Jump to content

Replacing Existing Crystal With Sapphire


Recommended Posts

I just purchased a used Citizen watch and would like to replace the crystal. It is a Black Eagle Skyhawk (if that really means anything... :) ) and the case number is C652-S030480.

 

I contacted Esslingers and they tell me there is no sapphire crystal available for that watch. But aren't most round crystals more or less standard shapes and profiles?

 

If I measured the old crystal couldn't I order a sapphire one that would fit?

 

 

Link to comment
Share on other sites

Hi dferrier, welcome to the forum! Your assumption on measuring and ordering is rather correct, only, it is not -- believe it or not -- as exact as you would think. When ordering generic crystals the rule of thumb is to order one size up and one size down in addition to the original measurements. The tiny difference can make a huge difference! :)

 

Saphire is expensive!

 

Cheers,

 

Bob

Link to comment
Share on other sites

Hi dferrier, welcome to the forum! Your assumption on measuring and ordering is rather correct, only, it is not -- believe it or not -- as exact as you would think. When ordering generic crystals the rule of thumb is to order one size up and one size down in addition to the original measurements. The tiny difference can make a huge difference! :)

 

Saphire is expensive!

 

Cheers,

 

Bob

 

Thanks Bob,

 

What I am thinking and correct me if I am wrong about this. I have never actually taken a watch apart (yet) and so I don't know if all watch crystals are custom fitted by model or if they are more generic.

 

My thought was that if they mostly come in standard sizes and shapes I could order the correct size and shape in saphire.

 

Or is that a vain hope?

Link to comment
Share on other sites

I just purchased a used Citizen watch and would like to replace the crystal. It is a Black Eagle Skyhawk (if that really means anything... :) ) and the case number is C652-S030480.

 

I contacted Esslingers and they tell me there is no sapphire crystal available for that watch. But aren't most round crystals more or less standard shapes and profiles?

 

If I measured the old crystal couldn't I order a sapphire one that would fit?

 

 

I've looked at this watch and it seems to have a flat crystal which is easy to find in all measures. However since you never worked with watches if this is an one time desire I'd recommend that you bring it to a local watchmaker to have it measured and replaced.

Edited by jdm
Link to comment
Share on other sites

dferrier,

 

Bob's advice re; ordering sizes 1 up and 1 down is particularly pertinent when replacing acrylic or cellulose crystals as they are not dimensionally stable over time and they usually shrink, so measuring the one you take out may not give you an appropriate size for the replacement.

 

I'm not so sure that it is quite so applicable to glass or sapphire though (no offence Bob) as these materials are much more dimensionally stable over time, so if you are taking out a glass or sapphire crystal, and assuming that it was a good fit when you take it out, it should provide an accurate size for ordering the replacement. Also glass and sapphire are ground to precise dimensions so what you get should be exactly the size you ordered. Check the thickness as well as the diameter though.

 

The only time I order a range of sizes for replacement glass is when the original is broken or missing and I have to measure the aperture in the case which is not so precise as it takes no account of the gasket. Otherwise I just order one the same size as what I take out and I've had no problems yet.

 

With acrylic though the manufacturing process can be a little less consistent and if you combine the manufacturing errors with age shrinkage and measuring inaccuracies (it's very easy to slightly deform the crystal whilst measuring with a calliper) you can see where it becomes necessary to hedge your bets. 

 

Obviously over time you build up a stock of unused crystals of varying sizes making it easier to change acrylic crystals in the future.

Link to comment
Share on other sites

Hi Marc,

 

None taken!

 

I just sometimes do this one up and one down when considering the plastic gasket that holds the crystals regardless of the material they are made of. My reasoning -- and findings -- is that sometimes those generic rings/gaskets come with different thicknesses/dimensions to the ones originally in the watch and the replacement won't fit well...also if still using the old gasket (not recommended in an ideal world), it may be deformed -- if still flexible and usable -- and the new crystal won't be able to compress it adequately creating a future door for water to crawl in. Also there is always the error inherent to the measuring device and the user: mainly me.

 

I've had all that happen a few times so now I err on the "too much" rather than the "too little" and as you say, the collection of crystals grow more and more... :)

 

Of course, another story is when the crystal is glued to the case or maybe when the watch is "brand new" and needs -- or the owner wants -- a new higher end crystal.

 

Cheers,

 

Bob

Link to comment
Share on other sites



  • Similar Content

  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • I've remained silent on this thread, and at the risk of upsetting everyone, the thing that worries me the most the the apparent absence of Mark. The moderators do a great job and the members also pitch in, and the site seems to run itself, but it is a concern for the future of this forum when the owner is absent for all intents and purposes. Like many of the comments above I would hate to log in one day and things be closed down as I rely on this site for ideas and knowledge and also cheer me up. maybe the Moderators could reach out to him, assuming he does not read this thread, and express our concerns and let us know the plans going forward? some kind of WRT ark
    • That was the exact reason for me starting this thread watchie. Still we haven't worked out how the regulars are going to hook up if it goes tits up. I honestly think something should be arranged to stay in contact, we all help each other so much. 
    • Yeah ive watched that a few times before,  i couldnt find my old school dividers to scribe it up 😅 Yep thats the guy i bought a roll from . Thanks Nicklesilver that answers that perfectly and more or less what i thought an experiment over time would prove . The jumper arm is quite thick along its length, i left it that way intentionally, i thought the original was probably very thin, i didnt see that it was already missing. Setting isn't particularly stiff as such just positive, i still need to take it out and polish where it mates with the stem release. 
    • Yes, "Sold out" is difficult to understand. There doesn't seem to be a lot going on. It's been nine months since any new video was published on the Watch Repair Channel. The Level 4 course on watchfix.com has been in progress for what feels like forever (several years!?). Maybe Mark's enterprises aren't doing well or perhaps already so profitable there's nothing much to motivate him for more material. Or, perhaps these days he's more into crochet. The real reason is probably something entirely different but it would be nice/interesting to know. I don't mean to sound gloomy or pessimistic, but I wouldn't be surprised to be met by an HTTP 404. Every day feels like a gift. Speaking of watchfix.com I've been postponing the "Level 5: Servicing Chronograph Watches" course for a very, very long time. Anyway, I just enrolled on it so it's going to be very interesting to see the videos. I must say, IMO there's nothing really that can compete with Mark's courses when it comes to presentation and video quality. It's simply world-class and makes me associate with some really expensive BBC productions.
    • Steel has some funny properties, or at least counterintuitive. The modulus of elasticity is effectively (not exactly, but close enough) the same for steel that is annealed and hardened. What changes is the point of plastic deformation* . If the movement of your spring doesn't pass that, it should work fine. It looks a little thick, I would thin it a bit maybe from the main body out about halfway, maybe 10-20% thinner (not in thickness, along its form). But if it works it works!   *So- if you have two bars of the same steel, one annealed, one at 600 Vickers (general hardness watch arbors might be), clamp them to a table so the same length is hanging out, and put a weight on the ends, they will bend the same amount. But if you continue to add weight, then remove it, at a point the annealed bar won't return to its original straightness. That's the point of plastic deformation. But up to that point, as springs, they are the same. However- their wear characteristics will be very very different. And getting the hardened bar past its point of plastic deformation takes a lot more effort.
×
×
  • Create New...