Featured Learn About Die Doubling...

Hi,
Each German coin is a knockout example of a coin struck by a doubled die!!! There is no doubt there are notches at the tops of letters and or numerals, The 1995 is outstanding! The others are very nice as well.
I have to start looking at my German Coinage, I've already checked my coins of Spain.

The sPanish coin is one I would like to see better pics of, There is an outside chance that it is struck by a worn die and the doubling is caused by what is caused Die fatigue. I thionk there is a good chance though that the coin was struck by a doubled die as well. Better pics will tell for sure.
Thanks,
Bill

 

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thnak you!
its hard to take better pix from the spanish one..

i will put all those coins to ebay.. therefore i have to know what kind of doubling they are.. so thank you for your explaning

 

Yeah, but the pictures I see in the Redbook, namely the 1937 doubled die, and the 1943 doubled die Quarters, look a lot like machine doubling. These look too confusing so I keep every coin I get that has any type of doubling because there will always be differences in opinions about doubling.

 

Mike is correct, you cannot believe everything that you see on a slab.
Recently I wrote to a seller (Ebay) who was selling a 'slabbed' coin (from a real low-budget slabber) listed and slabbed as a 1858/7 Flying eagle.
Nice coin, except that the piece was a small letter 1858, and the 1858/7 is on the large letters Flying Eagle cent.
I wrote to him (the seller) and broke the news. Strangely (no surprise) I never got a reply.
So, the lesson is: believe what you know is correct.
Many of the so called double dies are strike doubling. There are some early Barber quarters with strike doubling that is very deceptive.

 

pricing guides on line

can anyone reccomend where to look for prices and die varieties,or errors on current dimes, nickels and quarters?
or just prices in general
thank you

 

Die doubling and machine doubling

As a coiner I have made my share of doubled-images on coins. The true doubled-die is an artifact of the die-hobbing process. The master matrix (or hub) is pressed into a coned block of annealed tool steel to form the working die. If the impression is not quite deep enough the die-sinker will realign the die and hub and press again. Usually you can feel when the die and hub "lock" back in together... but sometimes there is a very slight shift of position, and a doubled die impression is made. They can be so subtle that they die-sinker may not even see it, and pass the die on to be heat-treated and sent to the press-room. I have inadvertantly made several such doubled-die impressions... even when I thought I was being meticulously careful to avoid them. The main solution to the problem is to refine the die-sinking technique so that a single push with the press created the impression and a second pass becomes unnecessary.

Remember that it takes a lot of dies to make a government run of coins. Typical maximum die life is somewhere in the neighborhood of 50,000 strikes per set. So if a billion coins are to be made with a certain date and mintmark, then it will take as many as 20,000 sets of identical dies to produce them!! That is an astonishing number! So the die-production shop is itself like a small mint operation. In my experience, the doubled die impressions always occur early in the die production process because the particular requirements of the die being made are still being learned. After a few double-strikes are done in the process of determining the correct tonnage setting for the hobbing press, there would be no more die doubling errors.

Machine doubling is something quite else... the idea there is that the die is perfect, but that the coin is struck twice with slight movement between strikes. It can only happen if the coin is struck twice, either on purpose (done to increase die-life by reducing press tonnage or for special proof strikes) or because of a problem in the feed and ejection subsystems. Once the coin is double-struck, the doubling image is because the second strike was not perfectly aligned with the first. This can occur in one of two ways. First, because the lower die in the set moves up and down in the collar it is not held firmly, wear or looseness in the alignment pin can cause a slight rotation of the die. Second, if the ways of the press are worn, the positioning of the upper die may be inconsistant.

In my experience, the machine-doubled image will be a rather "shadowy" doubling by comparison with die-doubling, and on close examination the shadow image will be found to be completely flattened into the field. Die-doubling will show clearly under magnification that there is are two separate images with relief showing between them and with the second image clearly above the field in relief. So I agree with the other people who've looked at the above photos of German and Spanish doubles that these are most certainly die-doubles and not machine-doubles, since they show clear relief.

 

When I try to use the links


How Doubled Dies are Created and Their Classes.

Determining Die Doubling from Other Forms of Doubling. (Requires Acrobat Reader)

Take the Doubling I.Q. Test.

Doubling: Worthless or Valuable?


I get
The webpage cannot be found


Is there any other way to access the pages? I'd like to learn more on the subject. By the way your article was excellent. Thanks.......

 

Those pages were taken down when Varietynickels was shut down a few years back. I'm in the working on getting varietynickels.com back up and going but from the looks of things I won't be able to use those articles.

Speedy

 

Nice thread!

 

Seeing as the articles are now unavailable, maybe they should de-sticky the thread?

 

1972 d bu Lincoln Memorial

This cent got my attention before I took a glass to it.
I know it appears to be machine doubling.
Yet, on the lettering of United I see lines about half way up the letters of T, E, and D. I did not think this would fall into the machine doubling category.

Also, along the edge of the memorial and the top of the first column there is 'doubling'.

I do not know if the pictures will show exactly what I am trying to explain.
But I am going to give it a try.

Thanks CT,
jeankay

 

1972 d bu Lincoln Memorial try 2

Arrgghh! Where did the pictures go?
Electronics and computers always take advantage of my limited knowledge.
Guess I will try to do this again.

 

After reviewing the information from the koinpro website linked at the beginning of this thread, I'm still not sure how to identify the type of doubling on a 1993 p quarter pictured below. My guess would be a worn die. The p mint mark is very weak and the IN in IGWT appears to be raised above the rest of the motto, could be just has an extra raised area surrounding it due to die damage. Could someone please post an opinion?

 

Thank You.

 

Thank you very much for posting this :smile
:thumb:
Just what I needed to know

 

1942 mercury dime

hi there, I am new to collecting coins and have found that error coins are more interesting to collect than normal struck coins, I have found this site to be very informative and joined in order to get true and real answers,my latest coin find purchase was a 1942P mercury dime that had a double date so I purchased it for $10.50 after closer observation I found that the coin also had a double R,T,Y in liberty and solid doubling on the underside of the winged cap, the most interesting feature with a 10x loupe is the double date appears to have the presence of the top part of a 1 under the double 2 the top of the 2 has a raised appearance and in the center of the 2 appears to also have a raised appearance that is in line with the upper top part of the 2 could this be.

 

mechanical/machine doubling maybe a die chip is all.

mechanical/machine doubling maybe a die chip is all.
These coins struck during the war years were just pumped out to meet demand and there is many minor mechanically doubled coins.

 

picture isn't that clear wish I could take better ones but this is not a die chip