The protruding eyes of the (amphibian) frog enable it to see in many directions without having to turn its head. The bulbous domes of the HM3 Frog have the opposite, but no less important, feature of enabling the time to be easily seen from many angles without having to turn the wrist. The Frog differs substantially from HM3 in that it is the aluminum domes that rotate under the sapphire crystals in the Frog, whereas it is the hour and minute hands that rotate around their respective stationary cones on HM3.
Rotating domes of this size and shape posed MB&F with a number of technical challenges. The hour and minute domes are machined from solid aluminium - chosen for its optimal strength to weight ratio. The domes weigh in at 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 incredibly demanding and only recently even possible at all. This is due to the fact that any slight imperfection in the sapphire might introduce a disconcerting magnification effect. The sapphire has to be shaped and polished to be perfectly uniform.
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 oversized date wheel is driven from the hours, the gearing driving the date had to be reworked as well.
The Frog may portray the time in a playful manner, but there is nothing but serious and meticulous attention to detail and care regarding the fine hand-finishing of the high-tuned engine purring within its lightweight high-tech titanium case. A close inspection of the case is rewarded with carefully thought out detailing including 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.
If the viewer's gaze manages to break away from the obiculate indications, it is likely to be arrested by the brightly-coloured 22K gold battle-axe winding rotor or the intricacies of the thoroughbred movement beneath.
The HM3 Frog is available in Grade 5 titanium with blued rotor or a limited edition of 12 featuring mark-resistant black-coated titanium with green rotor.
HM3 Frog: Don't jump to conclusions!
For more information, please download the HM3 Frog press release