MB&F - MB&F Legacy Machine Perpetual EVO Black
MB&F - MB&F Legacy Machine Perpetual EVO Black

MB&F Legacy Machine Perpetual EVO Black


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The LM Perpetual EVO comes in a case of zirconium, a metal rarely used in watchmaking due to the extreme requirements involved in machining this high-risk material. When zirconium is finely divided into a powder, as might happen when it is being worked into different forms by industrial tools, it is known to combust. During conventional machining processes, when metallic particles are constantly being created and dispersed through the environment, zirconium has proved extremely dangerous. The creation of zirconium metal parts has to be conducted under controlled, secure conditions.

Previously, this challenging metal was used in MB&F’s HM3 Frog and HM5. Zirconium’s biocompatibility and hypoallergenic and anti-microbial properties made it the ideal material for the organic curves of MB&F’s favourite amphibian, while its technical appeal and physical properties (lighter than steel, more durable than titanium) were a perfect fit for the motoring-inspired HM5. The LM Perpetual EVO introduces a new paradigm for MB&F — the use of zirconium is not in support of the journey of imagination initiated by the watch concept; it is the means by which LM Perpetual EVO will keep pace with whatever journey you choose to embark upon.



Conventional perpetual calendars are generally modules comprising the complication, which is fitted on top of an existing movement. The calendar indications are synchronised by a long lever running across the top of the complication and passing through the centre. As the date changes, this long lever transmits information to the appropriate components and mechanisms by moving backwards and forwards. This traditional system, while beautiful in its interplay of levers and components, is also extremely unwieldy, restricting movement construction in several key ways that would make something like Legacy Machine Perpetual a mechanical impossibility.

Created by Stephen McDonnell and premiered in 2015, the LM Perpetual Engine was — and still is — one of the most innovative perpetual calendar systems to exist in modern watchmaking.

In the traditional system, perpetual calendars assume that, by default, all months have 31 days. At the end of months with fewer than 31 days, the mechanism quickly skips through the superfluous dates before arriving at the 1st of the new month. Any manipulation or adjustment of the date during changeover can result in damage to the mechanism, requiring expensive repairs by the manufacturer. The dates can also jump or skip during changeover, negating the whole point of the perpetual calendar in the first place, which is not requiring adjustment for years. Or decades.

Legacy Machine Perpetual uses a “mechanical processor” consisting of a series of superimposed disks. This revolutionary processor takes the default number of days in the month at 28 – because, logically, all months have at least 28 days – and then adds the extra days as required by each individual month. This ensures that each month has exactly the right number of days. There is no "skipping over" redundant days, so there is no possibility of the date jumping incorrectly.

Using a planetary cam, the mechanical processor also enables quick-setting of the year so that it displays correctly in the four-year leap year cycle, whereas traditional perpetual calendar mechanisms require the user to scroll through up to 47 months to arrive at the right month and year.

The mechanical processor also enables an inbuilt safety feature that disconnects the quick-set pushers during the date changeover, eliminating any risk of damage while the date is changing.

In 2015, Legacy Machine Perpetual premiered the world's longest balance wheel pinion, connecting the hovering balance to the escapement on the back of the engine. This technical feat has since been showcased elsewhere in the MB&F collection, namely the Legacy Machine Split Escapement.


Technical specifications




Legacy Machine Perpetual EVO is available in three variations of 15 pieces each:

  • - Zirconium case with orange CVD dial plate 
  • - Zirconium case with blue CVD dial plate 
  • - Zirconium case with black PVD dial plate  




Fully integrated perpetual calendar developed for MB&F by Stephen McDonnell, featuring dial-side complication and mechanical processor system architecture with inbuilt safety mechanism. Manual winding with double mainspring barrels. Bespoke 14 mm balance wheel with traditional regulating screws visible on top of the movement. Superlative hand finishing throughout respecting 19th century style; internal bevel angles highlighting hand craft; polished bevels; Geneva waves; hand-made engravings.

Galvanic black dials with both SLN numerals and hands (except for the leap year and power reserve) 

FlexRing: an annular dampener fitted between case and movement, providing shock protection along the vertical and lateral axes. 

Screw down crown

Power reserve: 72 hours

Balance frequency: 18,000bph / 2.5Hz

Number of components: 581

Number of jewels: 41



Hours, minutes, day, date, month, retrograde leap year and power reserve indicators



Material: Zirconium

Dimensions: 44 mm x 17.5 mm

Number of components: 70 

Water resistance: 80m / 8 ATM / 270 feet


Sapphire crystals

Sapphire crystals on top and display back treated with anti-reflective coating on both faces


Strap & buckle

Rubber strap with titanium folding buckle.




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