Up Close: MB&F HM10 Bulldog

Clenched jaws and mad, bulging eyes.

MB&F has always been about pushing the boundaries of aesthetic and conceptual creativity in watchmaking, lassoing in everything from pop culture to science fiction to build its Horological Machines.

Reminiscent of the HM3 Frog and HM9 Flow, the HM10 Bulldog is the tenth watch in the series and another intergalactic timekeeper reassembling a robotic animal. While MB&F has historically been all about less-than-friendly animals, like a cyclops-chicken, luminous jellyfish, or giant spider, the HM10 is modelled on a domestic favourite (and perhaps also takes inspiration from the LM1).

The design language of the HM10 is a familiar one as it borrows liberally from MB&F’s past machines. Bulging eyes in the form of rotating displays take their cues from the HM3, while the suspended balance wheel under a high domed crystal is also found in the Legacy Machine series, and finally the mobile jaw that’s also a power reserve display brings to mind the vertical indicator on the LM1.

An elaborate body

It’s a complex-looking watch, so an explanation is in order.

Available in either titanium, or red gold with titanium accents, the HM10 has a flat, elongated body with a protruding pair of collets for the crowns, as well as two domed sapphire crystals on the front and back to accommodate the time display and power reserve indicator respectively.

At 54 mm by 45 mm, the HM10 does have a large presence – which is usually the point of a Horological Machine – but the overall shape, particularly in comparison to past Horological Machines, feels rather ungainly and less assertive than say, the HM4, which is arguably MB&F’s all-time best “machine”.

But despite the odd form, the HM10 wears comfortably due to the long hinged lugs (that have a narrow range of movement), which are the figurative front legs.

At the back half of the watch, the twin crowns also serve as the pivot points of the “hind legs”, which are shorter than those in front. One crown is for time-setting and the other for winding.

The hind lugs with the crowns

While the case design is doubtlessly polarising, the case quality is impeccable in typical MB&F style. The case body is predominantly brushed with a polished, recessed seam running along its edge. Amongst the finely-executed details are the polished necks for the crown collets that contrast against the brushed case body.

Similarly, the lugs are elaborately skeletonised, with polished curves and contrasting, brushed flanks. The outer and inner edges of the lugs are bevelled and polished, and even the inside faces of the lugs are brushed.

The lugs are elaborately finished with alternating brushed and polished surfaces

Though the two versions of the HM10 vary solely in metal and colour, they are starkly different in style and of course, weight.

The case of the pink-gold version appears larger and more prominent, while the homogeneous grey tones across the case and dial of the titanium version draws attention to the blue, domed displays, which bring to mind the “eyes” of the HM3 Frog.

A favourite element of MB&F design, the HM10 has two large, domed sapphire crystals, one on the front and the other on the back. The sapphire dome on the top creates most of the volume on the watch – it is 24 mm at the tallest point – and it is the reason the case sits high on the wrist.

The front crystal shows off the half-spheres that tell the time, as well as the oscillator and escapement. And the crystal on the back reveals massive, hinged jaws that open and shut according to the state of wind of the mainspring – something MB&F terms the “dental power reserve”.

Form movement

The highlight of the movement inside, as with many of MB&F’s movements, is the impressive, novel form and three-dimensional construction.

Shaped like a pear to accommodate the case exactly, the back side is dominated by the crown wheel and  barrel ratchet wheel that occupy most of the real estate.

The front and back

The barrel is flanked by a pair of gear trains – the primary train made up of gilded wheels runs along the left side of the movement and connects to the escapement to drive the time display, while the smaller, secondary train on the right of the movement is for the power reserve indicator.

Effectively a simple automaton in the form of a pair of moving jaws, the power reserve indicator shows fully closed jaws once the mainspring is empty. And because the jaws sit at a 90° angle to the power reserve gear train, bevel gears that mesh at a right angle are needed to create the motion of the jaws.

The barrel ratchet wheel partially visible in the upper half of the sapphire crystal, with the gilded wheels of the primary gear train to its left

The “dental power reserve”

The legacy of the Legacy

The characteristics and architecture of the movement when seen from the front are familiar as they borrow heavily from the LM1. In fact, the mechanics and design of the HM10 are almost a three-dimensional take on the LM1.

