ENGINE-TURNING
Engine-turning is an engraving technique where very fine grooves are carved with the help of a machine that allows for precise and regular machining of these grooves.
The most artisanal technique requires a traditional engine-turning machine that removes material with a graver. All precious materials can be engine-turned, from various types of gold to platinum and mother-of-pearl. Once the choice between the straight line technique and the round engine-turner is made, the machine is adjusted based on the pattern and material to be worked.
There are two categories of engine-turning machines depending on the type of work to be done: the straight line machine, which allows for linear decoration, and the rose engine, which allows for circular decorations where the grooves interlock and intertwine.
The quality of engine-turning depends on adhering to certain conditions: The graver must be adjusted according to the material used and the desired depth. A correct graver height is also essential to ensure the uniformity of the pattern. The piece must be laid flat to allow the guide to be in even contact with the surface all around.
As a traditional craft, engine-turning often reproduces ancient, classic designs. However, an engine-turner may also innovate to enhance brand identity. Their talent requires a good knowledge of mechanics and the machines that need to be renovated and maintained.
The piece to be engine-turned is mounted on the head of a lathe, in such a way that it can have a rotary movement. The end of the lathe’s spindle is held by a lever arm that pivots on the workbench itself, allowing the spindle to move forward and backwards. This movement is guided by a cam – called a “rosette” by artisans from Geneva – attached to the spindle with a fixture held to the workbench, highly visible.
There is a series of these rosettes with different shapes next to each other. This is the principle of the lathe. The combination of rotation and oscillation requires a fixed tool for the undulating cut. This graver must be very well executed and sharpened, and it is quite an art for the engine-turner, who, moreover, has a job that requires great attention.
The second type of traditional engine-turning lathe – the “straight lines” – is more compact, although its mode of operation remains unchanged. These machines are more commonly found today to save space. Moreover, the “straight lines” primarily produce rectilinear motifs.
The illustrated motifs carry very different names depending on their size and shapes:
- barleycorn
- rice grain
- clous de Paris
- crémaillère
- flinqué
- alternating flinqué
- old basket
- alternating basket
- basket
- circular basket
- radiant sun
- liseré
- fillet
- waves
- moiré drapery
- fabric
- radiance
- rosette
The engine-turner must be a very skilled artisan to stop the movement of the lathe in time to prevent the graver from cutting into the rest of the decoration. Unable to stop until the round is complete, they must exercise patience. Three to four passes in the same groove are sometimes necessary to achieve sufficient depth to capture light and give a mirror effect to the piece. Until the last second, nothing is clear, and it happens that after hours of work, the engine-turner must start from scratch.
Engine-turning was often used under a layer of transparent enamel; strokes of the graver forming sharp, tight, and equal edges gave a shimmering reflection. These watch backings were called “flinqué” cases.
Engine-turning is an ancient intaglio engraving technique that involves removing material to create regular and repetitive grooves on a metallic substrate. The goal is to produce very closely spaced grooves or interwoven patterns that play harmoniously with light.
Unlike hand engraving, which can create different forms such as landscapes or animals, engine-turning allows for the engraving of precise motifs repeated identically. Engine-turning is purely decorative; it has no function other than the emotion and pleasure it provides.
Engine-turning does not originate from watchmaking; it existed long before and was used on materials such as mother-of-pearl, wood, or porcelain. Horology appropriated this technique in the 18th century to make it a regular and refined element of decoration reserved for the most prestigious timepieces.
There is some divergence over the origin of the term. The technique of engine-turning is said to have been named after a worker called Guillot who allegedly “invented” it. This claim is repeated in the French language dictionary compiled by Émile Littré (1801-1881) in the 19th century, who himself got it from the 1750 edition of the Etymological Dictionary of the French Language by Gilles Ménage (1613-1692), a prominent grammarian and historian of the French language.
This version is contradicted in the 19th century as well. The Etymological Dictionary of the French Language (8th edition) by Auguste Brachet (1845-1898) informs us that “guillocher” derives from Guilloche, the name of the inventor of ornaments called “guillochis”.
