Let's talk doubling

Hi all.
This is going to be a tutorial on the 4 main types of doubling you will encounter in your searches, and how to tell them apart.
First, let me explain what a doubled die is, and what it is not.

-A doubled die occurs during the hubbing process of the dies. Up until the mid-1990s, dies were hubbed multiple times using the "multi squeeze" method. The die blank which is was to be hubbed was placed at the bottom of the "hubbing chamber", with the working hub (depicting the image to be transferred onto the working die) sitting above it. When the chamber was activated, the working hub would descend onto the die blank with hundreds of tons of force to transfer the image. At the time, one single hubbing was not strong enough to transfer a perfect image in one squeeze, so the die was removed and put into an oven to soften the steel and allow a better design transfer for the next squeeze. Once the die is finished annealing, it is returned to the chamber for additional hubbings. HERE IS THE IMPORTANT PART. If for some reason the die and the hub are not properly aligned, when the image is again transferred, it will not line up exactly from the initial impression, resulting in a doubling of the image on the die. There are 3 main classes of doubled die directly caused by the failure of a perfect alignment between the die and the hub.

Class I (rotated): This occurs when the die and hub are lined up correctly on the X and Y axis, but the die has been rotated about its center either clockwise or counter-clockwise. Famous examples include the 1955, 1969-S, and 1972 doubled dies.
Class IV (offset): this occurs when the die is offset from the hub along the X and Y axis. Doubling will appear to go in one single direction. Famous examples include the 1983 DDR and the 1984 doubled ear.
Class V (pivoted): similar to class I doubled dies, class V only differ in that the pivot point is elsewhere on the coin besides the center. This means that the doubling will be weakest at the point of the pivot and will be strongest directly across from the pivot point. Well-known examples include the 1995P-1DO-001 (pictured below).

Since the die itself is doubled, that means that ALL COINS STRUCK BY THE DIE WILL SHOW THE SAME DOUBLING, not taking into account die state and post-strike damage.

Now, what a doubled die is NOT.
-A doubled die IS NOT a coin that is struck twice when being minted. This is a common misconception for beginners, and I admit that I thought this was what a doubled die was when I first started out.

If you wish to learn more about the hubbing process as well as additional classes of doubled dies, feel free to visit doubleddie.com for more information.

Now we will go over what to look for in your searches.
The main things you should be looking for on coins is notching and separation lines. These two indicate that the hubbing was not correctly aligned. Since there would be 2 sets of letters if we were looking at "IN GOD WE TRUST", they would overlap at certain points and create notching at the corners.
Below is an example of 1995P-1DO-001...a class V doubled die with the pivot point around the date. This means that the doubling will be strongest opposite of the date; the motto above Lincoln's head. The black arrows point to the notching in the letters while the red arrows point to the separation lines. I would urge anyone searching for doubled dies to purchase an example of 1995P-1DO-001 as they are inexpensive, dramatic, and will show you what to look for.






The second type of doubling you will come by, and quite possibly the one most confused for a doubled die, is machine doubling.
Machine doubling has nothing to do with the hubbing process, and takes place in the coin striking chamber. As the hammer die comes down to strike the coin, it may bounce or shift slightly if the die was installed loosely. This flattens parts of the design. This is what gives machine doubling its Flat and shelf-like appearance. A good indicator of machine doubling is if both the date and mintmark show doubling in the same direction, as doubled dies and repunched mintmarks have had nothing to do with each other up until recently. Here is an example of a machine doubled 1944-S cent. The red arrows point out the areas on doubling. Notice that the mintmark is doubled as well, and the doubling is flat and shelf-like.




The third type of doubling is most commonly found on wheat cents of the 1950s. Commonly titled a "poor man's doubled die", this anomaly is not a doubled die at all. Rather, it is die deterioration doubling, caused by the overuse of dies. Notice how the doubling is more ghost-like than an actual doubling of the design. The anomaly is not full like a doubled die is, and is often limited to the last digit of the date.




The last type of doubling I will go over is split-plate doubling. Found exclusively on cents with a zinc core and copper plating (all cents 1983 and on), this form of doubling can often be found on the dates of early 1990s cents, and on the reverse of many cents as well. Split -plate doubling occurs when the copper plating on the coin splits open around certain design elements, revealing the zinc below. They can be identified by the appearance of exposed zinc and a rippled appearance that is found almost exclusively at the tops of letters if you are looking on the reverse.


