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  • Part 3 of 3 Seiko 7S26 skx Automatic Watch Service and Lubrication. Seiko 5


    Mark

    Published on YouTube: 13th May 2016
    Video Owner: Watch Repair Channel
    Total Views: 83978
    LIKES: 1147 DISLIKES: 12

    Watch Repair Course Level 1: https://goo.gl/kbZRSu
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    ERRORS IN THIS VIDEO:
    At 3:42 you may notice I have placed the Intermediate calendar setting pinion reversed. If you are following this video whilst rebuilding your 7S26 then please take note of this.
    At 4:55 you will see that the Intermediate pinion is now placed correctly.
    Even experienced watch repairers make mistakes sometimes :)
    
    In this video I am stripping...(Original Description Truncated to 500 Characters)

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    11 minutes ago, Mark said:

    At 3:42 you may notice I have placed the Intermediate calendar setting pinion reversed. If you are following this video whilst rebuilding your 7S26 then please take note of this.

     

    Important to note: reversing that pinion breaks it when trying to set. Ask me how do I know :)

    As with other Seiko parts, the up side is marked with a dot.

    Edited by jdm

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    1 hour ago, jdm said:

    Important to note: reversing that pinion breaks it when trying to set. Ask me how do I know :)

    As with other Seiko parts, the up side is marked with a dot.

    Yes - I can imagine as the leaves get caught on the watch plate recess. That's why I thought it important to make the point in the description - I have annotated the error also.

    @bobm12 suggested I should re-shoot that part and i'm inclined to agree with him, not re-shooting it was a little lazy on my part. Still... it shows i'm human :D

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    It might be worth re-recording for people viewing it outside YouTube. I watched the video within an app on my mobile phone so the annotations didn't appear. Having said that, looking at the pinion itself I could work out which way round it went.

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       Thank you for sharing these videos, clear, easy to follow and so interesting.

    I found the following image while looking through the Seiko Parts Catalogue/Technical Guide for Cal. 7S26 & 7S36 A.

    I would be most interested to hear your comments.

    Thanks again

    Vincentimage.png

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    Hi Vincent,

    There is a page somewhere where there was an actual experiment: The person reporting on this said he adjusted the rotor in a different way, let's call this, "not optimized way" and compared it with the way in the illustration/instructions you posted, let's call that "the proper way".

    His results were that the "not optimized way" would not give the movement all the reserve "the proper way" did. I must add that when you grab the movement, the rotor usually moves in such a way that it "protects" the hairspring. If it is donne in the "not optimized way" that won't happen.

    Just my take on it.

    Cheers,

    Bob

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    Worth to note, a person wearing the watch on the right hand should have the weight turned 180 deg. Seiko (of course) never mentions that. 

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    The oscillating weight movies by the movement of the wrist. It has nothing to do if it is worn on the right or left. Where do you get some of this rubbish from.

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    10 minutes ago, oldhippy said:

    The oscillating weight movies by the movement of the wrist. It has nothing to do if it is worn on the right or left. Where do you get some of this rubbish from.

    Differently from other makers, this Seiko uses a "magic lever" mechanism with an eccentric. Check in the picture above how the two marking must be aligned when the weight is at 3, for a watch worn on the left wrist. Attached the complete manual for your future reference.

    7S26C.pdf

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    Would you care to show exactly where in the documentation they talk about wearing on the left hand? I couldn't find that annotation...my eyes must be getting too old. Thanks in advance.

    Cheers,

    Bob

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    10 minutes ago, bobm12 said:

    Would you care to show exactly where in the documentation they talk about wearing on the left hand? I couldn't find that annotation...my eyes must be getting too old. Thanks in advance.

    What I'm saying is that Seiko do NOT talk about the wearing side, but indicates the weight at 3pm, that is crow down for the left arm.

    Edited by jdm

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    mmm, not sure it will affect anything when worn on either hand, wrist up or down and/or crown up or down. In the experiment I referred to it only talks about the reserve. Given that it optimizes the rotor movement not the magic lever (rotor efficiency). Those wind the same no mater how you move the watch, in either direction. It is, again, the oscillating weight the one that is centered for optimal rotation...and something to do with covering the hairspring when not in movement, like its resting point.

    The crown position affects the accuracy by other factors that come in play, not the winding by itself. Being automatic it is always assumed that when worn continuously (ideally), the watch has enough reserve to make the main spring force to be constant so its influence on those factors is...how can I put it, the same?, or maybe trivial....Of course, in real life (not ideal) we know everything is ultimately connected.

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    25 minutes ago, bobm12 said:

    mmm, not sure it will affect anything when worn on either hand, wrist up or down and/or crown up or down. In the experiment I referred to it only talks about the reserve. Given that it optimizes the rotor movement not the magic lever. Those wind the same no mater how you move the watch, in either direction. It is, again, the oscillating weight the one that is centered for optimal rotation...and something to do with covering the hairspring when not in movement, like its resting point

    When you optimize the rotor movement, you optimize the magic lever efficiency, because the two parts are linked together.

    The Magic Lever auto winding is most effective (at preserving power reserve) when the markings are aligned with the weight down (@ 3H), because that is where the shape of the eccentric makes so that the smaller oscillation (e.g. walking) of the arm causes the immediate grabbing of the pawls to the winding wheel.

