Tuesday, April 6, 2010

How to replace the balance and anchor (Seiko 6309-7040)

A few weeks ago I sat idly rotating my “Stephen Go” 6309 to obtain a full wind, when I noticed to my dismay that it had stopped running. Hmmm! Another shake and the second and minutes hands began to race around the dial before coming to a stop. (Watchmakers reading this: please don't spill the beans yet!). After a few minutes of deep thought I suddenly realized: something was wrong!


“Stephen Go” 6309 on stainless Super Oyster bracelet

Being more than averagely astute I realized something must be amiss in the movement, probably a result of my previous Enthusiastic Agitation. After opening the caseback and examining the movement through a stereo microscope I soon discovered the problem: one of the pallet jewels had become dislodged and was blocking the escapement.

This is apparently not entirely unusual on cleaned vintage watch movements, where the shellac used to hold the pallet jewels in place loses its ability to hold the jewels.

Refitting the pallet jewels is the domain of real watchmakers, requiring an understanding of the melting characteristics of shellac as well as specialized equipment. Correct positioning of the pallet jewels is also an art unto itself. Fortunately I had a spare 6309, non-working movement in a dress watch I had picked up for free in a previous deal. In a flash my keen mind knew what to do: rip the guts out of the donor movement and fling them into the patient!

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MATERIALS:

While I waited for screwdrivers, loupe and tweezers to arrive from Ofrei, I began to trawl the net to find out how the escapement works, and for tips on disassembly and assembly. The task actually did not seem too daunting.

  • Materials:

Screwdriver set
Caseopener
Tweezers
Loupe
Donor 309 movement
Headache tablets

  • Terminology used:




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RESULTS:


Caseback prior to opening using the rubber-ball caseback opener from Ofrei.


Unscrewing the rotor for removal, unnecessary for the operation but the donor had a rotor without pitting suitable for swapping.


Removal of the rotor.


Unscrewing the single balance plate screw.


Removal of the complete balance plate and balance. Ideally the balance and plate should be held together using the tweezers.


Balance removed showing the anchor plate and anchor.


Removal of anchor plate screws (2)


Anchor plate screws removed. (yeah, I know, I´m pushing it now, but I took LOTS of pictures )


Anchor plate removed, anchor ready for removal. Pictures like this are good when reinstalling parts!


Anchor removed. Its small! Look closely and you can see the one pallet jewel is sitting at an angle. This prevented the anchor in engaging the escapement wheel, causing the mechanism to unwind rapidly. It caused something else too, which I only discovered later...


Parts neatly sorted.


The donor, rear and front, a non-running 6309 sports watch I had picked up for free.


The donor anchor ready for replacing.


Anchor plate fitted. It took a little jiggling to get the spline on the anchor to fit into the jewel on the anchor plate. You really need a loupe for this work, everything else could be done without a loupe. When you suddenly see the little white dot (spline end) appear in the jewel, you know you are home!


Tightening the anchor plate. Move the anchor to and fro to check that the pallet jewels engage and release the escapement correctly. If not, the jewels are not seated correctly and you need to enlist the help of a watchmaker.


Arty photo showing the balance ready for fitting. I was getting quite excited now. Things would however, soon change.....(drumroll)


Carefully sliding in the balance and balance plate. A loupe is good here to make sure the splines click properly into their jewels. A very satisfying experience when they do. At this stage, the watchmakers in the video clips I had seen would give the balance a little shove and the watch would become alive, its little metal heart pulsing. Not so mine, the balance turned a few times and stopped, glaring sullenly up at me. Let me save a lot of time by telling you that a few DAYS went by, where I refitted the anchor and balance umpteen times, each time with no result: the balance was not making the anchor move. And suddenly (after some brain scratching) it hit me...


Balance with missing roller jewel (see EMPTY halfmoon shaped hole on balance: elementary, my dear Watson!) - possibly knocked off by the rapid unwinding of the movement when the pallet jewel failed. Hmmm. Luckily I had a donor balance lying ready, slipped it in and....IT LIVES! IT LIIIVES!! Wow, what a great feeling!


Nice´n´shiny replacement rotor ready for fitting.


Gratuitious final shot showing me screwing in the final screw. Done.
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IMPRESSIONS:

Well, that was rather fun and satisfying. Very tiring on the neck and eyes, though - I would hate to have to repair Big Ben. I have a great window ledge to work on, at shoulder height, with indirect light, that certainly helped. The loupe is like magic, transforming you to another world where you are oblivious of time (ooh, sorry, pun not intended) and surroundings. Its kinda neat to know that if I was in orbit on a space mission and my pallet jewel failed, I could do the repair on site, time our entry into the atmosphere AND save my crew of lovely Danish college girls at the same time! Incidentally, I ....what?....no, dear, I´m NOT sitting at the computer again, I....yes, dear, coming..

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