rileynp said:
First, I find it hard to believe "They fit the case perfectly" when they need alterations to actually fit over the crystal
Secondly, the crystal retaining rings are indeed supposed to apply downward pressure on the crystal while at the same time holding tightly to the case. Did you try using a crystal press to install the retaining rings before altering them? Have you done appropriate pressure/vacuum tests on cases with these aftermarket retaining rings to ensure they are doing their job correctly? Not going after you on the subject, but I would be careful to recommend an unproven aftermarket part that may potentially need alterations to fit in place. Hence my questions.
Oh and lastly, I see evidence of machining on original rings, why do you think they "have been cast from some kind of 'monkey metal'"? I don't argue that it is possible they were rough-cast and then machined to dimensions, but why call them "monkey metal"? Those that are cracked and rusted in my experience have obviously been ill-treated/cared for over many years.
The repro rings are a good fit onto the bare case - they fit snugly, requiring a press to push into place, and the use of a thin blade to remove. To me, they fit as well as an original, undamaged, ring.
The "problems" arise once the crystal, gasket and lower ring are in place. The inner diameter, where the crystal passes through the ring, has been very slightly too small on both occasions that I have tried to fit one. Despite applying as much force as I could with a quality crystal press, the ring would not clip right down over the case. Removing a minute amount of metal from the lower inner edge of the crystal aperture allowed the ring to seat correctly. YMMV, depending on the compressibility of the gasket, the diameter and bevel of the crystal, and the condition of the case and lower gasket ring. My guess is that the part is deliberately made with the crystal aperture slightly undersize, so that it can be custom fitted, ensuring a snug fit.
As far as I've been able to discover, there is no other alternative part available. IIRC, I was directed towards this part by a post on this forum. This aftermarket part, despite any reservations, must be a better solution than refitting a cracked original ring. If there is a better solution - a stock of original parts, perhaps - I'd be pleased to hear about a source.
AFAIK, the crystal retaining ring is there purely to stop the crystal falling out in everyday use. At high pressures, surely the crystal would be forced tighter against the gasket. As long as the initial seal is good, as the pressure increases, the gasket will provide a better seal. Once at depth, you could probably remove the ring, without affecting the waterproofing.
Maybe it was a bit harsh of to say that the original rings were "cast from monkey metal", but the ring is definitely the weak point on an otherwise excellent watch, and the quality of the material that it's made from is inferior to the rest of the case. The fact that it fractures suggests that it is diecast and machined, rather than machined from solid. The 2 failed rings that I've seen, and several unbroken ones, had the appearance of plated diecast parts, and the failure edges had the crystalline appearance of broken mazak diecastings, as used for Dinky toys. I suppose that this could be the effect of corrosion on an old fracture.
Sorry to ramble on, but I can't think of a better solution to the problem of a cracked retaining ring than the use of these aftermarket parts. If there is a better solution, please tell us.
