The E-Sylum:  Volume 7, Number 42, October 17, 2004, Article 9

ROCKER & ROLLER COINING PRESSES

  Michael Schmidt writes: "I made a slight error here -- I should
  have referred to the press used for the early Williow and Oak
  Tree coinages as a rocker press.  The rocker press used a pair
  of dies with curved oval faces and the planchet was squeezed
  between them with a rolling motion as they were rocked back
  and forth using a lever and gear arrangement.  Coins struck
  on a rocker press have a characteristic "S" shaped bend in
  their planchets.  (As the tree coinages do.)"

  Dick Johnson writes: "I purposely did not mention the roller
  press in my capsule history of coining press because of their
  inherent failure. In response to Michael Schmidt?s comments
  to my previous item on Coining Presses I can give the history
  of the attempts of a roller press to supplant the screw press
  (and later the Uhlhorn and Thonnilier coining technologies
  which not only are successful, but have been in continued use
  for over 190 years!).

  The roller die was invented by Kaspar Goebels in 1550 in
  Augsburg, Germany. The word for the roller die process is
  "taschenwerke" and the roller mill was called "walzenwerke."
  He attempted to get it accepted in Denmark, and later Spain
  without much success.

  In France Nicolas Briot in 1637 tried a similar roller press at
  the Paris Mint, failed there, took his technology to the Tower
  Mint in London, failed there, then was finally named mintmaster
  at the Edinburgh Mint in Scotland. He did have some success
  there in producing some large diameter coins on the roller press.

  The concept of roller production of coins - roll on the impression
  of both sides of a coin on a ribbon of metal, then blank it
  afterwards, that is, to cut out the circles after the design is in
  place. This was so alluring that it was tried again in the 20th
  century, by no less an industry than General Motors!  But they
  tried in the1960s and it failed again.  The process raised the
  temperature enough to melt the design off the face of the dies!
  This experiment is related by Eric M. Larson in an account
  published in Coin World (May 29 and June 5, 1995).

  There is also the concept of "upsetting" that is missing in roller
  die production.  Cutting out a circle leaves a burr on the trailing
  edge of any cut metal. Cut out the circle from the impressed
  ribbon of metal and you will always have a burr around the
  edge of one side. Upsetting prepares blanks not only by
  removing this burr, but makes the blanks completely round,
  and also slightly thickens the edge. (Collectors call blanks
  Type 1 before upsetting, Type 2 after upsetting).  An upset
  blank aids coining by making uniform circles and prevents
  jamming in a press.

  Someone may invent a better way to strike coins in the future,
  but don't look for this to be a roller press."

  Wayne Homren, Editor

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