VOCABULARY TERM: PRESSES, PART 1

Presses and Pressroom Practice. The machines in which coins and medals are struck and their operation. Presswork and presses replaced hammer coinage with coins created manually one blow at a time. Presses have evolved from manual hammer and screw presses to mechanical machines that spew out tens of thousands of pieces struck an hour in modern times. Factors of impression, speed, control and maintaining sustained quality have been important in press design and construction over the years. The pressroom – usually with presses of several makers or types – is where coins and medals come to life by die stamping under the watchful eye of a skilled pressman, the press operators and their foremen. As the need for coins increase, national mints have banks of coining presses, long rows of presses capable of spouting out large quantities of struck pieces.

Basic considerations. Presswork – striking and coining – all imply the manufacture of metal pieces by stamping with a press, the controlled force of form and image pressed into metal with dies. This process is cold coining, where the blanks are struck at room temperature (to transfer the design in the sharpest detail possible). Cold coining is in contrast to heating the blanks, called forging, (see drop forge). Striking a flat blank, as for coins and medals, is the meaning of coining (in metalworking); when more evolved work is performed, as bending or drawing, it is called pressing (outside the scope of this encyclopedia).

Historical Development of Striking Presses

For the first 2300 years of coinmaking, there were no presses. Coins were made one at a time by hammering. A blank of metal was placed between dies and a sledge was applied to the top die. Production was slow, and required the strength of a sturdy man who could wield a heavy sledge. With another workman willing to hold the two dies in place, remove struck pieces and replace with a fresh blank, the production was increased. This manual process, known as hammered coinage, proceeded under the management of a moneyer; it was the major method of coinmaking from 640 bc until as late as 1662.

Hammer press. Instead of a man wielding the sledge, why couldn't the sledge be lifted by a pulley and dropped down a channel to affect the blow? This was the concept Lenardo da Vinci (1500) had when he theorized how sheet metal could be blanked, and the blank be struck. His concept was brilliant, he had the same press doing both operations back-to- back, where the operator would do first one, then the other. We have no record that a Da Vinci press was ever built, but a press for striking only, similar to Da Vinci's concept, was used in Saint Petersburg, Russia, at an unknown time (probably long after more advanced presses were in use in Europe).

Primitive hammer presses (called klipwerk) were in operation for over a century in Germany and Sweden prior to 1763 when they were illustrated in a German encyclopedia. In Sweden the concept of the hammer was modified to a tilt hammer press. Powered by men or horses on a circular tread mill, the power was transferred by a capstan, this raised an arm with the hammer on the end; it would then trip and fall for the blow, the die slamming into sheet copper. The copper plates were heated before this striking, and the plate was moved from a center strike to the four corners where the die struck there as well, all in quick time. This is the well documented method of manufacture of Swedish plate money from 1644 to 1776.

Screw press. The screw press for striking coins was "invented" in 1506. An Italian, Donato Bramante (1444-1514) modified an existing press (perhaps a fruit or olive press) that year for striking lead seals for Pope Julius II (1503- 13). Renaissance artist Benvenuto Cellini used such a press in 1530, again for Papal seals, but further, he illustrated it in his book on goldsmithing.

The screw press was further developed by Max (or Marx) Schwab in Augsburg, Germany, in 1550, who also improved on the rolling mill and draw plates for preparing metal for blanking. The rolling mill was immediately accepted by goldsmiths in Germany, but Schwab wanted his equipment used for striking coins. He was unsuccessful in selling his equipment to the Venice Mint, where he first offered it, but the French ambassador learned of his improvements and ordered a set of his "engines" for the Paris Mint. These were installed in 1751 and operating early in 1752.

While the screw press was a major improvement it took more than a century to replace entrenched moneyers and hammered coinage. Moneyers fought the innovation despite the fact coins could be struck with a screw press in quicker time creating a far more uniform coin (and a better rim). The screw press was introduced at the London Mint in 1551, the moneyers revolted, the screw press rejected, and it was not until 1662, 111 years later that it finally was in full use there.

The same thing happened in France. Schwab's screw press was introduced to strike coins in 1552, but it wasn't until 1641 when coins were struck on a production basis. The development of the screw press, delayed for over a century, was then widely accepted at mints around the world. It was first powered by men, and continued so, but some mints adapted it for water power, then for steam power.

Roller press. Development of the roller mill led to the concept of impressing the rolled strip with the designs first, then blanking afterwards. The idea originated in Germany, but it was Nicholas Briot, who tried it first at the Paris Mint (1606-25), then at the London Mint (1633) and finally at the Edinburg Mint (1635-39). His concept was unaccepted until Edinburg where he accomplished coinage by roller die (taschenwerke). Despite these early attempts in Germany, Scotland and Spain, this form of coining never surpassed the mill and screw, of rolling the metal, cutting out the blanks first, then striking individual coins.

Development of Coining Presses

What the Industrial Revolution brought to coinmaking was the concept of how to do better repetitive steps, to improve the mechanization of striking coins. A blank had to be brought to a position where it could be impressed with both obverse and reverse dies, then the struck piece had to be ejected. A German, with great mechanical insight, best solved this task.

Uhlhorn adapts the knuckle-joint to coining presses. In 1812 Deitrich Uhlhorn of Grevenbroich, Germany, began experimenting with striking. Instead of one die going up and down (as on the screw press) he employed a knuckle-joint to allow one die to retract enough for the piece to be ejected, the next blank inserted, and the continuous action controlled by a flywheel. This was brilliant and it worked.

By 1817 Uhlhorn had perfected this press; he patents it and begins building presses in a factory he establishes. His first sale was to the Berlin Mint, followed by other mints as they learned of his new press. Uhlhorn, and his sons after his death in 1837, were to build more than 200 presses over a span of sixty years.

Knuckle-joint press improvements. With continued use, other improvements were adapted to Uhlhorn's knuckle-joint press. The layer-on of placing the blank in position was one of these improvements, as was the feeding mechanism. A Frenchman in 1833 in Paris, Thonnelier (first name unknown) was to do more to improve Uhlhorn's press than anyone. But he did not manufacture presses, he had no factory, he supplied drawings for presses to be built by local constructors.

The automatic feed eliminated exposure to loosing fingers as is present in all hand fed presses. Prepared blanks were fed by hand into a tube that brought the blanks into position. Later improvements were made by Taylor & Challen which made Uhlhorn-style presses under license. Even in the 20th century, as late as 1961, Horden, Mason & Edwards placed the toggle mechanism beneath the feed table for a final improvement.

Modern coining presses have reduced the size of the flywheel, enclosed the mechanism with a covering (no moving parts exposed) and have changed the feed to an indexing plate. Some presses continue a horizontal feed with vertical die movement; but one has a vertical feed with horizontal die movement. Modern presses are manufactured by Schuler and Grabener in Germany, by Reinhard & Fernau in Austria, by Heaton, Taylor & Challen, and Horden Mason & Edwards (now a division of America's Cincinnati Milacron) in England, by Raskin in Belgium, and by Arboga in Sweden.

To read the complete entry on the Newman Numismatic Portal, see:
Presses and Pressroom Practice (https://nnp.wustl.edu/library/dictionarydetail/516539)

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