Frequently asked questions
The micro engineering world of watches and watchmaking can be a daunting one with many words such as chronometer and chronograph often misunderstood, and the reasons watches require maintenance and how often. So, we have put together a brief explanation for the most common questions we get asked using simple and wherever possible non-technical language. If there is something you want to know which doesn’t appear on our list, please follow the link at the bottom of the page to contact us and we will come back to you with an answer.
How does a mechanical watch work?
The energy to drive the watch comes from the mainspring which is held inside a capsule called the barrel. The mainspring is wound through a series of wheels and pinions (Ratchet Wheel, Crown Wheel, Winding pinion, Sliding pinion, Stem and Crown) called the winding transmission. One end of the spring is hooked onto the barrel arbor and the other end engages with the wall of the barrel, as the winding transmission is turned the spring is wound around the arbor so applying tension to the mainspring. As the spring tries to unwind to get back to its “relaxed” position it causes the barrel to turn.
The “train of wheels” are responsible for transmitting the energy produced by the mainspring in the barrel to the “escapement” they are known as the centre or intermediate wheel, third wheel, fourth or seconds wheel and the escape wheel. The different number of teeth on each wheel and pinion or gear ratio ensure that each wheel rotates at a specific speed in relation to its neighbour.
The escapement is the heart of the watch controls the time keeping by releasing the power from the barrel through the train at a predetermined rate such as 21,600 or 28,880 beats per hour and is made up of the escape wheel, pallets and balance assembly. The balance has a fine spring mounted on its assembly which is the part that determines the timekeeping of the watch and ensures that the balances oscillates backwards and forwards. It is the balance receiving its impulse from the escapement that produces the familiar tick of the watch when held to your ear. The higher the number of beats in simple terms the more accurate the watch will be, because it will not be as adversely affected by knocks and bumps as a watch with lower beats per hour. The draw back to the speed is the faster the watch beats the quicker wear will occur, with the current design of Swiss lever much over 36,000 per hour and the “balance” is no longer controllable enough to tell the time accurately!
As the train of wheels can only turn at a specific rate governed by the escapement the centre wheel also carries the drive for the hand setting mechanism (intermediate hand setting wheel, Minute wheel, Cannon Pinion and Hour wheel) of which the hour wheel and cannon pinion comes through the dial to carry the hour and minute hands respectively at the correct speed to tell the time.
The majority of mechanical watches use hands to display the time but there are some digital formatted mechanical watches as well as various discs and coloured liquid tubes.
Additional complications can then be added to the basic movement and these are usually divided in simple or high complications defined by the complexity of the additional mechanism required to provide the function. Example, a date would be considered a simple complication, but a perpetual calendar which is a calendar displaying day, date, month and mechanically adjusts the calendar display for short months and leap years and would be a high complication. As complications are added to the movement they are built on the base movement in layers on the front or rear of the movement depending upon their function i.e. most calendar mechanisms are generally added to the front of the movement and chronograph and automatic winding mechanisms to the rear.
How does a quartz watch work?
The energy to drive the watch all comes from the power cell. The cell imparts its power through a circuit to a specially shaped piece of quartz crystal (Tuning fork shaped), which is held in a sealed capsule. The electrical power excites the crystal (Piezo Electric effect) causing it to vibrate 32,768 per second (Hz). As you can will appreciate from the speed of oscillation in mechanical watches mentioned above, this is why even a basic quartz watch can potentially keep better time than a handmade mechanical watch!
This signal is passed through the circuit board to a microchip which then reduces the pulses down to 1 every second. This single second pulse is then sent through the circuit board to the coil which using magnetism drives a small magnetic motor. If the watch has no seconds hand the pulse will usually be sent every 10, 15 or 20 seconds.
The motor drives a train of wheels using gear ratios to give the correct speed of rotation and carries the same hand setting mechanism as the mechanical watch (intermediate hand setting wheel, Minute wheel, Cannon Pinion and Hour wheel) of which the hour wheel and cannon pinion comes through the dial to carry the hour and minute hands respectively at the correct speed to tell the time.It is interesting to note that in the case of a quartz analogue watch 70% of the mechanism and gearing is the same as in a mechanical watch albeit with much reduced torque which is why the service interval is longer for an equivalent quartz watch compared against a mechanical watch.
In the case of a digital watch the signal from the microchip is transited directly to the electronic display. On an LED watch the display lights up the appropriate sections which show the time, on an LCD display the power is transmitted to the display using an electronic phenomenon called the twisted nematic effect.This electronic effect is like taking a pair of polarised lenses and holding one over the other, if they are orientated in the same direction you can see through them. If one lens is turned 90 degrees the light cannot pass through them and becomes black. Through the distribution of the electronic signal the appropriate segment of the display becomes black and these active or non-active sections show the time.
