In-Depth: MB&F LM Thunderdome Triple-Axis Tourbillon

The ultimate Legacy Machine.

The flying tourbillon wristwatch for women – the Legacy Machine FlyingT – that MB&F launched last year foreshadowed its latest watch – the Legacy Machine Thunderdome, boasting the fastest ever triple-axis tourbillon developed by independent watchmaker Eric Coudray.

No doubt multi-axis tourbillons are hardly new, especially after Jaeger-LeCoultre unveiled its first Gyrotourbillon in 2005 – which was also developed by Mr Coudray – but the LM Thunderdome takes the concept further by every metric, primarily by building on past ideas to achieve higher cage velocities than ever before.

Most intriguingly, the Thunderdome movement incorporates a tourbillon lever escapement first devised by Albert H. Potter – a talented American watchmaker who worked in Geneva in the late 19th century – as well as an unusual multi-axis tourbillon that utilises a carrousel for its outermost cage, christened the TriAx.

The ingenious construction of the tourbillon is thanks to Mr Coudray, who now runs complications workshop TEC Ebauches and is best known for the numerous exotic tourbillon movements he has developed. After his two-decades at Jaeger-LeCoultre where he became the resident technical genius, Mr Coudray worked for several brands of varying levels of credibility, including at Cabestan where he perfected its vertical tourbillon, and more recently at Cecil Purnell, where he created the Spherion tri-axial tourbillon, which has a similar construction to the Thunderdome.

Besides Mr Coudray, another, more prominent independent watchmaker was also recruited to develop the design and finish of the movement, as well as the guilloche dial – Kari Voutilainen.

Tantalum or platinum

It’s worth noting the LM Thunderdome is being produced in two editions: one in platinum that’s a limited edition of 33 pieces with a blue guilloche dial, and the other that’s featured in this article, which has a tantalum case.

The tantalum version is a limited edition of 10 watches to mark the 40th anniversary of Singapore retailer The Hour Glass, five with the same blue guilloché dial and another five with aventurine glass dials.

The LM Thunderome in platinum. Image – MB&F

Marvellously domed

While last year’s FlyingT for ladies has a similar case profile, it was just 38.5mm wide, while the Thunderdome is a substantial 44mm – and in tantalum.

A dense, inert metal, tantalum is greyish with a hint of blue and possesses a high melting point, which is why it is sometimes used to tip armour-piercing shells. It combines the heft of platinum with a greater durability and scratch-resistance than steel. Though less costly than platinum in its natural form, tantalum is tougher to machine, which is why tantalum watch cases cost as much as those in platinum, or even more.

In typical Legacy Machine style, the case is fitted with a dramatically domed sapphire crystal that emphasises the three-dimensionality of the carriage. But it is far higher than the crystal on any earlier Legacy Machine, at its highest point, it measures 22.5mm, which makes it half as high as it is wide.

The LM Thunderdome

Last year’s LM FlyingT

But despite its bulbous profile, the Thunderdome wears comfortably and elegantly on the wrist due to its flat case band and slim, gently curved lugs. It is in essence a wide but thin watch, capped with a huge crystal.

Under the domed crystal is an engine-turned blue dial produced by Comblémine, the dial factory owned by Mr Voutilainen and a favourite supplier of independent watch brands. Found on both the platinum and tantalum versions of the watch, the dial is decorated with engraved, radial waves, which further draw attention to the central tourbillon.

Though the guilloche is more typical of the Legacy Machines, and will probably be more popular, the other dial is striking in a different way, being made of aventurine glass. The sparkly material evokes deep space, and is at home with MB&F’s sci-fi styling.

Time telling is done via a white lacquer dial that’s inclined for better legibility but as a result obscures part of the tourbillon – which is a shame. And towering above, as with earlier Legacy Machines, is the V-shaped bridge with polished, rounded arms that holds the tourbillon in place.

The LM Thunderdome with an aventurine dial. Image – MB&F

The tri-axial tourbillon in detail

To appreciate the tri-axial tourbillon in the Thunderdome and understand how it differs from a regular triple-axis tourbillon, it is worth diving into the fundamentals of a basic tourbillon.

To begin with, we first revisit the ubiquitous Swiss lever escapement, found in practically every modern mechanical watch today.

The balance wheel, which oscillates at a precise rate, controls the release of the escape wheel via the pallet fork. The escape wheel in turn, is connected to the rest of the geartrain that drives the hands of the watch.

Animation of the lever escapement. Image – Wikipedia

Collectively, all these components comprise the escapement. However, the oscillating balance wheel and hairspring are susceptible to gravity effects. This is heavily dependant on the orientation of the watch, especially in the vertical positions common in pocket watches, and is known as positional error.

