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Case, hands and dial_
Marine chronometers inspired the presented pocket watch. For this reason, the
case was made of brass, however, for contrast, the pendant and the bow were
made of silver. Most parts were made in my own workshop without using CNC
machines. Basic machines such as lathes, milling machines and hand tools were
used to make the watch. For readability, steel hands were thermally oxidized
to blue. In my opinion, blued hands harmonize with black indexes on the
silver dial. For added complexity, the hour hand jumps once per hour rather
than smoothly, as is the case with most watches.
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Technical characteristics of the movement_
As in marine deck chronometers, a pivoted detent escapement was used.
Oscillation frequency of the balance wheel is 2 Hz. It is well known that
detent escapement has good friction properties but it is not shock resistant.
Due to this, I decided to make a pocket watch instead of a wristwatch.
Additionally, the watch was equipped with a tourbillon thereby reducing the
problem of poising the balance. Two barrels are used to ensure sufficient
torque. A major problem with watches using a tourbillon is the inertia of the
cage. For this reason, the tourbillon cage components are very thin and
delicate to reduce the inertia. The cage is very heavy, weighing 2 grams, but
the problem of inertia was reduced. In the escape wheel, the pinion and the
wheel are separated and connected via a bronze hairspring. There is a sleeve
with two rubies in the wheel, which runs on the steel axle of the pinion. The
hairspring is arranged in such a way that it holds the wheel on the pinion
(the wheel does not fall out). As soon as the cage is stationary, the
escapement wheel is released. The escapement wheel moves and the cage begins
to rotate. When the escapement wheel stops on the ruby, the cage continues to
move and winds up the hairspring, losing its kinetic energy, and then
slightly backs up. The backing up of the cage results from its high inertia
and the reaction force of the hairspring. In most tourbillon watches, the
cage stops with the escapement wheel, causing a temporary high force on the
escapement elements and undesirable vibrations. In the case of the presented
solution, a hairspring absorbs the vibrations, similar to solutions proposed
for example by Derek Pratt, Karol Roman etc. The balance wheel is equipped
with a Breguet-overcoil spring. There is no regulator on the hairspring due
to chronometric properties. Two screws on the balance wheel maintain
regulation of the oscillation period. Other screws are used to poise the
balance wheel. The tourbillon cage is also poised, by a silver counterweight.
Silver was used due to its high density.
Manufacturing of the components_
The presented watch is made of raw metals. No elements have been electro
painted or plated. Only the hands and three screws were thermally oxidized to
blue. Sulphide was grown on silver elements, this is what gives this darker
look to the dial and to the small plate with the signature. As it was
written, I made most of the parts myself. Every part was finished by hand. In
my workshop were not made: the watch chain, glass, 18 ruby bearings, balance
hairspring, 2 mainsprings and 28 of 40 screws. I did not engrave the
signature; it was made by a professional engraver.
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