Most quartz watches are accurate to 2 or 3 seconds per week, there are some higher precision quartz movements these in most cases work in exactly the same way as the standard quartz watch but have thermo compensation added to the circuit and can be as accurate as 2 or 3 seconds per year. As with all electronic devices the circuit and components will age over time and the accuracy can be affected, it is not unusual for the frequency of battery changes to increase as well.
Quartz watches normally fall into three categories: analog, digital, and analogue/digital.
Complications can also be added to quartz watches, sometimes these are mechanical modules added to the basic movement or are achieved using electronic programming to the integrated circuit.
What is a chronometer?
A watch that has passed a series of timing tests administered by an official chronometer-certification agency such as COSC.
Originally the word was used differently and meant a timepiece with a detentescapement found in ships clocks, or very accurate timepieces.
What is COSC?
Abbreviation for “Contrôle Officiel Suisse des Chronomètres,” or “Official Swiss Chronometer Testing office.” COSC is a Swiss government sponsored independent non-profit organisation established in 1973 that tests Swiss made watches at their three testing facilities in Bienne, Le Locle and Geneva.
To receive a certificate a movement is tested over a period of 15 consecutive days, in 5 positions and in three temperatures as laid out in ISO standard 3159.
If after the testing if the movement achieves an average accuracy of between -4 and +6 seconds per day then a certificate is awarded. Each COSC certificate refers uniquely to the movement tested and the number is usually engraved on the movement, because COSC testing is carried out before the movement has it’s dial and hands fitted and before it is placed in a case. COSC does not guarantee how the watch will perform when completed and worn by the end user. This is the reason many top manufacturers then carry out further testing including time keeping tests once the watch head is completed despite the movement having received a COSC certification.
What is a chronograph?
A device that measures an elapsed period of time independently but while also displaying the time of day. A stopwatch is not a chronograph. Most modern chronograph watches are equipped with a center-mounted seconds hand for showing the elapsed seconds and a sub dial or sub dials to show the elapsed minutes and if applicable elapsed hours.
A modern chronograph has two pushers on the side of the case usually one above and one below the crown. This configuration and the original single pusher format were invented by Willy and Gaston Breitling respectively. The top pusher operates the start and stop functions and the bottom pusher resets the chronograph seconds, minutes, and if fitted hour counting hands to zero. An example of a single push piece chronograph would be the Omega Chrono-stop where all functions are operated sequentially using one pusher. A chronograph watch may be but does not have to be chronometer rated.
What is the difference between an automatic and manual mechanical watch?
The difference between the two mechanisms is if worn daily and the wearer is moderately active an automatic will continue to work without the wearer having to manually wind the watch. A manual mechanical watch is one which requires the wearer to physically wind the watch each day using the crown. We recommend that a manual wind watch is wound at the start of your day for the watch to perform at its best.
The basic movement of an automatic watch and a manual watch are the same with the addition of a mechanism for the automatic watch which has a free-swinging weight or rotor. The weight swings due to the motion of the wearer’s wrist and arm and this motion through some additional gearing winds the mainspring. The efficiency of the rotor and therefore the winding is dependent on the activity of the wearer, if the wearer is not active enough the watches mainspring will not be wound sufficiently to deliver the required force and the watch will not keep accurate time. In this case the watch should be wound manually 30 to 40 turns of the crown every few days as required.
What does a full-service entail?
A Complete Service involves checking the watch’s functions and diagnosing the cause of any faults. The complete dismantling of the movement then begins and the correction of most faults and the replacing any damaged / worn parts is carried out as the watch is being broken down. All parts are then cleaned in a series of ultrasonic chemical baths which removes all the old oil, grease and dirt.
While the movement is in the chemical baths being cleaned the case will be completely broken down (The case back, bezel, crystal, pushers etc. are removed) and having removed all the seals and gaskets cleaned in large ultrasonic tanks and possibly refinished depending on the type of service and your instructions. Once the case is clean it is reassembled with new seals and gaskets which are lubricated as required with special greases. The case is now ready to receive the cleaned movement.
The movement cleaning should now be complete, and the pristine components are systematically reassembled and lubricated using up to 8 different fine synthetic oils and greases. The completed movement is now regulated on a timing machine and adjusted according to the manufacturers specification before having the dial and hands refitted. The watchmaker will now reset the clean movement into the watch case ensuring there are no hairs or dust in the case and recheck the watch regulation on the timing machine (This often changes once the movement has had the dial and hands fitted and the been reset in the case). Once the case is closed the watch is then tested for water resistance and the final aesthetic, timekeeping and power reserve checks are made to ensure the watch is performing correctly. If your car were to be serviced to the same depth this would be the equivalent of the stripping it back to the chassis and rebuilding it each time a service was required.
Once all this work is completed we return your watch to you with a 2-year international warranty on the work we have carried out.
Why does my watch need to be serviced?
Your watch is one of the fine stand in many cases almost constantly running precision instruments in everyday use that humans have ever produced.
