maxmsu Posted April 25, 2014 Report Share Posted April 25, 2014 Experts, The rep crystal cracked and water leaked... need to get it replaced, however, I have no idea what model # I should go with, need your help! At another forum, I was told this will fit: http://www.ebay.com/itm/Crystal-Ref-25-127-127-Rolex-CLARK-crystals-/231131768876?pt=LH_DefaultDomain_0&hash=item35d086e82c Can someone confirm? Many thanks!! Quote Link to comment Share on other sites More sharing options...
automatico Posted April 26, 2014 Report Share Posted April 26, 2014 Looks like your crystal retainer bezel was too tight, the case neck was too big, the crystal was brittle, the crystal was not a good fit...or a combination of faults. It all depends on the specs of your case, crystal retaining ring, and date offset. Whew! If everything is oem spec it is fairly easy to find a replacement but if not, it will be hit or miss. The 1680 uses a number 127 crystal. To get an accurate fit, you need the specs on a genuine case neck where the crystal mounts and ID of a genuine crystal retainer, then measure your case and retainer and see if they are the same. If yes, then you can use a genuine or accurate aftmkt crystal. Catch 22...many aftmkt replacement crystals are not exactly the same as genuine. Good luck! It's simple but it ain't easy. Quote Link to comment Share on other sites More sharing options...
Mendota Explorer Posted April 26, 2014 Report Share Posted April 26, 2014 Which is a better overall quality replacement - Clark or Sternkreuz? Quote Link to comment Share on other sites More sharing options...
automatico Posted April 26, 2014 Report Share Posted April 26, 2014 That depends on the exact outside diameter of the case neck and inside diameter of the crystal retaining ring. I put a Clark 127 on an MBK 1680 case and the crystal was too tight and shaved quite a bit of plastic from the inner edge. The crystal retaining bezel was also too loose with the Clark 127. The MBK case neck od was 28.2mm. I ended up using a Best-Fit 127 from a supply house but no telling who made it. To make matters worse, some replica case makers have goofball size case necks, crystals, and retaining rings so genspec parts will not fit. There is no quick and easy answer to your question because of so many variables in cases and crystals so you may need to invest in a high quality digital caliper (around $75 to $100) and go from there. I went through a half dozen crystals on a DW '5513' project and finally ended up with a Clark 19 and an ST bezel kit with the crystal retaining ring ID machined inside a little bit in a lathe. It was a lot of trouble but the DW case has a 28.0mm case neck and most aftmkt 19 crystals will not work. They come with an off spec crystal and spring wire bezel. Find a crystal that is a good fit on the case neck (not too loose, not too tight) and push it all the way down on the case then measure it at the top edge and the base. The top edge diameter will tell you if the crystal retaining bezel will start straight on the crystal without a lot of trouble and the base measurement is what you need to compare with the ID of the crystal retaining bezel...usually 1 or 2 tenths mm is all the difference you can get by with depending on how tight the crystal is on the case neck and how hard the crystal material is. Rigid crystal material will shatter if the crystal retaining bezel is too tight and flexible material will give a little. crystal is too loose = it will turn easily and has some side to side slack between the case neck and crystal crystal is too tight = shaves plastic and very hard to turn I have had a tremendous amount of trouble with acrylic aftmkt crystals fitting genuine and genuine spec rolex cases. I went so far as to buy a Mitutoyo 'Absolute' digital caliper to measure cases/bezels etc and it has really made the task easier. I also have a couple cheapo digital calipers and they simply will not give accurate readings over and over. You can find good deals on Mitutoyo calipers on eBay...the 500-351 and similar models are good choices. I know this was a lot of technical BS but if you are going to work on this stuff you will need a good caliper. I also use the caliper to measure MG crystals as well as crystal seats in older watch cases that use 'armored' and 'snap in' crystals. You can also tell a T10 (.9mm) stem from a T9 (1.0mm) stem etc as well as measure case tubes, crowns etc. I am NOT a watch expert by any means. I am an expert on watch BS. Ha! Quote Link to comment Share on other sites More sharing options...
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