this is a lathe line either, but I think this example is different from the WUFO/die rings.
1982-1983 cents commonly have spiraling and circular die polishing lines at the center of the coin (especially on the reverse). I think a rotating brush was used to polish dies in those years. I think this could just be an example of that, though an extreme one.
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Pillar of the Community
United States
1791 Posts |
At quick glance I thought maybe lathe lines but they would be symmetrical then. These are not.
Near the center when turning, the last 3/16" to the center can look very different than the rest of the face. This has to do with surface speed. The tool moves from the outer diameter toward the center at a given feed rate for a specific surface speed. The rpms of the spindle increase as this happens. At some point, the spindle reaches maximum rpm and so the surface speed decreases quite rapidly. Yet the feed rate stays for the programmed surface speed. Once the surface speed has decreased enough, a number of different things start happening such as tool deflection is no longer constant (tool bounces), metal tears rather than cuts, rubbing occurs because chips don't clear fast enough, etc. Surface speed at dead center is 0.
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Moderator
United States
94786 Posts |
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Bedrock of the Community
United States
73687 Posts |
Cool find! Errers and Varietys.
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Bedrock of the Community
United States
94367 Posts |
Interesting for sure. Can you sharpen that closeup?
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Bedrock of the Community
United States
10478 Posts |
Lathe lines are in the fields. Not sure what that is........  |
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Pillar of the Community
United States
3535 Posts |
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Pillar of the Community
United States
2731 Posts |
That texture around Lincoln is interesting, It would be nice to see some other photos there but I'm sure that is a tricky shot. It looks like the bottom of bay #7 is showing some partial concentric lines as well. Nice find NY.
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Pillar of the Community
United States
5770 Posts |
I like these "crop circles". Quote:
... This has to do with surface speed. The tool moves from the outer diameter toward the center at a given feed rate for a specific surface speed. The rpms of the spindle increase as this happens. At some point, the spindle reaches maximum rpm and so the surface speed decreases quite rapidly. Yet the feed rate stays for the programmed surface speed. Once the surface speed has decreased enough, a number of different things start happening such as tool deflection is no longer constant (tool bounces), metal tears rather than cuts, rubbing occurs because chips don't clear fast enough, etc... . This information is in relation to lathe lines correct, and not a die polishing tool? I wonder if these raised circular elements could be from polishing by a rotary tool going parallel to the surface of the die. Similar to the way it has been determined "Trail dies" are formed but having a circular look, instead of linear, when it occurs towards the center of the die. Words of encouragement are one of the major food groups.
We need to consume them regularly to thrive and grow.
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Moderator
United States
56855 Posts |
It would be great if we had a few mint technicians as members.They could answer a bunch of our questions. John1 |
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Pillar of the Community
United States
7505 Posts |
I agree with tanman, it make's a perfect sense.
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Pillar of the Community
United States
978 Posts |
This is about the best image I can get with my camera. The coin is not cooperating. LOL. Thanks for all the great feedback on this one. My vote is also with Tanman. Die polishing and either some slight PMD, and or other die damage.  "We are all flawed, some MD and some PMD." NYI Edited by NY Islander
09/30/2024 3:17 pm
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Replies: 19 / Views: 1,724 |
Posted 09/29/2024 11:40 am
