Machine Doubling?

[PocketArt]

This is the reverse of a 1971-D Kennedy Half. Am I correct to believe this is machine doubling?

 

There is strong doubling on "States of America," and "Dollar." Also, very faint doubling on "United" and "Half," but I can't pick it up on my camera.

 

[RWB]

Yep. Good call.

[Curry]

What is the difference between machine dubling and regular double dies? Im not too educated on that.

[RWB]

A "doubled die" occurs during manufacture of a working die. It takes multiple blows from the working hub (positive image) to bring up the detail in a working die (negative image). All blows must be accurately aligned. If one or more are not correctly aligned, there will be extra design impression in the working die. These are visible on a coin as raised outlines or details. The clearest examples are 1955 doubled die cent and 1934-D doubled die dollar.

 

Mechanical doubling occurs when the planchet wobbles slightly during the strike. Many similar piece can occur if the problem is a persistent mechanical failure such as excess wear on parts of the press. Mechanical doubling (aka 'shelf doubling' or 'machine doubling') is very common on coins of all types after about 1837-1839 when high-speed toggles presses came into full U.S. Mint use. These presses had tight machining tolerances and needed regular maintenance to produce the best results.

[Curry]

I understand it now, Thank you

[RWB]

It's OK to send a PM if you have a question.

[skippy]

What is the difference between machine dubling and regular double dies? Im not too educated on that.

 

This will help (by JT Stanton):

 

http://www.shieldnickels.net/articles/Stanton_DieDoubling.pdf

 

[RWB]

Machine doubling can also occur late at night, during vacation time. The machines leave their places and get together for social time -- exchanging bolts and hoppers, etc. -- sometimes they get unruly and take in too much lubricating oil and -- well -- stuff happens and sometimes one will get pregnant and then you have machine doubling. It's an indelicate subject, often ignored in High School mechanical drawing and machine shop classes -- especially in the bible belt where only begetting happens in the factory.

 

[coinman1794]

This is the reverse of a 1971-D Kennedy Half. Am I correct to believe this is machine doubling?

 

There is strong doubling on "States of America," and "Dollar." Also, very faint doubling on "United" and "Half," but I can't pick it up on my camera.

 

 

This is, without question, Machine Doubling.