The Reason
The first fully integrated chronograph movement to be produced by Dubois Dépraz. (Launched 2021)
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All Dubois Dépraz calibres and modules, are made with the goal of providing mechanisms to the watchmaking industry as a hole, they are not produced or sold under their own name. They are the most successful and largest company to produce large volume complications to virtually any brands, with an industrial and proven approach. They both develop ideas for companies, as well as bring their own concepts to the market for brands to adopt. They have an infrastructure that allows them to develop and prototype new concepts, producing the components in house, followed by the assembly and testing processes all within their own multiple facilities.
Below, 2 variants of the skeletonised design deconstructed below. Both with solid bridges, and different decorations on the upper bridges.
The centre of the bridges are etched out leaving a high border that is straight grained associating to the steel levers.
The same design shape of bridges but with polished angles and Geneva stipes. (The rotor removed)
The upper bridges skeletonised in order to view the chronograph mechanism.
(During the testing process the start/stop function was constantly activated over 6000 times, the flyback/return to zero function was activated more than 3000 times.)
Functions
Central chronograph seconds hand. Chronograph minutes and hours recorders concentrically assembled at 3 o’clock on the dial-up to 12 hours and 59 minutes. Constant small seconds at 9 o’clock. Power reserve indicator (> 72 hours) centrally positioned around the hour wheel. Instantaneous date ring. Automatic winding. Flyback function. Stop-seconds function when setting the watch.
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There can and will exist multiple variations to this calibre in relation to configurations of the counters, plus an approach to add additional complications such as the Dubois Dépraz perpetual calendar. The example shown below can also be made to the clients specifications in relation to bridge format and final decoration and colour.
The two views below are showing the front of the movement. The first with a skeletonised ‘working’ dial (i.e, a temporary dial allowing the mechanism to be tested and viewed prior to delivery to a brand.)
Total thickness 6,60 mmm diameter 32,00 mm. Frequency 4Hz, (28,800 VPH). Kif shock protection for the balance pivots and 51 jewels throughout the movement. There are 403 pieces in total that are assembled into 156 components to build a single movement.
To maintain the skeletonised effect the date disc is cut out allowing the normally hidden section underneath to be viewed. Only at 6 o’clock is the full number backed with material allowing here the ‘8’ to be viewed. Multiple different versions of this approach can be designed.
The distance between the centre of the movement and the two horizontal counters are both 8 mm. The two chronograph pushers are set at 30 degrees above and below the horizontal.
(During the testing process the complete time train ran through 650 complete cycles of the barrel being fully wound and unwound to ensure function and wear.)
The hands removed.
The 7 working hands used in the testing process of each calibre. The final client will design their own hands to match the brands DNA.
The larger dark grey diameter below the movement is the dial still in place. The ultimate diameter of the dial is dictated by the client.
The gold-coloured, screw-style eccentric, of which there are two, cuts into the dial foot to its left locking the dial in position.
The working dial removed.
The ball race for the automatic rotor. The ball race is held by 3 screws onto the lower bridge, the rotor itself is screwed onto the ball race with 6 screws.
The skeletonised bridges below reveal a series of wheels, the steel pinion and yellow wheel to the left are associated to the automatic. The two wheels, centre and right are for the chronograph mechanism.
In this version of the calibre the rotor is finished in a red gold 5N colour, the bridges in dark grey ruthenium and all steel work is either straight-grained and beveled by hand or polished flat.
In the centre of the image is the brain of the chronograph, a variation of a column wheel, different in design but identical in function. As the main operating pusher at 2 o’clock is activated, turning the chronograph on and off, this column wheel is turned allowing the levers that rest against it to be positioned either on the outer flats or fall in to the escalloped sections.
Below the column wheel under the bridge is the barrel.
The gold coloured screw heads shown are eccentric plugs that allow the chronograph to be adjusted when it’s set up during the first assembly.
The time keeping can be adjusted to qualify for COSC (Chronometer certification).
The rotor removed from the movement.
(The rotor was turned, on a simulator over 5,200,000 rotations when the calibre was originally tested fully assembled, to ensure no unforeseen wear due to either mechanical design or weakness in the materials used.)
The upper bridges are rhutanium grey the lower rhodium plated.
Recto-verso of the rotor. The final design is influenced by the client, below is a suggestion by Dubois Dépraz that allows the lower mechanism to be easily viewed and maintains the volume of the rotor mass remains closer to the exterior of the rotor.
The central dark grey rhutanium bridges are smaller in diameter to the overall calibre to allow the heavy rotor weight fixed to the outer section of the rotor to pass.
The finishing on the upper bridges is simple, circular satin graining and hand polished angles to accentuate the gears underneath
In the image below the driving wheel for the chronograph can be seen to the right, the coupling clutch wheel in the centre and the chronograph seconds wheel in the centre.
All penetration of the wheels (shown here) is controlled by the gold coloured eccentric plugs.
The balance assembly removed.
Below the balance assembly is the escapement.
The bridge holding in place the automatic mechanism removed.
The pinion assembly, driven by the rotor that drives the train leading to the mainspring.
