Europa Star: SWATCH GROUP – Stripping down the SISTEM51

Europa Star: SWATCH GROUP – Stripping down the SISTEM51

Europa Star WorldWatchWeb, 26 March 2014

Pierre Maillard with the expert assistance of watchmaker Denis Asch (L’Heure Asch)

The Sistem51 watch, which Swatch presented at BaselWorld 2013, only started to come off the automated production lines just before the Christmas holidays.

The first Sistem51 models were sold from a pop-up store in Zurich. Europa Star managed to get its hands on a few (at 150 Swiss francs each) in order to better understand this quite astonishing watch.



The Sistem51 owes its name to the number of components in its self-winding movement. The most astonishing characteristic is that, among these 51 components, there is only one screw! Normally there would need to be at least thirty. Another characteristic is that the production, assembly and adjustment of the Sistem51 is fully automated, without any human intervention. Besides these few snippets, Swatch has provided very little information. We wanted to know more, to understand how the movement was constructed, to test its performance. To do this, we asked the expert watchmaker from Geneva, Denis Asch ( to help us. Together, we opened up the Sistem51.



But before we opened it up, Denis Asch wore it for a while and subjected it to various tests. The first tests were for water resistance. The results were that the Sistem51 is perfectly water resistant, whether tested under pressure or not. Then, the Sistem51 underwent a whole series of precision tests: after the first winding, after 24 hours of wear, after 24 hours of rest, after 72 hours of rest, after full winding and waiting 30 minutes. First observation: the watch stopped after 93 hours of operation, which is a lot for a self-winding watch. Second observation: its amplitude is good, varying between 344° and 257° (after 72 hours at rest). Its delta on the other hand (which indicates the difference between its positive and negative variations in rate) is mediocre. The watch tested showed a delta of 18.4 seconds after the first winding (i.e. from -6.1 to +12.3 seconds per day), and ± 36 after 72 hours at rest (-6.9 and +29.1 seconds/day). But, surprisingly, another Sistem51 tested, which had been worn for a month, showed much better results, “almost chronometer level”, according to Denis Asch, with a delta of 8 (-4 + 4 seconds/day).

But since they were both purchased on the same day and from the same place, only hours after the watches came on the market, these two Sistem51 models should logically come from the same production lot. Could it be a problem with the settings of the robot regulators? “It would appear that automation does not guarantee a consistent quality in adjustment…” notes Denis Asch. “We can see the limits of machines in the quite sensitive area of adjustment, which depends on so many micro-details and delicate balances that have more to do with the human eye and experience,” says the man who as a watchmaker passed a few years in the strict Rolex school. “But having said that, these results are more than satisfactory. Swatch has always offered the best reliability and quality for the money, with Rolex being a case apart.”

After these first observations, we are about to open up this Sistem51 and see what is inside. We start by removing the spring bars for the strap (which means that the strap can easily be swapped for another). It is supple, made of a material similar to rubber, comfortable to wear and has the very “chic” detail of genuine contrasting colour stitching.


But the first problems occur when we try to open up the case that was not designed to be opened (the Sistem51 is not repairable: “that would have cost a lot more …”, says Denis Asch). First we try from the back because he thinks he has spotted a small pin. In vain. Half an hour later, we still haven’t managed to open it (but we did succeed in seriously ruining the back) and Denis Asch even managed to pierce his finger with a screwdriver. I have to go and find a plaster.

We try from above and the only solution here is to break the bezel, which seems to be glued on, to release the plastic cover, remove the hands, take out the crown using pliers (the stem is not screwed into the head of the crown but set directly into it) in order to finally remove the dial (a plastic disc).


The dial has no feet and it is set into the circumference of the case. Underneath we find the date disc and what immediately strikes our watchmaker is that there are indeed no screws. The minute wheel is visible (at 9 o’clock) and it is simply held in place by small metallic pins in the plate that covers the centre of the dial, a detail that shows the radical ingenuity that has gone into engineering this piece.


Now we have to turn the watch over to remove the movement. The oscillating mass remains attached to the back. It is a plastic disc that moves only in one direction and seems quite free. It is held in place at the centre by ball bearings that are clipped onto the head of the central screw. We manage to remove it.
The “mass”, if we can call it that, can be seen on the back: it is in thicker black plastic, which allows it to act as a weight.



The movement itself is held in place by plastic studs that are seated into small holes drilled around its circumference. Finally we have access to this famous, solitary screw. It is very short and once we have unscrewed it we can remove the self-winding assembly. But we have our doubts: does this screw not simply just hold the ball bearings for the oscillating mass in place? Because everything else seems to be soldered, riveted or studded.

We then remove the balance bridge, the balance cock – also in plastic – then the escapement bridge to access the escapement and the escape wheel. At this point, Denis Asch goes wide-eyed. He cannot believe it: the entire lever is in plastic, including the pallet stones, “this is the real prowess,” he exclaims, “because this is what determines the rate! I have never seen that before! And what’s more, in this plastic, the axes are metallic!”


From left to right and top to bottom:

The screw, ball bearings for the mass, two small gear wheels for the mass, a spring, a first bridge, the reduction gears for winding the barrel, the escapement bridge (cock), the escapement and the escape wheel.

Next we remove the gear train bridge and discover the second level of the movement. The barrel has a large diameter (which explains the 90 hours of power reserve). Unlike traditional barrels, which have two axes, this one is drilled in the centre and turns on an axis that is fixed on the mainplate. “It is details like this that show how, by simplification and optimisation, the engineers at Swatch have managed to reduce the number of components so drastically,” Denis Asch comments.

dsc_4309-2f68eWe move on to the gear train. To access it we must first remove the motion work bridge (at 3 o’clock) that holds in place the motion train and the bolt for selecting the different functions operated by the crown. But this motion work bridge, in plastic, is stubborn and does not want to be removed. It is one of the most complex pieces in the entire assembly with a number of smaller components apparently embedded inside it. Denis Asch tries to discern its secrets: “It is very cunning, very intelligent,” he muses, eyeglass in place. “They have grouped together as many functions as possible in order to keep the number of components down at all costs. As a result some pieces are assembled the opposite way to what is normal.” We have no alternative but to break this bridge in order to remove it. Having done this, we can count the number of components in the motion work.


The sprung-balance is not attached directly to the mainplate but to a metallic component, a sort of sub-bridge on the mainplate. Why? Probably so that the sprung-balance can be set independently during the production process, then simply be placed in its setting without any need to touch it afterwards (or to be more precise, so that the robot does not need to touch it afterwards). “What impresses me,” says Denis Asch, “is that such good precision is achieved even though the stud is attached directly to the mainplate! And look how the balance has been trued: there are milling marks visible to the naked eye.”


We note the same “reductive” ingenuity when we remove the third wheel and the last bridge: “Everything is arranged the opposite way,” explains Denis Asch, “the logic is inversed compared with a traditional movement.” We turn the movement over and by removing the bridge on the motion work side quite easily we can access the wheels that drive the hands and the date changing and setting system. There are six components in all and a plastic ring on to which the date numerals are printed.


And that’s it. Our watchmaker is dumbfounded: “It’s a miracle that it works, bravo…!”

We arrange the 51 components for a souvenir photo.
That was a Sistem51. Peace be upon its “soul” because it cannot be put back together again.


Source: Europa Star April – May 2014 Magazine Issue