The servicing of a watch can seem somewhat oblique and esoteric to the uninitiated. There’s truth to this; it’s a complex and highly-involved process that requires patience, organisation, and a great deal of training and experience – but it’s not some closely-guarded secret process that watchmakers don’t want made public. It’s difficult, but fortunately not too difficult to explain. We'll even stop using stupid words like 'esoteric'.
The first step is obviously to take the watch’s case back off. There’s a variety of tools you can use to get this done based on the brand and model of the watch, ranging from a simple flat blade to a unique dye cast tool designed to properly grip the case. It’s hugely important for any professional watchmaker to use and maintain proper tools – it’s necessary to keep screwdrivers sharp, for example, to keep from stripping screws in the movement. It’s very easy to tell if a watch has been worked on by someone without the requisite experience.
The movement is removed from the case, and the first part of disassembly is to take off the hands. Next, we remove the dial, then any calendar work. After that, we remove automatic mechanisms on the movement and let the watch’s power run out; letting the mainspring back to rest. We can then remove the barrel bridge, the mainspring from the barrel, then the train – leaving the escapement still attached to the movement for safety while cleaning, as it’s very fragile.
The ultrasonic cleaning machine cycles through multiple stages – in this case, two cleaning solutions, two rinses, and then drying. The machine uses ultrasound to agitate the solutions, producing strong forces that break up any contaminants; usually dust and dirt, but sometimes rust or other materials. The process is fully automated and takes around 45 minutes.
After the parts are fully cleaned, they’re ready for reassembly. It’s usually at this point that we identify any parts that need to be changed due to wear etc. as it’s much easier to inspect them properly with all the muck cleaned away. We use only genuine Swiss parts when working on a watch, so depending on the part – especially with old or obsolete movements – it can be a challenge to source.
This is a major reason for the difference in prices between an independent watchmaker service and the service the watch’s manufacturer will offer – most manufacturers will replace many parts of the movement as a matter of protocol, even if it isn’t necessary.
An important part of the reassembly process is oiling the jewels, pivots, and any other contact points on the watch. Obviously, wherever parts in the watch are in contact with others, there’ll be abrasion – which is why jewels are used to reduce wear, as they’re stronger than metal, with low friction – and proper lubrication is crucial to prolong the watch’s life.
With the movement properly oiled, it’s ready to be put on the timing machine. The movement is attached to a microphone on the machine, which measures the beats coming from the movement. By analysing this, the timing machine works out the watch’s amplitude – how many degrees the balance wheel is swinging; so a higher amplitude means smoother motion – and how many seconds the watch is losing or gaining, to test if it’s within the recommended tolerance. If it’s outside the recommended tolerance, this can be rectified by adjusting the regulating lever, to shorten or lengthen the amount of the hairspring that’s in use.
The machine measures a watch’s beats per hour. Every movement will have a standard range of beats per hour that it should fall within if working correctly – most high-end watches today beat at a frequency of 28,800 BPH, which is around 8 ticks a second. Generally, the older a watch is, the fewer its beats per hour. The higher a watch’s BPH, the more friction within the movement – so higher BPH movements need higher quality parts and better lubricants.
Once the movement is within its tolerance, it can have its dial and hands refitted, leaving it ready to be put back into its case.
If we’re refurbishing the watch case, this can require a variety of machines. We have four polishing machines onsite depending on the level of polish required, from taking out individual scratches on a case with the smallest mop wheel, to polishing an entire bracelet at once with the heavy duty one. We use a lapping machine for polishing any pieces that are flat, such as case backs. Next to the polishing machines is a bead-blasting cabinet, meaning we’re able to apply a matte finish if necessary.
After all this, the movement can be fitted back into the watch’s case, and put in the pressure testers to check it’s waterproof. We use a dry pressure tester which can test up to 10 bars of pressure, and a water pressure tester which tests up to 20 bars. If the watch passes the pressure check, we can set it to the correct time and leave it on test – usually for around seven days, in different positions – to make sure we don’t send out any work that isn’t up to standard.
As mentioned earlier, servicing a watch is difficult, complex, and time-consuming (if you’ll pardon the pun). It takes decades of experience to even be considered competent, and it would be very easy without that experience for things to go catastrophically wrong. But it’s because of that level of experience that any watchmaker takes a great deal of pride in their work. Every watch we service, we’re drawing upon years and years of learning and practice and knowledge. It’s a matter of pride that we service a watch to the highest standard we’re able to achieve.
It’s difficult, but fortunately not too difficult to explain.