Saturday, December 17, 2011

Watch Primer: Screw-Down Crowns

The crown is deceptively mundane in its ubiquity, but in truth much of the successful design and operation of a watch depends upon it. It provides the most direct interaction non-watchmakers will ever have with the watch's movement, and it represents the element of the watch most exposed to the outside world. In the case of screw-down crowns, it is also the part most likely to suffer wear and tear sufficient to require early replacement. 

Which brings me to one of my peeves about screw-down crowns: the ease with which they can be cross threaded - that is, screwed down with misaligned tracks so that they abrade and destroy one another - and suddenly require the costly replacement of the entire case.

While I've never cross threaded a crown myself (in part due to a precaution I always take, by lining up the threads by rotating the crown counterclockwise until I can feel the threads fall into position, then tightening it clockwise), I've had a watch purchase fall through when the seller discovered that cross threading had occurred, and ended up flipping another watch whose threads were partially stripped by the successive misuse of a long string of previous owners. Screw-down crowns are generally considered something of a sought-after feature, as they generally increase a watches' potential water resistance. Which is fine, I think, when the only times you'd have to unscrew the crown would be the occasional time/date adjustment. But their use with mechanical movements - which, by their limited power reserve and inherent inaccuracy when compared to quartz, require far more interaction with the crown - makes me wary of the frequency with which I have to screw and unscrew those delicate threads.

That is why in general, unless you intend to use the watch as a dedicated diver (in which case, yearly maintenance and pressure checks on the watch's seals become an absolute must), I would avoid screw-down crowns in mechanical watches, especially the rare (and counter-to-all-logic) models that combine the feature with a handwound movement. The delicacy of screw-downs is why I decided to sell off my Rolex Explorer I, and sadly, with every modern Rolex watch (with the possible exception of some Cellini models) incorporating the feature, I don't predict myself adding another to my watch box in the near future.

(As I managed to sell the Explorer for a little more than I purchased it, I had high hopes of replacing it with the similiar 116000 Oyster Perpetual with a blue sunburst dial with the same 3-6-9 design as the Explorer, but the screw-down crown remains a deal breaker.)

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