jmb Posted January 12, 2011 Report Share Posted January 12, 2011 I thought I'd pop up some pics that better "explain" a problem with the later PT and Cartel vintage cases. It seems that in addition to the problem posed by the oversize compression ring/plastic spacer the OD (outside diameter) of the rehaut on newer cases is usually to large. If someone forces a new crystal, like a Clark, down over this oversize "feature" the result is quite often a cracked crystal. Remember, Plexiglas does not take too kindly to being stretched a great deal. I received a PT 1665 from one of the Brethren for a new compression ring. The new Clark crystal had already been installed to the case so I was going to pop it out and discovered it wouldn't budge. I thought, "Uh-Oh..." I looked at everything under the 'glass and saw a pretty nasty crack with little vertical stress cracks all around the base. I measured the ID (inside diameter) of the crystal: And then measured the rehaut OD: This resulted in an interference of about .0105 which is about .006" - .007" too much. I have seen a couple with about .013" interference... There are two things that can be done. One approach is to machine the crystal ID to match up with the rehaut while another is to machine the rehaut OD to obtain a more reasonable fit - I prefer the later as it makes future crystal changes more of a DIY procedure. A fixture I fabricated with the same diameter and thread pitch as the case back was mounted in the lathe and the case was then screwed onto the fixture: After the case is snugged up onto the fixture it can then be spun and the rehaut OD turned to the proper size. I like to turn to about .002" interference which provides a nice "slip fit" but won't fall off under it's own weight. With this little issue out of the way all that remains is to make a compression ring to fit. Quote Link to comment Share on other sites More sharing options...
ubiquitous Posted January 12, 2011 Report Share Posted January 12, 2011 Nicely done, J! I especially like the fixture you created to mount the case up for lathe work. As with most things replica, it's amusing to ponder why the factory would change the case specs to match the incorrect retention ring, but I suppose it costs very little to machine off less material when manufacturing cases instead of scrapping stock/inventory of incorrect size rings to make new ones. The things they do to save a buck... Quote Link to comment Share on other sites More sharing options...
highoeyazmuhudee Posted January 12, 2011 Report Share Posted January 12, 2011 this is the exact reason as i explained earlier why a gen insert will never fit this watch. Quote Link to comment Share on other sites More sharing options...
Dizzy Posted January 12, 2011 Report Share Posted January 12, 2011 Damn thats cool JMB. I'll have to make an appt with you to work your magic on this PT1680 case I have here in front of me. I originally put a t-39 onto this watch and the crystal cracked all around the base exactly like this one in your pictures. Stupid Submariners! Quote Link to comment Share on other sites More sharing options...
chiman12 Posted January 12, 2011 Report Share Posted January 12, 2011 You can also sand the sides of the crystal down a bit instead of taking metal off the case. This would be an easier solution for a person that doesn't have the machinery like JMB! .007" is only .18mm...it will take not more than 15 minutes to do JMB...are you sure it is a PT case? Because I never had a problem fitting a gen crystal on my PT case with the cartel bezel... Quote Link to comment Share on other sites More sharing options...
jmb Posted January 12, 2011 Author Report Share Posted January 12, 2011 Dizz, I don't know if it's because maybe Clark's are just brittle or if this would happen with any acrylic crystal... I kinda wish they would make Lexan crystals - practically unbreakable, and are a bit more compliant... Just send it on and I'll take care of ya... Quote Link to comment Share on other sites More sharing options...
jmb Posted January 12, 2011 Author Report Share Posted January 12, 2011 Chi, I rarely saw this issue in the older/original PT cases but it seems more prevalent in the newer ones. I prefer to machine the case, especially if I am making the ring as the next crystal replacement would then no need any special "fitting" to be done. I have chucked up crystals in the lathe and increased their ID accordingly with a boring bar but once I made the case holding fixture it takes me about the same amount of time to do the case as it does a crystal... Oh, I think I've seen this on the Cartel cases as well which leads me to believe they both come off the same machinery... Quote Link to comment Share on other sites More sharing options...
d-rock Posted January 12, 2011 Report Share Posted January 12, 2011 You gentlemen do take this very seriously. Wow...that's impressive. Quote Link to comment Share on other sites More sharing options...
automatico Posted January 12, 2011 Report Share Posted January 12, 2011 (edited) "As with most things replica, it's amusing to ponder why the factory would change the case specs to match the incorrect retention ring, but I suppose it costs very little to machine off less material when manufacturing cases instead of scrapping stock/inventory of incorrect size rings to make new ones." I have always wondered about this too. I heard a rap tune through an open window while hiding out back of a replica factory just the other day... You fools think we care about cases an' kits! No Fool! Dat ain't it! It's 'bout the cost of three-sixteen an' carbide bits! Not fine finish an' proper fits! That's for fools dat buys the real sh*t! Uh-huh! Uh-huh! Edited January 12, 2011 by automatico Quote Link to comment Share on other sites More sharing options...
Mapman57 Posted January 12, 2011 Report Share Posted January 12, 2011 I heard a rap tune through an open window while hiding out back of a replica factory just the other day... You fools think we care about cases an' kits! No Fool! Dat ain't it! It's 'bout the cost of three-sixteen an' carbide bits! Not fine finish an' proper fits! That's for fools dat buys the real sh*t! Uh-huh! Uh-huh! Cool.......maybe that's a REP tune, not a RAP tune..... Swapped a Clark 127 in my PT 1680 - no problem Swapped a T39 and or a T19 in my PT 1665 - no problem Both cases from original early PT versions. BUT tight as anything to get on and off - so plenty of potential trouble! J - ever thought of moving to Europe - such great expertise? Quote Link to comment Share on other sites More sharing options...
jmb Posted January 12, 2011 Author Report Share Posted January 12, 2011 J - ever thought of moving to Europe - such great expertise? I'd like to visit England, Sweden, and Germany, but I think the politics most places in the "Old Country" are a bit farther left than what I would feel comfortable with as far as a place to live is concerned! Quote Link to comment Share on other sites More sharing options...
grifter Posted January 13, 2011 Report Share Posted January 13, 2011 jmb, that's awesome work! i wish i had the equipment to do what you do. the last time i shaved a case, i did it with a dremel and files. i'm still paying off the masseuses who had to work the knots out of my neck, shoulders and arms!! jk Quote Link to comment Share on other sites More sharing options...
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