Improving understanding of partial collar errors

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RogerB
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Improving understanding of partial collar errors

Post by RogerB » Thu Aug 06, 2020 12:43 am

This letter will help collectors better understand how partial collar error coins were created. I was not convinced that planchets might over-expand during improper annealing, but the Coiner says that is the most likely cause. Since Snowden had been Coiner several years earlier it's unlikely Bosbyshell was stating anything new.

April 21, 1884

Hon. A. Loudoun Snowden,
Superintendent

Sir:
In response to the letter of the Rev. J.A. Boyce of Stony Fork, Tioga County, Pa, addressed to you, enclosing a half dollar of 1877 struck in the Mint at San Francisco, handed to me for examination and report, I have the honor to state that in my opinion the piece is a genuine coin. It is one-1/10the grains light of standard weight, and resists the acid test.

There are two reasons to account for the appearance of the periphery – the most probable one is that the planchet became enlarged by overheating in the annealing, and was forced into the collar by the upper die – the lower dies striking it a moment later than usual.

The other reason to account for the trouble is the lower die may possibly have stuck in the collar after rising to enable a piece to become disengaged, and the upper die descending before the lower die loosened, forced only a portion of the planchet into the collar.

[RG104 Entry 1 Box 131 via NNP]

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PacificWR
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Re: Improving understanding of partial collar errors

Post by PacificWR » Thu Aug 06, 2020 2:02 am

Very interesting. Thanks Roger.

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LorenAlbert
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Re: Improving understanding of partial collar errors

Post by LorenAlbert » Thu Aug 06, 2020 10:25 am

Excellent. Thanks. In my limited knowledge of minting; I expected the planchet, if stuck in the collar, to strike the lower die rather than the lower die strike the planchet. I thought the lower die was stationary. Someone should write a book.

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messydesk
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Re: Improving understanding of partial collar errors

Post by messydesk » Thu Aug 06, 2020 1:41 pm

I'm not sure how the first scenario would produce a coin that's well-struck on both sides. If the anvil die was in the correct vertical position, the hammer would have to force it all the way into the collar in order for it to make contact with the anvil, thus giving it a proper edge.

The second scenario, with the anvil not being fully retracted between strikes, makes more sense to me.
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RogerB
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Re: Improving understanding of partial collar errors

Post by RogerB » Thu Aug 06, 2020 1:50 pm

LorenAlbert wrote:
Thu Aug 06, 2020 10:25 am
Excellent. Thanks. In my limited knowledge of minting; I expected the planchet, if stuck in the collar, to strike the lower die rather than the lower die strike the planchet. I thought the lower die was stationary. Someone should write a book.
There were two "varieties" of toggle press mechanism in use in the 19th century.

The German Ulhorn-type had a fixed plate to hold the collar, and the lower die chuck rose through
the collar to push the completed coin out. This is what Franklin Peale used when he created his
simplified version in 1835-36.

The French Thornier-type had a moveable plate to hold the collar, and the lower die chuck was fixed.
The collar rose for the strike and descended to push the completed coin out.

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Longstrider
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Re: Improving understanding of partial collar errors

Post by Longstrider » Thu Aug 06, 2020 2:18 pm

@RogerB Very cool. Keep these reports coming. So very interesting. Thank you.🐍

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