Thus, the tourbillon was invented as a solution by averaging out these errors. This is achieved by rotating the entire escapement assembly a full 360°, usually in 60 seconds, within a tourbillon cage.

However, the typical tourbillon only revolves around one plane or orientation. In modern times, as a demonstration of technical prowess, watchmakers have also come up with multiple axis tourbillons by nesting tourbillon cages within each other – much like a gyroscope.

In the case of the LM Thunderdome, there are three cages as it is a triple-axis tourbillon. In the diagram below, the first and innermost tourbillon cage is in green, with the balance wheel in yellow mounted on it.

Intriguingly, the balance wheel is a large, skeletonised hemisphere, which further enhances the animated motion of the tourbillon as it oscillates back and forth. It also conveniently allows space to house a cylindrical hairspring within – usually impractical on traditional wristwatches due to thickness, but offers better isochronism, as traditionally found on marine chronometers.

The first two cages of the LM Thunderdome, coloured green and orange respectively. Image – MB&F

The first cage is then housed within a second cage, in orange above, that pivots at a 90° angle relative to the first cage. The gearing is set up such that when the second cage rotates, it also simultaneously drives the first cage, via gear teeth as seen on the bottom rim of the cage.

By extension of that logic, the first two cages can then be housed in a third cage, as seen below in blue. Realistically, this is the practical limit of a multi-axis tourbillon, as this provides three orthogonal rotation directions that encompasses the three spatial orientations in 3D space.

The first two tourbillon cages of the LM Thunderdome, encased by the third cage in blue. Image – MB&F

However, unlike a conventional triple-axis tourbillon, the LM Thunderbolt incorporates a few distinguishing features. Most notably, the third cage is not a tourbillon but rather, a carrousel.

Unlike a tourbillon where only one pinion directly drives the cage, the carrousel has two driven pinions – one to drive the cage, and the other to power the escapement contained within. In the image below, the third cage in blue swivels around a pedestal, in bronze.

The carrousel mechanism of the third cage of the LM Thunderdome. Image – MB&F

If this was a traditional tourbillon design, the pedestal will be stationary, while a shaft running through its centre drives the tourbillon cage. However, as a carrousel, the pedestal also rotates together with the blue cage, albeit at a slightly slower speed. This relative difference in speed is what drives and powers the inner two tourbillon cages.

It appears superfluous at first, to combine a carrousel with a multi-axis tourbillon, but upon further meditation it makes sense. The carrousel allows the movement designers to control the speed which the inner two cages are driven, by varying this relative speed.

Without a carrousel, the third cage will have to rotate at a much slower speed that is visually less engaging, because the relative speed between the cage and the pedestal diverges too much, thus driving the inner cages unreasonably fast.

The cumulative position of the balance staff in 3D space. Image – MB&F

The combined axis of the three cages thus results in the escapement of the movement to rotate in a seemingly random orbit, which ideally exposes the balance wheel to almost all orientation in 3D space and averages its timing errors. But timekeeping is of less importance than the visual spectacle of the multi-axis tourbillon doing its thing, right in the centre of the dial.

The spectacle is enhanced by the speeds of the tourbillon cages, made to rotate rapidly by design. With the three cages completing a revolution of 8s, 12s and 20s respectively, this makes it the fastest rotating multi-axis tourbillon. Collectively, the three cages will reset to their original positions after 120 seconds – the least common multiple of the period of each cage.

Finally, there is a curious feature within the construction of the innermost tourbillon cage: it is not constructed like a traditional tourbillon with a cage that encapsulates the balance wheel, instead it is more of a platform that carries the tourbillon, an idea first found in the Montblanc Exotourbillon.

An inventive escapement

Besides the carrousel of the outermost cage, there is a little trick employed to allow the innermost cage to rotate quickly – a novel escapement.

In a typical tourbillon, the escape wheel has a tiny pinion that allows it to revolve around a fixed gear on the movement. This acts as a reduction gear that reduces the speed of the tourbillon, usually to the typical 60 seconds a revolution.

The LM Thunderdome however, requires the cages to rotate quickly. Thus, an idea of using a different escapement design was revisited – a fixed escape wheel, originally conceived by Albert H. Potter (1836-1908), a New York native who moved to Geneva in 1875. Though not widely known today, New York-born Potter was one of the most prominent American watchmakers of his generation, highly regarded for his gorgeous, organically styled pocket watch movements.

