Watches - Feature Article

Watchmaker's Corner: Inside a pre-owned Rolex 3135 Movement

In our Watchmaker's Corner series, we'll be sitting in with our experienced watchmaker, Michael Nolan, as he walks us through the ins and outs of some of the most sought-after watch movements on the market. For our first article, we went back to an interview I wrote up for aBlogtoWatch this time last year, a piece we couldn't resist revising here, in which Michael tells us everything we need to know about the heart of the Rolex Submariner, the Rolex 3135 calibre.

One of the benefits of having an in-house watchmaker is that they're often more than happy to give us a closer look at the insides of these intricate machines, which is a luxury most high-end watch owners don’t get. They offer us the sort of insight that goes way beyond the marketing spiel of the brands, pointing out where the watches stand out or fall short, or, in other words, which ones are really worth their hefty price tags.

When I asked our watchmaker Michael, or “Mickey” as he's known in the office, if we could do an article series interviewing him on the most popular watch movements on the market—while he strips them down and walks us through servicing them—at first he appeared a little worried about how much time I was planning to tack onto his already super-busy schedule. But he soon came around to the idea and the result was an encyclopaedia of insight into the Rolex 3135 movement—Rolex's workhorse movement used in the Rolex Submariner and Rolex Yacht-Master, amongst others. In the below interview, Mickey tells us how the Rolex 3135 works, how it's serviced, and how it compares with its main rivals.

rolex 3135 movement service watchmaker

So, Mickey, today you’re going to take apart a Rolex Submariner?

Yeah that’s right, I’m going to strip down a Rolex Submariner Date 16610 with a 3135 movement. It’s probably the most common Sub out there. They were made from the late eighties all the way up until 2010. This particular one is from 1995. It’s just come in. It looks to be in pretty good shape, but it’s fast, so it needs checking over.

If I were to have a limited knowledge of watch mechanics (speaking hypothetically, of course!), would you be able to quickly skim over the basics for me?

No worries. So, when you wind the watch, you’re contracting the mainspring. This gives it energy, because it then wants to expand. This energy is what drives the watch. It’s transferred to a finer, coiled spring, called the hairspring or balance spring, which then expands and contracts like a beating heart. The hairspring then drives a tiny wheel, called the balance wheel, which swings back and forth in harmony with it. The swings of the wheel determine the watch’s timekeeping.

So, the first thing I do is check for magnetism. This is a really common problem, and it’s very simple to fix: we just stick it next to a demagnetiser and press a button, which neutralises the charge. Once the hairspring is not being influenced by magnetism, we can get a true reading on the timing machine.

Now I'll measure the amplitude of balance wheel swings. That’s the degree of wheel rotation on each swing. If the amplitude is low, then each swing takes less time, and this usually means the watch will be fast. In a freshly serviced watch, we want the amplitude to be between 270 degrees and 310 degrees.

To measure it, we use this machine that works by reading and timing the vibrations of the escapement. It’s like a heart rate monitor. Each swing of the balance wheel is one beat. A Rolex 3135 caliber runs at 28,800 beats or vibrations per hour. Each mechanical watch runs at a specific frequency according to its make up.

rolex 3135 movement service watchmaker

How does the watch lose amplitude?

If it’s not magnetised, then more often than not, it’s caused by dirt or congealed oil, or it could be other issues, like wear in the train wheels or the mainspring getting old and no longer keeping tension. We’ll check for magnetism first, but it probably only needs cleaning and oiling. Then we’ll check the different parts for wear and end-shake, and swap out the mainspring.


Yeah, so if you take one of the wheels by the staff with a pair of tweezers and give it a light shake, it has some give, because its pivot sits in oiled jewels. You want it to move a little but not be loose. You learn to gauge it over time.

Then, we’ll need to check the hairspring, it should be dead flat from every angle, and the coils should be exactly the same width apart. You see, it’s pinned in the middle at the collet and then it’s pinned at the outside, so you can actually manipulate it, because it has two points, but it’s a bit of a nightmare to do that - I’ve got one in there that looks like a bird's nest.

