Several forum members have asked for “more technical information” about watch movements. A reasonable request, and there is a lot of information available elsewhere. I especially recommend several books by Donald de Carle or by Henry Fried, as well as Walt Odets’ watchmaking articles on the Internet. I’m neither a watchmaker nor technically inclined, so my watchmaking knowledge has its limits.
Still, as an introduction for some of you, I thought I’d show an IWC Calibre 77 movement, and point out a few of its features that makes it special. This might help you understand how to judge a movement, but on technical subjects like this I stand to be corrected.
I personally think the Calibre 77 is among IWC’s most beautiful movements ever made. Only 10,500 were made, and only from 1917 to 1921. Most were sent to the US market, and most were cased there rather than in Schaffhausen. The movement came in various jewellings, but frequently 21 jewel models are found –higher than typical and unique for IWC at the time. Various finishing techniques were used. The movement was relatively thin for a pocket watch of its era –at 4.3 mm, and had a relatively standard width, with a diameter of 16 ¾ ligne which is about 38 mm –actually slightly smaller than some. Like watches of this era, it had a Brequet overcoil on its hairspring, and it beat at 19,800 vph –somewhat faster than the more traditional 18,000 vph pocket watches.
But these are statistics. What really distinguishes the cal. 77 movement, in my opinion, are its aesthetics. It’s a pretty movement –well-balanced in design. And also the finishing, while not unique in the world of Swiss watchmaking, is really high. In my opinion, it might be the best “finished” movement made by IWC.
I’ve pointed out a few characteristics in the above image:
This is one reason the design is called a “finger bridge” movement –the pieces that hold the wheels look like fingers. However, this one is technically a “cock” since it is attached at only one end. Separate cocks and bridges require more work to produce –there’s more fitting and more edges to finish. But also they make disassembly easier –in theory, less parts need to be removed during a repair.
This, in contrast, is a bridge. Note how it is connected at both ends. Also here you can see well the stripes –what sometimes is called “Geneva stripes” or Côtes de Genève. This is a finishing techniques that has several variations and different names –technically, these stripes aren’t “Geneva”, You can read more in several on the Internet, one of which is at montresuisses.blogspot.com/2006/05/movement-decorations-dcoration-horlogre.html
These finishing marks are applied by hand, and in theory some believe that they help avoid deposits of minute particles. They are part of fine watchmaking, although most of IWC’s products are more functional and plainer. This degree of finishing on Calibre 77’s is relatively unique for IWC, at least for the era.
Also, as long as you’re looking at this bridge, notice the screws. The slots are relatively clean. Often, a poorly maintained watch will have a brute-handed watchmaker insert almost any size screw-driver and twist, which will mangle or at least mar the slots. Inspection here can often tell how well the prior servicing was. A few here reflect some mars, especially the two beneath the winding stem.
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(continued in Part 2 due to length)[i]