The pawl/steel lever acts against the first wheel ensuring it can only turn in one direction when the rotor turns anti-clockwise. When the rotor turns clockwise the small steel pinion moves out of engagement with the first gold coloured wheel and the steel pawl pushes against the wheels teeth. The small circular spring below the pawl ensures a small tension between the pinion and pawl.
To the right of the escapement, under the balance cock is the stop-piece or hack, which pushes against the balance when the watch winding crown is pulled into setting position, to stop the watch from ticking so the seconds hand can be set to the exact time..
The main-plate is cut away to accentuate the dimensionality of the movement, allowing the movement of the balance to be viewed through the dial, date ring and main-plate.
The balance bridge and Swiss anchor escapement. (Pointage 20.3)
The upper bridge, upon which the rotor is held is removed revealing the full mechanism underneath.
All of the wheels are circular grained and then plated before the teeth are cut.
The first set of chronograph wheels removed.
Historically there are two forms of chronograph mechanism in relation to driving the chronograph mechanism. One is the vertical clutch mechanism, used in wrist watches since the 1960’s and first seen in early pocket watches dating back to the 19th century. The above version, in concept, has been used more often. The clutch sliding towards and away from the chronograph wheel whilst the drive wheel (4th wheel) constantly drives the coupling clutch wheel integrated into the assembly. One of the unique construction design elements of this system shown above is a safety mechanism that prevents the coupling clutch from moving out of engagement with the chronograph seconds wheel if the watch was to receive a severe impact.
The coupling clutch that holds the wheel that engages with the driving wheel, and in-turn drives the chronograph seconds wheel.
The hammer assemblies that return to zero the chronograph functions. The angles and straight graining have been finished by hand.
The motion of the start-stop mechanism is smoother than in many chronographs due to the pivoted operating lever and double push-piece lever the pusher acts against.
The start-stop operating lever activated by the 2 o’clock pusher is the last largest lever in the construction.
In the centre of the image is the chronograph seconds wheel brake. This pieces pushes against the chronograph seconds wheel when the chronograph has been stopped but not returned to zero.
The chronograph seconds wheel brake. The gold-coloured eccentric plug lifts the hammers when the chronograph functions are about to be returned to zero.
An example of one component made of 3 pieces.
The column wheel and the spring that acts upon it indexing its positions.
The foot of the spring is angled and polished by hand, the surface straight grained using 3M abrasive silicon paper also finished by hand.
The barrel bridge upon which the majority of the chronograph mechanism sits removed.
The click for the ratchet wheel sits to its right in the image.
The majority of the watch dismantled, leaving in place the final part of the gear train and the upper 4th wheel that drives the chronograph.
The main-plate and lower bridges are mat finished before being rhodium plated.
The upper fourth wheel that drives the chronograph.
The under-dial design follows the design of the automatic bridge, holding in place the relevant components but pierced out to be able to see the components underneath.
(During early tests the date disc was indexed manually over 1800 times through the accelerated turning of the going train and again over 1800 times running the calibre’s naturally to ensure its functionality and identify any weaknesses in construction.)
(The clutch mechanism for the stem was tested over 8500 complete turns of the cannon-pinion, the piece that carries the minute hand.)
The barrel has also been skeletonised to view the mainspring.
Between 5 and 6 the pawl that indexes the date ring can be seen. At 8 the main-plate is machined to allow the date to be clearly viewed.
The yellow wheel next to the 29 carries a lever that is inked to the instantaneous date change mechanism.
The power reserve indication illustrates a maximum of 72 hours.
The power reserve indication mechanism.
The three meshing steel parts are driven by the smallest, the pinion. The pinion in-turn drives the quarter segment rack which meshes with the central wheel upon which the power reserve hand sits.
To the left of the jewel and below it is part of the rapid date change mechanism.
In the centre of the image is a red jewel. The jewel guides a tube and pivot, the tube carries the hour recorder hand and the pivot, the minute recorder hand.
The dial side dismantled.
The setting mechanism still in place as well as the majority of the rapid date change mechanism.
The winding crown and stem were turned over 40,000 complete turns to check the winding mechanism. The rapid date change was turned in excess of 1200 turns to check the repeated functioning of the correction system. The stem was turned over 11000 times to ensure the manual setting of the hands resulted in no ware.
The date disc. The size of the date is adjusted to be able to optimise the space available when viewing it.
The containers the movements are stored in whilst being tested.
The specialised movement holder with pushers for testing the chronograph during and after assembly.
Summary
A fully integrated chronograph with automatic winding and power reserve indicators. Technically innovative with securities integrated into the coupling clutch protecting the chronograph against impacts affecting the chronograph function whilst in use. Smoother operating function than normally found on many chronographs due to the double lever operating system on the primary start function. Designed to be produced in large volumes or tailored to a clients specific aesthetic requirements on a small production.
By altering the form of the bridges the overall look of the calibre can be personalised to a clients DNA/specifications.
Pierre Dubois, CEO of Dubois Dépraz
To learn more about Dubois Dépraz