The revolution of 1835-37

[jtryka]

No, I am not talking about a political revolution, but a revolution in coin production! I just read an interesting article in the most recent JRCS Journal (for those of you who don't know, JRCS is the John Reich Collectors Society, a group of collectors devoted to the study of gold and silver coins minted before the Liberty Seated design, website: www.jrcs.org). So, this might be a little esoteric for some, and for the experts among us, my thoughts may be somewhat simplistic, but I thought there might be some interest in the early minting process. So here goes nothing!

 

The article was entitled, "Early U.S. Minting Methods - Part II: Die Sinking" on pages 4-10 of July issue. Basically, the early production methods for US Coins involved the creation of a master hub, and then a master die from the master hub, then working hubs were created from the master die, and then working dies from the working hubs. The mystery comes in the details. These early hubs and dies were created with just the central designs, while the mint engravers were forced to put the edge details (date, stars, lettering and dentils) as well as the detail of the shield for coins with an eagle/shield reverse design. This no doubt was a LOT of work for the mint, but the bigger question was why? Why was this work necessary, especially since European mints were sinking complete dies for some time.

 

Some theories have arisen, but the author debunks them. Taxay in "The U.S. Mint and Coinage" put forth the idea that the incomplete master dies were used to extend their lives since the steel and hardening processes used by the mint were inadequate. But, the author's review of mint records shows that the steel and hardening processes were identical to those used in Europe. Breen thought that the mint's presses were not powerful enough for the task, and that only new steam presses could do it. This again cannot be true since the European didn't use their steam presses for hubbing, and in fact the US MInt used a screw press to hub complete dies for seated dollars in 1835 or 1836 (before the arrival of the first steam press) and continued using a screw press for hubbing at least until the arrival of the first hydraulic press in 1893.

 

It seems the answer lies in a field trip that Mint employee Franklin Peale made to Europe in 1833. He went (with the blessing and permission of mint officials) to learn from the European mints how they hub complete dies. It seems the mint's inability to hub full dies was the result of their lacking an appropriate method, rather than the raw materials or equipment. During the hubbing process, the steel goes through a process called work hardening, where the steel becomes harder as the design is stamped into it. In addition, metal rises up at the rims further inhibiting the transfer of the full image. The Europeans used a multi-step process that involved heating and machinging the dies between each step to mitigate the impact of work hardening.

 

So when Peale returned in 1835, he brought these new methods with him, as well as a new "portrait lathe" from France. These developments allowed the mint to make partial master hub and master dies, but then add all the details to the working hubs to make full working dies, thus eliminating a lot of engraving work that used to be done directly on the working dies. All of this was a giant leap forward in methods that no doubt contributed to the revolution in US coinage that occurred in the late 1830s, like Gobrecht dollars, and the Liberty Seated designs on silver and the Coronet designs on gold created by Christian Gobrecht.

 

That's the summary of the story, I hope I didn't put any of you to sleep!

[ursabear-migration]

Interesting post! I haven't read the journal, and it didn't put me to sleep...

 

So what I want to know is about the master hub technique... Are the machines used at the time of this coinage revolution the same ones that they're using now? I read somewhere once that the hub tools are over a hundred years old. Inquiring minds want to know...

[jtryka]

No, they no longer use the screw presses (at least as far as I know), however they may still use the hydraulic presses that were introduced in 1893. That would be over 100 years old, however I will defer that answer to someone that is more knowlegable on current mint techniques. Also you must remember the change in the hubbing techniques made in the early 1990s, though I am not sure of the details of that change, all I know is that afterwards the relief of coins dropped and they started really looking bad!

[lclugza]

The relief of US coins was lowered in the 1990s to accomodate the "single squeeze" hubbing technique (which made the designs look awful, in my opinion; bring back the original relief designs!)

If I recall correctly the old screw press was used to make Proofs through 1894, and also Charlotte and Dahlonega made their coins with screw presses- at a time when Philadelphia (and perhaps New Orleans and San Francisco, too?) were using steam presses.

Interestingly, the date was punched into each working die by hand until 1909, when it became part of the master die. For the new gold designs in 1907 and 1908, the date was also part of the master die.

[jtryka]

As an illustration, I decided to link some photos of my favorite bust half produced from dies made under the old method! Sorry for the bad lighting in the scans but it was the only way I could come close to capturing the colors in the rim toning.

 

1827 Obverse

1827 Reverse

[Oldtrader3]

Modern coin presses, over about 16 tons, are primarily over center (eccentric linkage) flywheel, variable speed AC Electrical motor contolled. The last time that I read anything about the Mint processes, they were installing Bruderer 40 ton and up, (Swiss made) high speed (up to 700 strokes per minute) electric presses. They are the creme-de-la-creme of punch presses even when I was involved in progressive die press forming, years ago.

 

Smaller production presses <16tons are normally done with a hydraulic press and a pneumatic hitch feed. This is a slow process limited to about 60 stokes per minute.