Longest time without service

Yes.


It depends. Watches are not all alike in terms of the quality of components, soundness of design, etc. You are asking a question that is akin to asking "How tall can a tree grow?" and it depends on what type of tree it is.

For example some watches have strong mainsprings and can overcome a lot of additional friction that is present when oils have dried out, and even when the parts begin to wear. One of those watches will run longer than a watch that may have a more fine balance between the strength of the spring and the running torque under normal operating conditions. One will stop sooner when the oils dry up and one will run longer, but the one that runs longer will be more impacted by wear when it does finally stop.


Again it depends. Some designs are more easily repaired when they fail than others. Most of the watches I get for servicing already have some sort of problem, so they are either not running or are not keeping time, or some other function is not working correctly. I rarely get watches that are just being sent for routine, preventative maintenance. It does happen, but not that often.

Many people who send me watches for servicing don't know when the watch was last serviced, so often I don't have that sort of history, but there are two different examples of watches that I did get the history of. First one is a vintage Tissot:



The owner bought it in the early 60's, wore it for dress use only, and never serviced it. Don't know the total running time, but it had run long enough to wear this pivot out pretty well:



The barrel bridge was worn substantially from the barrel arbor - this hole should be round:



The main plate was also worn from the barrel arbor - you can see how much with the arbor in place:



I sourced a new barrel bridge and installed a bushing in the main plate to repair it:



The balance pivots ran dry for so long they wore an indent in the cap jewel, and this of course flattened the balance pivots:



This was an extensive repair to say the least, and in the end not inexpensive to fix.

A more modern watch is a Sinn model (ETA 2824-2 movement) that a good customer of mine had given to his father, who wore it daily for 7 years. Pretty much all the oils had dried up, and all the wheels were worn out...











You can see that some wheels in this watch that was only 7 years old, are more worn than from the watch that is 50+ years old. Newer watches often don't have the same level of hardening on pivots, so they wear faster than vintage, but it really depends on the watch and maker. No maker is immune to wear inside the watches, but some watches hide it better than others from the wearer. Many watches have weak spots that will wear quicker than the rest of the watch - some of those are easily repaired with replacing a cheap part, and other may require replacing things like the entire main plate - this is usually a very expensive thing to replace.

There are certainly circumstances where letting the watch run until it stops will be the most economically effective thing to do, in particular if it is a modern watch with plentiful parts available, and you are sending it to the brand for servicing. However using this same thinking with all watches is not ideal - if you have a vintage watch that parts are difficult to get, you want to do what you can to keep the parts inside the watch from wearing out, because the premium for those hard to find parts will make for expensive repairs down the road.

The worn wheels in that ETA 2824-2 are maybe $15 each, and I've paid as much as $150 for one vintage train wheel that was discontinued. I have a watch in the shop now that is vintage and needs a new escape wheel - the cheapest one I have found so far is $200, so I am still looking. Rare parts on a vintage watch easily double the cost of service or more...

Here is a barrel bridge from an Omega Cal. 1109 (essentially an Omega branded 2892) - the arrows point to where the next views will be and point at the wear spots



This is the lower red arrow from the above photo - this boss is worn badly:



This is the upper red arrow, and the "eye" shaped boss is worn more than any other I've seen...



Even with this level of wear (and again all the wheels were worn out in this watch, so it wasn't just the bridge), this watch was running when it arrived. Not well, but it was running, so it's pretty difficult to say just how worn a watch can get before it actually stops.

Cheers, Al

Thanks Al.

Sobering.

I think it's kind of like asking
"How close can I stand to the edge of the cliff without falling off?"
Eventually you are going to get too close, or wait too long for service and be sorry.

Forced might be the wrong word...and depending on the watch, the parts might not very expensive. For some vintage watches, parts are plentiful and cheap, but others not so much. I don't service a lot of Eterna watches (no particular reason for that, other than not being asked to) but my gut feel is that parts for this brand are not terribly hard to find for the ones that I have serviced, but of course it would depend on the movement.

Putting a watch back together with worn parts is certainly possible, but it's not recommended. The watch is not going to perform properly, and it would essentially be a waste of the money you are spending on the service.

My general philosophy is if you don’t know when it was serviced last, it’s time. To use the car analogy again, if you buy a used car and have no documented service records, it’s best to get all fluids replaced and a full inspection so you have a baseline.
I totally get not wanting to throw $300+ at a watch that you paid $100 for- sometimes fun old beaters we just run until they don’t. But if it’s a watch you actually want to own for the next decade+ it’s worth it.