1964 D Quarter ... RPM?

Agreed - most likely caused during the ejection process I believe.

Looking at this particular case first, the shape of the D is altered on the bottom but not on the top, thats a dead giveaway of Machine Doubling damage. For this to be an RPM, it would have to have been punched with two different sized Ds and that didn't happen. So on this coin, the MM is damaged.

As a technicality, if we can identify individual punches of a mint mark into a die, it would be an RPM.

I am not sure how anyone could identify a punch that was done in such away as to make the mint mark look like a machine doubled mint mark and that it was done by an unsteady hand. The only way that I could imagine this would be to witness the punch and then to view the die immediately after the punch and before it went into service.

I suppose that scenario is possible but since the end result on the struck coin would not be able to be identified as such it would still likely be called Machine Doubling damage.

To go further with your scenario though, you can see mint marks such as you describe on coins of every date Washington quarter (that has a mint mark) from 1932 to the present. From 1932 to 1990, it is not likely that there would have been that many unsteady hands:-)

And then it does not explain how mint marks can look that way after they were made a part of the design and not punched into the dies any more.

Also, since the mint mark is the smallest detail standing alone on the reverse of (in this case) a 1964 and earlier quarter dollar, it would be prone to hanging up as a coin is ejected from a die and being damaged. We see exactly the same thing on Franklin half dollars and coins of other series.

Going a step further, we know that Machine Doubling damage can effect one or more things on a coin. I have found literally thousands of coins of all denominations, including silver Wash. quarters that had more Machine Doubling on things other than the mint marks.

It seems more logical that since Machine Doubling damage is so common on every coin, of every series, That these are not caused by an unsteady hand punching in mint marks but by the fact that Machine Doubling damage simply effects mint marks in an almost infinite number of ways.

Thanks,
Bill

Hi gettingbrowned,

With RPMs once you see one, you'll know you found one. :-)

There is always a period in the learning curve where a person is not confident of their abilities to identify something yet. I was there once:-) So threads like this are really good. As people see the reasoning behind why I think something is or isn't something they can then use that reasoning to determine what they are looking at on their own.

It doesn't make me infallible but I get it right 99% of the time:-)

I am happy to have helped.

Thanks for your kind comment,
Bill