Certified: Ferdinand Berthoud backs up the chronometric performance of the FB 2RE.2 with independent data
The results of the Fleuritest chronometry test cycles for the new Ferdinand Berthoud FB 2RE show impressive chronometric capabilities
The full name of the manufacture is Chronometrie Ferdinand Berthoud, a name that clearly signals a performance claim. All watches presented so far were always impressively constructed and beautifully designed, but only now the brand supplied comprehensive test data for the performance of its latest FB 2RE.2 chronometer sourced from timekeeping experiments executed by the independent Fleurier Quality Foundation, i.e. the standardised Fleuritest protocol.
(Chronometrie Ferdinand Berthoud FB 2RE.2)
Let’s just say the results impressively live up to the name of the manufacture…
The Cal. FB-RE.FC represents classical chronometer construction excellence
Before we delve into the timing results let me recap the construction of the movement driving the FB 2RE.2, the manufacture Cal. FB-RE.FC:
(The Cal. FB-RE.FC)
Rarely have I seen a movement so streamlined to timekeeping as this one (and quite honestly, timekeeping per se is of far lesser importance today for a watch than – perhaps, regrettably – its entertainment value – another discussion!), and likely also very few that present those constructional details that serve improved performance as openly as this one. In fact, that’s essentially all you see…
(Optimising isochronism along the entire geartrain. Image © Ferdinand Berthoud)
The general construction of the Cal. FB-RE.FC comprises classical, finest performance-increasing details, and also the materials used are traditional ones – there is no silicon or nanotubes to be found. Specifically, the gear train is equipped with two major mechanism both intended to regulate energy flow, one at the source and one at the end of the geartrain:
(1) Regulation of torque at the source: mainspring
The fusee-and-chain system, cherished by collectors for its ‘old-world’ charm recalling table and pocket chronometers, ensures that the torque fed from the mainspring barrel into the geartrain is constant regardless of its winding state.
(Fusee-and-chain as well as Maltese Cross system)
With this mechanism, the energy of the mainspring is transferred from the barrel (right, constant diameter) by means of a miniature chain to a conical fusee cone (left, variable diameter) such that the diminishing torque of the mainspring is compensation, i.e. offering a first means to improve isochronism.
(Chain almost uncoiled from the barrel (front), and wrapped around the fusee (back))
(The FB 2RE.2 has a window on the case band to view the chain)
Ferdinand Berthoud goes one step further: in addition to using the fusee-and-chain to compensate torque drop of the mainspring, the watchmakers further added a Maltese Cross to limit the usable fraction of the mainspring: if not limited, the comparatively large mainspring would provide about 80h of autonomy. In practice only 60% (about 50 hours) of this energy is actually used.
(Maltese Cross with the 6 fingers allowing for 6 barrel rotations, and the power reserve indicator below)
Of the original 8 possible rotations of the mainspring barrel the Maltese Cross allows for only 6, thereby preventing the spring from supplying too much (at the beginning of the power reserve) and too little energy (at the end of the power reserve).
(2) Regulation of torque at the end: escapement
To further ensure that disturbances resulting from meshing of gear teeth or residual compromises to mainspring isochronism are minimised, the Cal. FB-RE.FC is equipped with a remontoir d’égalité, essentially an intermediate escapement coupled with a constant force spring which delivers precisely defined amounts of energy to the escapement proper.
(The remontoir d’égalité. Note the fine spring beneath the escape wheel and the aerodynamic balance wheel (above), and the finely finished triple-shaft stop wheel (below))
Ferdinand Berthoud describes the remontoir as follows: