WS 19: Servicing a SEIKO Chronograph 6138

The automatic winding system has now been removed. The column wheel is nicely visible at 11 o'clock as well as the different levers and springs. The lower part of the picture gives us already an idea how BIG that balance wheel of the 6138 is.
This balance wheel measures 11.75 mm and is almost 4 mm bigger in diameter then a SEIKO Automatic Caliber 7005 balance measuring 9.2 mm. A larger balance wheel means generally better accuracy and it is a nice job of those SEIKO engineers to accommodate such a big balance in such a compact movement.

Just when I went to the bedroom searching for a note with all those measurements taken yesterday, I found this huge moth sleeping upside down at our bedroom window. Since Rob and I had discussed the size of some butterflies yesterday - some with wingspan up to 8 inches - this makes for good occasion to smuggle these two non-watch pictures in here. Only yesterday morning I spotted one of those huge butterflies, first I thought it was a small bird. The flapping of the wings did not look right. I was one of those very large and beautiful butterflies with black and white patterns on the wings and a beautiful yellow body. Since that one was too far away, you get to see two pictures of the also pretty big 5 inch moth having a nap while I am typing this report.

 

And to give you an even better size comparison, another picture I took seemingly touching the moth which of course sits on the outside of the window.

Now back to the servicing report, the automatic winding system has been removed, the hands and dial have been removed. Now let us have a look at the dial side.

Please click on the picture to read on >>>