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Help indentifying cause of error
- Thread starter numidan
- Start date
I am happy to see that we are not the only ones puzzled. Numismatics research requires many experts in various fields and sad to say that there are very few machinists that fully understands the minting process participating in our forums. That is why I registered on your forum to ask for your help. Hope you are all okay with that!
Of course you are welcome here!
We love great pictures and a good mystery.
You make me want to run upstairs and check my nickels.......
-brino
First question, Are the 2 coins in the pics of the same year and from the same mint?
Every year is new dies to be able to change the date.
Just looking at coins for sale I can see small differences (other than the date) from year to year.
Every year is new dies to be able to change the date.
Just looking at coins for sale I can see small differences (other than the date) from year to year.
A story about toonie (Canadian two dollar coin) counterfeiting I had to see!
Our mint goes to great lengths with multiple technologies to dissuade this kind of fraud.
This coin has a outer ring and centre made of two different metals; not easy to copy.
Here's a direct link:
https://www.vancouverisawesome.com/vancouver-news/toonie-con-man-suspects-vancouver-1940156
Really? .....washers used to fill most of the coin roller is certainly NOT a complex heist.
I am surprised he got as far as $30,000.
-brino
Our mint goes to great lengths with multiple technologies to dissuade this kind of fraud.
This coin has a outer ring and centre made of two different metals; not easy to copy.
Here's a direct link:
https://www.vancouverisawesome.com/vancouver-news/toonie-con-man-suspects-vancouver-1940156
Really? .....washers used to fill most of the coin roller is certainly NOT a complex heist.
I am surprised he got as far as $30,000.
-brino
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Yes exchanging coin rolls for bills should have raised red flags quickly
The coin with the mystery lines appears to be a much sharper impression than the one without. Sharper impressions result in more localized deformation. In addition, note that the mystery lines all connect to an existing feature. Is it possible that these are cracks propagating from the existing lines due to high localized stresses and (perhaps) lower ductility of the blank? Microscopic examination would help.
I started thinking about this again the other night.
I dug up about 50 nickels and inspected them under the microscope.
None showed the same as the abnormal one above.
There were however some differences....
-most had light scratches that I assume are from normal circulation
-some had deeper marks, not sure the cause
-I believe there were at least three slightly different designs; mostly noticeable in the beaver tail
Unfortunately, I do NOT have a camera setup on that 'scope......
-brino
I dug up about 50 nickels and inspected them under the microscope.
None showed the same as the abnormal one above.
There were however some differences....
-most had light scratches that I assume are from normal circulation
-some had deeper marks, not sure the cause
-I believe there were at least three slightly different designs; mostly noticeable in the beaver tail
Unfortunately, I do NOT have a camera setup on that 'scope......
-brino
It was my impression the coin dies were hand engraved. My theory is that the die got damaged late in the production cycle and that a local repair was made to permit finishing the cycle prior to thr new year's coins. A repair would remove material from the die causing a raised area on the struck coin.
My 5¢ (CAD)/ 3.685¢(USD)
My 5¢ (CAD)/ 3.685¢(USD)
A few lifetimes ago when I visited the franklin mint, From what I remember, US coin dies are made by hand engraving a master, which is like 18 to 24 inches in diameter. Then they use a machine like a pantograph to make the actual size die. They can make many dies after the master. A damaged die would be simple to replace.
Sorry for late reply.
As soon I get them, I will post them!
http://www.error-ref.com/
Design is implemented on a Matrix. The Matrix is used the create the master punch (positive image). Some slight modifications can occur on the master punch. The master punch is then used to create several working dies (hubbing process). The working dies are polished and buffed before being used on the press to mint the coins. During the minting process, maintenance to the working die is done to prolong its life. Eventually the matrix, master punch, and working dies gets destroyed.
Based on rough measurement estimates, the width and height for parallel lines seems to be on average about 4 mils .
My question:
Therefore, do you think the tools available in 1992 were able to do such a repair and if yes, can you provide me with some reference of what you think could have been used?
Thanks everyone.
I am waiting for the close-up pictures to be taken but was told not to expect miracles
As soon I get them, I will post them!
If you are interested in understanding the many types of errors found on modern coins, this web site is the most complete offering good explanation on the various errors you will find. It is possible that designs are different from year to year but highly collectible and sought after when it is within the same year!
http://www.error-ref.com/
Agree but it depends on the damage. Here is a brief overview on minting process.
Design is implemented on a Matrix. The Matrix is used the create the master punch (positive image). Some slight modifications can occur on the master punch. The master punch is then used to create several working dies (hubbing process). The working dies are polished and buffed before being used on the press to mint the coins. During the minting process, maintenance to the working die is done to prolong its life. Eventually the matrix, master punch, and working dies gets destroyed.
This is most plausible cause of what happened.
Based on rough measurement estimates, the width and height for parallel lines seems to be on average about 4 mils .
My question:
Therefore, do you think the tools available in 1992 were able to do such a repair and if yes, can you provide me with some reference of what you think could have been used?
Thanks everyone.