The LM1 had a pair of sub-dials for the time, both sitting below a balance wheel suspended by an arched bridge, as well as a vertical power reserve indicator – all elements that have been translated into the HM10.

The LM1

On the HM10, instead of flat sub-dials, the hour and minutes are displayed on a pair of rotating domes – an element taken from the HM3 Frog.

To reduce energy consumption, the domes are aluminium and milled until they are paper-thin, allowing the movement to have the same 45-hour power reserve as the LM1 with its conventional, less energy-hungry display.

While the time-telling domes are the visual highlight on the front, the beauty actually lies in the visible mechanics. All of the key bits of the movement are prominent, symmetrically arranged, and well finished.

The escapement, held in place by an anchor-shaped bridge

In traditional MB&F style, the balance is extra-large and held aloft by an arched, black-polished bridge – which is all very impressive. The balance runs at the slow and attractive frequency of 2.5 Hz – so you can really observe it swinging back and forth – and is attached to an overcoil hairspring, a neat old-school detail.

Because the domes take up significant space, the balance wheel had to be raised even higher than on the LM1, requiring an extended balance staff, which extends from the towering balance wheel down to the main plate where the escapement is. So even though the balance and escapement are located on the same side of the movement, the balance wheel is almost separately from the escapement, a trick first performed on the MB&F LM Perpetual.

The highly polished, arched balance bridge, and below it the slots in the plate that reveal some of the motion works that drive the domes

Finishing and decor

MB&F watches adhere to a high standard of finishing inside and out, and the HM10 is no different.

Notably, the finishing of the brand’s sci-fi Horological Machines has improved over the years – the HM10 ranks as one of the best machines in that regard – closing the gap between them and the classically-inclined Legacy Machines that were conceived from the start to be highly decorated.

The finishing of the HM10 is done to a similar level as found in LM movements, albeit lacking the elaborate, artisanal details like the inward and outward corners on the anglage as well as gold chatons for the jewels.

Here the movement bridges are ruthenium-plated for a dark grey finish, and decorated with finely-executed Geneva stripes. All of the bridges boast polished bevels on their edges that are completed by hand, likely with a polishing tool. And the winding click spring, for instance, is notably well finished, having a straight grained top, along with bevelled edges and countersinks.

The winding click spring visible just below “Swiss Made”

Bridges covered in textural Geneva stripes, with jewels and screws in polished countersinks

Another appealing bit of finishing is found not on the movement, but on the power reserve: the jaws are sandblasted with contrasting, polished teeth

Concluding thoughts

After the technical novelty of the recent LM Thunderdome Triple-Axis Tourbillon – the most complex MB&F to date – it is hard to be impressed by the HM10 in the same way. The HM10 is a mishmash of past elements of earlier Horological Machines, but reconstituted in a novel form. Moreover, the design and shape of the case is overly eccentric, even for an MB&F watch.

However, if creating an emotional impact with a mechanical work of art was the goal – mission accomplished, and then some.

But while design is subjective, it has to be pointed out that the fit and finish of the HM10, inside and out, is top notch. As far as avant-garde, sci-fi watches go, MB&F places first in finishing.

Key facts and price

MB&F HM10 Bulldog
Ref. 100.TL.BL (Titanium case with blue time domes)
Ref. 100.RL.B (Red-gold and titanium case with black time domes)

Diameter: 54 mm by 45 mm
Height: 24 mm
Material: Titanium, or 18k rose gold and titanium
Water resistance: 50 m

Functions: Hours, minutes; power reserve indicator
Frequency: 18,000 beats per hour (2.5 Hz)
Winding: Hand-wound
Power reserve: 45 hours

Strap: Blue calf with Velcro closure (titanium); brown calf with gold folding buckle (rose gold and titanium)

Availability: Already at retailers
Price: US$105,000, or €92,000 (titanium); US$120,000, or €105,000 (rose gold and titanium)

For more, visit mbandf.com.


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