Hairline Cracks in Jewels

[RyMoeller]

I'm looking for a little feedback regarding cracks in jewels- specifically hairline cracks.  I'm working on a piece now that has a hairline crack in the upper balance jewel.  Under the microscope the crack doesn't appear to structurally change the pivot hole- that is to say the hole is still nice and round although the crack does extend from the hole to the edge of the jewel, however, the amplitude drops significantly (~80 degrees) when the watch is placed in the crown down position and the watch slows also by about a minute and a half per day.  So the question is, can this hairline crack be causing the loss of amplitude and time?

I should note that I've poised the balance and inspected the pivots which are round and straight so I'm starting to think the crack is the culprit.  I won't know for certain until the replacement jewel is fitted but if anyone has experience to share I'd love to hear it.

[IllinoisWatch]

yes it can cause problems. what type of movement is this?      

[RyMoeller]

It's a Pierce 134.  They are notoriously finicky little beasts.

I'll post a picture of the cracked jewel just as soon as I get back to my workbench.   

[RyMoeller]

Well I forgot to upload a picture until today but better late than never I suppose!

I've ordered the replacement jewel and am feeling a lot better about it as close inspection has revealed two cracks and also a nice divot where the pivot collided with the jewel at some point int he past.

[StuartBaker104]

Out of interest, have you had a good look at the pallet lever jewels (the escape wheel ones, not the pivot ones). I have seen a few Pierce 134s with chipped lever jewels - not sure if they get a particularly hard ride or just been unlucky.

[RyMoeller]

On 12/19/2016 at 0:44 AM, StuartBaker104 said:

Out of interest, have you had a good look at the pallet lever jewels (the escape wheel ones, not the pivot ones). I have seen a few Pierce 134s with chipped lever jewels - not sure if they get a particularly hard ride or just been unlucky.

Oddly I haven't seen damaged pallet jewels yet on a Pierce.  In my previous experience I've noticed quite a few damaged jewels on the chronograph bridges though.  Not sure why that's the case but I believe I've replaced three of them this year.

This Pierce has been a real treat.  A cracked center jewel and a chipped upper balance cap jewel in addition to the above mentioned pivot jewel.  Luckily for me the cap jewel is only chipped on the topside.  Who knows how that happens? 

Oh and replacing the center jewel was a fun endeavor.  I had to fabricate a punch for my Seitz tool in order remove the damaged jewel as it was set in the bottom of the minute pinion post and could only be pushed out from the dial side.

 

[ramrod]

i'm glad i read this thread. i was going to post a question about my seiko 7s26, but this might be the answer. i serviced it last week and got it to running fine - as long as it is dial down. when i turn it right side up or on it's side, it slows to a crawl or stops completely. i will have a look at the jewels to see if they are the culprit.