Thank you for this, I'm planning to buy gen parts for my 116710ln but still wondering if it's worth the time and money when its running -25s/d ootb. I've been wearing a gen sub and seamaster for good part of my life and spoiled by their performance, so it's hard for me personally to live with an expensive, physically accurate rep with seiko 5 performance.
Servicing the movement can help with amplitude — both increasing it and getting the amplitude to deviate less in different orientations (in general amplitude is highest in dial up/down, and 20-30 degrees lower in 9/6/12 down).
Servicing the movement can help with amplitude — both increasing it and getting the amplitude to deviate less in different orientations (in general amplitude is highest in dial up/down, and 20-30 degrees lower in 9/6/12 down).
But a service won’t change the poise of the balance wheel (how symmetric the mass is distributed). Nor will a service change how linear of a restoring force the hairspring provides. For a watch to keep good time across different positions, it needs a well poised balance and a hairspring that provides a restoring torque that’s linear to rotational displacement.
As @KJ2020 mentioned, gen balance wheels are very carefully poised. Tiny amounts of material are iteratively removed from the heavy spots on the wheel to make it as symmetric as possible. By comparison, rep balances go through 1 or 2 poising steps during manufacture (see pic below where there has been only one correction).
The second thing is the hairspring… on gen Rolex watvhes the hairspring uses a Breguet overcoil to make the response more linear. On reps that’s not possible because reps have a regulated balance not a free sprung balance. Furthermore, the materials used in rep hairsprings are not the same as those used by Gen manufacturers. Gen hairsprings are made of exotic alloys like niobium-zirconium or even out of pure silicon. These exotic materials are resistant to magnetic fields and are very stable across different temperatures. Rep hairsprings are probably made of a non-magnetic iron-nickel alloy. There’s nothing wrong with iron-nickel, but it’s not as resistant to magnetism and it will change depending on temperature.
Gotcha, so I guess it'll be highly unlikely for a serviced rep to run within coscServicing the movement can help with amplitude — both increasing it and getting the amplitude to deviate less in different orientations (in general amplitude is highest in dial up/down, and 20-30 degrees lower in 9/6/12 down).
But a service won’t change the poise of the balance wheel (how symmetric the mass is distributed). Nor will a service change how linear of a restoring force the hairspring provides. For a watch to keep good time across different positions, it needs a well poised balance and a hairspring that provides a restoring torque that’s linear to rotational displacement.
As @KJ2020 mentioned, gen balance wheels are very carefully poised. Tiny amounts of material are iteratively removed from the heavy spots on the wheel to make it as symmetric as possible. By comparison, rep balances go through 1 or 2 poising steps during manufacture (see pic below where there has been only one correction).
The second thing is the hairspring… on gen Rolex watvhes the hairspring uses a Breguet overcoil to make the response more linear. On reps that’s not possible because reps have a regulated balance not a free sprung balance. Furthermore, the materials used in rep hairsprings are not the same as those used by Gen manufacturers. Gen hairsprings are made of exotic alloys like niobium-zirconium or even out of pure silicon. These exotic materials are resistant to magnetic fields and are very stable across different temperatures. Rep hairsprings are probably made of a non-magnetic iron-nickel alloy. There’s nothing wrong with iron-nickel, but it’s not as resistant to magnetism and it will change depending on temperature.
Expecting a $100 Chinese fake movement to run COSC for any length of time may likely end in heartbreak. They’re simply not manufactured, inspected, and QC checked to Swiss standards. You may, however, get a decent life and performance from one if you keep your expectations in check.Gotcha, so I guess it'll be highly unlikely for a serviced rep to run within cosc
