If I’m getting this all correctly, Rolex and Omega are attempting to prevent water ingress through the crown in similar but opposite ways, by creating a screw down/in crown that seals tightly.
The Rolex uses an external threaded tube, whereas the Omega uses an internal one, both with the corresponding crowns.
So I was curious if you thought one design was superior to the other in any parameter you chose to highlight- durability, ease of service, user interface, fit and finish, one easier to cross thread than the other, etc. Or, I does it really make no difference at all, and one could be interchangeable with the other?
Well, there are a few things off the top of my head...
Internal threads are better protected - just a fact.
They both seal fine, even with the crown unscrewed.
For replacement, Rolex uses a rather crude tool compared to Omega's design, but that's not a significant thing.
Probably the biggest thing for me is the way the crown functions when you screw it down. On all the Rolex watches I've owned or serviced, when you compress the spring inside the crown to screw the crown down, it disengages the stem from winding the movement. There is (for lack of a better term) a little clutch like mechanism inside the crown. I've not taken one apart to see what this actually looks like, but that's not really important to this point - these systems fail. I've had a number of watches where you must apply slight traction to the crown while you are trying to wind the watch, or the crown slips and it won't wind or set. In my experience, once this starts to fail, it's only a matter of time (and often not much time) until it gets to a stage where you can't use the crown any longer.
In an automatic watch, there is absolutely no reason to have this clutch system inside the crown. In a manual winding watch with a screw down crown, it makes perfect sense, because once the mainspring is fully wound, you have to disengage the crown to screw it down. But in an automatic watch, this is just another potential point of failure for no real reason.
In contrast, Omega's screw down crowns (modern versions anyway) do not disengage the stem when you compress the spring inside the crown. I took this photo to show the difference between a fresh seal and a worn seal in the crown, but it also shows the telescoping part of the crown post, and as you can see it can't turn relative to the rest of the crown as it's telescoping in a hexagonal tube:
So in this way, Omega's crowns simply cannot fail in this manner. I prefer this design personally.
Now I'm sure I'll get replies that people have owned Rolex watches for years and never had this issue, or that the Rolex crown must be better because it's Rolex's design after all (I once had a Rolex guy tell me that Kif shock springs were far better than Incabloc, and when I asked him why he responded "because Rolex uses it, it must be better"
🤦). But these are my experiences seeing more watches than most collectors will ever see.
Cheers, Al
