Watch Accuracy

The Watch Superstore posted this on 31 Jul 2015

 

Watch Accuracy

 

Mechanical Movements

• Accuracy of Mechanical Wristwatches - what to expect

• Maintenance and Frequency of Service

• Things To Be Aware Of With Regards To Accuracy

• Quartz/Battery Operated Watch


Mechanical Movements


Made up of tiny screws and miniature springs, mechanical watch movements are complex yet they can last more than a lifetime if they’re taken care of properly.


The Accuracy of Mechanical Wristwatches - What to Expect


Accuracy is crucial when it comes to watches. Any error can mean that you are not given the correct time and even if a watch was 99% accurate, it would display the time incorrectly by almost a minute and a half every day, which defies the point of a watch.


Accuracy depends on a few different elements:


Position:

A watch will lose or gain time if it’s resting in a single position because they are designed to adjust for this natural change. When you wear your adjusted watch, it will automatically be working to account for changes.


Temperature:

Differences in temperature impact the operation of your watch. Hot and cold environments can cause the individual parts of your watch to expand and contract, which can change the shape and therefore the accuracy of the watch. Although most watches now account for these changes, it’s best to avoid exposure to extreme weather.


Here is a table to show the accuracy standards in mechanical wristwatches.


Modern Mechanical non-COSC Certified watch

   

Poor

+/-10 seconds per day

99.988% accuracy

Normal

+/-5 seconds per day

99.994% accuracy

Excellent

+/-3 seconds per day

99.996% accuracy



Modern Mechanical COSC Certified watch

   

Poor

+6/-4 seconds per day

99.994% accuracy

Normal

+/-3 seconds per day

99.996% accuracy

Excellent

+/- 1 seconds per day

99.998% accuracy


When you purchase a watch from us, you should allow it around four weeks to settle. After this time, if the watch is not keeping time as you would expect it to, there are tw things you can do:


Regulation

When a watch is consistently too fast or too slow, you can take it to a watchmaker so that they can regulate it for you - a common procedure.


Adjustment

When a watch inconsistently too fast or too slow, you will need to get the balance wheel adjusted. This takes a little more time than regulation.


Maintenance and Frequency of Service


Made up of tiny screws and miniature springs, mechanical wristwatches require maintenance from time to time.


Over time, the gears of a watch begin to alter as the lubrication becomes thinner and so this can affect accuracy. As discussed above, the accuracy can be retained by regular maintenance but after many years, the watch will need to be completely serviced. This can be done in a couple of different ways but we recommend that an overhaul every five years is sufficient. This can cost upwards of £200, depending on the type of watch you have. Waiting any longer than this can mean that your watch parts are enduring unnecessary stress and may mean that they would need to be replaced. During this complete service, your watch movement will be regulated, cleaned and lubricated and where necessary, parts will be replaced.


Things To Be Aware Of With Regards To Accuracy


Magnetism

Very occasionally, the coils of the hairspring can become magnetised and they can stick together, causing the watch to suddenly become too fast. Thankfully, it’s a simple task to rectify this, using a demagnifying machine.


Tangled Coils

Less likely than magnetism, tangled coils can be caused by just a knock to the movement and can also cause a watch to run too fast. Again, a watchmaker will be able to rectify this for you.


Overall Poor Operation:

It’s very unlikely that you will find this issue with your new watch, but could be an issue if a watch is over five years old. If the watch is running too slowly and is not rectified by regulation, does not maintain a power reserve or simply stops working whilst it’s on your wrist, take it to your watchmaker. The worst case scenario would be a complete overhaul and we would suggest that any watches with this issue are returned to the manufacturer so that they can carry out the proper procedure according to their process.



Quartz/Battery Operated Watch


What is a Quartz watch?

With quartz crystals providing a constant electronic signal for timekeeping, Quartz watches are some of the most accurate available. Quartz crystals are piezoelectric, which means that when they receive mechanical pressure, they generate an electrical charge and vibrate if an electrical charge is applied to them. The reason that they can keep such accurate time is that they can be cut at a consistent size and shape, which enables them to vibrate at thousands of times per second, making them extremely stable resonators.


Accuracy:

The more accurate alternative to mechanical watches, Quartz watches can boast a plus or minus 1 second per day accuracy. Whereas mechanical watches have many factors affecting accuracy, Quartz watches will keep a consistent time to whatever the original accuracy is. There are a few factors that can impact the timekeeping of a Quartz watch, such as MRI equipment or x-ray equipment.


Outperforming the COSC requirements for accuracy used on mechanical wristwatches, the Swiss testing authority have created a set of Quartz specific tests and standards, requiring the watch to stay accurate to no less than 0.02 seconds per day.


Most manufacturers don’t get their watches accredited by the COSC as it’s an expensive process that would impact the retail price of the watch.


Here is a table to show the accuracy standards in Quartz wristwatches.



Modern Quartz (battery) Operated non-COSC Certified watch

   

Worst Case Scenario

+/-2 seconds per day

99.997% accuracy

Typical

+/- 1 seconds per day

99.998% accuracy

Excellent

+/-0.5 seconds per day

99.999% accuracy



Modern Quartz (battery) Operated COSC Certified watch

   

Poor

+/-0.02 seconds per day

99.99998% accuracy

Normal

+/-0.02 seconds per day

99.99998% accuracy

Excellent

+/-0.00 seconds per day

100% accuracy


Quartz watches benefits:

  • Fewer moving parts mean lower service cost compared to mechanical watches. A service of a Quartz watch can include canging the gaskets, water resistance testing and lubrication, etc.

  • Less general, day-to-day upkeep because there is no need to wind a Quartz watch.


How to retain the accuracy of your Quartz watch:

  • Get your watch tested annually for water resistance.

  • Ensue your watch gets a complete service on every other battery change.

  • Ensure your watchmaker can open, seal and test the watch when they are replacing your battery.

Categories: Knowledge Base