The Daniel Roth 8-Day Tourbillon, Ref. 197

At this stage, we are introduced to a special movement base, which he uses to test the proper functioning of the tourbillons as finishes assembling them.

The peculiarity of this “contraption” is that it allows him to examine how the escapement is functioning, and to conduct all necessary tests, without the hindrance of a rotating carriage!

This picture illustrates how he receives the components necessary to assemble a tourbillon cage from the Daniel Roth stocks.

We were told that the tourbillon parts will require very little, if any, finishing when they are received by the watchmaker for assembly.

His first step, is to ventilate these pieces on his workbench, so that they can be readily available as he requires them.

You can see here the bottom of the tourbillon carriage, with the escape wheel already in place ...

... the top of the carriage, ...

... the tiny anchor as well as the bridge which covers it and the escape wheel, ...

... and, of course, the balance wheel with the hairspring already affixed to it.

It's interesting to note that hairspring is received already colleted and vibrated.

The first step in the assembly of the tourbillon cage consists of inserting the jewels in the carriage and in the escape wheel/pallet cock.

He then assembles the pallet and escape wheel, and checks for the correct contact between the pallet stones and the escape wheel teeth.

The tourbillon cage, at this stage, looks like this (it is being held in a special holder designed specifically by Daniel Roth for this purpose).

The cage is then moved to a different holder, and the three pillars are screwed onto it.

The cage is then removed from this second holder, ...

... and this is what it looks like at this point.

A special tool is then used to check the precise adjusting of the jewels, to ensure that the correct endshakes are present.

He then prepares to screw the pinion underneath the lower carriage ...

... and fastens it in place.

This is the pinion which is driven by the third wheel, and which causes the cage to rotate around the fixed fourth wheel.

The cage is then mounted on the special movement, so that the various aspects of the escapement can be properly tested, and ...

... if necessary, the “depth” of the anchor endstones is adjusted using this special tool.

This tool, when in use, sits on a warmer and allows for the precise adjustment of the pallet stones. The shellac softens under the gentle heat, and the stones may then be moved as required.

The top part of the cage is then assembled, using these components.

The stud cover is screwed onto the stud holder, and then fitted to the upper carriage.

Note that as the balance wheel is free-sprung, there are no curb pins.

The seconds pivot is then screwed on top of the upper carriage, which, once assembled, looks like this.

Occasionally, the outer stud of the hairspring will have to be repinned.

Despite the lack of need for this operation in this particular instance, the head of the "Atelier des Grandes Complisations" was kind enough to demonstrate this very delicate operation for us anyway.

Note that the stud which he is picking up with his tweezers is almost too small to be seen with the naked eye!

Here is the balance wheel once the operation is complete.

The longer portion of the pin holding the stud in place will be cut once he is sure that he no longer needs to make any adjustments to its position.

The orientation of the colleted spring is then set to match this diagram.

The balance wheel is then set onto the lower portion of the carriage, and the two bridges of the carriage are then screwed onto eachother.

The complete tourbillon cage at that point looks like this.

The assembled tourbillon cage then needs to be “poised”.

This bascially means balancing it so that there are no heavy spots around its axis, so that gravity does not adversly affect its turning.

This is done on a special tool, which has two parallel ruby bars on which the two pinions of the tourbillon cage are set.

The carriage is given a very light brush or puff of hair, and examined. If the carriage rocks back and forth to a stop, it is not in poise. If it slowly comes to a stop in the direction of its original rotation, it is in poise (i.e. it has no heavy spots).

Almost certainly, the first few times around the carriage will not be poised, as the escapement naturally biases it.

The poising of the carriage of this Daniel Roth tourbillon is achieved by adding weight in a most clever and tidy way. The three pillars which hold the two bridges of the tourbillon carriage are in fact hollow, and tiny slivers of soft lead are added inside the pillar(s), as indicated by the poising tool (in this case, that would be the lightest of the three, which rests at the top when the carriage stops rocking). The carriage is then tested for poise again, and the whole process is repeated until a satisfactory result is achieved.