Blog: Servicing a Mechanical Watch

I make additions and corrections to this web site frequently, but because they are buried somewhere on one of the pages the changes are not very noticeable, so I decided to create this blog section to highlight new material. Here below you will find part of one of the pages that I have either changed or added to significantly.

The section reproduced here is from my page about watch movements

If you have any questions or comments, please don't hesitate to contact me via my Contact Me page.

Watches Need Servicing

A watch needs to be cleaned and oiled every so often because the oils and greases used to lubricate the moving parts thicken then dry out. Oil or grease that is dried out cannot lubricate the moving surfaces adequately and they wear or, even worse, over time oil can mix with dust from the atmosphere to form a grinding paste that wears parts. Spare parts for old watches are often not available, so a worn out part can mean that an old watch cannot be repaired economically or at all; such damage can be terminal.

Modern watches with fully sealed waterproof cases can go longer between services than older watches with less well sealed cases. Case joints that are not well sealed allows dust and fluff into the case. Fluff is a nuisance, but dust is worse because it can combine with oil to form a grinding paste that quickly wears components. Old watches with less than fully waterproof cases should be cleaned and oiled every three or four years, more modern watches with fully waterproof cases can go longer, five or six years.

Watches that are not fully jewelled are more prone to wear of the bearings in the plates, which is where the extra jewels are fitted in a fully jewelled movement. With a watch that has less than 15 jewels, you need to be more alert to the need for regular cleaning and oiling to avoid wear in the plates.

If you wind up an old watch and it seems to be running OK, bear in mind that a watch will continue to run for a surprisingly long time without being serviced, but by continuing to run a watch that has not been serviced you will be building up wear and damage inside the watch that you can't see – see the section below about damaged stem bearings to see the damage that winding a watch everyday can do if this mechanism is not adequately lubricated. This will become apparent when eventually the watch stops, at which point the damage might be so bad that it cannot be repaired.

Replacement parts for old watches are usually no longer available. In theory all the parts can be made for a mechanical watch by a skilled watchmaker, but this is expensive and might not be economic. And some parts are easier to make than others - I wouldn't fancy trying to make a balance spring, and these are now getting in short supply for older watches – even stocks of some mainsprings are running down. And I still haven't repaired the damaged stem bearings shown in the section below. I know how to do it in theory; bore out and sleeve. But in practice, accurately boring and sleeving a bearing in a wristwatch plate a few millimetres thick is not an easy operation without expensive equipment that most watch repairers don't have.

Remember that these old watches have survived through many years and events until now, and it is your responsibility to take care of them and make sure you pass them on in good working condition. A mechanical watch that is regularly serviced could still be working just as well in centuries from now as the day it left the factory; you can't say that about electrical or electronic watches.

Regular servicing is particularly important for old hand wound watches because

The cases tend to be not very well sealed, especially if they are jointed (hinged), so fluff and dust can get in and mix with the oil form either a sort of gum that can stop the watch working, or worse, a grinding paste that wears the moving parts.
The keyless mechanism (the mechanism that winds the watch or sets the hands when you turn the crown) of a hand wound watch takes a lot of stress through being used every day, and can wear badly if not adequately lubricated - see the discussion about this in the section below, and the picture of a badly worn bearing.

There are two methods of cleaning and lubricating a movement:

