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Frequently Asked Questions

What is a mechanical watch?

The power that drives a mechanical watch comes from a specially designed and precision manufactured spring. When a mechanical watch is wound, energy is imparted into this mainspring. The watch keeps accurate time by the highly regulated release of the energy stored in the mainspring. A mechanical watch differs from a typical quartz watch in that it uses purely mechanical components to keep time, rather than batteries or any other external elements. Mechanical watches typically can run for about 40 hours on one full winding of the mainspring. The basic design of mechanical watches has changed little in the past fifty years. What has changed is the use of high technology and modern materials in the design and manufacture of the watches.  

Why do all watch manufacturers recommend “winding” automatic watches?

Like the mechanical watch, the automatic watch is powered by the energy stored in its mainspring. Unlike the mechanical watch however, the automatic watch is powered by the movement of the wrist which activates the mechanism to wind the mainspring. When you put on the watch for the first time, there will be no energy stored in the mainspring. To give the watch an initial power boost to ensure it operates efficiently, all watch manufacturers strongly advise automatic watch owners to manually wind the watch before wearing. Some 30-40 turns of the crown should be sufficient. Similarly, if you have not worn your automatic watch for more than 24 hours, you should again wind the watch to boost the power. If you take your watch off at night, a quick 5 to10 turns of the crown will again top up the power.  

What does "17 jewels" mean?

Higher quality mechanical watches have traditionally used jewelled movements. This means that jewels (originally natural, now synthetic rubies) are actually used as the bearings for the various moving parts in the watch mechanism. A typical hand-wind movement today will have only 17 jewels as a full complement. Some really high-engineered or ultra-thin movements will add a few extra jewels to further protect against any wear, but these do not usually exceed 21-23 jewels. However, automatic winding movements, and movements with additional functions such as chronographs and calendars, can greatly increase the total number of jewels. An automatic winding movement, for example, will add an extra 4-8 jewels.          

What factors affect the accuracy of a mechanical watch?

For a mechanical watch, the habits of the owner can affect the operation of the watch. How long it is worn each day, when it is wound, even what position it lies in when it is not being worn, can all play a critical role in determining how consistently a watch runs. Although a typical mechanical watch might gain or lose as much as 5 minutes per week, it is possible, by adjusting the watch to fit a wearer's regular habits, to achieve much greater accuracy.  

None of these factors make any difference with a quartz watch. With quartz, temperature is the only variable that affects the accuracy of the movement.

   

What is a reasonable expectation of accuracy from a wristwatch?

 
Reasonable Accuracy Expectations by Type of Watch (seconds) Worst Typical Best Best Accuracy
Vintage mechanical watch +/-60

 

+/-35 +/-5 99.9826%
Modern mechanical watch +/-30 +/-15 +/-2 99.9942%
Modern mechanical watch chronometer certified +6/-4 +/-3 +/-1 99.9977%
Modern quartz watch +/-2 +/-1 +/-0.1 99.9998%
Modern quartz watch chronometer certified (very rare) +/-0.02 +/-0.02 +/-0.0 99.9999%
 

All watches tend to gain (or lose) a few seconds over a period of time. After all, these are small mechanical or electro-mechanical devices that are counting out 86,400 seconds per day, every day! Even if a watch is 99.9% accurate, it will still be out by a minute and a half in just 24 hours! (Or as much as 10 minutes per week). The minimum accuracy standard for automatic watches according to the Swiss Watch Industry is 99.7%.

 

With an automatic watch, why should I never adjust the date between 10pm and 2 am? An automatic watch with day, date display, calendar, etc, has a considerable number of interconnected wheels and other components. From 10pm onwards, many of the wheels will start linking to each other in preparation for the daily changes of day & date. If you try to manually change the date at this moment, you are altering their adjustment and this may result in damaging the mechanism. After 2am, the wheels are no longer linked to each other and date adjustment is perfectly safe.

     

What is a Reserve de Marche?

A Réserve de Marche (or Power Reserve), is an indicator that displays the approximate number of hours of power remaining in the mechanism of an automatic watch. It is a very sophisticated and useful indicator for an automatic watch, as the wearer can see at a glance if the watch needs winding.    

What is a Big Date Calendar?

Many watches have a calendar on its main dial. The day-of-the-month is usually displayed through a small window and is presented in the 1-31 format. These “windows” are usually small and can be difficult to read. Some watches have a Big Date calendar, with two separate larger windows which are easier to read, and more in keeping with some watch designs. Big Date calendars are driven by 2 wheels, one (first digit) numbered from 0 – 3 and the other (second digit) numbered from 0 – 9.
This of course does mean that Big Date calendars usually have to be manually adjusted at the end of each month (from 30 – or 31 – to 32, 33, 34, etc up to 00 and finally 01).  
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