In sweeping up a few loose ends from the past few months of behind-the-scenes activity, this brief entry documents a point of arguably insignificant interest but which may provide some useful enlightenment to folk employing the services of the Seiko Instruments NH36 workhorse in self-build or modified watch projects.
My recent experiences with the day/date NH36 and date-only NH35 movements have highlighted a singular hazard of adapting the former for use with date-only dials. In one or two of my recent self-build projects, I have modified NH36’s by removing the day disk along with its accompanying components and using the movement with just its date disk in place.
To be honest, this practice is entirely unnecessary because the day disk will be hidden from view when a date-only dial is fitted but the problem is that I know it’s there and its redundancy is troubling! However, it turns out that the date disk fitted to the NH36 is not the same as the date disk fitted to the NH35. The numbers on the former are printed to conform with the ideal spacing between the day printed on the day disk and the date on the date disk, with both visible through a single pillar box rectangle.
In the correct application, everything is correctly centred but when using the date disk from a NH36 with a date-only dial, the date is not centred in the date aperture, but rather sits conspicuously to the left.
With the two disks side-by-side, we can see that the date on the NH35 disk (right-hand image below) is printed further to the right than is the case with the NH36 disk (left-hand image).
The only solution is to replace the NH36 date disk, or date dial as Seiko calls it (part number 0878 206) with the date dial from the NH35/37 (part number 0878 208).
The result of such a swap is a much more satisfactorily centred date.