The first method places the complete movement in the cleaning machine through a wash and two rinses, the second rinse containing a lubricant, and that's it. There are two problems with this method. It seems to me that the cleaning fluid will not be able to clean difficult to reach places such as the jewel holes with the pivots in them, although I understand that the end or cap stones are removed before cleaning. These need to be cleaned thoroughly to remove congealed oil. Perhaps a powerful ultrasonic machine can do this. I am sure that a single, necessarily very fine, lubricant cannot be ideal for all the different duties of each part of the mechanism, from the fast moving but lightly loaded balance staff to the slow moving but heavily loaded keyless mechanism. This method is certainly quick and cheap, but the downside is probably that it needs to be repeated more often than a full strip and oil.
The second method, and the only valid one in my view although it is more expensive, is a full strip, clean and lubricate, where the movement is completely dismantled, the parts are cleaned and rinsed in a specialised watch cleaning fluids, each component then examined for cleanliness and further cleaned if required, e.g. the jewel holes are "pegged out", which means a sharpened piece of special wood is pushed into the hole to remove any last traces of dried gummy old oil, and the movement then reassembled with the correct lubricant applied where it is needed. I use at least four different lubricants depending on the duty of each component, ranging from a grease for the keyless mechanism and barrel arbor pivots where there is high torque and low speed, through to a light oil for the pivots of the faster train wheels, and a thixotropic grease for the escape pallet faces. These specialised oils and greases are very expensive, the grease that is used only on the pallet faces works out at well over £100,000 per gallon! (fortunately I don't buy it by the gallon.)

Before committing your watch to be serviced it is always best to ask which method will be used, simply for the avoidance of doubt. I once purchased some equipment from a watchmaker who used to work for the principal jewellery retailer of a reasonable sized town and an Omega agent. He told me that he used the first method on Omega watches for many years. I was astonished. There is no doubt that a quick dunk like this will get a watch going, but the lubricant carried in the final rinse has to be very thin because it has to go everywhere in the movement without gumming it up, so it doesn't last very long, and it can't adequately lubricate bearings under heavy load such as in the keyless mechanism for winding and setting. More wristwatches are scrapped because of worn out bearings in the keyless mechanism than due to any other reason - see the section on keyless mechanism below.

Badly worn stem bearing

Stem Bearings

Stem wound and set watches, that is the type of watch that you wind up by the crown and set the time by pulling crown out away from the case, incorporate a "keyless mechanism". It is called this because you don't need a separate watch key to wind or set the watch, hence the watch is keyless. The most common "shifting sleeve" form of keyless mechanism was invented in 1845 by Adrien Philippe, who later joined the Geneva company of Patek to form Patek Philippe. You can read more about the various forms of keyless mechanism at Keyless Mechanism.

The action of turning the crown to wind the watch or set the time is carried into the mechanism by a metal shaft called the "stem". When you pull the crown out to set the time, the stem is drawn out and the keyless mechanism, a system of levers, disengages the winding mechanism and engages the time setting mechanism.

If a watch is manual winding, then it has to be wound every day to keep going. Although the stem winding keyless mechanism is a clever piece of design, the bearings are small and not jewelled and there is no adequate provision to ensure that they remain lubricated. The keyless mechanism is truly the Achilles' heel of a keyless watch.

If a watch is not regularly serviced and grease in the stem bearings renewed they can wear heavily. It is not unusual that a watch that otherwise runs perfectly well becomes impossible to repair because of wear in the stem bearings and keyless mechanism, so it pays to be aware of this potential problem.

Wear in the stem bearings is the Achilles heel of manually wound watches. Automatic watches that wind themselves as the wearer moves around do not suffer anything like as much from this problem, because the stem is only used occasionally.

The picture here shows the outer stem bearing in the bottom plate of a watch. It is very badly worn - the tops of the ridges standing up from the bearing surface give an idea of where the original surface was and how much wear has occurred.

This degree of wear has been caused by the wearer winding his watch while it was on his wrist. Although it is physically possible to slide a finger between the crown and your wrist to wind the watch, this picture shows you why this is a very bad idea. Jamming the finger between the wrist and the crown causes excessive side force on the crown and the stem, which has to be carried by this bearing. And as you can see, the bearing is not adequate to withstand this treatment and wears badly.

The moral of this is: always take off your watch to wind it, avoid applying sideways force to the crown, and have the watch serviced regularly to get the stem bearings lubricated. If you wait until your watch stops running or you can no longer wind it, it might be too late!

If you have any comments or questions, please don't hesitate to get in touch via my Contact Me page.