What Is A Skeletonized Watch? A Simple Question With A Complicated Answer
Openworked, skeletonized, open dial, skeleton dial – they’re used somewhat interchangeably but they don’t mean the same thing.
The various terms used to describe a watch in which some part of the movement is visible or in which the dial is to some degree reduced or absent in order to show the dial side of the movement, are used without a great deal of precision but there are in fact some significant differences in what they mean. To begin with, there are of course conventional watches in which the movement is not visible at all – a solid caseback and a solid dial, which was pretty much the only option you had until the earliest display backs were introduced (the earliest commercially produced watch with a display back that I’m aware of is the Omega “Kleerback” De Ville which started production around 1962). One very important early pioneer in the use of open dials was Bulova, which introduced the Accutron Spaceview, which was originally introduced in a gold case in 1960 and was at first intended to be a demonstrator model for dealers.
Demand turned out to be much higher than Bulova anticipated and they began to offer Spaceview watches in stainless steel cases starting in 1962.
The Structure Of A Watch Movement
To understand the different types of openworked watches it helps to know a little bit about how watch movements are constructed. A simple watch movement consists of a mainspring barrel, a gear train or going train, and the escapement and balance. These are all on the back of the watch, and are held in place on the mainplate by bridges.
The back of the movement isn’t called that in watchmaking; instead, that side of the movement is called the top plate, as it’s what’s uppermost when a watchmaker’s working on a watch.
The opposite side is under the dial and usually not visible. There’s not much to see there – there are the motion works, which actually move the hands (driven, in a traditional movement, by the center wheel pinion, which pokes through the mainplate from the top plate side) the keyless works, for winding and setting, and that’s it. Additional components for complications can be found on the bottom plate side of the movement as well. These can be anything from a simple calendar which adds few additional parts, to more photogenic and sometimes extremely complicated mechanisms like a moonphase, or the components of a minute repeater or perpetual calendar. Under-the-dial-work is generally called “cadrature” and open dials are most interesting when there is an interesting mechanism to look at.
This is not to say that there are not wildly different levels of beauty and quality of execution in keyless and motion works, by the way. One great example is from Roger Smith – you could pretty much pick any Roger Smith movement secure in the knowledge that what’s hidden under the dial has been executed with as much care and craft as what’s on the top plate side.
One point worth making just as an aside, is that Roger Smith’s movement finishing is very different from the conventional Swiss-French style, which is what most of us have been trained to think of as high grade finishing; a familiar example is Philippe Dufour. Smith’s movement finishing, on the other hand, is derived from the traditional English style, which generally used gilt (gold) plating, and, typically, a three-quarter-plate movement (also seen on the Lange 1). Prior to the use of nickel, and then rhodium plating on brass, many movements used gilt plating on mainplates and bridges (Breguet’s work, for instance) and George Daniels once memorably wrote that when watchmakers “have no technical problems to solve, they divert themselves by giving their movements a jewel-like finish.”
Open Dial Watches
An open dial watch is just what it says – a watch with a dial that has been reduced or eliminated in order to allow a view of the movement. (This is also, more or less, the definition given by the Illustrated Professional Dictionary Of Horology, which despite its occasional imperfections is the closest thing we have to consensus on watchmaking terminology). Sometimes, but not always, this is combined with an openworked or skeletonized movement. In a conventional movement, there is not a lot to see on the dial side – most of the action is on the bottom plate side, where there are more dynamic components to look at (including the rotor for the automatic winding system, if the watch is automatic).
Once you get away from fairly simple movements, there starts to be lots to see under the dial. I’m going to plug De Bethune here, who debuted their first in-house movement in 2004, which has a distinctive, delta shaped bridge. I have always wondered if Denis Flageollet knew from the outset that this would lend itself to being viewed on the dial side of the watch; in 2005, the company launched the DBS, where the delta bridge is on the dial side. The movement has basically been turned back to front and rotated 90º counterclockwise so the delta bridge is pointing upwards; the keyless works are consequently now located at the 12:00 position.
