Seiko 1520B

Description

A rare representative of Seiko is the baguette caliber Seiko 1520B, which has got a width of less than one centimeter. While its production time, 1972-1982, is known, the differences to base caliber Seiko 1520 are unknown.

As not to be expected otherwise from Seiko, it is very well made, and of course we have ruby bearings everywhere neccessiary.

The gear train bridge has got a few oddities:
It not only covers the whole gear train, but also the mainspring barrel. Furthermore, two of the bearing rubies are framed in pressed chatons and so adjusted in height, and last but not least, the escape wheel bearing has got a cap jewel, which is shock-protected with an Omega-shaped spring.

The already mentioned gear train is constructed in the classical way and consists of mainspring barrel, center minute wheel, third wheel, seconds wheel and escape wheel.

Due to the limited space of this movement, seconds- and escape wheel overlap, which means, that the dial side bearing of the seconds wheel is located above the escape wheel.

Regarding the lever: Probably also due to the lack of space, the lever is constructed as a lateral lever, meaning, that it is not symmetrical, but has got its fork attached to one of the lever pallets.

As balance, a two-leg Glucydur anular balance is used, beared in two inhouse Diashock proection bearings. It beats with 19800 A/h and can be adjusted at the hairspring key only.

On the dial side, you see the compareatively large Diashock bearing and the yoke winding system.
To reduce a little height, upper and lower edge of the movement plate are slightly slanted.

In the lab

Timegrapher result

We have large rate differences between vertical and horizontal positions, which should be reduced, if a professional revision was made.

Technical data

Usage gallery