B&F has been making different, original horological “machines” since 2005. Lauded by the watch cognoscenti, the brand has been called many times to the stage to collect awards at the Grand Prix d’Horlogerie de Genève (GPHG), one of the most important dates in the watchmaking calendar.

Its run of seven GPHG awards began in 2010 when the HM4 Thunderbolt took home the Design award. In 2012 the Legacy Machine N°1 was doubly rewarded with the Public award and the Men’s Watch award. In 2016 the Legacy Machine Perpetual won the Calendar Watch award. In 2019 the Ladies Complication Watch award went to the LM Flying T, and in 2021 the LMX topped the Men’s Complication Watch category while the LM SE Eddy Jaquet Around the World in Eighty Days claimed the Artistic Crafts award.

The only thing missing from MB&F‘s list was the coveted Aiguille d’Or, presented to the best watch overall. Now that, too, is mission accomplished, after this ultimate distinction was presented to the LM Sequential EVO at last year’s ceremony.

How did this watch come to be? What difficulties had to be overcome? In what ways is this double chronograph an improvement – and what is it used for? Stephen McDonnell enlightens us.

The only thing missing from MB&F’s list was the Aiguille d’Or, a mission accomplished by the LM Sequential EVO.

Born in Belfast, Stephen McDonnell spent 14 years in Switzerland where he trained at WOSTEP. He now runs his own workshop in Northern Ireland and is a long-time collaborator with MB&F.

Can you do better?

The Northern Irish watchmaker lives and works outside the Swiss ecosystem but is no stranger to its micro-mechanical challenges. He’s often the one who takes MB&F into new terrain  including areas that were not on the brand’s radar. In 2015 he designed the LM Perpetual, despite Max Büsser’s dubbing perpetual calendars “boomerang watches”, because they leave the workshop then come back with the mechanism jammed. The chronograph was another category the brand had apparently ruled out: Büsser didn’t want a seconds hand on any of his dials. But history tells a different story…

The movement that Stephen McDonnell has designed combines functions that previously could only be performed by multiple chronographs together.

Flashback to the 2016 Dubai Watch Week. The LM Perpetual was fresh from its GPHG success and Max Büsser had recently bought a Tiffany & Co. split-seconds chronograph pocket watch at auction. He was eager to show his new acquisition to MB&F Friend Stephen McDonnell, who was clearly underwhelmed by its functionality. Somewhat crestfallen, Büsser retorted, “So can you do better?” A glint in the watchmaker’s eye suggested that not only he could, he already had an idea in the back of his mind. And there it was: MB&F would make a chronograph… but it would be like no other chronograph before.

“Can you do better?” A glint in the watchmaker’s eye suggested that not only he could, he already had an idea in the back of this mind. MB&F would make a chronograph… but it would be like no other chronograph before.

The idea that became the Sequential originated with Stephen McDonnell’s interest in sports timing and particularly timing laps in motor racing. The problem when using a conventional chronograph is the inability to stop timing to record the end of one lap while simultaneously and instantaneously resetting and restarting for the following lap. In the early days of sports timing, Longines, Omega and Heuer circumvented this difficulty by mounting two or more stopwatches, operated by a lever, on a frame. Except no-one wants to wear multiple chronographs under their shirt sleeve (or has enough hands to operate them!). Stephen McDonnell’s idea was therefore to incorporate this functionality into a single chronograph.

A double chronograph

The first challenge he faced is inherent to any manual-winding chronograph, whose sole source of power is the mainspring barrel. As Stephen McDonnell explains, whenever a conventional chronograph is started, the amplitude of the balance drops by 20 to 30 degrees, which directly affects precision. Adding a second chronograph doubles this energy loss, and was therefore not an acceptable solution to the problem he had to resolve.

