The resurgence of the Unitas 6497 and 6498 and emergence of the Seagull ST36 began with the popularity of the Panerai line of watches around the year 2000. Other manufacturers seized on the trend and began using the Auguste Reymond SA (ARSA) movement first released in 1950.
Manufacturers began using the 6497/98 for inexpensive pocket watches. Arnex became the most notable company to use the Unitas movement from 1971-1979. The movement laid dormant until the late 1990's as large wristwatches became gained popularity.
Today, the Unitas movement has emerged as one of the most popular for manufacturers. It's also popular with hobbyists who find large form pocket watches easier to work on.
Hobbyists continually encounter finding dials and cases to match. The following gallery should give you an idea of the range of sizes used in different cases. The first case below only uses a 37.25 mm dial. When I purchased that cases, I expected any of the 38.9 mm and 39 mm to fit. That was a surprise.
 |
| 39.9 & 39 mm |
|
 |
| California Dial 36.5 mm |
|
 |
| 34.5 mm |
|
|
 |
| 38.9 mm |
|
 |
| 38.9 mm |
|
 |
| 38.9 mm |
|
|
 |
| 34.95 mm |
|
 |
| 39mm |
|
 |
| 36 mm |
|
|
 |
| Case Size 47 mm uses 37.25 Dial |
|
 |
| California Dial 37.25 mm |
|
|
|
 |
| Case Size 44 mm uses 38.9 mm Dial |
|
 |
| 39 mm Dial |
|
Couple of Important Observations
First, notice the size of the cases and dials immediately above. I bought the dials and cases separately. The 47 mm case takes a smaller dial than I supposed. I'll bet neither of us would have guess that. Fortunately, I had dials to fit it including the California dial and a smaller Marina Militare dial. Both presented problems.
As you can tell the California dial doesn't accommodate a second hand. The Unitas 6497/98 movements have second hands at the six and nine o'clock positions. To work with the dials, the second hand pivots must not protrude over the front plate. So, ETA and Seagull have employed short fourth wheel pivots, flush with the front plate, to allow two hand dials to work with the movements instead of three.
(
NOTE: I have only found one supplier with short 4th wheels and you can find them by clicking
here. If you don't have the skills to change out the fourth wheel, don't try it. Take it to an experienced watch repair person.)
The Marina Militare and the dial to the right hand side of the top row, top table, require ETA or Unitas 6497 movements with a second hand in the 9 o'clock position. You'll soon discover those caliber extremely rare in the used market. It requires a crown at the 12 o'clock position.
Seagull's ST-36 movements with a second hand in the 9 o'clock position are plentiful. Finding those movements is difficult. The ST-36 is a $30 movement. The Chinese vendors on eBay and Amazon want $50 for them.
Matching cases and dials create challenges for watchmakers (not repair persons). One needs to know which cases work with what dials. Watch out for people who sell cases and don't give specs for the dial. Even if you ask, you might get the wrong answer. The seller may not know.
Wrap
I hope this information helps. It's written so you won't wind up with a bench full of dials and cases that don't match. It's easy to do if you look for bargains on eBay and similar sites.
Respectfully submitted
