Cracks For Gene & Mike

Lou,

I too have wondered about the similarities between the die failures of certain dates. For instance the "Y" crack/break of the 1922-D Peace dollars, as well as the crack that runs around the whole obverse in circular manner. There are so many so similar that I too questioned "WHY?" I am interested in what you have to say on the subject.

Right you are fioti, that one looks like a crack at the top with what appears (from the photo) to me to be a planchet flaw under it.

I think that nearly all coin dies will show cracks here and there. What I was referring to though was the types of cracks that seem to surface in certain years or on specific denominations. I believe that when a crack appears on a die, there was a reason for it and that reason is metal fatigue. The specific reason for the metal fatigue depends on a good many factors, including the fineness, specific composition, and processing of the ore grain used to make the steel, the temperature at which the steel is annealed, the length of time that temperature is maintained, the manner and duration of cooling, the number of times the die was annealed, the final hardening of the die, etc, etc. Radial cracks are a fingerprint of one of the many factors that may contribute to improper annealing, peripheral cracks are an indicator of yet another thing that went wrong in annealing. Sunken dies, bubbles in the dies, surface oxidation, premature central die breaks, are all specific indicators, symptomatic of improper annealing procedures, methods, or materials.

For those who feel that cracks are caused by clashes, excessive strike pressure, extended die wear, or any number of other causes, I really have nothing to say about all of that stuff; those beliefs are long held by collectors, dealers and other 'experts', so I see no sense in arguing those points.

That is what I said, and what I meant, Mike. I, like you, do not believe that all dies made from a working hub will be identical, but I do believe that there will be some, (perhaps many) that will be so close, that one cannot be told apart from another.

I will say this though, if you can imagine the impact of 150 tons of unrestricted pressure upon two dies, it would be rather
extremely naive to think that either die would remain in fewer than ten pieces (much less ever strike another coin). Clashes were no more than very light touches, (kisses) of the dies. The travel of the lower die is fixed at zero. The travel of the upper die is purposefully adjusted to bring up the strike in a planchet, not to obliterate the opposing die.

You may be right Mike, but, unless you know how many die pairs were actually used, how would you know if you had identified them all or not?

On the other hand, if you knew that there were 233 die pairs used for the 1921P Morgans, yet you were only able to identify 156 pairs, might this not suggest that there may be dies that so closely resembled one another that they appeared as the same?

I just blew half an hour composing a post which the network ate because Comcast picked the wrong moment, yet again, to lose DNS service. I am beside myself with rage.

I won't try again tonight.

The root cause was annealing.

For instance, if heated at the correct temperature, but for too long, the result on the steel will be that the ferrite grains will enlarge, the cementite molecules within the pearlite become strained or elongated, causing the cementite membranes to form weak junctures to the ferrite resulting in inherent fissures and cracks. (A brittle die, more susceptible to peripheral cracks).

The grade or purity of ore and its granular fineness were not accepted in exacting measure, it was rather a hit or miss sort of thing. The sources of ore varied, as did its processing.

Master dies, hubs, clashes, the works of Franciscan monks, etc, had nothing to do with cracks in the direct sense, they may have served only as catalysts to exploit these inherent deficiencies within the dies themselves.

I know that I tend to blame nearly everything on improper annealing, but annealing is not now, or was then, an exact science. Optimal dies were the exception rather than the rule, and this is because of the ore grain, and its treatment. It remains a controversial subject to many, and there are many, many methods of annealing depending on the material involved and its intended use.

What I originally meant by my post was that over the Fall and Winter months, it might be interesting to see if you could come to any conclusions as to what may have been the cause of the particular cracks that you see on individual coins.....what sort of crack might come of a die that was over heated? What sort of effect would there be on a die that was cooled too quickly? A radial crack might imply what? (That sort of stuff).

MD Mike has already been thinking about all of this evidently:



It would be interesting to me to see what others might come up with, I already know what I think, but being the only one thinking about it, what fun would it be to share that at this point ? I am alienated, and I'll lose interest in this very quickly, and I'll be off onto something entirely different. When someone else brings it up again in the future, my interest and memory will reemerge.

Again some many great thoughts on a great topic,,
I can agree somewhat with both of your ideas on the die idea, which I will get back to in a moment, as I think the main culprit to ALL of the varied issues is the annealing process....
Why could this be? in today's processes there is very exact control over the materials as well as exactness in tolerances with today's technology and if the exactness is within plus or minus 100,00o of an inch we can do it...
So lets look at 1878 and its annealing process, to anneal is to heat to specified temperature in order make the material workable...
HEAT? lets see they didn't use, Electricity,......they didn't have "Natural GAS" until 1901.....I guess twigs and leaves, yes thats right "THEY USED WOOD" according to the Great Enclopedia..and for the day it was was plentiful and cheap....and there is onl;y one thing about wood, It does not all burn uniformly...as a past LOGGER I got to know wood pretty darn well, and even as most of us know hard woods burn hotter and longer, what is not so commonly known is the different parts of the tree burn differently as well as how dry it is..wood with a higher moisture content burns cooler, than a well dried chunk of wood at say 6% moisture content...the end result is an exact eveness of uniform temperature can not be accomplished..They did however average the ball park figure..
The heating process is the key point to the annealing process in which they had not total control of, yet they did have enough control to get the job done with some side effects, the first side effect takes place with the Hub in coping the master it took up to ten strikes , I believe its one strike per day, as took time to heat up the furnace and its die cool down time, the result is in those days the next days fire up of the furnace and getting the hub ready for a restrike to get this hardened die with the desired impression, it didn't exactly expand(from the heat) to yesterdays position whereby an impression next to an impression, very small mind you....occurs from the next strike to get this image into the hub....these we know as hub doubling,,,not a doubling from the "DIES" used to produce the coins...this expansion due to non uniform heat also explains why some features are doubled or more and others are not..the metal did not expand evenly/uniformly...if it were we would have every feature doubled as in the double die like the 1955-s penny...
Now I do have a thought , with the number of dies needed to be produced were there more than one hub made?
from the hubs being finished, one would think that any number of die's made from this would, should or could be exactly the same...in all essence as I have made many a mold in the industrial industry....
yes they are all alike, but as Mike would point out even twins will have the slightest of variances, so it really depends how anal we get in superficial differences in the dies....Truely there are more differences that occur in the "dies life" than any where else..
Annealing was essential in both the production of the dies as well as annealing the silver in all its beginning stages as an ingot and forming sheets, resizing into usable/handleable strips and before its being struck...
Knowing that annealing is in the fore front of the entire process,,,understanding the side effects of non uniformity that will occur as they could not absolutely control temperature, there is also another side of annealing, and that is the effect it has on the metal itself, beyond the uniform expansion we see from the hubbing process..
Blacksmiths would be the first to know, when metal is heated it can be hardened or softened depending on how it is cooled, Zee has already pointed out what happens to metal on the microscopic/atomic level, annealing and its process if not exact can have just that not a uniform strentgh through out the die , where by dies can crack over time, yet it is true that it is an in-evitability to beat on something for so long before it will break down, and the did, I do not know if there was a listing which stated how long every die lasted, a rough guess is about 50,000 average coin's..yet in 1878 the first die only lasted a supposed 303 strikes,,,,, I will leave this here......