Major coupe for a wannabe watchmaker...

Joined: June 19th, 2009, 6:51 pm

August 15th, 2009, 4:41 am #1

I have been working on servicing some Chinese vintage ST5 powered watches for Mark(Zoodles) and ran into some issues.

I posted about the one with the missing tooth on the third(?) wheel and gave a tear down summary on the one with the beautiful Sea Gull stripes.
That one was running about 5 to 6 minutes fast per day and I regulated it back to a could of seconds per day before servicing it. I did notice that after regulating it that the amplitude of the balance was erratic; speeding up and slowing down; ie the amplitude kept changing.
Well, after the service, the watch was more erratic than before and would stop running when I picked it up or moved it. After disassembling and reassembling it several times with no change; I took the time to look closely at it under my 10x loupe.
I discovered that the amplitude of the balance wheel directly correlated to the rotation of the escape wheel!

After observing it very carefully, I saw that each full revolution of the escape wheel caused the balance to change at the same frequency.

To test this out, I swapped the escape wheel from the other ST5(the one with the toothless 3rd wheel). As soon as I dropped the balance back in place, the movement set off like a race horse and hasn't faltered since I'm timing and regulating it now, so it and the other ST5 should be on their way back to Mark in a couple of days

The sad part is that Mark sent me three watches and only two are going back; the third one is now a repository of unobtanium parts for the long out of production ST5 caliber.

While I would have liked to return all three watches to Mark in perfect working order; I am still happy for the experinece of having been able to work with this caliber and learn how well made it is/was

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Joined: December 4th, 2008, 11:34 pm

August 16th, 2009, 11:57 pm #2

root cause of the amplitude problem??

BTW - don't feel too bad about the 2 out of 3 performance. Maybe spare parts will become available to you & you can complete the task 100%! As these watches become better known, sources of parts may well be uncovered as folks realize there's some value in "advertising" them!

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Seiko Matsuda
The Patron Saint of Seiko Collectors
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Joined: June 19th, 2009, 6:51 pm

August 17th, 2009, 2:22 am #3

changing out the escape wheel did the trick.

I'm guessing that either the escape or the wheel it drives were interfearing with one another. Chances are it was just a bad fit because both this one and the donor run fine now.

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Joined: July 19th, 2008, 3:38 am

August 17th, 2009, 8:25 pm #4

Maybe. You have to put it in a set of calipers or maybe you could see it on the poising table, watch for the wobble.

Cheers,
Randall
____________________________________________________________
Seikoholic #1
Dr.Seiko,
Specializing in Seikology, Seikotherapy, and other Horological Dis-ease.
Made in the U.S.A.

"Like my old Granddaddy used to always say; the less a man makes declarative statements, the less apt he is to look foolish in retrospect."- Q.T. Four Rooms
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Joined: July 19th, 2008, 3:38 am

August 17th, 2009, 8:29 pm #5

Beings as it was an escapewheel, you could probably see the results of a bent pinon on the escape wheel if you where checking the locking on each tooth as it goes around. I have used that before to detect slightly bent escape wheel pinons that are affecting timing.

Cheers,
Randall
____________________________________________________________
Seikoholic #1
Dr.Seiko,
Specializing in Seikology, Seikotherapy, and other Horological Dis-ease.
Made in the U.S.A.

"Like my old Granddaddy used to always say; the less a man makes declarative statements, the less apt he is to look foolish in retrospect."- Q.T. Four Rooms
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Joined: June 19th, 2009, 6:51 pm

August 18th, 2009, 4:25 am #6

12.5X magnification, the cog teeth all looked clean and nicely formed.

The thing is that the suspect escape wheel seems to run just fine in the donor movement.

I'm still not completely happy with the way the balance is working. I may try swapping the center wheel as well.

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Joined: June 19th, 2009, 6:51 pm

August 18th, 2009, 4:29 am #7

Maybe. You have to put it in a set of calipers or maybe you could see it on the poising table, watch for the wobble.

Cheers,
Randall
____________________________________________________________
Seikoholic #1
Dr.Seiko,
Specializing in Seikology, Seikotherapy, and other Horological Dis-ease.
Made in the U.S.A.

"Like my old Granddaddy used to always say; the less a man makes declarative statements, the less apt he is to look foolish in retrospect."- Q.T. Four Rooms
and I'm not sure what a poising table is...remember I'm just a pawl buster

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