7S26c: Oscillating weight - does this need attention/repair

[mcc]

Hi,

HAPPY CHIRISTMAS! :)
(sorry for my English, I am not a native speaker...)

My SEIKO SNK809 ( 7S26c movement) shows a (at least to me) strange behaviour:
If used normally (at my whrist) it looses more than a minute/day.
When roating the clock by hand around the axis of the hands to wind it up it looses about
10-15 sec./day
When I held the the clock vertically and move it in that position in horizontal direction back and
forth there seems something loose inside (the oscillating weight?????)

Is it normal that there seems something loose inside the clock?
What can be the reason for the clock for not being fully wind up if used regulary?
IF the oscillation wheight is loose: Is it possible to fix it myself? How can I determine
how much I need to teighten what screw?

Thanks a lot for any help in advance!

Cheers!
mcc

 

[Nucejoe]

The rotor screw can get loose. Causing this.

Google,  seiko 7s26c ranfft  to see a picture of the movement. 

Rotor bearing may need repair/ replaced too.

 

 

[jdm]

33 minutes ago, Nucejoe said:

The rotor screw can get loose. Causing this.

Rotor bearing may need repair/ replaced too.

It is not practically feasible or convenient to replace only the bearing on these Seiko mov't. It is not even available as spare part.

The auto winding mov't must be checked on various points beside just the central weight being loose, which is kind of unlikely because if so it would have come completely off with time. 

• Bearing condition, that is how much free swinging there is. Something like the video below.
• Shape of the magic lever tips, if worn it must be replaced - which requires disassembly main bridge.
• Condition of the knurled wheel where said tips bite. It supposed to be lubricated but that is most often neglected by both factory  and "watch repairers"
• Orientation of the weight when reinstalled, to get max efficiency. In theory that should be reversed when watch is worn on right arm.

What I suggest to the OP is that he only gets the watch correctly regulated on the timegrapher by an budget watch shop. Anything else is likely to exceed the cost of a new same watch, which is about USD 60.

 

Edited December 24, 2019 by jdm

[mcc]

Hi,

thanks for the information!

the watch is less than an year old. So I think, "wear and tear" should not be impacted the watch that much. I think (read: I dont know...): Could an initial misassembly/forgotten oiling etc. in the manufacturing process having influenced my watch?

I read several times (and noticed it with another 7S26c-based watch of a colleque of mine) that the "something in the clock" sounds to be loose when the watch is moved like I described it in my initial posting.

But I dont know the age of any of the other watches...

I am trying to evaluate, whether my watch behaves like any othe 7S26c-based watch or whether I have a problem, which needs to be fixed...:

Is it quite common, that something (the oscillating weight?) feels/sounds loose?
Is it ok, that the oscillating weight has some tolerance in movement perpendicular to normal rotational movement?

Thanks a lot for any help!
Cheers!
mcc

 

 

[jdm]

19 minutes ago, mcc said:

Is it quite common, that something (the oscillating weight?) feels/sounds loose?

Your watch is of an economical type, produced in very large numbers, so it can happen that some units may have slightly faulty parts.

The video above shows how the efficiency of the rotor is easily evaluated.

As long the auto winding keeps it running all is good, but if you are bothered by its sound then you will need to replace the rotor, movement, or the entire watch. 

[bklake]

I gave my 16 year old nephew an SNK809.  6 month later, he gave it back saying it would not wind any more.  The rotor was loose.  I don't know what he did to this poor watch in such a short time.  I tightened the rotor screw and sent him on his way.  No problems since. 

There is a proper orientation for the rotor.  Read the 7S26 technical guide for easy to understand pictures. 

[Nucejoe]

22 hours ago, mcc said:

Hi,

thanks for the information!

the watch is less than an year old. So I think, "wear and tear" should not be impacted the watch that much. I think (read: I dont know...): Could an initial misassembly/forgotten oiling etc. in the manufacturing process having influenced my watch?

I read several times (and noticed it with another 7S26c-based watch of a colleque of mine) that the "something in the clock" sounds to be loose when the watch is moved like I described it in my initial posting.

But I dont know the age of any of the other watches...