• A simple quartz watch has around 45 components, but over 80 individual parts,
• A basic automatic mechanical watch has around 80 components, but over 150 individual parts,
• A simple chronograph has just over 100 components, but over 200 individual parts.
Some of the tolerances between components are as small as tenths or even hundredths of a millimetre and routine servicing is essential to keep them in good working order. The materials used to build your watch have been carefully chosen by the manufacturer to work together and minimise friction, but whenever you have moving parts interacting with each other they will be subject to wear over time.
To put this in perspective, the balance wheel in an average gent’s automatic watch is normally just over 1 cm diameter. If this little wheel resting on steel pivots less than a tenth of a millimetre were allowed to roll instead of oscillating and the watch was serviced every 3 to four years this little wheel would roll a distance greater than the equator of the earth! (24,900 miles)!
When should I get my watch serviced?
We recommend that you have a full service carried out every 3-5 years on a mechanical watch.
For a quartz analogue or analogue/digital watch we recommend every third battery change or every 7 years whichever comes first.
A pure quartz digital watches do not need servicing as there are no moving mechanical parts other than the pushers.
What is magnetisation?
As your mechanical watch contains steel parts it can become magnetised, as the magnetism builds within your watch it will affect the accuracy of its timekeeping. Magnetic fields are produced from many everyday objects including laptops/computers, fridge doors, magnetic tablet cases, speakers, mobile phones especially when charging, induction stoves, magnetic catches on handbags, medical equipment, security scanners etc.A magnetic field will not cause permanent damage, but it can result in poor timekeeping and will usually make your mechanical watch gain time excessively, in very extreme cases the watch can come to a complete stop. Some mechanical watches have a Faraday Cage which is a protective inner casing made of a soft iron in which the movement sits. This cage provides a kind of magnetic absorption / protective shield routing the magnetic fields around the movement, and greatly reducing the effects of magnetisation.
Most modern quartz watches are not usually adversely affected by magnetic fields in the way a mechanical watch could be.
Our workshops are equipped with demagnetising equipment. If you need your watch to be demagnetised, then this is a straight
forward process that can be undertaken without having to open the watch case.
What does Power Reserve mean?
The Power Reserve is the period of time a mechanical movement will run from the mainspring being fully wound and left to run until the mainspring’s power is exhausted and the watch stops.
Most modern watches have a power reserve of 40 hours or more.
What settings should I set my watch-winder to for my watch?
We recommend 750 rotations per day as a simple guide for most watches. You will need to check your watch instruction booklet or the internet to find out if the automatic movement in your watch winds in both directions or only in one. If it only winds in one direction you need to know which direction in order to set the winding box correctly and its motion maintain the running of your watch.
Using a winding box has the advantage that other than rapid changing the calendar to correct the date for short months your watch will keep going and will be ready to wear when needed. We still however recommend that the watch should be given at least 20 rotations of the crown before wear to ensure the watch performs in wear at its best.
Keeping your watch in a winding box is also better for the watch and its lubricants. Although modern synthetic lubricants are not as susceptible to ageing and thickening as the mineral lubricants used in the past, watches which sit for long periods of time in a safe or static box not running usually require servicing sooner than the same watch which is kept running.
How do I send my watch in?
You can register your watch through our website and request packaging t be sent to you or you can send you watch to:
Stonebridge House, Main Road, Hawkwell, Hockley, Essex, SS5 4JH ensuring your watch is placed in protective bubble wrap boxed and sent to us using Royal Mail Special Delivery Service with the maximum insurance.
Can I arrange a tour of the technical facilities at STS?
If you contact our main number one of our directors would be happy to arrange a personal tour of our workshops and show you the process your watch follows during a full service or partial repair.
Each of the “resistance depths” are not the actual depth that the watch can be used at, but a measurement of pressure which the watch can withstand before any leakage occurs. This we understand is very confusing to the public because the water resistance value appears to suggest a depth to which the watch should be safe to operate at.
The reason these pressure values are so important is when you dive or jump into water the force exerted upon the glass, case, button,pushers and seals is the equivalent of smashing the watch against concrete. Even though the pressure only lasts for hundredths of a second, it can be enough to dislodge seals and allow water to penetrate the case and damage the movement, dial and hands. Equally when doing something as mundane as washing up when you move your hand through the water the pressure being exerted against your hand varies and can easily if you move your hand quickly exceed the 3-bar pressure resistance of a “splash proof” model.
Another variable to be considered is that if the water has any kind of chemicals or detergent mixed in it these can lower the viscosity of the water, and in effect make the water “thinner” and therefore easier to pass any seals protecting the case.
Any watch being used as a water-resistant model must be rinsed with tap water each time it is used in either a pool, lake, river or the sea and must have the seals checked annually. If at any point the watch should leak it must be taken to an authorised agent as soon as possible for correction.
The table below we hope will clarify what the different “depth” really means and are based on our interpretation of the ISO standards 22810 for water resistance and 6425 for diver’s watches.