3rd Tutorial
Study of types of doubling
I have seen many topics on this forum who asked the intervention of members to identify the type of doubling found on their coin. To properly identify the types of doubling, take the time to read the explanations of a Mortar Set,
Die Deterioration Doubling, Die shift, Repunched Die and Doubled Die that could be found on this site (
http://www.coinsandcanada.com/coins...rieties.php) or other sites on the web.
Observe the following drawing. It compares the reliefs of hub doubling (WDD) and
Mechanical Doubling (MDDe) to a normal coin.
From this, we can defined two categories, doubling inside of the relief (MDDe) and outside of the relief (WDD). It is very important to see this difference because if the apex's edge of a suspected doubled die coin is smaller compared to a normal coin, in all cases it is
Mechanical Doubling (Also known as "Die Shift", "Ejection Doubling", "
Machine Doubling" and "Die Chatter").
Conversely, if the doubling is outside of the relief, further investigation is required. We need to explore the edges of the doubling to clearly identify the type of doubling. I have defined two subcategories, rough/un-uniform edges and smooth/uniform edges. In the subcategory rough/un-uniform edges, this is not really doubling but the appearance of a doubling. Mortar Set and
Die Deterioration Doubling are found in this subcategory. In the other subcategory smooth/uniform edges we find Repunched Die and Doubled Die.
In the US, Doubled Die is then broken down into 8 different classes;
Class 1, Rotated : misaligned in a clockwise or counterclockwise direction.
Class 2, Distorted: hub's design moves toward the rim between hubbings.
Class 3, Design: die bearing another design.
Class 4, Offset: misaligned in an offset direction.
Class 5, Pivoted: misaligned via rotation with a pivot point near the rim.
Class 6, Distended: hub that was distended.
Class 7, Modified: modified between the die's hubbings.
Class 8, Tilted: die and/or hub is tilted during a hubbing.
Coin Expert can be used to study the relief on a coin and quickly determine
Mechanical Doubling from hub doubling. Coin Expert can also be used to identify the class of a doubled die by determining the movement of the hub.
Here are the steps to follow;
Take a coin without doubling as your reference coin.
Click to activate the "trace" option, to outline the details you want to study. Double click (or press Esc) to terminate.
Save trace (F4)
Take the coin with doubling.
Align the coin with the outline and determine if the doubling is outside or inside the outline (relief).
If it is outside, determine if edge is rough/un-uniform or smooth/uniform by using the zoom function (press "Page Up") or moving the coin to align the doubling with the outline.
Conclude
Posted 05/22/2013 4:05 pm
