The MB&F Legacy Machine Sequential EVO, A Symphony In The Key Of Watchmaking

In 2022, MB&F launched a chronograph unlike any I’d ever seen before – well, unlike anything anyone had ever seen, I suppose. That chronograph was the MB&F Sequential EVO, which is classified at MB&F as one of the Legacy Machines, rather than a Horological Machine. The Sequential EVO is a highly unusual double chronograph, with an innovative train layout and a newly designed vertical clutch, and incorporates a mechanism called the Twinverter, which allows the owner to start and stop the two chronograph trains either independently or simultaneously.

The Legacy Machines

There are essentially two kinds of watches at MB&F – the Horological Machines, which are typically no-holds barred exercises in design intended to push or even break the conventions of watch design. Inspired by science fiction, Japanese manga, the automotive world, and the aviation (and sometimes, other worlds as well) the Horological Machines also require innovation in mechanics for every Machine, since every Machine handles the task of timekeeping, as well as the display of time, differently.

The Legacy Machines are on the other hand, a series of answers to the question, What would MB&F have created if the company had been started 100 years ago? The Legacy Machines therefore tend to be more conservative in design overall than the Horological Machines, although “conservative” is relative. All of the Legacy Machines are characterized by something you certainly would not have seen in any conventional watch from 1892, which is a century before the first Legacy Machine was introduced in 2012. That common feature is a large balance wheel elevated well above the plane of the dial (sometimes, more than one) which gives the Legacy Machines a kinetic appeal not found in conventional timepieces and which is certainly far more dynamic and three-dimensional than a simple cut out in the dial to expose the balance. (It is also technically considerably more difficult; the balance staff must be very long and the stability of the oscillator system has to be as carefully executed as the classic, 19th-century style movement finishing).

The Art Of The Chronograph

The LM Sequential EVO was created by Belfast-based watchmaker Stephen McDonnell, who also designed the  2015 Legacy Machine Perpetual Calendar. The LM Perpetual calendar was an ingenious re-imagining of a traditional perpetual calendar – because of the central position of the balance, the perpetual calendar mechanism had to be engineered to fit around it, which ultimately required a series of novel technical solutions as well.

For the Sequential EVO, the basic inspiration were mechanical lap timers created by companies like Heuer and Hanhart, which were designed for accurate timing of successive laps. These generally consisted of several stopwatches mounted on a board, with a single lever controlling all of the stopwatches. The arrangement allowed successive laps to be timed more accurately than starting and stopping each chronograph separately (and was more robust and more flexible than the very expensive rattrapante chronograph). In the course of developing a technical solution to this particular problem, McDonnell ended up producing the first significant advance in chronograph coupling systems since Seiko rolled out the world’s first vertical clutch automatic chronograph in 1969.

The Sequential EVO, I hasten to add, is not an automatic chronograph – there is a practical reason for that, which is that the intentions and execution of the watch and movement (and this is one of those situations where watch and movement are more synonymous with each other than usual) are antithetical to the whole idea of a self-winding movement. (It occurs to me that while there have been plenty of automatic Horological Machines – the battle axe shaped rotor is as much a signature element in the HM series of watches as anything else – that there has never been and I imagine never will be an automatic Legacy Machine)

Instead, the LM Sequential EVO is a visual celebration – of two things. First, it is a celebration of the machine-ness of watches – the two enormous intermediate wheels for driving the minute counters look like something out of a Victorian steam engine. And secondly, it is a celebration of what Stephen McDonnell has called one of the unique features of high end watchmaking, which is the deliberate creation of mechanical beauty which, although unnecessary functionally, is essential to expressing the intellectual beauty of a mechanism in concrete, visible form.

The Sequential EVO consists of two independent going trains, with vertical clutches on the fourth wheels of each train; since the fourth wheel rotates once per minute, the chronograph seconds hand is usually driven by the fourth wheel. The two chronographs have mirrored start, stop and reset pushers on either side of the case (the upper pusher on either side is the start/stop pusher, and the lower pusher is the reset pusher). The pusher at 9:00 is for the Twinverter, which is a system of levers which reverses the running state of both chronographs at once when it’s pushed. In practice this means:

• If neither chronograph is running, both will start.
• If both chronographs are running, both will stop.
• If one chronograph is running and one is stopped, pressing the Twinverter pusher at 9:00 will stop the one that’s running, and start the other. The Twinverter in this case inverts the function of each chronograph, hence “Twinverter.”

The Twinverter therefore allows for the timing of successive intervals, without interruption, of up to 30 minutes each in length; you can use it as a lap timer (in the spirit of the Heuer and Hanhart timers that inspired it) but you can also use it for other timing needs – you can use it, for instance, as a chess clock, although I have to say, I think watching the chronograph in action would throw off my game.

From the back, you can see the general layout of the two going trains more clearly. The two mainspring barrels are at 12:00 and 6:00, and the two cocks at 3:00 and 9:00 are for the two vertical clutches. The pinions of the two fourth wheels drive the two very large titanium intermediate wheels, which in turn drive the minute counters.

