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Upsetting.  (2) The process of pre-forming the edges of round blanks prior to striking. Upsetting is a metalworking step necessary for coining pieces with dies and a collar, particularly intended for high speed coining presses. Blanking usually leaves sharp edges, shear marks and burrs on the metal disks as they come from the blanking press.

The upsetting process – called rimming in England and the machine is a rimmer – removes these burrs, marks and helps form better edges on the struck coin. (It is also called by the confusing term edge marking as well.)

By pressure and rolling, the upsetting machine accomplishes the following:  (1) removes the burrs and smooths the edge, (2) rounds the edge, (3) makes the blanks perfectly round, (4) thickens the edges for the raised borderedge thickening is a typical metalworking process – (5) makes every blank a uniform diameter, usually several thousands of an inch less that the aperture in the collar to be used in the press, and (6) reduces die wear.

Upsetting does not form the reeding on the edge – this is done by the collar – but it does prepare the blank so it can enter the collar aperture. By pre-forming the blank, up- setting's greatest contribution to coining is to reduce jams in the coining press, reduce the amount of metal displaced during coining, and with the thickened edge, helps form the rim which lessens wear on the coin design during circulation.

Collectors call the blank as it comes from the blanking press a type one or FIRST PROCESS BLANK; after it is upset and exhibits an upset rim it is a type two or SECOND PROCESS planchet. Both steps, of course, are necessary to create a coin planchet prior to the piece being fed into a coining press.

Upsetting is mandatory for any high speed coining operations, and it can only be performed on blanks that are round. Thus upsetting is not necessary for medal striking for several reasons:  the speed is slower, most medals are hand fed, struck with open face dies and not collar dies, plus some medals are struck on blanks of UNUSUAL SHAPE.

Upsetting helps reduce coining anomalies such as a FIN (caused by improper size blanks or coining pressure).  Also in production run pieces upsetting provides a rounding at the RIM/EDGE JUNCTURE (from the rounded edge of the blank). angle[RWB1] .

Although the use of the coining techniques of the aperture collar and upset blanks had been published in mint literature during the early 1800s, these processes were considered as closely guarded trade secrets at many national mints. Nineteenth century mint personnel were pledged not to reveal any facts about these techniques (presumably to prevent counterfeiting). The penalty was to have a hand chopped off.

History of upsetting.  The first concept of edge thickening came about when mint workers tried to treat blanks with edge lettering on a blank before it was struck. Pierre Blondeau was the first to do this in France, but he was enticed to come to London in 1649. He struck his first coins from upset blanks there in 1651. His primitive method was improved by Jean Castaing back in France in 1685. Both methods were similar in that they forced the blank between two grooved bars, one fixed and one that moved back and forth (by rack and pinion action).

Blanks were edge thickened by this rack and pinion method to the end of the 1700s. It was Matthew Boulton who improved the process of upsetting between 1788 and 1797 at his Soho Mint in Birmingham.

Boulton devised a way to force round blanks between a rotating grooved disk with a fixed bar in the shape of an arc also with a grove. He mechanized his rimming machine with this rotating disk and powered it by his steam engines. His large cartwheel penny of 1797 could not have been struck without first pre-forming the blanks by upsetting (what he called "rimming").

Ralph Heaton, founder of the Heaton Mint in Birmingham, obtained Boulton's

rimming machine and modified it slightly. He manufactured these riming machines and sold them to mints around the world through his company, Ralph Heaton & Sons. In 1859 the firm patented a method of feeding blanks into their rimming machine to speed up the process.

Other rimming machines were made and sold to mints by Taylor and Challen, a

mint equipment company also of Birmingham. This firm was in competition with Heaton.

But a dramatic advancement in upsetting machines came in 1860 when a

mechanic working in the Royal Mint, London, Meredith Jones, developed a different method of rimming, with the grove on the face of the rotating disk. His rimmer was called the "Jones Marking Machine" and could be easily altered for different diameter blanks.


C66 {1988} Cooper pp [early] 101-106, [modern] 193-199, 241.

excerpted with permission from

An Encyclopedia of Coin and Medal Technology

For Artists, Makers, Collectors and Curators


Roger W. Burdette, Editor

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