A very aristocratic example of an open dial watch is Philippe Dufour’s Grande et Petite Sonnerie.
The level of complexity on display is quite overwhelming, and it’s also in dramatic contrast to the view from the back. Repeating and chiming watches work by using a system of cams (driven by the hour and minute hands) and levers (which sense the time by contacting the cams) and racks (attached to the levers; the teeth on the racks trip the hammers) and since the entire system is driven by the motion works, it’s mostly located on the front of the movement. On the back, you can see the going train and the hammers, gongs, and regulator (for controlling the speed of the chimes) but the whole magical dance of the repeating system is usually hidden.
Skeletonized And Openworked Movements
“Skeletonized” and “openworked” are usually used more or less synonymously, which can lead to a little bit of confusion because there are actually a couple of different kinds of skeletonized movements.
The first kind are those which are designed from the start to be open. Such movements give the brand the chance to make more unusual or specifically design-oriented movements since you can shape the mainplate and bridges any way you want, within reasonable constraints. Cartier is very good at this sort of thing – there are plenty of examples but the Santos de Cartier Skeleton watch illustrates the point nicely, as does the more recently released Santos-Dumont Micro-Rotor.
Skeletonized and openworked are both verbs and imply that something was done to modify an existing movement, which was the original meaning of the terms. This is the most traditional approach. In traditional openworking, a watchmaker takes an existing movement, pierces the plate or bridge and then, with a very thin saw, removes as much metal as possible without compromising the functionality of the movement. This is a highly specific sub-genre of watchmaking with its own set of criteria, the most important of which is the amount of transparency you can achieve.
There are two ways of openworking a previously existing movement. One is to use modern EDM (electrical discharge machining) in which an extremely thin wire is used as the cutting element. The technique, also called wire erosion or spark erosion, can produce extremely fine and very precise cuts. EDM puts little if any mechanical strain on the metal and its reliability and controllability means that most manufacturers creating openworked watches use EDM to openwork existing movements.
The other and much older way to do it is to use a piercing file and very fine hand saw. This is time consuming and much more difficult, obviously, and there are very few watchmakers left who skeletonize movements in this way; Berlin-based Felipe Pikullik is one. Either technique – EDM or handwork – removes metal but of course, that’s just the first step; the edges created need to be beveled and polished and often, an haute horlogerie brand will also engrave what little horizontal surface area remains. Patek Philippe’s ref. 899 is a classic example; at Phillips “Game Changers” in New York in 2019, there was a gorgeous example of openworking at the highest level.
Understanding Openworking And Skeletonizing
Although the terms are used loosely I personally think we should use them with maybe a little more precision – especially in distinguishing between open dial watches and actual skeletonized watches; and we should distinguish between movements designed with an open configuration from the start, versus those that are skeletonized versions of pre-existing calibers.
Each approach is different and each offers something of value. In an open dial watch you might have a chance to see the interplay of components whose action is normally hidden (a repeater for instance). In an open configuration movement designed that way from scratch, the maker gets a lot of control over the bridge architecture and can produce effects that would otherwise be impossible. And in skeletonized pre-existing calibers you get the pleasure of appreciating just how daring watchmakers can be in removing metal and then finishing the remaining, lacy, spiderweb of metal that supports mobile parts of the movement.
The one criticism sometimes voiced by folks looking at openworked and skeletonized watches is that legibility suffers. This is absolutely a hundred per cent true but then if what the watchmaker wanted was maximum legibility, they wouldn’t have set out to make a skeletonized watch in the first place. I have always felt that it’s important to understand what a watchmaker’s goal or a brand’s goal is in producing a watch and after all a repeater is not a dive watch (at least, 99 per cent of the time). Skeletonizing a movement can be a very, very time-consuming process but it’s a demonstration of craft worth preserving and appreciating on its own merits.
Top image, Breguet Tourbillon Extra-Plat Squelette.