Why Is My Coin Not A Doubled Die?

Why is my coin not a doubled die?
Some have asked that question here many times. But in order for a coin to be a doubled die, it has to come from a die that has hub doubling, hub tripling or hub quad, doubling on the die. A large number of posts here are determined to be Machine Doubling. What does that mean? It means the coins devices were altered, after the strike, damaging the fresh new coins devices, that was just struck. The die movement, after the strike bumps, hops, swings or several of the previous happening all at once, damaging the coins devices. The die is a normal die and die movement after the strike caused this damage. This appears as a flatten edge on one side of the devices. Most often the coins will have a contour on the devices. What does that mean? The devices on a coin are tapered. Narrow on the tops of the devices, and wider at the bottom of the devices. This allows the coins to fall off the die after the strike.

If this was the other way around narrow at the bottom and wide at the top of the devices, the coin would be stuck into the die and never come off. But when viewing the coin the normal sides will show the lighter color on the tops of the devices, and the wider areas will look darker in color and they reach the fields.

Note on these devices? The right sides of the devices have the lighter to dark appearance. But on the devices on the left sides where the Machine Doubling happened, you don't see the contour, so you see light at the top and even lighter color on the bottom of the device. Why? Because that area is flat. flat surfaces tends to reflect light a lot more than and a contoured device. On a doubled die you can sometimes see a double contour when the spread is strong like the lower example above.
But there are other issues that do not make a coin a doubled die. This is the point of the discussion. First we will consider how dies are made:

Note the top of the image it mentions: Galvano. That is the plaster/epoxy model the coin is to look like when the coin is finished. But this needs to be reduced and the design transferred on to a Master Hub (Positive relief like a coin). Note on the image it mentions only one is made. Then it is transferred on down the line on this image, Master Die, Working Hubs (Positive design like coins) and then the Working Dies.(negative to strike the coin in positive) The Master die (a negative design to make hubs with) usually there are only two made. (sometimes more when there is an issue that is noticed on the Master die, but sometimes not noticed until later on) Those hubs and dies are pressed into the stock material for the Working Hubs. (Positive relief several made) Then the Working Hubs are used to create dies. (Lots of them)

So what is master die doubling?
We hear about doubled Master dies. What does that mean? The first Master Die is created from the Master Hub. If the Master Die has doubling on it all hubs will later have that same doubling and several dies, that will have that same doubling.

What happens if a master hub has doubling?
So you will have a large percentage of dies with the MDD and some without it that was created on the other die. So there is a 50% chance of the whole coinage of that denomination that year, could all have master doubling. This happened in 1972/ All three mints dies have the same master die doubling.

While this looks like a doubled die, it is always the same on a very large percentage of the coins struck that year.

Why aren't coins called doubled dies that has master die doubling?
When doubling is passed on a lot of coins the same it will make them common. Some may argue that the doubling is on the die? But the collectable doubled dies, are when the doubling is created on the die. The larger the spread, the more interest is shown to collect them. If they are common, the are not desired to be added to a collection. Finding them is easy. A true doubled is hard to find. And Machine Doubling is more common that MDD coins.

How do they determine MDD ( Master-Die-Doubling) and WHD (Working-Hub-Doubling) is affecting doubled dies I'm finding?
The doubling on the dies are exactly the same from die to die on WHD. Back when the mint marks were added to the dies, you could tell that that this happened, because of the mint mark locations being different. So several dies were created from a Doubled Working hub. But since 1990, the mint marks on the dies are part of the design.. The locations on all mint marks forward from then, are in the same location, from the Master Hub. So then you have to look closer to see if the same doubling is noticed. But when the dies show different markers/cracks/chips breaks, ETC, then you know it is an issue with a doubled working hub.

What happens if a Master Hub has doubling?
This can happen, but they check for this a lot closer as that could make creating everything all the way down, a huge expense. If there is an issue, they create a new Master Hub.

What can happen on a Working Hub doubled die, that still makes it, a doubled die?
John Wexler is showing the one that are Master Die Doubled, Working Hub Doubled example on the years he has noticed this. An interesting one is on a 1966 SMS half dollar:

Read the red/black box on this image. This example has the doubled Working Hub 002. doubling the die. This die has a doubled die, besides, the Working hub doubling. Did you note why it is different than just a Working hub die? I put the extra affected areas added to the full coin image. The doubling also happened when the die was being created. Making this a doubled die despite being a Working Hub doubled example. So because hub doubling from the dies creation, Working hub and Master Die Doubling can happen, This is not the first time this has happened. On the 1972 DDO-009 it is a MDD with a doubled die on it. So it is the creation on the die itself that makes it a collectable Doubled Die. Probably be a tough coin to find on the 1966 half dollar, being it is a SMS coin, less were struck of them.

Why do some attribute them as working hub doubling, and why others do not?
Some may not realize it has been discovered that it was an issue with a Working Hub. So they haven't discovered that yet. Some are more open minded and recognize this issue and have to redo all their numbers for their dies. Filling in the holes as time goes by.

So I know this is a tough subject. But after working with is for a while it will all sink in.