Armin Strom Tourbillon Assembly Process

Assembling a tourbillon at Armin Strom
Don Corson, February 2013

Last year we were able to be present at the launch of the Armin Strom Tourbillon watches. See here , here and here.  The watches presented there were part of a special series of a 4 watch set for the launch of the model.  At BaselWorld this year we will see the first pieces of the standard series and the production is now running.  To get some insight into the production of these watches I visited the shop in Biel this week.

This is the watch we are talking about in its ruthenium and red gold livery, the model "Fire".  In this post I will show the assembly of this watch and in a following post I will show some of the parts production and decoration.

The watch we will see the assembly of here is one of the special series that went around the world for 4 presentations at the launch.  Thus the case is no longer in perfect condition.  What is interesting during the assembly is to see the level of decoration that is being applied on each part.  Note, for example, that the bridge is decorated on both sides, even there where the only person who will ever see it (apart from us, of course) will be the watchmaker who every couple of years does the cleaning.
This is the "kit" of parts and assemblies that will be put together to make our watch.

Here we see the plate from the dial side.  Note the dark ruthenium plating and the fine spotting.

The plate is also decorated from the bridge side.  I had always presumed that decoration on the bridge side, the inside, of the plate would have a negative influence on the dimensions.  To my question I was answered that the decoration is considered in the design so that the needed tolerances are always held.  This is, however, only possible on relatively large parts such as the plate.  Small parts are generally not decorated on the contacting surfaces.

The first parts mounted are the two barrels.

The going train in a tourbillon is very simple, only two mobiles separate the barrel from the tourbillon cage.  The first is mounted here from the bridge side.

Then the bridge, engraved with a "Fire" design is mounted and screwed down.

Then the tourbillon bridge is mounted.

Now the movement is turned over and the second train mobile mounted with its own bridge. 

Then the fixed wheel of the tourbillon is set in place and screwed down from the bridge side.

The crown wheel bridge is the same as is used on the 8-day movements.

After placing the rachet wheels the engraved brides are placed and screwed down.

Next we add the setting wheels and the setting bridge.

Now the movement is ready to receive the tourbillon itself.

The tourbillon is an assembly that is completed and tested by itself.  Note that the power from the going train goes through the pinion in the middle which turns the entire tourbillon assembly.  The smaller pinion that one can (almost) see on the right gears with the fixed wheel that has already been mounted in the movement and the relative movement of the entire tourbillon turning to the fixed gear turns the escape wheel. 

The tourbillon is mounted between two jeweled bearings.  The lower one is in the tourbillon bridge, the upper one is the tourbillon cock which here includes the dial ring with the seconds engraving.

Because so much in a tourbillon watch is done in the tourbillon itself, once a working and preadjusted troubillon is installed the work is almost finished.  A little wind and the tourbillon already starts ticking.

With the open dial side of this watch the dial itself does not amount to very much.  After putting in place it is held in place with two small screws.

Now the hands are mounted, starting, of course, with the lower hand, the hours hand.

When mounting the hands one must watch out that they don't touch and are perfectly parallel.

During all this work the movement has been held in a temporary mounting ring.  This ring is held with the same two screws that hold the movement later in the case.  Because of this ring the movement never touches the movement holder used during assembly and so never takes any blemishes from it.  But now we will mount the movement in the case so the ring has to go.

The movement is then placed in the case from the front, the stem inserted and then the movement is screwed into the case.

The case is then closed front and back.  The back has an o-ring and is screwed shut.  The front besel is a press fit with a sanfil gasket.  Of course any dust and other "things" are carefully removed before closing.

The case press allows closing without leaving any blemishes as does a special fixture to pull down the last bit on the screwed shut case back.

Now we put on the band and are ready to go.

Note the depth of the movement seen from the dial

In general I am not a fan of open-dialed watches.  But these watches from Armin Strom are different.  They have not simply opened a hole in the dial that allows seeing something of the existing movement below, they have created movements what were meant to be shown from the beginning.

I would like to than Antti, the Armin Strom watchmaker who suffered through my endless questions while assembling the movement for his patience and the knowledgeable discussion.
Don



This message has been edited by DonCorson on 2013-02-08 12:27:35 This message has been edited by AndrewD on 2013-02-11 12:57:54