McDonnell’s answer was to completely rethink the chronograph’s construction. Enter the first ever jewelled vertical clutch. Whereas friction-reducing jewels are normally pressed into a bridge or main plate (which are made from a soft metal such as brass), the jewels for the LM Sequential EVO are set directly in the hardened steel pinion, using the sertissage technique for setting stones in jewellery. The Northern Irish watchmaker observed that when the chronograph was running, there was no change in amplitude. He had found the solution that would enable the Sequential to exist!

The movement of the LM Sequential EVO by MB&F

This wasn’t the only obstacle that arose during the Sequential’s multi-year genesis. In a classic chronograph construction, the axis of the seconds hand is always close to the axis of the minutes hand. In the Sequential, the two minutes counters are positioned at the top of the dial, some way from the seconds counters. This distance implies a potentially significant energy loss, which adds to the energy loss associated with the friction spring when the chronograph is engaged. Stephen McDonnell’s solution was to use two large wheels to drive the minute counters and no friction spring.

There was no lightbulb moment but a slow process of problem-solving to arrive at the two thinner wheels in titanium which reduce inertia by a factor of five compared with the initial prototype.

But there was trouble ahead. After leaving the first prototype running overnight, he woke to find the chronographs had actually gained 10 minutes with respect to the basic movement. The reason, he discovered, was the high inertia of the large wheels driving the minute counters; each time the gear train stopped, the wheels would continue to turn and cause the clutch to slip, making the chronographs gain time. He resolved this by optimising the clutch and redesigning the wheels to be thinner and lighter. Compared with the development of the LM Perpetual, he says there was no lightbulb moment but a slow process of problem-solving to arrive at the two thinner wheels in titanium, which reduced inertia by a factor of five compared with the initial prototype.

The Twinverter

MB&F’s twentieth calibre therefore integrates two column-wheel chronographs into a single movement, together with the revolutionary “Twinverter” binary switch. How does this work in practice? Both chronographs are started, stopped and reset by two independent pushers, and can be operated separately. The Twinverter is actuated by a fifth pusher at 9 o’clock. As its name suggests, it instantaneously and simultaneously inverts the two chronographs’ status: if both chronos are stopped, it starts them; if both are running, it stops them; if one is running and the other stopped, they are inverted. This enables multiple timing modes, including split-seconds and lap timing: an unprecedented combination in a chronograph.

Timing sub-durations, such as individual laps in a race, becomes child’s play. One press actuates the Twinverter which stops one chronograph and instantly starts the other, allowing ample time to note the first measurement and reset to zero.

The Twinverter is actuated by a pusher at 9 o’clock. As its name suggests, it instantaneously and simultaneously inverts the two chronographs’ start/stop status.

The LM Sequential EVO enables multiple possibilities for measuring elapsed times. In independent mode it times events with different start and end times, including when they overlap such as, McDonnell suggests, boiling eggs and cooking pasta. In simultaneous mode, it times two events that start simultaneously but have different end points, with the advantage over a classic split-seconds mechanism that it can measure differences greater than one minute. In sequential or lap-timer mode, it measures intermediate times for a continuous event in multiple stages, including times of more than one minute. Lastly, cumulative mode measures the cumulative duration of two discontinuous events, such as two chess players’ moves.

An extraordinary watch... for daily wear

Cased in zirconium, which is lighter than steel, in a 44mm diameter, this remarkable timepiece proves to be supremely wearable. Its integrated rubber strap fits perfectly to the wrist. The sapphire crystal is angled to reduce height and thickness, thanks to which it slips comfortably under a shirt cuff.

The LM Sequential EVO is water-resistant to 80 metres and incorporates MB&F’s FlexRing shock-absorbing system to protect the movement. Every effort has been deployed to make this out-of-the-ordinary watch something that can be worn in ordinary, everyday life… provided you have the CHF 160,000 to pay for your choice of an atomic orange or coal black version.

The original challenge was to improve the precision and functionality of a split-seconds chronograph. Stephen McDonnell has done exactly that, to the great delight of Max Büsser and admirers of superlative watchmaking everywhere.

The LM Sequential EVO opens up multiple timing possibilities.