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 Replies: 12 / Views: 2,108 |
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Pillar of the Community
United States
887 Posts |
***Please correct me if anything is incorrect*** Mint or Strike Doubling (MD/SD, one in the same AFAIK) is caused by a loose die vibrating on the return from the striking of the planchet. These vibrations will occur each time the die strikes a new planchet until the die(s) is tightened, but each vibration would be different for each strike I would think. So while all planchets struck with that loose die will show Strike Doubling, will they each show the exact same doubling? Ie, are there strike doubled coins out there that are exact copies of each other, or are they like fingerprints and snowflakes, each one different from the next? Logic tells me that they should all be somewhat different, albeit maybe only microscopically. If there are multiples of a coin with (what appears to be) Strike Doubling, does it, or can it, become a variety? Or would it be something else if it's been shown to repeat? |
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Rest in Peace
10197 Posts |
Short answer not exactly, similar is possible. Realize MD happens because the die is loose and bounces on contact like a hammer hits a nail. Depending on the cardinal point of adjustment needed is the basic angle of deflection. It may appear in one direction or multiples different ones. Dependenent upon the hydraulic back pressure of the press, how many bounces and which direction. May have a heavy shelf like appearance(1st bounce) slighter as the energy bleeds off. There may be multi-shelves, or two/three different directions. Another MD is a shaving effect, angled from bottom to top of device, this is because of sharp edges on die devices slicing material off. So it would be impossible to identically form two coins with same effect. This is why there is no cataloguing of this kind of error. When thinking of other errors such as cracks Cuds, and die breaksthis is a damaged die error which is replicated. Edited by Crazyb0
09/01/2017 01:02 am
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Bedrock of the Community
 United States
12477 Posts |
Quote:***Please correct me if anything is incorrect*** Mint or Strike Doubling (MD/SD... I don't think "Mint Doubling" is the term. From what I've seen, MD can be used to mean Machine Doubling or Machine Damage. Beyond that, I don't think MD is a precisely repeatable event and each coin will show, at a minimum, very slight differences. As Crazyb0 said, that's why they are not catalogued. It would be similar to trying to catalog lamination errors, none of which can be exactly the same. In Memory of Crazyb0 12-26-1951 to 7-27-2020
In Memory of Tootallious 3-31-1964 to 4-15-2020
In Memory of T-BOP 10-12-1949 to 1-19-2024
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Pillar of the Community
United States
2843 Posts |
Quote:MD can be used to mean Machine Doubling or Machine Damage. Or Mechanical Doubling. And as far as the question, I imagine that there could be a few to several coins with such imperceptible differences that they could be called identical. More importantly, however, I dont think that would ever be called a variety. I think varieties refer to dies more than to coins. In that sense, the die being loose would not be called a variety of said die. That's my opinion. |
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Moderator
 United States
23522 Posts |
Machine Doubling (how I hate that term, for the implication that it's "doubling") can happen at any time, on any press, to any planchet struck from any die. The looseness conditions under which it manifests don't even always result in an MD coin. Nothing the Mint does at any step in the process can have an effect on whether it manifests or not; the "looseness" which results in such strikes can still be within accepted adjustability parameters for the press. The variations resulting in MD strikes are in the ten-thousandths of an inch, and that's not an easy standard to maintain when you're moving chunks of metal whose weight is measured in pounds back and forth at iterations of two or three per second, with 100 tons of contact pressure involved. It's like claiming an "error" for the slightest displacement of ink at a single point of a bill printing. So, no, not a "variety." Ever.  I would suspect, at an atomic level, that no two MD events are precisely identical. Anyone got an Electron Microscope and a couple billion Cents to confirm?
