« How Watchmakers Open Watches »
Whether it's servicing, a battery change, or an authenticity check: many jobs on a timepiece require its case to be opened and closed properly. Watchmakers rely on professional tools for this, matched to the type of caseback and freely available to any enthusiast. In this article, we explain how to carry out the job smoothly and why high-quality watch tools are essential.
Before You Start: The Case Holder
Even the best case opener and years of experience won't help if the watch slips while you're opening it and picks up annoying scratches. A firm grip on the case is therefore crucial. This is especially true for screw-down casebacks, such as those on dive watches, whose tight threading takes considerable force to break loose on the first turn. To keep the watch securely in place, experts use so-called case holders or movement holders: similar in design to a vise, they come in a range of materials from aluminum to wood and hold even irregularly shaped cases (think chronograph pushers) securely. At the same time, they are designed for fine adjustment and gentle handling of the timepiece, which sets them fundamentally apart from the much cruder bench vise. The latter should therefore never be used as a substitute for a case holder, which you can get in high-quality versions for around €20 to €40.
Opening a Watch Case: Screw-Down vs. Snap-On Caseback
Whether you need a holder depends largely on the type of caseback. It is highly recommended for screw-down casebacks, while snap-on casebacks can easily be handled without one. The two types also differ fundamentally when it comes to case openers. The easier procedure applies to the snap-on (press-fit) caseback, which watchmakers open with a so-called case knife: inserted into a small notch between the case and the back, it pops the cover off with a prying motion. It's a straightforward process, but its success depends on the quality of the case knife: if you order a cheap version for two euros, the soft steel it's made of can bend the first time you use it and – far worse – leave an ugly gouge on your watch.
The process is somewhat more complicated, but still manageable, with a screw-down caseback. Here you need a classic case wrench: equipped with various bits for the different notches in the caseback (round, hexagonal, or triangular notches are common, for example), it has three adjustable "jaws" to fit the case size. Once you've found the right bits, a rotating handle and a separate adjustment wheel help you set the spacing. Then seat the tool firmly, turn it once to the left, and the caseback comes loose. If you want to open your watch case yourself, you should pay attention to decent quality here – even more so than with the case knife. Cheap case openers are a dime a dozen, but their poor workmanship usually keeps the jaws from sitting firmly and makes damage far more likely.
Case Closers for Snap-On Casebacks
The big advantage of a screw-down caseback: closing it doesn't require a separate case closer, just the opening process reversed in the opposite direction. The snap-on version, on the other hand, needs exactly such a case closer to seat the snap-on back firmly again. Known as a caseback press or press-fit tool, this instrument works on the lever principle and clamps the timepiece between two pressure plates. Under normal circumstances, only a little force is needed to seat the back properly. With highly water-resistant dive watches, however, ordinary case closers are often not enough, which is why heavy-duty lever presses are used here. In every case, it's crucial to use the supplied plastic dies matching the case size to prevent slipping and possible damage.
When in Doubt, See a Professional
If you want to close or open a watch case without prior experience, high-quality watch tools alone won't guarantee success. Even seemingly simple steps have their pitfalls, as closing a screw-down case shows: if you don't seat the back perfectly straight and then turn it to the right with the classic case wrench, you risk cross-threading the fine threads. Then there's the often overlooked but important matter of gaskets: water-resistant watches usually have sealing rings (so-called O-rings), which age naturally and are put under particular strain when the case is opened. So even if the back appears to be refitted perfectly, the water resistance may end up significantly lower than before. If you want to close your watch case again, you should therefore seriously consider replacing the gaskets, taking the correct diameter and thickness into account.
Opening and closing a watch case is by no means child's play. Although the long-term savings may seem tempting, doing it yourself always carries a higher risk than taking the watch to a watchmaker. The more expensive the timepiece, the greater the potential material damage – not to mention its sentimental value. That's why we recommend that every layperson and motivated collector leave the work to a competent expert when in doubt. At the latest once the case opener has done its job and a mechanical movement is due for servicing, real expertise is needed anyway. And if you treat yourself to an Omega, Hublot, or Breitling, your prized piece deserves the right care as well.
Conclusion: Precision and Quality Make the Difference
Case closers and openers make quick work of removing both screw-down and snap-on casebacks, but they absolutely must be of good quality and used properly. If you feel confident and want to carry out a simple job such as a battery change, you can save on watchmaker fees and buy your own tools. If you're unsure, however, we strongly advise against experimenting on your own. Anyone who opens a watch case without wanting to damage it should be absolutely sure of what they're doing.
