What is the difference between Machine Doubling and a true Doubled Die? I have seen many examples of both, but haven't been able to quite figure them out well 'cept for the '55 DDO, I can't really tell the difference. Any info? Thanks.
True doubling occurs at a point when the design is being transferred from the hub to the die, and is sometimes referred to as hub doubling. Sometimes, the doubling occurs in the transfer from the master hub to the master die, and this doubling would be evident on all working hubs and dies. Most often, the doubling occurs in the transfer from the working hub to the working die. With that said, true hub doubling will create a secondary design image that has rounded devices and/or split serifs, whereas, machine doubling (also called mechanical doubling or strike doubling) will appear flat and shelf-like. If you look closely at most letters and numbers, you can see that the face (or top) of these are rounded, and it is this curvature that shows in a true doubled die. This rounded appearance can also be evident on doubled profiles where the device curves down to the field. Machine doubling occurs when a working die becomes loose in the retaining collar, and the vibration of the machinery causes it to "chatter" (move back and forth very rapidly). As the die withdraws from impact with the planchet, it scrapes across the surface of the planchet creating the flat, shelf-like secondary image of the device. Chris
A good site showing various Non-collectible types of doubling: http://koinpro.tripod.com/Articles/OtherFormsOfDoubling.htm Lincoln Cent Resource site has photographic examples: http://www.lincolncentresource.com/FAQ/machinedoubling.html This is a visual explanation from Coppercoins:
Thanks, diggit! As I mentioned, most often the top of the letters will be slightly rounded rather than squared like the model shown in diggit's post. (I assume this was done merely for simplification.) This is an intentional design aspect to add strength to the die. If you know anything about architectural engineering, you will know that an arch is much stronger than a squared span because it distributes the load more efficiently. The same is true for the working die. By rounding the letters, there is less chance of die breaks along an edge. Chris
An addition, most of modern coins have dies that are produced by a "single" squeeze of the hubbing ( and here is where the various arguments come in play), as this squeeze compresses and then releases, the hubbing die may "chatter, rotate, move, etc, producing a working die with a doubled image. This is the 6 finger and a whole lot of other varieties that are "doubled die" due to the doubled image working die, that were so popular with the Lincoln series of the 4 reverses. I prefer to think of it as something far less than a true doubled squeeze "doubled die" Jim
Everyone knows the US Mint manufactures coins but many seem to overlook that the US mint also manufactures dies. Each are a finished good in their own right produced in two distinct and seperate manufacturing processes. One finished good of course are the coins we hold and spend every day and the other finished good is a piece of manufacturing equipment used in the manufacturing process to produce those same coins. So here is a simplified explanation. I hope it doesn't confuse you more. Mechanical doubling, plate split doubling, die wear doubling are anomalies on a coin originating and attributable to the COIN manufacturing process. Doubled die is an anomaly on a coin originating and attributable to the DIE manufacturing process.
Understand what's happening in a typical doubled die. One fully-intact image is punched adjacent to another fully-intact image. Thus, while, for whatever reason, it's rarely mentioned, in a typical doubled die the "top" or "primary" image is always going to be fully-intact. To wit, note, above, how that top or primary image in the machine doubling example is thinner than that in the normal example and how in the hub doubled example it's rather identical in terms of both length and width.
OK guys, this all helps..............somewhat. But what about this one ? The area that looks like a possible engraving "error" to me is the rounded inside of the top indent of the 2nd "5". The digits appear "fuzzy" when in hand, like they are wider by a bit than the normal variety. The cent is bright red AU58+ The added with of the numbers looks "rounded" to me. I couldn't match it to any of the coppercoin pics, of course. I do appreciate your thoughts on it. Maybe some day I will get it right ? Thanks, gary
The enlargement is a bit too fuzzy for me to tell, but one giveaway that it is probably machine doubling is the mintmark because these were punched into the working die after it was made. Chris
What you have is a "poor man's doubled die". It is caused by die deterioration. It is not an error. Unethical sellers promoted this with a fancy name and made a lot of money. They still show up on ebay and some buyers not knowing any better get taken for a ride.
Thanks. This is the only "poor man's" I have found so far. Now I can label it correctly. I have looked at a lot of 55 D cents too ! lol Is that rounded area inside the top of the second 5 one of the things to look for with die deterioration ? I am pretty good at spotting varieties, but am still trying to get educated on the doubling errors. gary
