RWG Technical Posted March 12, 2012 Report Share Posted March 12, 2012 Not sure what is going on, but this is the second time in less than a week that I have found cracked jewels on an A6497-1. This is the only time I have come accross this problem, it's very rare except in old pocket watches that have been tinkered with by the unskilled. Both times the jewels were the top escape jewels (the one you see through the caseback), this one is only cracked through one side, the other was cracked completely accross in 2 pieces. Replacement is not straight forward, my Seitz Jewelling kit doesn't have the required 10/170 replacement jewel (10 is the size of the hole in 1/100mm and 170 is the diameter in 1/100mm). My sizes are 160 and then 180. So in order to install the 180 diameter jewel, the existing hole has to be broached to 0.179mm, the 0.001mm smaller diameter for the hole is what is needed to press fit the jewel and secure it to the escape c0ck. I am suspecting that something is happening during assembly, given that the pivot on the escape wheel is only 0.09mm in diameter, it's unlikely that it's causing the breakage, the pivot would fail before the jewel did. Most likely the installation of the jewel into the c0ck is where it's failing. Here's a picture of what I found today. Keep in mind that the jewel is sapphire, next harder substance is diamond. So if you have a cracked jewel, with a sharp edge made of sapphire, with a steel pivot turning in it and rubbing up against the sharp edge...guess what's going to happen and eventually fail. Hint...it won't be the jewel. All the more reason to never take for granted that all is ok, even on a new movement. Critical to inspect each and every part and component, you never know what you'll find...anyone else come accross this defect? Quote Link to comment Share on other sites More sharing options...
URkuk Posted March 13, 2012 Report Share Posted March 13, 2012 Thanks Rob, Perhaps all the owners of the new 390 with the closed case back should at least open the case and take a peek? I personally would not know where to look but I'm sure many here do...I suppose I could alert Josh but not sure if that would do any good. Quote Link to comment Share on other sites More sharing options...
hackR Posted March 13, 2012 Report Share Posted March 13, 2012 great post, R...once again, thanks!... haven't had this problem --- that i know of! --- in my 6497 movements...but did have the same jewel crack in an genuine eta 2836-2 movement in a rep steelfish... Quote Link to comment Share on other sites More sharing options...
Jkay Posted March 13, 2012 Report Share Posted March 13, 2012 Bothersome ... Quote Link to comment Share on other sites More sharing options...
RWG Technical Posted March 13, 2012 Author Report Share Posted March 13, 2012 It's very odd and unusual. Two in the last week is a lot, since zero were found before this...hopefully not a trend. Both watches were completely different models, one a franken, one new, so no link that I can make at this time, except maybe the movements were the same source. Even if members did open the caseback and found a cracked jewel, how would they fix it? You need a good loup to see the crack and when the movement is assembled, the jewel and pivot are oiled, it's not easy to spot a crack, a piece of lint can also look like a crack. Hopefully others can share any further info. Quote Link to comment Share on other sites More sharing options...
Rolexman Posted March 13, 2012 Report Share Posted March 13, 2012 Good info. I haven't serviced an 6497 for a while so I can't really ad to this thread. Untill now I found loose jewels and extra jewels floating around yes...but no cracked ones. This is a scary development for rep buyers. The life span of a movement with a cracked jewel is very low. Quote Link to comment Share on other sites More sharing options...
freddy333 Posted March 13, 2012 Report Share Posted March 13, 2012 Can you trace the watches to a single seller, who may be getting his watches from the same factory? I think you have to assume that either someone got a defective run of jewels or someone is installing them incorrectly. Of course, with reps, either (or both) scenarios are likely. Quote Link to comment Share on other sites More sharing options...
RWG Technical Posted March 13, 2012 Author Report Share Posted March 13, 2012 Can you trace the watches to a single seller, who may be getting his watches from the same factory? I think you have to assume that either someone got a defective run of jewels or someone is installing them incorrectly. Of course, with reps, either (or both) scenarios are likely. Don't know if there is a connection. Trying to estalblish some sort of link is beyond what little spare time I have at the moment... I think it's random, like the bent and broken seconds posts. Quote Link to comment Share on other sites More sharing options...
kbh Posted March 13, 2012 Report Share Posted March 13, 2012 This kind of fits into my unprovable theory that replica factories end up bulk buying all the movements that fail the factory's quality assurance tests. Every time I've swapped a movement with a new one from a legitimate company like Cousins or O'Frei, they seem to be of much better quality. Particularly the A21j movements. Quote Link to comment Share on other sites More sharing options...
Nanuq Posted March 13, 2012 Report Share Posted March 13, 2012 I was going to say this happened to me once in a hockey game, then I saw you're talking about watches. Mea culpa! Quote Link to comment Share on other sites More sharing options...
Utheman Posted March 13, 2012 Report Share Posted March 13, 2012 maybe they're using rep jewels... Quote Link to comment Share on other sites More sharing options...
Logan Posted March 13, 2012 Report Share Posted March 13, 2012 Interesting point Utherman, maybe they are lower grade jewels from a makers who hasn't quite figured out the process yet, or even made from glass or similar? Quote Link to comment Share on other sites More sharing options...
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