Discussion
BrassMan said:
Just idly pondering lens height on dive and dive-style watches. On many, the lens stands noticeably proud of the bezel, leaving it wide open to serious knocks. Is there any reason for this? Considering that even the sub. shows this, it can't be lazy design or engineering, can it?
You're confusing your watch with your glasses.Eleven said:
BrassMan said:
Just idly pondering lens height on dive and dive-style watches. On many, the lens stands noticeably proud of the bezel, leaving it wide open to serious knocks. Is there any reason for this? Considering that even the sub. shows this, it can't be lazy design or engineering, can it?
You're confusing your watch with your glasses.
This is known as a top hat
and this is a super dome.
Edited by andy tims on Sunday 18th May 17:49
Ignoring any fashion / styling issues it's basically a question of strength, hand clearance and avoiding too much bulk, especially with rotating bezels.
The crystal needs to be thick enough to safely take the rated pressure, plus taking knocks (within reason) at pressures it might actually be subjected to. In the Military watch magazine thread I posted an example of what happens if the crystal's too thin - a 1mm crystal spontaneously shattered at about 10 bar.
The inside of the crystal also needs to be far enough away from the dial to clear the hands safely. That clearance and the crystal thickness determine how high the face of the crystal will be.
Finally, look at the photos posted earler. If the bezel is raised to protect the crystal in either of those then the bezel itself is going to be absurdly bulky. Not only will that make it less comfortable to wear, it'll greatly increase the risk of the bezel itself being knocked and possibly broken away from the case (they're only clipped on in most cases).
An occasionally scratched or chipped crystal is a lot cheaper to replace than a bezel that's forever getting knocked off!
The crystal needs to be thick enough to safely take the rated pressure, plus taking knocks (within reason) at pressures it might actually be subjected to. In the Military watch magazine thread I posted an example of what happens if the crystal's too thin - a 1mm crystal spontaneously shattered at about 10 bar.
The inside of the crystal also needs to be far enough away from the dial to clear the hands safely. That clearance and the crystal thickness determine how high the face of the crystal will be.
Finally, look at the photos posted earler. If the bezel is raised to protect the crystal in either of those then the bezel itself is going to be absurdly bulky. Not only will that make it less comfortable to wear, it'll greatly increase the risk of the bezel itself being knocked and possibly broken away from the case (they're only clipped on in most cases).
An occasionally scratched or chipped crystal is a lot cheaper to replace than a bezel that's forever getting knocked off!
Hesalite/acrylic/mineral glass/sapphlex are all weaker than meral - so you might be able to get away with a slim'ish metal case but the cystal needs to be much, much thicker to withstand the pressures. Crystal and crown are the weak spots.
Material tech has moved on from acrylic of course and sapphire crystal is far, far stronger; wearing a Deepsea (WR 3900m + 25%) today; it's the first sapphire crystal from Rolex that has needed a dome, the 1220m Sea-Dweller didn't require it. It's 5.5mm thick but due to the thickness of the case is actually integrated reasonably well! My old 70s Sea-Dweller has a Super-Dome acrylic like Andy posted above. It's my second one and I have never knocked it.
Material tech has moved on from acrylic of course and sapphire crystal is far, far stronger; wearing a Deepsea (WR 3900m + 25%) today; it's the first sapphire crystal from Rolex that has needed a dome, the 1220m Sea-Dweller didn't require it. It's 5.5mm thick but due to the thickness of the case is actually integrated reasonably well! My old 70s Sea-Dweller has a Super-Dome acrylic like Andy posted above. It's my second one and I have never knocked it.
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