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Reinventing the perpetual calendar


Maximilian Busser and his Friends have done it again. Their latest invention, or rather reinvention, is the perpetual calendar. The Legacy Machine Perpetual is the fourth creation by MB&F in the Legacy Machine collection. As Maximilian Busser himself likes to say, the Legacy Machines are the machines that MB&F would have created 100 years ago. They are a contemporary reinterpretation of traditional watches. Just like the previous Legacy Machine creations, the Legacy Machine Perpetual positions the over-sized 14mm balance wheel right in the centre of the dial, nicely tucked under the summit of the dome-shaped sapphire glass. The balance wheel of the watch hangs above all the other elements on the dial, such as the day, date and month indicators as well as the hours and minutes indicators.


A highly complex mechanical movement

For any watch brand, creating a perpetual calendar movement is a real challenge since the perpetual calendar complication is definitely one of the most complex developments to bring to life. Indeed, the movement must be conceived to include a real mechanical processor capable of counting precisely the days of each month and of each year, be it a normal year or a leap year. A watch with a perpetual calendar movement is a technical achievement in itself and only few watch brands have fully mastered the complexity of perpetual calendar watches. Also, beyond the technical challenge represented by the perpetual calendar movement, remains the aesthetic challenge of displaying all the information in a legible, intuitive and appealing way. For MB&F, this is one of the first attempts to go into proper horological complications. Previously, the watches made by Max Busser and Friends were complicated because of their display rather than displaying complications.


Keep it simple and readable

Maximilian Busser did not equip his Legacy Machine Perpetual with a dial. Below his central over-sized balance wheel so typical of the Legacy Machine collection, the movement reveals all its complexity and is entirely skeletonized. The time is indicated on the hours and minutes sub dial positioned at 12 o’clock. The days of the week are on a disk at 3 o’clock, the months on a disk at 6 o’clock and the retrograde date on a disk at 9 o’clock. For perfect symmetry and visual balance, the retrograde leap year indication is positioned left and right of the month disk in the lower part of the dial. Compared to the first and purest of all Legacy Machines, the LM1, the Legacy Machine Perpetual will appear as highly complex. Yet in reality, all elements are displayed in a logical way and the three-dimensional construction of the watch enables each element of the calendar to truly stand out.


Irish horological thinking

The MB&F Legacy Machine Perpetual reinvents the technological approach behind the perpetual calendar in the sense that in traditional constructions, perpetual calendars assume that, by default, all months have 31 days. At the end of the months with less than 31 days, the mechanism quickly skips through the next dates before arriving at the 1st of the new month. In the case of the Legacy Machine Perpetual, the architecture of the watch does simply not allow a similar technological approach (the axis of the hour and minutes hand is not in the centre), which is maybe what pushed Maximilian Busser and his Friends to reverse the basic assumption. Instead of assuming that that each month has a maximum of 31 days, why not assume that each month has at least 28 days. A “mechanical processor”, in charge of counting the days of each month, will then add on the extra days as required by each individual month. This ensures that each month has exactly the right number of days. Instead of skipping, the Legacy Machine Perpetual only adds what is necessary. This solution came from the brain of Stephen McDonnell, an independent Irish watchmaker and friend of Maximilian Busser.


A fool-proof system

This new horological interpretation of the perpetual calendar breaks with the traditional codes of mechanical watchmaking. The mechanical processor (patent pending) imagined by MB&F and Stephen McDonnell is fool-proof since there is no “skipping over” redundant days. It also allows for a quick setting of the leap year and features an inbuilt safety feature that disconnects the pushers during the date changeover, thus eliminating any risk of damage while the date is changing.

For his first real high-level complication, Maximilian Busser has the test summa cum laude. Accompanied by Sephen McDonnell, he has achieved to reinvent one of the most prestigious watch complications that has existed for more than 150 years. And on top of that, he has achieved to stay true to the DNA of the Legacy Machine collection, with its large flying balance wheel positioned centre stage. 

Technical specifications

edition in 18k white gold (grey face).
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 14mm balance wheel with traditional regulating screws visible on top of the movement. Superlative hand  nishing throughout respecting 19th century style; internal bevel angles highlighting hand craft; polished bevels; Geneva waves; hand-made engravings
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: 18k 5N+ red gold, 18k white gold or platinum 950 Dimensions: 44 mm × 17.5 mm
Number of components: 69 components
Water resistance: 30 m / 90’ / 3 atm
Sapphire crystals on top and display back treated with anti-reflective coating on both faces
Black, grey or dark brown hand-stitched alligator strap with gold / platinum folding buckle matching case material.

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