Sorry for the very long post, but I wanted to make sure to cover all the bases I felt needed to be covered. I hope this helps a lot of people in their coin roll searches, and that beginners will be able to more easily identify certain types of doubling.
Don't be discouraged if you don't find a doubled die immediately...my average is about 1 in 2500 cents if I am bankroll searching.
Remember...have fun and keep up the hunt!

Simon

 

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GREAT read! To be honest, I've been collecting for about 7-8 years now, and up until this read I thought a doubled die was a double struck coin. I learn something new every day on here! Thank you for this amazing information! :yes:

 

Glad that it helped! Hopefully my explanation of doubled dies was not too complicated to understand...

 

it been very helpful.. Id like to thank you personally for this article simon.. I have been collect cent for years this has help me a lot.. with identifying where I have been going wrong collect oddities I find in circ.

 

I ssaved this I present it to my guild..

 

Wow thanks! Let me know how the presentation goes.

 

What are the characteristics one would expect to see on a coin due to pivoting and squeezing in the production of a hub as opposed to a die?

 

If doubling appeared on a hub as opposed to a working die, all the dies produced by that hub would also have the doubling. I don't think there are any strong examples of a master or working hub being doubled, as there would be so many produced by the following dies that the number of coins produced with the doubling would be in the millions. There technically isn't a difference in characteristics aside from doubling occurring earlier in the hubbing process usually being not as strong.

 

Very good thanx.

 

Are all machine doubling coins worthless or are there exceptions to the "rule" Also, if one has a coin with a RPM AND split plating, does the split plating part decrease the value of the RPM? (like cancel out some of the value...)

 

Samisue,

Extreme MD can carry a premium. People will argue as to whether it should, but the fact is that it can. Strong examples of slide type MD bring some nice premiums.

http://error-ref.com/slide-doubling.html

As for the value of the coin that shows an RPM and split plating, it would depend on how much, if any, the split plating interferes with the RPM.

 

Awesome! thank you! That gives me a little hope as i have found plenty of MD's. As I go back through, I shall examine the differences in extremities and judge from there or ask....as for the split plating, it would be on the reverse, per usual

 

If you are covering all the bases, you should also include and describe 'Ejection Doubling' as well... look for raised elements, on the devices themselves, above the normal level of the devices, usually along the same leading edge.

Ken Potter has an excellent example here: http://koinpro.tripod.com/OFD/19591cEJDBL.jpg

 

I don't come by ejection doubling as often. This tutorial is about the 4 main types of doubling that I most often encounter in searches, and what I imagine most other people do as well. I don't even have an example of it to photograph.

 

Wow! all the wondering, maybe..could it be..just.., took me what 4.5 minutes to read? Outstanding information source for those that read/view here often~~~~three beers to you!!!!!

 

ok went to ebay---pcgs#7496943-MS 66rd---nice stuff =-an excellent example of what you have described!~~

 

I encounter it quite frequently on the reverse (i.e., hammer die) of Canadian small cents, especially in the 1956-1959 dates. I'll try to find a good mint state example to photograph.

This could lead to an interesting debate: since ejection doubling is imparted on the coin, after the pressure of the dies have already struck the coin - is it a form of post strike damage?? The doubling occurs in the striking chamber, but not a function of the strike itself (unlike machine doubling and die deterioration doubling)... does that make it a legitimate striking variety, or just a curiosity...

Food for thought...

 

I recently discovered some VERY, VERY nice doubling going on with a commemorative half. Its not quite as prominent as the 1995 Lincoln Cent, but its most assuredly there and on several letters. I wish I had better photography skills to show this off, i may try and give it a go tomorrow, as i am very curious if it is a known variety for these coins or what type of doubling it is exactly.

The coin I am referring to is a 1920 Pilgrim half-dollar. Anyone else have one of those with some doubling on the reverse? It is all over the words 'TERCENTENARY CELEBRATION'

 

Anyone know what's going on with this pilgrim half? Here are the pictures. The doubling is nice at least to me I'm just not sure what type of doubling I am seeing.

Without further ado the pictures:

The 'I' and 'M' from PILGRIM



The 'T, E, R, C, E & N' in TERCENTENARY



This picture shows the 2nd 'T' and 3rd 'E' doubled in TERCENTENARY



What do you guys think? Any value to this doubling?

 

It's MD. Re-read Simon's original tutorial for telling the difference.