|HM3 Chocolate Frog features a "chocolate" PVD coated Grade 5 titanium case and a 22K red gold rotor. It is available in a limited edition of 10 pieces.|
The HM3 frog, as it is known, was actually released a year ago by MB&F, the Geneva-based company that creates highly limited editions of artistic and technically innovative timepieces. Its latest timepiece creations are two new versions of the frog, the Chocolate Frog and the Frog Zr. HM3 refers to the third version of the company’s groundbreaking horological machine, which powers the watches and serves as the foundation for its elaborate and unusual designs.
|HM3 Frog Zr in zirconium with a purple 22k gold rotor. It is available in a limited edition of 18 pieces.|
The case of the Zr watch is made of zirconium, a metal highly resistant to corrosion that, to my limited knowledge, is rarely, if ever, used for watches. The chocolate frog’s case is made of PVD-coated Grade 5 titanium.
The two sapphire-encased bulbous domes of the HM3 Frog are designed to replicate the protruding eyes of the frog. They are actually conical gauges used to display the time. One displays the minute and the other the hour. Aluminum time indicators rotate beneath the sapphire crystal, enabling them to be easily seen from many angles, the company said. This is substantially different from the previous versions of the HM3, in which the hour and minute hands rotate around their respective stationary cones. (pictured: HM3 Frog available in Grade 5 titanium with blue 22k gold rotor.)
Maximilian Büsser, the company’s founder, said creating the domes in such a way was a challenge. Solid aluminum was chosen for the time indicators because of its optimal strength to weight ratio. The domes weigh just over 0.5g. They are milled first from the outside and then the inside to arrive at a paper-thin wall thickness of just 0.28 mm, which reduces their energy requirements to an absolute minimum.
Even the fabrication of the semi-spherical sapphire crystal domes was demanding because any slight imperfection in the shape might introduce a disconcerting magnification effect, Büsser said.
The Frog's unusual method of indicating time necessitated the development of a new gear train for the HM3 engine. This was because the aluminum hour dome of the Frog rotates in 12 hours compared to the 24 hour revolution of the HM3 hour hand. And as the date wheel is driven from the hours, the gearing driving the oversized date display had to be reworked as well.
While the Frog is playful in its application, the work behind it is serious. A close inspection of the case displays a carefully thought out detailing that includes a figure 8 engraved around the domes that mirrors the form of the display back (revealing dual ceramic bearings); distinctive clover-head white gold screws; and an engraved arrow discreetly indicating the easy to read over-sized date.