The midnight modding (day changes at midnight)

[Francisco]

This is what you normally have. Day and date changes at midnight, but at different hours:

Follows a IWC topgun, with ETA disks and with the modding for synchronizing day and date at mid

Do you like it?

Regards,

Francisco

Edited March 19, 2010 by Francisco

[RWG Technical]

The day and date on the 7750 are not designed to switch at the same time, they are supposed to be staggered with the date changing first, followed by the day.

The two gears are offset from each other, it's not a mistake in assembly and this offset should never be changed, genuine ETA's have index marks showing the offset of the gears. Just have a look at the assembly procedures on the ETA site to see the offset and alignment marks. 7750 ETA swisslab site assembly procedures click here click on "Assembly", then "Next" until almost the very end and you get to parts "Day star driving wheel" 33.021 and "Date indicator driving wheel" 33.020, you can clearly see the alignment marks and offset.

The reason for the offset is simple, it requires a lot of energy to switch the day or date, this is why they only switch one at a time. Trying to switch the day and date together will overload the movement and affect timekeeping, and probably cause the movement to stop running.

Everything for a reason, changing one item on a movement will affect a dozen more things, and should never be done without a full understanding of the original design of the movement.

Sorry to bring bad news, but I would not recommend this modification be done, it is not a good idea.

[gran]

Interesting read indeed. Nice to learn the reason for this phenomenon. Thank you The Zigmeister and Francisco

[Francisco]

Thanks The Zigmeister for your comments.

I knew that issues and I was checking personally the movement... I did not find any problem at all.

regards,

Francisco

[Drulee]

Everything for a reason, changing one item on a movement will affect a dozen more things, and should never be done without a full understanding of the original design of the movement.

Sorry to bring bad news, but I would not recommend this modification be done, it is not a good idea.

Everything is not always done for a reason, sometimes things are overlooked, not considered a priority, or maybe just not thought of as a flaw by some. Designs, including great ones, are often improved upon by people who like to tinker and see why things have been done one way, or why they can't be done another - you, of all people should know that

I think just so long as you are fully prepared to end up with a broken movement, one should go ahead and 'mod' to ones heart's delight, and share your findings.

Of course updates on the movement's operation in the long run would contribute to demonstrating no harm has been done. And these 'experiments' should only be done by those who understand the mechanics of the movement, which I would say Francisco does.

I applaud Francisco for once again entering the "Grey area" of our rep movement design and offering insight into why things are the way they are, and how one can 'tweak' it to make the way you would like it to be

[maxman]

Thanks to Francisso and the zigmeister for sharing there expertise and knowledge.

[Francisco]

well, this is an old post... but for that reason is good to know that that watch is still runing correctly. And a friend of mine tried too and had no problems.

But it is true that the movement has to be push two wheels at the same time... so it needs more power to do it..

regards,

Francisco

[wtchgk]

The day and date on the 7750 are not designed to switch at the same time, they are supposed to be staggered with the date changing first, followed by the day.

The two gears are offset from each other, it's not a mistake in assembly and this offset should never be changed, genuine ETA's have index marks showing the offset of the gears. Just have a look at the assembly procedures on the ETA site to see the offset and alignment marks. 7750 ETA swisslab site assembly procedures click here click on "Assembly", then "Next" until almost the very end and you get to parts "Day star driving wheel" 33.021 and "Date indicator driving wheel" 33.020, you can clearly see the alignment marks and offset.

The reason for the offset is simple, it requires a lot of energy to switch the day or date, this is why they only switch one at a time. Trying to switch the day and date together will overload the movement and affect timekeeping, and probably cause the movement to stop running.

Everything for a reason, changing one item on a movement will affect a dozen more things, and should never be done without a full understanding of the original design of the movement.

Sorry to bring bad news, but I would not recommend this modification be done, it is not a good idea.

Is your statement about the date changing before the day correct? And if so, what am I missing? I recently assembled a movement following the ETA assembly procedures and the day changes before the date. I was surprised because all my Asian movements changed the date first and then the day when I received them. I took a closer look at the geometry of the movement and the ETA assembly procedures and it seems that according to the procedures the day indicator driving wheel moves about 5 degrees ahead of the date indicator driving wheel (towards hitting the teeth of the day and date wheel respectively). In addition, it appears that the spacing of the teeth of the day indicator is slightly more dense than the spacing of the teeth on the date wheel. So it would seem that according to these procedures the day should change before the date.

[planatlas]

Como siempre un 10, Francisco.