Rolex Movement Question

[isampark]

I read from somewhere that movements for second subdial located at 6 o'clock position is very hard to master, since no readily available swiss eta movement are designed to have second subdial at 6 o'clock.

What I also heard was that even IWC is using a modified ETA movement with extra bridges to run Portuguese Chronographs with second subdial at the bottom , not using an in-house created movement.

I am not an expert so wanted to ask TRF. Is this in some sense true? If so, how is the movement in all the ROLEX Daytona watches? How do they manage to have perfect second subdial at the bottom?

[George Ab]

It is my understanding that sub seconds is not readily available on standard quality movements such as the ETA 2892-2. This does not pertain to chronograph movements. A number of manufactures who purchase a movement from ETA such as Ulysse Nardin will gear the movement to position it from its standard design center position to a subdial. The UN 1846 is an example that comes to mind.

Chronograph movement such as Rolex's 4130 were designed to use a sub dial for seconds so no modification of the base movement is necessary for the purpose. For IWC chronographs, IWC starts with an ETA 7750 an extensively modifies to enhance performance, but no mod is necessary for the sub seconds.

[isampark]

Wow, thank you so much for the in-depth answer George!

I am learning a lot today :)

[cameronweiss]

There is a readily available ETA caliber that has sub seconds. It is basically a 2892-A2, but I don't remember is exact caliber # Right now.

[1000km]

Sub seconds is actually far easier to make than centre-seconds from a watchmaking point of view. The sub seconds hand runs directly from the drive train rather than needing an additional gear, which is the case for centre seconds movements. The ancient ETA 6497 movement (which is derived from a Unitas pocket watch design) for example has sub seconds.

[Cubeistan]

Originally Posted by Zen6152

The Rose Of Love - Gene Vincent

(Mornin, Rob, Rock, Philip)

[Tools]

Originally Posted by 1000km

Sub seconds is actually far easier to make than centre-seconds from a watchmaking point of view. The sub seconds hand runs directly from the drive train rather than needing an additional gear, which is the case for centre seconds movements. The ancient ETA 6497 movement (which is derived from a Unitas pocket watch design) for example has sub seconds.

This is true..

Originally all seconds hands were at sub-6 since it can be direct geared there. It was an innovation to add extra gearing and the center-post to run sweep seconds.. Seems common now, but a hundred years ago was almost unheard of..