Dating waltham movements
In fact, the apparently huge variety of Swiss watches is explained by this phenomenon: once the basic layout in a round movement of the barrel, train wheels, escapement and balance was arrived at, there was little scope let alone need to change it.If you look at a bunch of movements, either all savonnette or all Lépine, then you can see that the pivots of the various components are all in basically the same places.
These are usually fifteen jewel movements with a straight line Swiss lever escapement, bi-metallic temperature compensation balances and Breguet overcoil balance springs.
This was pretty well the top specification for Swiss watch movements at the time and has never really been much improved on.
It can be difficult to identify movements from the shape of the plates or bridges.
Although some movements such as the IWC calibre 64 leap out to the experienced eye, other are less easy because of similarities between the products of different manufactures, and manufacturers altering bridge shapes for different customers.
Apart from small considerations of ease of manufacture and assembly, the major factor determining their shape is pure aesthetics, and differentiating a product from a rival manufacturer's.
The shape of the fingers (cocks) and bridges is more of an aesthetic consideration; so long as all the pivot holes and screw holes are in exactly the same places, then bridges of very different shapes can be freely interchanged.Some manufacturers produced many different movements with the same layout and train components but different fingers and bridges.Contents BTCo: Beguelin, Damas Longines 13.34 Gallet Electa wrist Gallet Electa pocket IWC calibres 63 and 64 Stauffer Eterna Tavannes cal 330 - 333 Tavannes cal 370 - 371 Fontainemelon 1 Fontainemelon 2 Fontainemelon 3 Fontainemelon 4 A.Schild calibre 137 General Watch, Helvetia Marvin series 362 Dimier Brothers It is a small selection of often unidentified movements that I have been able to positively identify.I don't intend to show movements with their makers names on them, because they are already identified.The idea of this page is to try to identify otherwise unknown movements found in the type of watches that I collect, which are principally Great War era men's wristwatches with 12 or 13 ligne movements.