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Authored by 2manywatches October 6 2002 at 2:21 PM
So, you got a hole in between your lugs! Your a happy Camper (scans and essay)

We all were discussing the vintage King Seiko`s the other day, and the question came up, "Whats that screw there in between the lugs for".

Well Ladies and ger........ fellow SeikoHolics, I`ve been working on a few of these, and I wanted to share with you what it is, and what can be done with the hole.

The screw you see actually comes out, and directly behind it is a regulating screw attached to the regulating curb pins.

In this case above, the screw had broken off, and was stuck in the case. Because I find this feature one of the real jewels of these King Seikos, I endevored to make it right. It intailed drilling out the broken screw, retaping the hole, and installing a oversize screw that would do the job.


I would like to note that all of the damage you see surrounding the hole was pre-repair, and that this case was in fairly ruff shape to begin with.

OK, heres how it works, but first: this is one of two systems I`ve seen. This is the later style, the earlier style has quite a bit more craft, in that the worm screw actually goes into the balance Dingling, where it turns a seperate ball in grove lever.

This later style, as shown here belowe, is at 7 o`clock on the movement, and can be identified by the large stamped peice of metal bridging the regulater to the adjusting screw.

The all works due to two design priciples. First, the ball in groove lever construction. Writers note: I`m calling it a ball in grove, as I`m not sure what the real term would be, if anyone knows, I`d be happy to know if theres a more appropriate term for the design.
And second, a fixed pivot, combined with an elongated hole, alowing the back and forth movement of the regulating bridge.


The ball and groove sockets are outlined above.


And the pivoting mechanism is shown above. The bridge pivots on the right hand screw, which has a shoulder so that it does`nt secure the bridge, it simply locates it. And the sloted hole on the left has the same thing, with the screw head having a shoulder, allowing the bridge to move in and out.

So in the scan belowe, Ive simply connected the motion of the parts with arrows, so the you can see how the system works, the cause and effect if it were.


So if your turning the screw in, or clockwise, it`ll slow down the regulation, and the opposite is true, if turning the screw out, or counter-clockwise, the movements regulation is advanced.

Unfortunatly, this system is not without it`s disadvantages. The biggest problem is that there is a fair amount of slack in the adjusting screw, and its not as responsive as it would seem. You can be turning the screw, turning, and not see any effect, and then all of a sudden, you`ve overshot your desired mark, and the whole process starts over again, as you try to go the other direction. To be honest, when I was regulating this watch, I madly wished for a screw back, and a simple regulator lever.

I did manage to regulate the watch, and in the last 24 hrs, its lost 1 second.

I`ve only seen these setups on the King Seikos with either a 5246, or a 5626 movement. Ive seen it mostly on the chronometer marked watches, but it has also appeared on some non-chronometer marked watches. Exactly what watches came with these, I`m not certain, but rest assured, if theres a screw at the bottom lugs, its got this set up in it.

Now, the real tragedy to this story is that I dont have one of these watches in my collection yet, and this artical is bound to raise awearness of this unique feature, and well, you know what`ll happen,:^)

So for those that have one of these, enjoy it. And for those that dont, well, half the fun is the hunt.

Love your Seiko`s gentelmen.
And best regards,
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