Oris Automatic Chronograph

The Oris

Oris offers great watches at reasonable prices here in th US. I like this one for the overall quality factor - the case is a nice weighty stainless, with indestructable Saphire crystal. The dial craftsmanship is excellent, with fine detail that's fascinating under a microscope.

Oris designs are somewhat retro without dwelling on the "trendy" aspects of retro. Oris has stood up to modern style stampedes and maintains their own fashion, concentrating on designs that depend on a high level of detail.

What's fascinating to me is that the entire movement is driven by a single oscillating wheel. This watch was THE watch that drew me into the hobby. Consider that the watch keeps nearly perfect time regardless of the number of gears on-line at any time (that is, regardless of having the chronograph turned on or off).

The Valjoux

There are three chronograph movements which account for almost all [automatic] Swiss production, listed here in my own impression of market share:

  • Zenith El Primero
    Also used in the Rolex Daytona
  • Valjoux 7765 / 7750 / 7751
    Manual / Automatic / Automatic with additional display wheels
  • Lemania 5100

Of these, the Valjoux shows up in perhaps the greatest number of different models. I like the Valjoux - this one is a 7750.

The 7750 shows up in many chronographs. I know of Fortis, IWC, Breitling, Sinn, Omega, others too. Check out more details at Christoph Ozdoba's page in Switzerland. If you want to check a watch to see if it has the Valjoux, just set the rotor in motion and press the watch face-down on a table. If you hear the bearing rumble or "scrape" as it spins, that's the one!

It is a great movement, noise aside. Many watch companies offer it with a chronometer certificate. I've found this one to be accurate to within +/- 2 seconds per day easily. The general feeling is very precise - the crown detents, winding, date advance all feel crisp and exact.

The 7765 supports a date wheel, chrono seconds on the center shaft, minute totalizer at 12:00, hour totalizer at 6:00, and seconds subdial at 9:00. The 7750 adds automatic winding. The 7751 adds month and day wheels, usually at the 11:00 and 1:00 positions, plus 24 hour indicator or moon phase wheel. The date, day, month windows can be placed anywhere + modified.

Technical

Winding: Automatic, winds in one direction.
Wear-to-Rundown Ratio: Slightly higer than 1:1.
Rotor Bearing: Ball + track (noisy by design).
Crystal: Front: saphire, Back: mineral glass.
Case: Stainless, polished. Stainless screw-down back.
Crown: Not screwed down.
Hack Set: The movement halts for setting to a time sync signal.
Buttons: Not screwed down. 
Lug Spacing: 20 mm

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