His original idea was to forgo the escape wheel with pinion entirely, and redesign it as a stationary part instead, which the pallet fork of the tourbillon cage engages with directly. This effectively bypasses the reduction gearing, and allows for a faster rotation speed of the tourbillon cage in a mechanically compact way.

In the case of the LM Thunderdome, the fixed escape wheel, below in grey, has inward-facing teeth. This allows the pallet fork of the innermost tourbillon cage, in green, to interact with the escape wheel directly, without any reduction gearing and therefore achieving a speed of one revolution in eight seconds.

The Potter escapement in the LM Thunderdome. Image – MB&F

It is worth mentioning that this is not the first time such a fixed escape wheel design has been used in a modern watch. One such example can be found in the Franck Muller Thunderbolt, the fastest ever single-axis tourbillon, making one revolution every five seconds.

The Thunderbolt tourbillon was invented by Jean-Pierre Golay, the veteran watchmaker then working for Franck Muller Watchland. Mr Golay applied to patent the construction (patent WO2011006617A1), but the patent was not granted. His construction, however, is a single axis tourbillon, and consequently far simpler than the triple axis construction of the LM Thunderdome.

Extract from patent WO2011006617A1 for a tourbillon with fixed escape wheel

Design and finishing

To power such an energy-consuming complication, the movement is equipped with three barrels that unwind in parallel, arranged in a semi-circle. As a result, half the back is dominated by the barrel ratchet wheels, along with a large power reserve display.

The movement is almost symmetrical in its layout, with an open architecture that reveals the large wheels driving the carrousel of the tourbillon.

And as with the earlier Legacy Machine movements, the Thunderdome calibre exhibits a high level of finishing and wonderfully classical details, which is the result of Kari Voutilainen’s discerning eye.

The movement is replete with classical details, including wide Geneva stripes, polished bevels, and gold chatons for the jewels of the going train.

Especially noteworthy are the sharply executed polished bevels, or anglage, on the numerous bridges. Even minute details are finished with the same degree of attention, such as the bevelling on the spokes of the wheels, and the straight graining on the winding clicks.

Importantly, this is the first LM movement to feature Voutilainen’s signature spiral finishing, or solarisation, on the barrel ratchet wheels, as opposed to the simpler sun-ray finish found on the earlier calibres.

Concluding thoughts

While multi-axis tourbillons in general tend to recall the slightly dated, maximalist approach to watchmaking of the 2000s, the LM Thunderdome is arguably the most technically intriguing and inventive take on the well-used idea. It is a combination of new and old ideas – most notably the unique escapement and carrousel construction – while being executed in a modern, yet remarkably elegant way.

Though it’s difficult to be impressed by a multi-axis tourbillon over a decade after they first became fashionable, the LM Thunderdome is an impressive watch.

Key facts and price

Legacy Machine Thunderdome

Diameter: 44mm
Height: 22.2mm
Material: Tantalum or platinum
Water resistance: 30m

Movement: Developed for MB&F by Eric Coudray and Kari Voutilainen
Functions: Hours, minutes, and TriAx tourbillon
Winding: Hand-wound
Frequency: 21,600bph, or 3Hz
Power reserve: 45 hours
Strap: Blue hand-stitched alligator strap with folding buckle

Limited edition: 10 in tantalum (five each with aventurine or blue guilloché dial); 33 in platinum
Availability: Tantalum exclusive to The Hour Glass; platinum at retailers and boutiques
Price: 376,000 Singapore dollars for the tantalum edition; US$280,000 in platinum

For more, visit

Correction May 22, 2021: The patent for the Franck Muller Thunderbolt tourbillon was not granted, unlike what was implied in an earlier version of the article.

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Hands-On: Zenith El Primero Defy 21 Carbon

High frequency, and ultra-light.

Zenith’s streak of high-tech watches – including this year’s Defy Inventor and El Primero Double Tourbillon – began in 2017, when it unveiled the El Primero Defy 21.

The watch is a chronograph with a dual-train construction that accommodates a high-frequency chronograph with a resolution of 1/100th of a second and a lightning seconds hand that whizzes round the dial once a second.

Originally offered only in ceramic, titanium or gold, the high-frequency chronograph is available in a featherweight carbon composite case – arguably best suited to its styling and complication – with the launch of the El Primero Defy 21 Carbon.

A familiar style

The unusual movement of the Defy 21 is inspired by the similar constructed movement in the TAG Heuer Mikrograph, one of many high-frequency chronographs devised by Guy Sémon, the resident technical guru at TAG Heuer, a sister company of Zenith. Notably, the Mikrograph and the Defy 21 are the only serially produced, 1/100th of a second chronographs on the market today.