What happened to it?

My guess is someone’s gone at it with tweezers, and they’ve messed it up. Someone that doesn’t really know what they‘re doing and doesn’t have the right tools.

rolex 3135 movement service watchmaker
Mickey opens the case and passes me an eyeglass.

Considering you have worked at Omega, how do Rolex movements compare to Omega for you, do you have a preference?

Definitely Rolex. Ha! No. I mean, both brands produce excellent movements. What I like about them compared to most other brands is that they’re relatively straightforward to work on, and they’re reliable, you know. The movements have their differences, but as far as durability and quality goes, it’s a tough one to call.

I really like some of the Omegas actually. Omega have been using their own co-axial escapements since 2007. They made a lot of noise about these escapements having less friction between the parts and needing less servicing as a result. I have to admit, they are real workhorses and they rarely need any parts-replacing.

That sounds good. Do you have a favourite movement from either brand?

For me, the best thing Omega have done is the Aqua Terra with the Co-Axial caliber 8508. It’s full of silicon parts and non-ferromagnetic parts, so it doesn’t rely on an anti-magnetic case like the Rolex Milgauss. It’s 15 times more resistant to magnetism than the Milgauss.

I know it sounds fussy, but magnetism is one of the main issues we deal with. People don’t realise how much it affects your watch and how often it happens. These components are made of steel. Take a balance spring, for example. It doesn’t take a strong magnetic field to make those coils attract each other. This shortens the amplitude and speeds up the watch.

People come to me and say, “My watch is not keeping time.” So I usually ask them what they do. There are loads of jobs where people come into contact with machines or appliances that could magnetise the watch: doctors work around x-rays, people that travel through airports a lot going through x-rays, electricians work with electrical appliances with strong magnetic fields, sound engineers around stereos, all these things can affect the watch. Sometimes people tell me they take it off for the night, so I ask them where they put it and they say, “Next to the alarm clock.” Well, that’s got a magnetic field too, and so does your phone.

It doesn’t damage the watch, but it makes it irregular. You even magnetise your tweezers just working on it, that’s why you see watchmakers banging them on the desk, because it knocks out the charge.

rolex 3135 movement service watchmaker

But you said you preferred Rolex overall?

Yeah, it’s a matter of taste, really, but there are some small differences. Rolex movements are generally very consistent in how much time they gain or lose each day. For me, the quality really is better in a Rolex. Take the Helium valve in the respective divers, for example. In the Omega Seamaster Ploprof, it’s screwed on and secured with Loctite to seal the valve, it can be really tricky to replace this. It works fine, of course, but I don’t think securing it with adhesive is ideal.

Or there’s the date function. The Rolex 3135 date ticks over instantaneously. The date mechanism is on a spring; at twelve o’clock, it jumps. An ETA or Omega might change gradually, at one second before or after. Yeah, it’s not majorly important, but it’s the little differences that add up, you know.

What about the difference between the Rolex 3135 and, say, an ETA movement?

Well, there’s a lot of difference there!

Such as?

I’ll give you a couple of examples.

First, there’s the finishing. Many parts are rhodium plated, so they look fantastic, you can see they’re a lovely milky color. Also, edges are chamfered or beveled, and surfaces are polished. All this makes it ever so slightly easier to service. Easy to service means happy watchmaker. This is something Rolex take into account, and believe me, that’s a good thing!

Then, there’s the steel. Rolex swapped all their steel to a different type about 15 years ago. The new steel is more resistant to corrosion and finishes very well. No one else uses it, probably because it would mean changing all your tool bits too, and that’s a very expensive change to make.