The Twinverter system is the star of the show in terms of functionality, but the vertical clutch system is at least as interesting and ingenious.

Above is the vertical clutch system, plus the fourth wheel. The actual fourth wheel is outlined in red, and turns constantly; the two fourth wheels are geared to a single escape wheel.

And this is the vertical clutch proper. As you can see, the clutch pressure plate is up top and when the chronograph is activated, the clutch drops into position on the fourth wheel and the bottom-most wheel starts to turn. The seconds hands pivot on the axis of the fourth wheel and the bottom-most wheel drives the intermediate wheels, which drive the minute counters.

The shaft of the fourth wheel, you’ll note, is actually hollow and the fourth wheel rotates around the shaft of the vertical clutch chronograph driving wheel, which is static until the chronograph is switched on. That means that the shaft itself has to be jeweled, and since it’s made of stainless steel, you can’t friction press the jewel into place, the way you can with a conventional brass movement plate – instead, the jewels are set in place and then, a metal shoulder is raised around them.

The reason this is such a big deal, is that normally, no matter what the chronograph coupling system is, the chronograph is out of the power flow of the going train (doesn’t matter if it’s a tilting pinion, vertical clutch, or lateral clutch chronograph). This means that the chronograph seconds wheel is apt to flutter (since there has to be some play in the gear teeth or they won’t turn at all). To address this, virtually all chronographs have a friction spring under the chronograph seconds wheel.

Omega Speedmaster caliber 1861

Above is an Omega caliber 1861 with the chronograph train removed; the friction spring is visible at the center of the movement, just under the Delrin (nylon) brake (image is from the Speedmaster deconstruction article on The Naked Watchmaker, which I promise, if you’re a gearhead and don’t know about it already, you will love). You may have heard if you take an interest in these things, that one of the problems with chronographs is that balance amplitude drops off when the chrono is switched on and that friction spring is the reason. You can’t really dispense with it – not if you want a flutter free seconds hand and don’t we all – but even in a properly adjusted chronograph, you can still get a drop of up to 30º. (This will vary depending on the specific configuration of the chronograph, especially vertical clutch chronographs; Revolution has an excellent in-depth discussion of the advantages and disadvantages of different vertical clutch chronograph setups).

There are a number of different configurations in modern vertical clutch chronographs but none which have all the features of Stephen McDonnell’s design for MB&F. The jeweled upper and lower pivots for the clutch/fourth wheel assembly, as well as the stability of the assembly, have a number of advantages, one of which is that when the chronographs are switched on there is no drop in balance amplitude at all. (If you’re interested in a much more granular analysis of the LM Sequential EVO, I did an in-depth story when the watch was first released, but the detail there is well beyond the scope of this story).

Intermediate driving wheel for the minute counter; the wheel is driven by the vertical clutch under the cock at the bottom of the image, and drives the minute wheel from its pinion.

All of this ingenuity would be a bit wasted, of course, if the watch weren’t so beautiful. Movement finishing gets a lot of ink these days, but movement design is essential for movement finishing to really shine (to make a feeble joke) and I’m sure we can all think of watches which are technically clever as all get-out, but which have, alas, a sort of Rube Goldberg quality that undermines the whole enterprise. The finish in the LM Sequential EVO is first class – one of the basic guiding principles of all the Legacy Machines is that they should be finished to the best standards of first-class 19th century watchmaking. But without a harmonious and visually pleasing design, with striking variations in dimensions and coherent visual rhythms, you could easily end up with something  that’s magnificent technically but a bit of a mess aesthetically. In the LM Sequential EVO, there is no such disconnect.

I don’t think anyone has better expressed how important the connection is between aesthetics and physical beauty – which is today, more than ever, not necessary for functional excellence – than Stephen McDonnell himself, in a presentation he gave at the last Dubai Watch Week. If you’ve never seen it – and it was such a celebrated presentation I’m pretty sure you have – there’s no better way to spend an hour than to hear McDonnell drill down into what makes watchmaking rise to the level of art.

I don’t know that the question of whether or not watchmaking rises to the level of art is all that relevant, actually. The basic questions that really need to be asked when you’re looking at a piece of fine watchmaking aren’t abstracts of classification. The real questions are, does the engineering make sense? Is the design of the mechanism serviceable and capable of fulfilling the promise of longevity that you expect from fine watchmaking? Is the movement design visually coherent as well as mechanically sensible? Does the whole thing work as a whole – does it pass the clichéd litmus test of being greater than the sum of its parts?

To a certain extent this is a matter of taste, of course. At the same time, though, to the extent that it is possible to claim that a watch is objectively beautiful, I would say that of the LM Sequential EVO. Not only does it represent a high water mark in modern watchmaking, it represents absolutely everything – ingenuity, originality, and real sense of connection, even communion, with its makers – that makes independent watchmaking so compelling.

See it here