Due to the movement’s dual-train architecture – essentially two independent movements on one base plate – the case is a large 44mm in diameter and 14.4mm high. But being carbon composite, it manages to remain lightweight despite the size.

At the same time, the predominantly black colour scheme across the case and dial also makes the watch look smaller than it is, especially compared with versions of the Defy 21 in gold or titanium.

Visually, the case is typical of the material, which is made up of carbon fibre threads randomly arranged inside a polymer, creating the distinctive marbled appearance. The angular case design is matched with a skeletonised dial, a common combination that is in vogue today.

The chronograph registers sit at three and six o’clock, while the power reserve indicator for the chronograph barrel is at 12. Despite its complexity, the dial remains legible as it is composed of different layers and shades of black, allowing the various indications to be easily distinguished, at least in daytime.

Overall, the look is a common one, shared by brands ranging from Richard Mille to TAG Heuer. But the Defy 21 is more than just a sporty design; it is intriguing because the movement is genuinely inventive and also technically interesting. And most importantly, the Defy 21 is also reasonably priced as such watches go, making it by far one of the most compelling buys in the segment of high frequency chronographs.

Dual architecture

But more than the design and the materials, the Defy 21 is all about the movement, and the challenges that have to be overcome in order to achieve the chronograph frequency of 50Hz, or 360,000 beats per hour.

While a higher frequency chronograph results in greater resolution, the laws of physics dictate the drawback increase with the frequency. For instance, starting and stopping the chronograph causes energy supplied to the the timekeeping balance wheel to fluctuate, which impacts its amplitude, which in turn impacts rate.

In addition, the higher the frequency, the more impulses and rotations of the escape wheel and gear train occur per period of time . Hence, more power is needed to keep the escapement going, and the friction generated by the rapid motion of the escapement in turn requires more frequent servicing.

To solve this, the El Primero 9004 movement inside the Defy 21 has two independent sets of mainsprings, gear trains and escapements – in essence, two independent movements – isolating the high frequency escapement so that the activation of the chronograph doesn’t affect timekeeping.

The independent movements inside the Defy 21: the mainspring and balance for the chronograph in red, while that for timekeeping in purple

Similar twin-train constructions can be found in watches like the Jaeger-LeCoultre Duometre a Chronographe and the Breguet Tradition Chronographe 7077, each with its own unique solutions to isolate the chronograph and ensure a stable rate.

The Duometre features separate mainsprings and gear trains but a shared escapement with the regular timekeeping train driving the escape pinion and the chronograph train directly engaging the escape wheel. On the other hand, the Breguet Tradition chronograph has two entirely separate transmission systems but a linear, blade-like mainspring for the chronograph that buckles when the reset button is activated.

The Defy 21, in comparison, has a more straightforward and robust solution that allows it to operate at a much higher frequency. The timekeeping escapement runs at the commonplace frequency of 5Hz, while the second chronograph escapement, which starts only when the chronograph is activated, operates at 50Hz, allowing the stopwatch to measure up to 1/100th of a second, at least on paper, since user error will far exceed its smallest unit of measurement.

The larger balance wheel for timekeeping

The pallet fork and escape wheel, which is the fastest rotating wheel in the transmission system, are both silicon, a material that operates without friction and requires little energy, being less than a third the density of steel. Thus, it reduces inertia and wear, which is particularly crucial in a high frequency movement.

While the initial batch of Defy 21 watches were equipped with carbon hairsprings, Zenith has since stopped using those exotic balance springs. Now the Defy 21 movements are equipped with tried and tested Nivarox hairsprings, the industry norm.

To enable such rapid oscillation, the balance wheel for the chronograph, which is visible through the case back, has been reduced in size and fitted to a much shorter hairspring. The balance staff is fitted with KIF shock absorbers both on the front and back to prevent it from breaking when subjected to hard knocks.

A higher frequency in turn also means that the chronograph mainspring unwinds quicker. Thus, even though the barrel for the chronograph is almost as large as that for timekeeping, it only contains a 50-minute power reserve, as compared to the 50 hours for the timekeeping system.

And because both barrels are independent, they are also wound separately. The timekeeping mainspring can be wound manually by turning the crown counterclockwise and also via the rotor, but the chronograph mainspring can only be manually wound via the crown.

To match the case and design, the bridges of the movement are blackened and brushed, while the rotor is open-worked into the Zenith star logo. The finishing of the movement both on the front and back is mechanical but clean, and more importantly, appropriate for the graphic style of the watch.

