Machine Doubling (MD)

[jcuve]

First i would like to thank you very much for this great lesson..... i finally can differentiate between both or at least i think i can ;)

I have a question regarding the cause of the doubling ..... for the MD i understand the cause but for the DD, how can a lost part of the die add the same shape and size of the date ? Hope you pardon my ignorance but i thought that DD would be a result of hitting the coin twice... if you could explain it more to me, i would appreciate it very much.

Thanks

I'm not sure what you mean by DD, do you mean Doubled Die (Hub Doubling) or a Double Strike? A Double Strike is easy as it is creating by two (or more) separate strikes from a die, whereas MD is created by some of the extra energy from a single strike where the Die Face bounces or vibrates up and down or in some rare cases drifts sideways.

A Doubled Die is created from the Hub, which is a positive (and looks like a struck coin), that has been misaligned in a subsequent hubbing (or moved during a single hubbing - post '97). The positive parts of the Hub stick out and create impressions (incuse) into the Die Face; in essence holes or cavities replicating the design. In the hubbing process once you create an incuse area, adding to that incuse area within the area of the fields always makes the design a little larger. You can experiment with this by making impressions of a coin in clay (or play-dough) and then turning or offset the coin and making another impression.

I hope I am answering your question...

[EgCollector]

You certainly did and by DD i meant Double Die as a word but Double strike as a meaning so you actually explained double strike and taught me Double Die

Thank you Jason very much

[strwrght53]

excellent photos expertly illustrated can't help but learn from them...thanks

[wapa]

Hey Jason, being fairly new at this coin stuff it might help to explain how and what a DD (bad name) hub doubling is caused. (I may have missed the explanation in the new section.) My understanding is that DD or hub doubling is caused when making or re-stamping the die itself and has nothing to do with striking the coin. Whereas MD is caused when the coin is actually struck. What is the best way to talk about hub doubling? Does saying a DD create confusion? I know until I researched terms I was confused. Double dies has been such a standard for so long. We reference things like DDO or DDR etc.

This brings up a question is once a die goes into or back into service what is the life of the die? I guess if there is a a die that is damaged and creating a hub doubled coin how many coins would be made until it is taken out of service? I imagine there is some QC during the striking and if there is a damaged die that it would be taken out of service in short order. Hence making that damaged coin that much more valuable. I guess the question would be is do you know how many coins that would be struck before the die is taken out of service for repairs or out of service permanently? I mean just a guess. There must be a ton of reasons for a die to be taken out of service before is normal use life. I guess I am just wondering if there is like 1000 coins struck to 50,000 coins struck or??? I hope I understand some of this stuff anyway and it all makes some sense.

[Seeker7]

Fantastic pics! I am starting to learn the difference between DD and MDD. I want to thank you for the time and effort you went through to set these examples up.

[Seeker7]

I enjoyed the tutorial! Thank you for helping us rookies get it straight.

[addictedtocoins]

Thank you very much ! This is very helpful !

[Drav3n]

This was a great tutorial mate! Thank you so much. I, being a newer collector was looking just for this type of information. Coupled with a few other tutorials that I have read I believe that I will be well on my way to building a decent collection. Thanks again!

[josht]

Great tutorial and great pics! Thanks

[Neighbor]

Thanks for the awesome thred, your very talented teacher. Plus the knowledge gained, I now have the perfect point of reference!