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Rest in Peace
10197 Posts |
SsuperDdave, excellent point. Had not considered tolerances in relation to the mini/micro level. No two coins outside of die "altered damage" (for lack of better term/explaination)or a true hub doubled event should be viewed as identical. At the micron level even a 1955 DDO is not "Identical", only "similar"(matter of semantics, folks!). MD is varied, one coin to the other. A "die crack" will even vary from one strike to another, progressive deterioration, strike pressures, foreign material entrance, the Die Stage categories. It is within these minute changes that makes each error coin(die error, strike error and hub doubling) such a fascinating field of study! |
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Pillar of the Community
United States
2775 Posts |
Quote:
Ie, are there strike doubled coins out there that are exact copies of each other, or are they like fingerprints and snowflakes, each one different from the next? Snowflakes. Thanks, Doug. Food for thought. http://www.error-ref.com/?s=machine+doublingMore food for thought from coops library.  |
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Pillar of the Community
 United States
887 Posts |
Awesome responses everyone. The reason I'm asking is this; if you do have multiples of a coin that does have what appears to be identical Strike Doubling (to appease the crowds), couldn't it actually be a doubled die, and not MD/SD? Or is there another reason you could have a doubling that is repeated across multiple coins? I'm way early into what I think may be something, but wanted to get others' opinion on my thought process. It may be nothing, or it may be something. |
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Rest in Peace
10197 Posts |
Halo1st, exactly the point I was making above. Sent you PM Beefer. The difference is WHEN and HOW true DD is introduced into the coining process. MD, what you reference as Strike Doubling" is just that, happenscwhen coin is struck. A doubled die is introduced during the process of of making the dies, the hubbing process. It is a part of the die, therefore it replicated on each coin the same. Edited by Crazyb0
09/01/2017 3:05 pm
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Pillar of the Community
United States
2775 Posts |
Seems to be a similar question, but now turned around. Note, the reason I very rarely jump in with a quick MD or SD response any more is because of what I think you're asking. There are known doubled dies that are attributed that look like MD to me. Upon realizing this I stopped jumping the gun and try to check or follow up with known resources. I found judging by verbal description or sometimes the appearance alone is not always accurate. There are other factors to weigh, that can make or break an attribution. A slight difference can suggest a different die or even MD, but yet appear identical.  Thanks, Doug. Edited by Halo1st
09/01/2017 3:40 pm
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Rest in Peace
10197 Posts |
Doug, wise man! Suffer from foot I mouth disease/at times myself. Have even had a complete mimick of a 1970S proof, after even posting pix here the jury was split. Sent it to John Wexlers, came back as MD. I'd post it here but...awaiting computer from repair shop.  I'm currently in process of writing up a very easy to understand book on the comparison of DD to MD, illustrated w/pix, Coops, mine, other CCF members, Mike Diamond's (love the ref you linked above, used it a lot in book). I'm calling in "Coin IDing for Dummies", yellow cover and all! It'll be available on Word format and free for all. Its meant for newbies mostly, since the majority of questions revolve around this topic. Especially the "I'm gonna be rich by cheerypickin' this here penny!!" ones. Simple premise is if you know the WHEN and HOW of doubling, you have the keys to the kingdom, what/how true hub doubling is formed, how/when striking errors occur. Even have a section of "Little Johnnie in the Garage with ______" errors. Been quite the learning experience so far for me, hope to have it completed in a few weeks((Need my computer!). I just might include this thread as a reference, good question/answer/info posts! Excellent!  |
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Bedrock of the Community
United States
73688 Posts |
Not exactly a repeatable event, but it can happen to any coin. It only happens when the Die gets loose. Great question. :)
Errers and Varietys.
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Pillar of the Community
United States
2775 Posts |
Crazyb0 I was responding to Beefer518 question. Guess I should have added that above. Thanks, Doug. Quote:The reason I'm asking is this; if you do have multiples of a coin that does have what appears to be identical Strike Doubling (to appease the crowds), couldn't it actually be a doubled die, and not MD/SD? |
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Replies: 12 / Views: 2,108 |
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Posted 09/01/2017 01:28 am
