They call functions on mechanical watches "complications" for a reason, but sometimes things get so complicated that it's time to start over. That's the reasoning that led MB&F and Irish watchmaker Stephen McDonnell to produce the Legacy Machine Perpetual – a wristwatch that includes a perpetual calendar with a reinvented movement that's more compact and reliable than conventional designs.

A perpetual calendar watch complication is more than just the standard day/date window. It's a special movement that not only shows the day of the week and the month, but can adjust itself for the particular month and the year automatically without adjustment for years, decades, or even centuries. The problem is, perpetual calendars are tricky. Months are not of uniform length and neither are years. Add in leap years and their arcane rules and putting together a mechanical train that keeps in sync with the real world is no easy task.

If this isn't bad enough, perpetual complications are usually an add-on module that's built on top of a base movement, which is an inelegant solution. They depend on a component called the grand levier (big lever), which runs along the top of the complication and through the center of the movement. By moving forward and backwards, it transmits the information about the date changes to the various components of the watch. This takes up a lot of space and restricts how the day and date can be displayed – usually in cutout windows. Needless to say, this restricts the design of such watches and makes them run to the large side.

Conventional perpetual designs use a default 31-day month and adjusting the date means the complication must fast-forward through unwanted days for short months and up to 47 months for leap years. This makes them tend to skip. In addition, the mechanism is easily damaged if adjusted while the date is changing.

"I call perpetual calendars boomerang watches because they come back for repair so often," says MB&F owner and creative director Maximilian Büsser. "The mechanisms jam, block, break, or jump days when they shouldn’t."

The Legacy Machine Perpetual tries to overcome these problems with a new movement, which uses a "mechanical processor" to calculate dates. It's made of a series of superimposed disks with a planetary cam for quickly setting the year, it replaces the conventional grand levier system architecture and allows for a more flexible and compact design.

Instead of sitting on a base movement, the calendar complication is integrated into the other components. Meanwhile, eliminating the grand levier means that complication doesn't need to sit on the periphery and can move to the center of the watch.

To make it more reliable, the Legacy Machine Perpetual uses a default 28-day month instead of 31, then adds extra days to make up the specific month. In addition, the adjuster pushers automatically deactivate while the calendar is changing, so the mechanism doesn't get a chance to skip, jam, or break.

The Legacy Machine Perpetual comes in a choice of an 18K red gold or platinum case made of 69 components and measuring 44 x 17.5 mm. Water resistant to 30 m (90 ft, 3 atm), it has sapphire crystals front and back treated with anti-reflective coating. These reveal the movement, which discards the traditional dial in favor of a skeleton design to show off the works.

The manually-wound, double-barrel calibre has 581 components and 41 jewels operating at 2.5 Hz off a 72-hour power reserve. The parts are decorated with internal bevel angles, polished bevels, Geneva waves, hand-made engravings. These are topped by a suspended 14 mm balance wheel for an eye-catching effect. This is connected to the movement by what MB&F say is "likely to be the world’s longest balance wheel pinion."

The display on the open dial is made up of the time readout and a set of skeletonized subdials that show the day of the week at 3 o’clock, the power reserve at 4 o’clock, the month at 6 o’clock, a retrograde leap year indicator at 7 o’clock, and the and date at 9 o’clock. These subdials seem to float above the movement thanks to hidden studs and is an arrangement made possible by eliminating the grand levier. Topping off the features is a hand-stitched alligator strap in black or dark brown with matching gold platinum buckle.

The Legacy Machine Perpetual is available in a limited edition of 25 pieces in red gold priced US$145,000 and 25 pieces in platinum for US$176,000 in platinum.

The video below introduces the Legacy Machine Perpetual.

Source: MB&F

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