1970 D pennies

[N-6241]

filedata/fetch?id=45474&d=1597109575&type=thumb Hello Coneca members, i am new to the Coneca forums and am glad to be part of the community.
I have been sorting through my jugs of pennies and have come across a curious mint irregularity in the position of the D mint marks position on 1970 D pennies. I was wondering why there seem,so far, to be four different locations of the mint mark. I have included a photo of 4 coins all 1970 D, unfortunately i am unable to get all four coins in an zoomed in photo.I would like to hear from anyone who can elaborate on why the mint marks on the coins are in different locations.
Thank You and look forward to any thoughts on this group of coins

[MintErrors]

Hello,
Welcome to the Forum. I am Gary K, a CONEVA State Representative for Virginia.

Prior to 1990 or so, The US mint employees had boxes of newly made "working dies" made from a master die. Lets use the US mints located in Philadelphia, Denver and San Francisco. When the working dies were made, they did not have a mint mark on them. This way the dies could be made of the year and transferred from Mint to Mint. Then, when the working dies were getting prepared to strike blank planchets into coins, the US Mint employees would manually add the proper mint mark to the working die before it was installed on a die press to create coins.

John Wexler (www.doubleddie.com) has a great example of a US Mint employee getting ready to add a mint mark to one of the dies:



This photo, courtesy of Error Trends Coin Magazine (ETCM) and Arnold Margolis, shows a Mint engraver getting ready to punch a mint mark into a working die. The working die is held in a vise. His right hand is positioning the mint mark punch and the mallet that he will use to tap the mint mark punch into the die is being held in his left hand.

Notice that this procedure was all done by hand. Back in the day, they simply used the field ( the flat level part of the coin) below the date as an acceptable area for the mint mark to be placed. They placed it where they thought was appropriate and gave it a good tap to apply the appropriate mint mark to the working die. That working die then is added to a machine and it starts producing those 1970-D Lincoln cents as you mentioned. A working die ( whether it was the obverse (front of a coin) or the reverse (back of the coin) could strike a few hundred thousand coins before it was worn or ready to fail. There were typically a dozen or so machines frantically hammering new coins at any given time. That means there would be at least 12 different locations of the "D" on the 1970-D Lincoln cent. As new dies replaced failing ones, a "D" was added to the new working die and added to the machine, adding more possibilities where the D mint mark would be.

As far as the placement, all of those coins look like they are in acceptable field (flat) area of the coin below the date.

But you are on to something else here. It is a good idea to know the placement of a mint mark. People who certify Re-punched Mint marks (RPM) and Doubled Die Obverses (DDO) coins can use the mint mark position to help tell if the coin is actually a particular RPM or DDO or Doubled Die Reverse (DDR).

CONECA has a website managed by James Wiles called www.varietyvista.com . Within that site is a list of coins that CONECA recognizes as a variety. Its a good place to use to get to know mint mark types, varieties such as a Doubled Die Obverse (DDO), Doubled Die Reverse (DDR), Re-punched mint mark and more.

Before you get excited about Doubled Dies or Re-punched mint marks, I suggest you research what worthless doubling is, like machine doubling, strike doubling and the like. The two websites mentioned in this post will help you identify a doubled die and a RPM correctly.

I visit this forum as often as I can, if you have any questions related to coins, feel free to ask.

[koinpro]

I'd like to make one slight "correction" to Gary K's excellent response. In his first sentence he says "The US mint employees had boxes of newly made "working dies" made from a master die." This in not actually correct. A Master Die is used to make what is called a "Working Hub" (also referred as a "Hob" by most of the old time and some of the newer engravers or referred to as a "Punch" in Canada). It's the Hub that is then used to make the working dies not the Master Die. The Master Die is only used when a Hub wears out or breaks and a new one is needed.

As an aside since we are on the subject it should be noted that there are times when this process is reversed. This is what I have coined as "Retro Hubbing". In this case a "Working Die" is used to create a Hub (most likely because neither a Master Die or Master Hub was produced as a back up). As such the Working Die will transfer any defects that are unique to that one die to the hub and the hub will then transfer those defects to the working dies and if a worn Working Die that has lost some details is used in this process, the resulting Working Dies produced from that sequence of events will be equally weak. Canada's 1975 Proof-Like nickel dollars with the "Detached Jewel" and some weakness in other areas is the result of Retro Hubbing. Interestingly, all those with the Detached Jewel at the rear of Queen Elizabeth II's tiara are the result of retro hubbing. All of those coins struck from hundreds of dies exhibit minor MD Hub Doubling while those with the attachment show no hub doubling which is the only evidence that the coins with the detachment are from dies made from a different hub.

Some of the Later strikes of the so-called "Friendly Eagle" Ike dollar will often exhibit muted die cracks that were seen on some of the earlier strikes due to this process. This situation had the Ike Dollar Group completely baffled until I explained to one of their members how it had to have occured. Canada has used Retro Hubbing for many dies/hubs in the distant past as explained in the book Striking Impressions that was sold by the Royal Canadian Mint a number of years ago (and can still be found on Amazon at very low prices)

In my work having Silver Rounds manufactured for me I have used the Retro Hubbing process twice. One time to make a hub for which I never had made a hub or Master Die in the first place but needed to make a new working die to replace one that was cracked and no longer met OSHA standards. I was able to have what appeared to be a die crack (but at this stage technically wasn't a crack) on the new hub by having my engraver remove the crack with graver tools (after which I sent the new die out to be hardened, polished, proofed out.

The second occurrence was when I decided to use the original working die cut by my engraver to knock out 1000 silver rounds for a customer that did not want to wait very long to get the marketing firm's order. So I had the die proofed out and used to strike 1000 rounds for that customer (and a few hundred for myself) and then had it sent to the company that makes my die blanks and hubs to make me a hub from that already used die. In this case the rounds from the Retro Hubbing process cannot be distinguished from the earlier strikes from my first use of the die since it only struck 1000+ rounds (and never cracked or exhibited any defects that could be transferred during this process).

For completeness I should note that John Wexler did indeed have permission to use the photo of Edgar Z. Steever punching Mintmarks into dies from Arnie Margolis. However that the image is now the property of Fred Weinberg and David Camire. So Wexler is crediteding Arnie for permission is correct since he got it from Arnie Margolis while he was alive. But if you see it in use by me or anybody who got it from me, Fred Weinberg should be credited as giving permission to use it. Before I used it I put a nice black border around it. If anybody uses that version (for which I don't care and I'm sure Fred doesn't either) please credit Arnie as the photographer and Fred Weinberg as the one giving permission for its use.

In my Coin World VIP Tour (as it was billed by CW) Learned that the Mint was getting between 1.5 to 1 million strikes per die before it was retired. I forget how many were struck when using them for Mint Set coins but it was a much smaller number at which point the die was retired for that use and used for regular business strikes. By looking at our current flatter-field Shield reverse now on our cents I'd guess they are now getting even more coins from a die.

Enjoy
KP