The Unitas 6497-1 (or Unitas 6498-1) is a great choice for a homage project.
The hand-wound mechanical movement is just the right size, sturdy as a tank, and a true pleasure to work with and troubleshoot.
ETA Mecaline 6497-1 specifications:
- Hours, minutes, small second @ 9 o’clock (6 o’clock for 6498-1)
- 16.5”’ (36.60 mm) in diameter
- 4.50 mm height
- 18,000 vibrations per hour (2.5 Hz)
- 17 Jewels
That being said, you might need to modify the 4th wheel if you are looking to fit a homage two-hand dial that does not accommodate a small seconds hand.
The standard 4th wheel on a 6497-1 (or 6498-1) has a long pivot to accommodate the small seconds hand.
4th wheel with long pivot for seconds hand part # (based on The Ebauches System of numbering):
- ETA 6497-1: 224 / 620
- ETA 6498-1: 224 / 621
The 4th wheel will need to be modified by shortening the pivot just enough so that is is flush with the main plate. If you are not comfortable modifying the 4th wheel yourself, you could get yourself a 4th wheel with short pivot without post for seconds hand.
4th wheel with short pivot without post for seconds hand part # (based on The Ebauches System of numbering) for ETA 6497-1: 220/1019
The below picture shows the two 4th wheels (before and after modification) side-by-side:
Once the 4th wheel is modified and available for use, the only thing left is to swap it inside the movement:
The Train wheel bridge is jeweled and connected to the main plate by two screws. The three jewels from left to right hold:
- Third Wheel
- Fourth Wheel
- Escape Wheel
The 4th wheel sits in between (on top of) the third wheel and escape wheel.
Replace the standard (long pivot) 4th wheel with the modified (short pivot) 4th wheel.
Make sure all three wheels are properly positioned upright before carefully re-assembling train wheel bridge on top, making sure all three pivots are jeweled.
Once everything is aligned, gently push down on train wheel bridge ensuring no gap between bridge and main plate, before tightening two screws.