Lincoln cent doubled dies not equal between mints.

[coppercoins]

Has anyone else noticed that the number of P mint doubled dies for a number of years are much higher than their D mint counterparts, while cases of the opposite are very seldom the case?

Take 1960 for instance - discluding the proof doubled dies (because they would naturally be only P mint) there are still a much higher number of different dies for the P mint than for the D mint according to all the published (and some non-published) sources. Same thing for 1936, 1937, 1943, 1962, 1963, 1964, and probably others I can't spit out right off the top of my head. In fact the only year I can think of right off that D mint doubled dies outnumber the P mint doubled dies is 1957.

Why is this? Any clues out there, I don't have one. I can easily make the observation by having studied the series, but there has to be something in the minting process that would explain it. I believe in all of the years I mentioned that all the dies were prepared at the same place (the Philly mint), so they should be more or less equal in number. Hmmm.

[rnealw]

Now that you mention it. how odd. I never really payed attention.

[Robert]

1. Philly is the "main" mint. Perhaps they do the training for most hub operators. A continuous flow of newbies corresponds to lots of DDs over the years. (I personally don't like this theory).

2. Different equipmment made by different companies used at the 2 mints. Large equipment is often "custom" built (to fit in a specific space, for example). Maybe the Philly presses are just plain not as good as the Denver ones.


Other observations/ questions:

1. When did DDs start to become "common"? I don't think there are very many DDs from the early years of Lincoln cents. Seems to me that they became "common" in the late 50s. There might be a correlation to the # of cents minted, but then again how many 1944 DDs are there? And that was right in the middle of WW2.

2. Why the peak around 1960-64? Did mint employees get progressively lazier at that time? Was their equipment getting bad (was the 1968 hub the same as the 1909 hub?)? Did they get new hubbing equipment after that?

3. Are DDs the result of honest human error? Mischief (the 55 is really significantly off)? Or mechanical malfunction?

[coppercoins]

Up until around 1996 all dies were made in Philadelphia. Both of your observations become moot with that fact tossed in. Why the dies didn't receive equal distribution in number of doubled dies is a complete mystery.

your other observations:

1. The number of doubled dies for any given date has little to do with age. There are a LOT of different doubled dies from 1936 through 1941, and it's likely that there aren't more known from the earlier years because there aren't as many nice grade coins to scope. Rolls of 1918 Lincolns in BU have become quite rare and pricey, while rolls of 1955 Lincolns are rather common and inexpensive. The craze for searching rolls for doubled dies didn't really get started until the 1960s, about the same time as a couple of other things - people saving rolls and bags of coins increased dramatically, and the mintage of coins went up steadily through that time. Some of it does have to do with the number of coins minted, but much more of it has to do with the economy and the fact that by the 1960s cents were "cheap" and easy to save without robbing the bank account. A roll of cents was an unusual thing to see in 1918, much less having the 50 cents to part with for one. That was more than most people made in a day at the time.

2. Mostly for the reasons stated above, but one of the big reasons for the peak around that time was a surge in the number of proof sets (thus proof dies) made. Many of the listings from 1956-1964 are proof dies because the details are so much crisper and so much easier to spot doubling on. By 1968 when proof sets came back, they had cleaned up most of their act.

3. Mostly mechanical malfunction, but they have been caused by mischief as well. It has been reported that most of the 1972 doubled dies were caused because a mint worker filed off the keys that hold the hub in proper alignment in the press causing a surge in the number of doubled dies for that year.

[Robert]

I didn't know that all were made in Phila til 96. But were they made on the same actual machine or separate ones? Maybe the process for making the Denver ones was easier/different than for the Philly ones. Like the keys that were filed off. Did the Denver press have the same keys as the Phila press? They might not if the press were made by different manufacturers.

In other words, would a Philly hub fit directly on a Denver press (without modification)? I don't know.



1. Assume there is one DD 1964 cent for every 100 unc 64 cents. Then for every 100 BU 1918-S cents there should be one DD 1918-S? Is that really how the distribution is? ( I think the avg salary for 1918 was more like $2 per day but your point is well taken)


2. So again coin condition/ die state is the most important criterion. Older DDs are then just as common on a per-coin basis as ones from the 60s. So many of those unc 1909 and 09-VDBs I see at shows must be DDs.

[Bob P]

I think one of the most common reasons for the vast difference in the amount of Doubled dies between the mints is Quality Control. Even though most of the dies were made in Philly and shipped to Denver where their mintmark was punched, many of those dies were not used. Many years ago, It was a known fact that the Denver mint had a much more stringent quality control program that Philly did. This resulted in many of the suspect dies being destroyed.
I am trying to retrace the way I found out all this information. There is a web site that gave numbers of dies delivered versus dies used at each of the mints since 1844. It also had information about each branch's quality control program. I will research it again and post the link once I find it. It is very intersting indeed!

Bob P

[coppercoins]

Robert - Your math is off a bit in this manner...

The dies were used longer in the earlier years because they were so expensive to make - the dies were replaced sooner in the later years because they were cheaper. This means more coins per die in the earlier years. In addition, far fewer coins were made in the earlier years, thus fewer dies were used. Both together would say something like this:

For every 100 coins at complete random from 1918, you might find 20-30 different dies. For every 100 coins at complete random from 1960 you might find 70-80 different dies. The numbers are likely off, but the idea is a true statment.

Secondly, there weren't different presses for the different mints. All the coining dies were made in bulk without mintmarks and stored in the same place. They were pulled out of a vault when ordered, mintmarks punched, then they were shipped to the branch mints. I believe Bob "could" be incorrect about the mintmarks being added AT the brainch mints, I read otherwise in Wexler's book a number of years ago. At any rate, it really doesn't matter, the DIES still came from the same shelves in the same vault and were made on the same presses.

Now...Bob's statement is a very intriguing one, and could very well put a complete solution to the question. If 100 dies were sent to Denver in a shipment and 30 of them were discovered to be flawed because of a doubled design, they could well have destroyed them, thus coining fewer examples of doubled dies. But I ask this...especially in the earlier years, dies were very expensive to make and ship. This is evidenced by the extreme die wear on many earlier branch mint Lincolns, and the cause of the famed 1922 "no-D" cents. With problems like this, do you really think they would have destroyed 30 dies out of a 100 die shipment just because of microscopic doubling? Something still doesn't completely jive here.

[Robert]

What about San Fran circulation strike doubled dies? How rare are those?

1918P,D and S = 369 million
1960P and D = 2,168 million

Call it a 7:1 mintage ratio.

So the ratio of dies used is more like
(75 dies per 100 coins/25 dies per 100 coins)*(7:1) = about 20:1.

So between the higher mintage and the shorter die life, the mint used about 20 times as many dies per "coin" than they did in 1918.

I realize the 25 and 75 are guesstimates but am I grasping what you're saying?

I know you know more about this stuff than I do.

[Bob P]

I thought of that very point Mr. Chuck, but I don't believe we were talking those sorts of numbers. First of all, it is very difficult to ascertain how many flawed dies there were. In addition, a few still made it out with the D mintmark, so their QC wasn't perfect. The Denver mint made significanly fewer cents during the early years. Was that because of the capacity of the mint, or because of the lower number of dies sent out there?
I guess we can all second guess the reasoning for this rather unique problem, but I think we can put a few of these "guesses" together and not be too far off. I personally believe that the better QC program, coupled with the significantly fewer dies used accounts for some of the disparity. Would you agree?

Bob P