Reducing Machine

A Reducing Machine was a type of pantograph lathe used until the 21st century to manufacture coin dies. Prior to the machine's introduction, designs were cut by hand into metal dies by a specialist engraver. The reducing machine changed this by allowing artists to create designs on a larger surface area and then have them scaled down and cut into a die automatically. The most successful version of the machine, created by Victor Janvier, was used by mints all around the world, including the US Mint, which operated one as late as 2008, when it was replaced by CNC milling machines.

History

Contamin Pantograph

From 1836 to 1867 the US Mint operated the first die-engraving pantograph invented by a now forgotten French inventor whom the machine is named after. It used a rotating cutter to copy a design.^[1]

Hill Pantograph

During the mid 1800s Englishman C. J. Hill developed a variation of the Contamin whereby the electrotype was traced horizontally using a treadle. Hill sold his idea to William Wyon, the then chief engraver at the Royal Mint who sold a machine to the US Mint in September 1867.^[1]^[2]

Janvier Reducing Machine

In 1899, French engraver Victor Janvier patented a design which solved the inefficiency problem. By using twin cone belt drives that pointed in opposite directions dies could be cut much faster by increasing the speed as the cutting point moved outwards. After several days a reduction punch is produced, which is then used to produce working dies.^[3] Machines using Janvier's improved design were bought by the British Royal Mint in 1901^[4] and by the US Mint in 1907.^[5]

CNC Reducing Machine

Janvier's mechanical system simultaneously performed three operations: mechanically "scanning" a physically enlarged relief model, then reducing it, and finally engraving it into steel along a spiral track from the center toward the periphery.

The improved, redesigned, and digitalized concept replaces the physical relief model with a computer-generated one. The points of the digital model are guided onto the machining line using three stepper motors, thanks to proprietary software.

For this innovation, Milenko Topalov from Serbia (Vojvodina) was granted a patent in 2024. Milenko is a self-taught maker of numismatic replicas and a Guinness World Record holder as of August 1, 2022, for creating the smallest coin replica (2.73mm in diameter).

EXTERNAL LINK Royal Mint Reducing Engine webpage https://www.royalmintmuseum.org.uk/journal/curators-corner/janvier-reducing-machine/

References

^ ^a ^b "Reduction Machines at the Mint". 1881o.com. Archived from the original on 19 December 2016. Retrieved 26 June 2017.
^ "The Janvier Die-Engraving Pantograph". coinbooks.org. Archived from the original on 5 April 2018. Retrieved 26 June 2017.
^ "Design and Die Making Video Transcript". Royal Mint Museum. Archived from the original on 11 June 2017. Retrieved 26 June 2017.
^ Challis, C. E. (1992). A New History of the Royal Mint. Cambridge University Press. p. 541. ISBN 978-0521240260.
^ "How Dies are Made". doubleddie.com. Archived from the original on 12 July 2017. Retrieved 26 June 2017.

[1881o.com-1] "Reduction Machines at the Mint". 1881o.com. Archived from the original on 19 December 2016. Retrieved 26 June 2017.

[2] "The Janvier Die-Engraving Pantograph". coinbooks.org. Archived from the original on 5 April 2018. Retrieved 26 June 2017.

[3] "Design and Die Making Video Transcript". Royal Mint Museum. Archived from the original on 11 June 2017. Retrieved 26 June 2017.

[4] Challis, C. E. (1992). A New History of the Royal Mint. Cambridge University Press. p. 541. ISBN 978-0521240260.

[5] "How Dies are Made". doubleddie.com. Archived from the original on 12 July 2017. Retrieved 26 June 2017.

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