Operation of the Mint's old medal press as used for medals and proof coins pre-1894

RogerB

“The striking of medals in the coiner's department of the United States Mint has for years been by means of the screw and fly press.

“The screw in this press is six inches in diameter, and there are three threads with a pitch of three inches. The double-lever attached to the head of the screw is thirteen feet in length, or six and one-half feet either way from the center of the screw, and upon the ends of the arms are mounted balls weighing about I 50 pounds each.

“Three men are employed in the working of the press, one to arrange the blanks to be struck upon or between the two hardened steel dies, while one at each end of the lever furnish the power to raise the screw, and then by a rapid movement cause the same to descend to the work, they being careful at the proper moment to step aside to avoid being struck by the recoil of the lever. Two and one-half revolutions of the screw give with all the force the men can impart a blow or pressure equivalent to 250 tons. In the striking of a four-inch diameter medal some fifty or sixty blows are necessary to complete the medal. The blank, which becomes hardened by the force of each blow, must be annealed each time, consequently, the amount of labor bestowed makes the cost of such medals quite high.”

Smudge

What time period is this from? Interesting post, thanks.

Zoins

Here's an image of a screw and fly press being used along with a photo of one:

https://www.thevintagenews.com/2016/03/03/the-early-modern-period-striking-coins-with-a-screw-press/

Coinosaurus

That's pretty cool. I'll view these 19th c. U.S. Mint medals with a bit more appreciation.

The only thing they don't answer is whether the guys in the Mint protected their ears, or if they all went deaf.

Ronyahski

@Coinosaurus said:
That's pretty cool. I'll view these 19th c. U.S. Mint medals with a bit more appreciation.

The only thing they don't answer is whether the guys in the Mint protected their ears, or if they all went deaf.

Huh?

RogerB

@Smudge said:
What time period is this from? Interesting post, thanks.

The quoted material is from 1894. It is part of a longer article about the changeover to a hydraulic press for proof coins and medals.

There was no hearing or sight protection at US Mints or other factories.

ricko

I bet it was a noisy place to work...as were many industries back in the day. No requirements for hearing protection or other safety measures that are common today. Cheers, RickO

RogerB

[More information is in From Mine to Mint]

Smudge

Thanks. Burly men I guess. Lots more noise with hydraulic presses probably.

CaptHenway

@RogerB said:

@Smudge said:
What time period is this from? Interesting post, thanks.

The quoted material is from 1894. It is part of a longer article about the changeover to a hydraulic press for proof coins and medals.

There was no hearing or sight protection at US Mints or other factories.

When did they start making all of the Proof coins on the hydraulic press?
We certified several 1895 Proof dollars during my time at ANACS. “Finning” (partial wire rims) seemed to be a problem on them.

Kudbegud

Very interesting. Thanks for posting.

RogerB

RE: "When did they start making all of the Proof coins on the hydraulic press?"

1894. A fin is a production defect caused by a mismatch between collar, planchet upset, and die. It is not directly related to striking pressure. (See MCMVII DE for excellent examples.)

ECHOES

@Kudbegud said:
Very interesting. Thanks for posting.

+1