Thoughts on small and shapely ladies
errr... I mean small and shapely Seiko movements made for ladies!
Regular readers may have seen a few Seikos walks or my technical articles here. I have had about 100 Seikos in my hands and on my bench in the last 90 days; 20 of those were ladies watches. Although I've seen many mechanical movements of all types, and probably 50 ladies watches, I've never had the occasion to compare multiple tiny movements before. I've been amazed at their stubbornness in continuing to run no matter how unhappy they looked. Is it good luck? Engineering? Careful waterproofing of the case? Delicate handling by a proud owner? Let's look at some examples to see what Seiko has been doing.
Seiko 1520 Made 1972-1982 Manual wind, no day/date, no seconds, 17 Jewels; 9.6 x 19.8mm x 3.5mm, 19,800 bph
A different example of the 1520 movement
Seiko 1520B - 17 Jewels (notice the fibers around the stem and the balance)
OVAL SHAPED MOVEMENTS
Seiko 11A - Built 1955-60: Manual wind, no day/date, no seconds, 17 Jewels; 15 x 13mm x 3.5mm, 21,600 bph
Seiko 10C -
Seiko 10C - Manual wind, no day/date, no seconds, 21 Jewels, 15 x 13mm x 3.5mm, 21,600 bph with better finishing, same architecture of plates and pivots
Seiko 21D - 17 Jewels, better finishing, same architecture of plates and pivots
Seiko 2206A - Automatic, quick-adjust day & date, seconds, 17 Jewels; 17.2 x 5.9mm, 28,800 bph, 32 hours
Seiko 2706A - Automatic, day, date, seconds, 21 Jewels; 17.2 x 5.7mm, 28,800 bph, 32 hours
Notice that this movement has an entirely different architecture than the one above.
Seiko 1944B - 23 Jewels, 12.9 x 19.2mm x 4.4mm thick; several jewels have shock protection and it offers hacking seconds, Tokyo stripes, and Swiss Chronometer certification
Since a high beat movement runs at a higher frequency than a regular movement it requires more power. The mainspring uses Seiko’s Diaflex steel and is 260mm long and .1mm thick -- giving 40 hours running time.
The balance is only 6.80mm in diameter. This watch is about 55 years old yet it still runs very well!
PS - here the small curvy lady looking at a Seiko