    You can check that easily by looking at the pawl action when the marks are aligned, compared to when are not.

    That is why the rotor has to be installed like in the picture above. Here's an article that explains the matter in more detail https://adventuresinamateurwatchfettling.wordpress.com/2012/09/24/an-intermission-notes-on-the-7s26-autowinder-efficiency/

    Edited by jdm

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    I think we were referring to the same article and the point is, you are saying exactly the same regardless of which hand we use the watch on!...which is the origin of this little aside. Optimization for the magic levers to move not for wearing the watch one way or another since the magic levers, once optimized, will do the job exactly the same, i.e. winding the watch.

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    consider a crank shaft, con rod, and piston in an engine.

    If you align the axis of the crank, the gudgeon pin, and the crank pin all on the same line, then a (for the sake of arguement) 5 degree rotation of the crank either way may result in (say) a 10mm linear displacement of the piston.

    Now rotate the same crank 90 degrees such that a line from the gudgeon pin to the crank axis is at right angles to a line from the crank axis to the crank pin. Now that same 5 degrees of crank rotation results in (say) 25mm of linear displacement of the piston.

    This is the same for Seiko's magic lever. The end of the lever attached to the rotor is connected to a pivot that it slightly displaced from the axis of rotation of the rotor, just like the crank pin on a crank shaft. The rotation of the rotor causes a linear oscillation of the magic lever so that the pawls of the magic lever alternately pull on the teeth of the first reduction wheel.

    I think that most people would agree that the (normal everyday) activity that most efficiently winds an auto is going for a walk, as the arms naturally and effortlessly swing to and fro as we walk, resulting in a similar movement of the rotor. The arm naturally hangs down as we walk so the watch tends to be in crown down (on the left wrist) or crown up (on the right wrist). It therefore make sense for the rotor to be aligned such that the magic lever pivot to rotor axis line is at right angles to the magic lever pivot to first reduction wheel pivot line when the watch is either crown up or crown down, as this results in the greatest linear displacement of the magic level pawls as the rotor swings through an arc, and therefore the most efficient winding.

    If you get you crank timing out by 90 degrees in an engine you will have major problems:Dat least in the Seiko nothing gets damaged, however, winding efficiency will suffer.

    This is not an issue for those who use a watch winder that performs full rotations of the watch, but Seiko's target market, at least for those movements that use the magic lever autowinder arrangement, is the average man in the street who has never even heard of a machine that winds your watch up for you.

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    All Seiko autos I have repaired and it must run into hundreds use the "magic lever" mechanism with an eccentric. I have never ever come across anyone who has brought their repaired watch back and complained that it doesn't run its time and stop when wearing on their wrist regardless if it's right or left, it's more likely not to function correctly if it's a bracelet fitting and its lose on the persons wrist.  

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    2 hours ago, oldhippy said:

    All Seiko autos I have repaired and it must run into hundreds use the "magic lever" mechanism with an eccentric. I have never ever come across anyone who has brought their repaired watch back and complained that it doesn't run its time and stop when wearing on their wrist regardless if it's right or left, it's more likely not to function correctly if it's a bracelet fitting and its lose on the persons wrist.  

    Most, if not all of the budget or lower end Seiko autos use the Magic Lever system for the auto winder. It is only when you get into the mid-range movements like the 5106 or 5606 calibres found in the LordMatics and PressMatics and such like, as well as the top end Seiko calibres used in the King Seiko's and the Grand Seiko's, that Seiko uses a more conventional set up with reversers, and the issues of winding efficiency and rotor orientation go away.

    Also, I'm not sure that the question of left handed or right handed (and therefore crown up or crown down with the arm hanging down) is an issue as the orientation of the 3 pivot points will be 90 degrees either way. It is only if the watch is oriented crown left or right during the majority of the winding activity, or if the rotor is inadvertently incorrectly fitted that winding efficiency is impacted.

    Even then, the loss of efficiency may never be noticed. If a watch that has a >36 hour power reserve from full wind is only winding at 67% efficiency, it will still get a 24 hour power reserve from a days activity which would normally give a full wind. If that watch is worn every day, then it will never stop and the watchmakers error will never come to light. It would only be if the watch was left unworn for more than 24 hours that the watch would stop, and quite likely the average "man in the street" would just assume that it was because he wasn't wearing it. I would be quite suprised to find that any more than just a few % of people actually know what the power reserve of their watch should be, and actually go out of their way to test it. And those that do are almost all likely to turn up on this forum:thumbsu:

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    Thank you everybody for your interesting input, what a privilige to be a member of this group with its wealth of knowledge and experience.

    Cheers Vinvent

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    Just to finish off I can't remember any of the cal I worked on. I'd be surprised if the ones you have mentioned were about back in the 70's and 80's, my history of Seiko watches is none existent. :DA good discussion all round.  

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    10 minutes ago, clockboy said:

    The confusion might be coming from the Seiko Auto only winds in one direction (I think clockwise)

    No, it's a bi-directional system, refer to following picture.

    Seiko-Magic-Lever.png

    There's no confusion, we were all saying the same thing.

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