Eugène Jaquet (1884-1951), a Swiss horology historian, writes that a certain François Guérint from Geneva is the inventor, although he does not cite his sources. Engine-turning was practised in Geneva around 1670, which seems unlikely given that it was over a century before Guérint’s birth, making this claim improbable.
Etymologically, “guillocher” is a 16th-century term that may come from the Italian ghiocciare (“to drip”, “to dribble”), itself a blend of goccia (“drop”) and ghiotto (“glutton”); it is assumed that ghiocciare means “to ornament with interlaced lines” due to the architectural sense of the Latin gutta, the Italian goccia, and the French goutte.
Another suggested origin is that the term could be derived from guille (“stick”), a variant of quille (“skittle”) because of the shape of the ornaments (Alain Rey, Historical Dictionary of the French Language, Robert Dictionaries, Paris, 1992, 6th edition, 2022).
Initially applied to jewellery, mainly female accessories such as powder cases, mirror backs, etc., engine turning was used as early as 1786 by Abraham-Louis Breguet (1747-1823), who is almost certainly the first to use it for metal dials. This form of decoration was favoured by the master watchmaker, who used it extensively. His universally recognisable motifs were named, among others, “clous de Paris”, “rack”, “flinqué”, “barleycorn” and “rice grain”, or “old basket”. He would be followed by many other watchmakers.
Engine-turning as a freeform engraving on watch cases only appeared around 1770 and was very rare before 1790.
Over the centuries, engine-turning machines have been refined, especially in the 18th century, to work with precious metals. This technique experienced an extraordinary boom throughout the 19th century, but then, went through a lengthy period of neglect. Training in engine-turning gradually disappeared in favour of engraving. For decades, the lack of interest in this art led to a marked decline in the activity.
Against all odds, the 1980s saw a modest resurgence of interest in this age-old technique, coinciding with the rebirth of mechanical horology.
Since the 2000s, major brands have revived it within their manufactories, and independent watchmakers have shown an interest in passing on this expertise. For instance, Kari Voutilainen has launched an ambitious engine-turning school project by hiring George Brodbeck – the 2023 Gaia Prize winner – and barely saving several traditional lathes.
Despite digitisation, engine-turning remains an ancestral technique that allows for the creation of unique pieces. The machine then becomes an extension of the engine-turner’s hand because it is they, based on their sensitivity and experience, who apply the necessary pressure for engraving to avoid any irregularities.
For hand engine-turning, it is the piece that moves in front of the fixed graver, as opposed to milling where it is a rotating tool that moves along a piece.
Each piece engine-turned by hand will have the particularity of revealing brightness and creating a sense of relief, thus giving a volumetric effect.
Specialized enterprises and artisan engine-turners are now very rare. Engine-turning is pure craftsmanship. There is no school for training and the necessary machines are no longer manufactured.
Prestige brands resort to very rare ancient machines which they restore. The pieces to be engine-turned are particularly cared for in terms of flatness to avoid any deformation of the motifs. They are also softened and matted with finishing paste, to highlight the marks of the guide during the actual engine-turning process.
Engine-turning calls upon qualities that are as much artistic as they are technical, notably mechanical. The complexity of this work and the necessary skill limit this type of decoration to high-priced watches.
Engine-turning machines have not been manufactured since the 1960s. The machines are therefore also true collector’s items. The oldest functioning machine dates back to 1770. It belongs to an independent engine-turner who handles it with care.
It is often the craftsmen themselves who repair their machines when they break down.
Engine-turning patterns can also be achieved with CNC machines, comparable to those programmed for engraving. This method is suitable for large series but does not allow for any customization. The motifs are often developed in digital design before being produced.
Machines are taught to reproduce the techniques of manual engine-turning. This means that the artisan knows how to perform manual engine-turning and has all the necessary experience to use these machines. An operator is capable of doing machine-controlled engine-turning but would approach it solely from a mechanical perspective, and the result would not be identical. It is the engine-turner who is responsible for the piece they make. It is they who have watched each line being drawn one after the other, so it is they who can attest to the quality of the piece.