A look at the Reverse changes between IIa & IIc shield nickel reverse hubs

[dooly]

 

I know that there were lots of hubs used for each of these years but i was interested to see what would show up if you overlaid the 2 hubs .. and if you line up the 5 this is what you get .. so in supposition that the 5 did not move or change (unlikely) but i could not get the letters to line up..

[messydesk]

Send me a PM with the two layers of the overlay separated out and I'll show you a neat overlay trick that will really make the differences clear, and tell you how I did it. I'm assuming you used Photoshop.

[physics-fan3.14]

Were the letters and numbers hand punched into the dies at this point?

[Mr.Mcknowitall]

Yes.

Resprectfully,

John Curlis

[skippy]

The entire reverse was created by hand punching. Someone even found the purchase record for the big 5 punch. Stars and letters were definitely hand punched.

 

So it's not a given that the 5's would line up relative to the edges of the coin. But it's a good starting point for showing where star and letter placement changed.

 

Oh, I'm not aware of how denticles were created at this time. If someone knows, please fill me in.

 

There are more than 2 reverse hubs for shield nickels. You can see the rest here:

 

Reverse Hubs

 

[Conder101]

The master die was hand punched, not the individual working dies. In the early years they punched a master die and raised a working hub from it then used that to make working dies. Later they went to the Master hub/master die/working hub/working die system we are more familiar with today.

[messydesk]

Here's a different take on an overlay of the IIa, IIb, and IIc hubs using the pictures from the website skippy posted, although perhaps not what you're used to seeing when you think overlay. It produces an interesting result where you can still correlate each coin with its features. Step-by-step, assuming a basic understanding of Photoshop layers, here's the process:

 

1. Put each picture in a different layer and make a traditional overlay, making rotation, translation, and scaling adjustments to line up fixed reference points, in this case, the 5. This shows there is a difference, but it makes it hard to tell what they are.

 

 

2. Run a high-pass filter on each layer, with a radius of 3 pixels. (Only one layer shown). This accentuates the edges and makes the background of each layer (i.e., the blank fields) all the same gray level.

 

 

3. Adjust the curves on each layer to make the fields (currently gray) black and the edges (currently black and white) white. The curve adjustment looks kind of strange, but this does the trick. (Note: while the edge detection filter could be used to replace this and the previous step, the results don't look as nice.)

 

 

4. Apply the photo filter (under Image->Adjustments) to each layer using distinct colors. Since I had three layers to merge, I chose red (IIc hub), green (IIa hub), and blue (IIb hub). For two layers, green and red work nicely. Set the density of the filter to 100% and uncheck "Preserve Luminosity".

 

 

5. Set the blend mode for the layers to "Lighten." The result will look like this:

 

 

The 5 is essentially white. Severe inconsistency in punch positions seem to be between 11:00 and 2:00, where you see all three colors distinctly. Magenta (red+blue) is where IIb and IIc line up well (TED S). Cyan is where IIa and IIb line up well (left denticles, UNI). Yellow is where IIa and IIc line up well (parts of some stars). You can also see the ring of red denticle edges inside the cyan denticles on the left side, showing how the IIc denticles are shorter than the other two. There may be some error in the registration step, and by using points on the 5 as reference points, this misregistration will be magnified toward the edges. I think I got it pretty good, though.

[dooly]

Top job that love it should be the new cover for the next book .. i could not help myself and i had to fiddle with it .. hope you don't mind .. also can i use it as my new avatar please

 

 

[RWB]

Nice work!

[messydesk]

Looks great with the marks cleaned up! By all means go ahead and use it as you wish. Glad you like it.

[Keigwin]

Very nice. I like it. Nice work John and dooly.

Lance.

[dooly]

Looks great with the marks cleaned up! By all means go ahead and use it as you wish. Glad you like it.

 

cheers ..

[skippy]

The master die was hand punched, not the individual working dies. In the early years they punched a master die and raised a working hub from it then used that to make working dies. Later they went to the Master hub/master die/working hub/working die system we are more familiar with today.

 

Yes, that's what I meant. Thanks for the clarifications.

[skippy]

Nice work on the overlays!

[dooly]

Tried it as my avatar .. did not work never mind

[RockMyAmadeus]

Very cool.

 

Speaking of which, anyone know what prompted the diameter change between Shields and Liberties...?

[Conder101]

My understanding was that they thought it would help with the die cracking problem. And it may have done some good. The V nickel dies still cracked, but not to the extent the shield dies did.

[skippy]

Conder101's answer matches my understanding. The striking force on a hard metal spread over a larger surface area reduced die stress.

[messydesk]

The design may have had a lot to do with it as well. I can picture that the wreath on the shield nickel obverse together with the ring of stars on the reverse provided more leverage for the expanding metal to tear apart the die than did the Liberty portrait paired with the reverse wreath.

 

Would the shorter, fatter, deeper denticles on the Shield IIc reverse made any difference other than being more durable?

[RWB]

As Conder101 noted -- The change in diameter was made to increase the coin's thickness and reduce the diameter in an attempt to cure some of the die failure problems. Reducing diameter allowed less total force to bring up the design, and the thicker planchet made more metal available to fill the design. Also, note that fine lines were well-known starting points for cracks.

[skippy]

The change from shield nickels to liberty nickels was in the other direction, decreased thickness and increased diameter.

 

Just to make sure we're all the words the same way: If you had a stack of a certain number of coins, thicker coins would stack higher. Changing only the diameter would not affect the height of the stack.

[Conder101]

Changing only the diameter would not affect the height of the stack.

The height of the stack is also affected by the strength of the strike. Better struck coins (higher pressure) have more fully struck up rims and so stack higher. So it would be possible for better struck thinner planchets to stack higher than poorly struck thicker planchets.

 

Also changing the diameter would affect the height of the stack because the weight was not changed. If you hold the weight constant and increase the diameter, the thickness of the blank HAS to decrease.

[skippy]

Changing only the diameter would not affect the height of the stack.

The height of the stack is also affected by the strength of the strike. Better struck coins (higher pressure) have more fully struck up rims and so stack higher. So it would be possible for better struck thinner planchets to stack higher than poorly struck thicker planchets.

 

Also changing the diameter would affect the height of the stack because the weight was not changed. If you hold the weight constant and increase the diameter, the thickness of the blank HAS to decrease.

 

For simplicity, I was assuming that the devices on the coin do not strike up higher than the rims. That makes the coins stack poorly, and is not the usual practice of the mint. I could have noted my assumption.

 

For the latter point, I didn't say anything about holding the weight constant. In fact, I was assuming you would not hold the weight constant, but that you would hold the thickness constant. Again, I could have noted the assumption, but it sounded even more confusing when I tried to do so.

 

The only point of the commentary was to try and make sure that we were using the terms "diameter" and "thickness" the same way, as it appeared RWB might not be in his most recent commentary.