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Measuring Die Rotation

5 posts in this topic

I have a set of coins I would like to document more than normal.

All of the coins are in slabs.

One of the factors I'd like to measure is the amount of die rotation to at least the nearest 5 degrees.

My 0 degree reference will be the obverse, i.e., the obverse will always be considered to have been struck perfectly vertical and it's the reverse that is the total cause of the rotation.


So using the slab itself as my starting 0 point I have two measurements to make:

1. Very often the obverse is not aligned perfectly in the slab so I need measure the rotation of the obverse with respect to the slab.

2. Then I need to flip it over and measure the rotation of the reverse with respect to the slab.


Then I can combine the two measurements to come up with the die rotation.

My first test demonstrated to me that this process is a LOT easier said than done


Since I'm starting with an upright obverse as my initial reference I need to know what "upright" is.

Here are two images of the obverse of my test coin.

#1 is oriented to the date (a line touching the top of the "1" and "7").



#2 is oriented to stars 1 and 13 (a line touching the bottom of those two stars).



The date orientation required a rotation of 15 degrees.

The stars orientation required a rotation of 7 degrees.


I know which one looks better to me BUT which one is correct per US Mint definition?

Or is there such a definition?



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I found this statement on a website about die rotations.

"a device designed to measure a coins rotation. There have been several made over the years but the only one currently available is called a "ROTA FLIP" by LEROY VAN ALLEN."


They sell one here at Brent Krueger. rotaflip

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The problem with trying to determine the die rotation for an early coin, such as a bust half-dime, is that we do not know for sure the exact alignment intended by the early mint. In fact, as I understand it, throughout the production run of any size, the dies would be adjusted in order to get the best possible strike.


So I think it may be a tough go to measure the die rotation of these early pieces with any degree of precision. That's why the only rotation worth a premium is at about ninety degrees or more. Anything less, and it could almost be assumed that the mint intended it.

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Thanks, people.


I went ahead and ordered that Rota goodie.


And I'm going to make the assumption that the obverse orientation should be with the DATE being horizontal.


And James, thanks for the observation.

It sounds reasonable.

But without confirmation from Mint documentation I have to establish my own baseline.


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