An MB&F Legacy Machine Perpetual EVO, In Titanium
A highly unusual and innovative perpetual calendar, with a movement created by Stephen McDonnell.
The Legacy Machine Perpetual EVO was launched in 2015, and it’s the first collaboration between MB&F and watchmaker Stephen McDonnell, who has gone on to become something of a celebrity in the watch world in his own right (something to his own surprise, I think). The Legacy Machines stand apart from the Horological Machines in that they are deliberately intended to be more traditional in their approach to watchmaking than the HM watches; Max Büsser has said that the idea was to create the kind of watches that MB&F would have made had it been started in the late 19th rather than the 21st century. While the Horological Machines make extensive use of highly modified shaped movements, the Legacy Machines generally use more traditionally configured round movements although they too have their design idiosyncrasies, including the use in all of them of the so-called “flying balance” in which a large diameter balance floats above the surface of the dial side of the watch, under an arched balance cock.
The first Legacy Machine, LM1, was released in 2012 and the Perpetual EVO was at the time, and still is, one of MB&F’s most ambitious and technically complex watches. The Perpetual EVO is as the name suggests, a perpetual calendar but a very unusual one, and its technical innovations are a direct result of trying to design a perpetual calendar around the flying balance.
A perpetual calendar is a watch that is programmed to show the correct day throughout the year, in months with either 30 or 31 days, and is also programmed to switch from February 28th to March 1st correctly – and from February 29th to March 1st in a Leap Year. The day on which the calendar switches at the end of each month is handled by a cam with notches in its edge – in a traditional perpetual calendar, there are 48 notches of varying depths, representing a full four year cycle of months; a variation on this system is to use a 12 notch cam with a smaller square cam sitting at the position for February, which rotates one full revolution every four years; in a Leap Year that cam presents a slightly different face which changes the switching date at the end of February from the 28th to the 29th.
One basic characteristic of the system is a very large single lever which coordinates the switching of all of the date indications. Here’s an example from an A. Lange & Söhne Grand Complication pocket watch, which was the basis for the 2013 Grand Complication wristwatch.
The perpetual calendar plate has a 48 step program cam, or wheel, at 12:00 with the date indication on the right, and the day of the week on the left. If you put a hand on the pivot of the program wheel, then you also have a Leap Year indicator. The multi-armed lever that controls and coordinates switching is above the large moonphase disk and as you can see, it has a nose that sits on one of the steps of the program wheel. The problem with this configuration for the Perpetual EVO is that the arrangement of components doesn’t lend itself to the flying balance configuration, with the balance in the center and visible on the dial side, and the time shown in a subdial at 12:00. For this reason, McDonnell had to come up with a more compact solution which ended up getting called the “mechanical process.” A picture being worth a thousand words and a video worth a thousand pictures, here’s a video MB&F shared at the time of the launch which shows how the system works.
As you can see, the mechanical processor is much more compact than the program wheel and big lever design. One other major difference is that while the program wheel takes as its default, a 31 day month from which days are subtracted in order to arrive at the correct switching date, the mechanical processor takes as its default, a 28 day month to which days are added, to arrive at the correct switching date.
There are separate subdials for the date, day of the week, and the month, as well as a power reserve at the lower right, and a rather unusual retrograde Leap Year indicator at the lower left, which gives you a little extra something to look forward to when the date changes at midnight on the December 31st of a Leap Year.
While as is the case with all Legacy Machines, there is a lot of action on the dial side, the movement plates and bridges are beautifully finished as well, with many beautiful details throughout. These include the very sharp transitions (and beveling) on the bridge over the crown wheel (at 9:00 in the image) and the overall layout of the movement, which is asymmetrical around its vertical axis and more symmetrical (although not entirely) along its horizontal axis. The escape wheel and lever are visible at 3:00 and the lower pivot for the flying balance is under the antishock assembly, right at the center of the movement, which is signed by Stephen McDonnell.
The Perpetual EVO was first released in zirconium and then in titanium; this is one of the titanium models. It’s a remarkable achievement both artistically and technically. The lavish display of three dimensional horological architecture speaks for itself; however the design creativity would not have been possible without considerable mechanical creativity as well. If you’re interested in hearing from the man himself about his creative process, I highly recommend a presentation McDonnell gave at Dubai Watch Week in which he talks about the very difficult and sometimes extremely frustrating work involved in designing the successor to the Perpetual EVO, the Sequential EVO.
As with any MB&F watch, the Perpetual EVO is best understood as a manifestation of a particular philosophy – it is sometimes criticized on the grounds of size and legibility but the goal in making it was not to produce a classic perpetual calendar, but to create a highly architecturally unusual variation on the traditional complication. I don’t think it should be criticized for not emulating the layout of a traditional perpetual calendar as that was not the goal; you don’t criticize an URWERK, for instance, for not being a Calatrava ref. 96. I think on those criteria – originality, and the degree to which it succeeds in fulfilling its design mandate – this is a very beautiful and enormously successful design. It has been said of Breguet that to own one of his watches is to have the brains of a genius in your pocket; to own the Perpetual EVO is to have the brains of a genius – Stephen McDonnell – on your wrist as well.