Concluding thoughts

The Defy 21, regardless of its iteration, is a tremendous feat – especially for what it costs, starting at just over US$10,000 for the entry-level model in titanium.

However, at US$17,800, the El Primero 21 Carbon costs almost 60% more than the version in titanium, a material that surpasses carbon in strength and rivals it in weight.

The difference between the two is purely aesthetic. In the grand scheme of what the watch is all about – which is its incredible mechanics – styling is almost negligible.

That being said, other high frequency chronographs are even more expensive, or do not quite measure up.

Comparable watches include the Montblanc Timewalker 1000, which was a limited edition and priced higher, and also the F.P. Journe Centigraphe, which is technically not a true 1/100th chronograph as it relies on a traditional 3Hz escapement and a decoupling mechanism. And there’s also the TAG Heuer Carrera Mikrograph, which is comparably priced but slightly inferior in specs. The Defy 21 is, in short, a value proposition.

Key facts and price

Zenith Defy El Primero 21 Carbon
Ref. 10.9000.9004/96.R782

Diameter: 46mm
Height: 14.4mm
Material: Black carbon composite
Water resistance: 100m

Movement: El Primero 9004
Functions: Hours, minutes, 1/100th of a second chronograph, chronograph power reserve indicator
Winding: Automatic

Frequency: 36,000bph, or 5Hz
Power reserve: 50 hours

Frequency of the chronograph balance: 360,000bph, or 50Hz
Power reserve of chronograph: 50 minutes

Strap: Black rubber topped with blue fabric or black carbon fibre

Availability: At boutiques and retailers
Price: US$17,800, or S$27,000

For more information, visit


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Hands-On: F.P. Journe Octa Réserve de Marche Prototype


As has become tradition, a good part of Phillips’ upcoming New York watch auction is a memorabilia sale of sorts, including watches owned by Marlon Brando, golfer Jack Nicklaus, and astronaut John Glenn, as well as the Urwerk worn by Robert Downey Jr. while playing Iron Man in Avengers: Endgame.

The auction also includes a piece of historical horological memorabilia: an F.P. Journe Octa Réserve de Marche prototype.

The prototype is largely identical to the later, serially produced version of the watch – the case is platinum and the dial, yellow gold – but is marked as a prototype on the case back, and also bears the various traits unique to early watches made by Francois-Paul Journe.

The cal. 1300

Launched in 2002 and discontinued in 2014, the Octa Réserve de Marche was the brand’s first entry-level wristwatch, powered by an automatic movement, the cal. 1300.

Originally conceived to have an eight-day power reserve – hence “Octa” – the movement instead has a power reserve of 120 hours, or about five days.

Reputedly constructed with a gear train borrowed from a robust and well-known hand-wind movement plus an extra-large mainspring, the cal. 1300 was the base calibre for the entire Octa line. Although a variety of complications were added on top, ranging from the Octa Chronograph to the annual calendar of the Octa Calendrier, all versions of the movement had identical height of 5.7mm regardless of function.

The slimness and smart construction did come at the expense of reliability, and early examples of the Octa watches were generally finicky, with the oversized date especially prone to breaking down.

As was the case for F.P. Journe’s first generation of movements, the bridges and base plate of the prototype movement are rhodium-plated brass, instead of the 18k red gold that’s now standard.

And the movement is notable for having straight Côtes de Genève, found only on the earliest Octa movements, instead of the circular striping, sometimes known as Côtes circulaires, of subsequent calibres.

The current generation Octa movement with the bridges and base plate in 18k red gold, as well as circular striping on the bridges


According to Phillips’ watch department head in the Americas, Paul Boutros, this prototype is one of three made, all of which were given to individuals who supported F.P. Journe in its early days.

This particular watch was one of a pair – both nearly identical but with slight differences in finishing – given to a husband and wife who were involved with the brand. The couple have consigned this watch, but are holding on to the other. And the third watch is now owned by a board member of F.P. Journe, according to Mr Boutros.

The watch shows all of the characteristics – and imperfections – of early F.P. Journe watches. That includes a relatively shiny gold dial and a sub-dial that is metallic and silvery (as opposed to white). Another distinguishing featuring is the shallow etching on the case back, instead of the deeper engraving that later became standard.

It’s worth noting that watch is well worn, inside and out, and could do with an overhaul, though that’s not going to have any impact on the price, which will surely be substantially above the high estimate.

Estimated at US$30,000-60,000, the Octa Réserve de March Prototype is lot 73 in Game Changers that takes place on December 10, 2019 at Phillips in New York. For the auction catalogue, visit


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