Another major difference is the accuracy. This is mainly due to the balance in the 3135. Rolex and other companies—Patek Philippe, for example—use a “free sprung balance.” The difference being the balance bridge in the ETA movements has two pins that the hairspring breathes through. You can move the pins with a regulating arm to adjust the timekeeping. In the free sprung setup you adjust Microstella screws on the inside of the balance rim, which speed up or slow down the balance due to the inertia in the balance—think of a ballerina in a pirouette, she brings her arms in closer in order to speed up her spin. This is easier to adjust and doesn’t restrict the hairspring, which means more accurate timekeeping.

That sounds good. You mention Patek Philippe, how does the Rolex 3135 line-up alongside a Patek movement, then?

Well, again, it’s a totally different ball game. Patek movements are often extremely complicated, and all the parts are handmade. This is why they’re so much more expensive. You can argue that this means they’re better, but I think the fact that Rolex use so much machinery is not necessarily a bad thing. Rolex claim to use machinery only where a machine does a better job than a human. I think this makes sense, and it means consistency too, which is great from a watchmaker’s point of view.

rolex 3135 movement service watchmaker
Mickey takes out the mainspring, one of the most delicate parts of the movement.

You have to be careful here, because if it springs out, it could blind you. It would fly around the room. Generally, we just swap the mainsprings instead of trying to work them, but it needs to be the right one with the right strength for the watch.

You see the fish tail at the end of the spring? It has two pieces, so it slips on the inside of the barrel. If this was just a wind up mechanical watch, there would be a piece that would attach to the inside of the barrel, and it wouldn’t be slipping, because you wind it, and it gets tight. This, you can keep on winding, and it’s not going to break the main spring, it just keeps slipping on the inside.

So if you’re wearing it, it’s always going to be fully wound, generally, if you’re quite active, that is. Some older gentlemen come in and go, “It’s not keeping time.” So, I ask, “Well, how mobile are you these days?” Usually the watch is actually working fine, but they’re… the watch isn’t actually winding all the time, you know.

Haha. Many Submariners come at different prices, are the movements any different?

No. They use the same movements, but they might have different case materials.

How have the Sub movements changed over the years?

There may be minor tweaks and upgrades to individual parts, but the movements are pretty much the same. The main difference is the new steel.

A lot of the time, you see a watchmaker with their ear to the watch when they’re winding it. They’re trying to work out whether it’s fully wound or not. They’re listening out for the end of the spring, the fishtail, slipping inside the barrel, it’s a very faint noise, but we know what to listen for. If you’re testing it and it’s not fully wound, then it will give you a wrong reading. Then we test it for about 24 hours to see if it’s stable. If not, then something will need adjusting, often the mainspring.

rolex 3135 movement service watchmaker
Screws are of varying widths and lengths and are generally miniscule. A watchmaker needs to take utmost care when dealing with these as they are expensive to replace, "one sneeze could cost you £500."

Now it all gets cleaned. Afterwards, I check the parts for wear or bruising. Then, I oil all the teeth and the jewels. Generally, a clean and oiling is enough. I’ll only replace parts that really need replacing. Rolex can be pretty generous with dishing out new parts.

I bet. Which parts are most often replaced?

The mainspring and the second wheel; the second wheel takes a lot of power.

How much do pieces cost?

Prices vary. A mainspring could cost you £25. A new hairspring will cost you about £150, as you have to buy the wheel with it. They’re very delicate — if a watchmaker doesn’t know what they’re doing, they’ll break it.

At this point, Mickey put the parts in the ultrasonic cleaner and we finished our interview. All in all, I was with Mickey for about two hours while he gave me an in-depth lesson on the complex workings of the Rolex Submariner movement, how they are serviced and why they are the top mass-produced movements out there.

But beyond that, I left the workshop in awe of the intricacy of the movement’s design and function, and also of the difficulty of the watchmaker’s job. As well as now having a far deeper appreciation for a Rolex, I’d had my first insight into a more than 250-year-old art of watchmaking. I was now intrigued and genuinely looking forward to our next interview, which we agreed would be based on the much-hyped Omega co-axials.

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