I am trying to evaluate, whether my watch behaves like any othe 7S26c-based watch or whether I have a problem, which needs to be fixed...:

Is it quite common, that something (the oscillating weight?) feels/sounds loose?
Is it ok, that the oscillating weight has some tolerance in movement perpendicular to normal rotational movement?

Thanks a lot for any help!
Cheers!
mcc

 

 

Tolerance not to a point that can be felt/ loose. 

 

[mcc]

Hi,

@Nucejoesorry...I don't understand your answer ... I am no native speaker ...

Thank you for pointing me toe the technical guide of the 7S26c movement!
The one I have stored on my computer is a 11 page PDF paper. Is it that one? I saw the instructions for the correct alignment of the
oscillating weight and the rest of the winding mechanism, checked my watch and at least this part is OK.

What I am still exploring are the reasons for the slight perpendicular movement of the oscillating weight. Is this the way it is (all 7S26c movements are that way), is it a "problem" of my watch and can easily be fixed (for example the lubrication of the ball bearing was missed in the production process, is it a problem of my watch and it is fatal, because the perpendicular movement puts mechnaical stress to the rest of the movement,.......more interations of thoughts of the why and the reasons follows here.....

When tightening the oscillating weight: How much is OK? Is there any impact on the ball bearing itsself, when the screw of the oscillating weight is tightened ?

For estimating the ability of my watch to wind up correctly: What amount of movement is exspected to be enough to wind up the watch fully ?

I am only curious...sorry

Thanks a lot in advance for your help!
mcc

[jdm]

1 hour ago, mcc said:

because the perpendicular movement puts mechnaical stress to the rest of the movement

No, it does not "stress" the rest of the mov.t, however if it's extreme the rotor rubs on the main bridge marking it, as well very likely not winding.

Quote

When tightening the oscillating weight: How much is OK? Is there any impact on the ball bearing itsself, when the screw of the oscillating weight is tightened ?

Tightening does not impact the working of the ball bearing. Threading and contact happen only on the inner hub, nothing else is affected. Then "how much" tightening which you have repeatedly asked , although the manufacturer does not specify a torque, it is enough to tighten keeping the screwdriver in the tips of three fingers only, and stopping when the screw ends turning. That is pretty much the same as with any other screw of a watch, where small body drivers and just two fingers are used.

Quote

For estimating the ability of my watch to wind up correctly: What amount of movement is exspected to be enough to wind up the watch fully ?

Very little, as in wearing the watch staying home for few hours only. Seiko's bidirectional "magic lever" is an extremely efficient. When it fails to fully wind the watch the problem is with the mechanism, not the owner's activity.

Edited December 26, 2019 by jdm

[mcc]

Hi jdm,

Thank you for your information!!!

I checked the watch for scratch marks with a magniying glass and found none. Rotating the clock around the axis of its canon pinion (and hopefully I dont messed up all these special words) let rotate the oscillationg weight partly with it (so there is no relative motion between the weight and the rest of the watch) about a "quarter of an hour" til it swing down to it rest position again.

About tightening the screw in the middle of the oscillating weight:
That are good knews: For me and my untrained eyes it was not clear form the drawing of the technical guide, whether that screw also was part of the construction of the ball bearing itsself as sometimes found at the bearings of pedals of older bicycles).

Is there any way to recognize, when the watch is fully wind in opposite to "just wind enough to no to stop".... ?

Sorry...questions over questions...but technic - regardless what - make me curious...

Cheers!
mcc

 

[jdm]

1 hour ago, mcc said:

Is there any way to recognize, when the watch is fully wind in opposite to "just wind enough to no to stop".... ?

Yes, the proper way would be checking amplitude (search this forum or the Internet to learn what that means), using a timegrapher or equivalent app - again, these are very often discussed here. That will also show the accuracy of the mov't, and the it's general "health". A trained eye can also give a ballpark amplitude estimate.

Another way is winding at the barrel, if you can feel the mainspring starting to slip right away that means it was fully wound. But it's a very faint feedback, which one has to develop a sensitivity for.

Edited December 26, 2019 by jdm