There are 4 tiny screws in the rim of a balance wheel. Why ?

[chowkanhung]

http://www.rolex.com/en/rolex-watche...rom-hairspring

Chow

[padi56]

Originally Posted by chowkanhung

http://www.rolex.com/en/rolex-watche...rom-hairspring

Chow

Thats how they regulate and make fine ajustments to the beat rate timing achieved by turning the Microstella adjustment screws and nuts.The two smaller Microstella screws make adjustments of one second for each turn, and the larger Microstella, two seconds for one turn.

[RolexYM]

Originally Posted by padi56

Thats how they regulate and make fine ajustments to the beat rate timing achieved by turning the Microstella adjustment screws and nuts.The two smaller Microstella screws make adjustments of one second for each turn, and the larger Microstella, two seconds for one turn.

In essence, do you really need FOUR screws? Wouldn't 2 be enough...since you really only need to correct it via 1-2 seconds increments at most (most of the time), not like a whole minute. I think that Omega 2500 caliber only had 2 screws...the newer 8500 caliber has 4. So, i guess the magic number of screws is 4, but i wonder why exactly??? Doesn't Patek or someone like that have a million of them on the balance wheel??

[padi56]

Originally Posted by RolexYM

In essence, do you really need FOUR screws? Wouldn't 2 be enough...since you really only need to correct it via 1-2 seconds increments at most (most of the time), not like a whole minute. I think that Omega 2500 caliber only had 2 screws...the newer 8500 caliber has 4. So, i guess the magic number of screws is 4, but i wonder why exactly??? Doesn't Patek or someone like that have a million of them on the balance wheel??

With four perfectly opposite to each other gives almost perfect balance and much finer adjustment. The Microstella screws are designed in such a way if the screw is screwed inward, the balance speeds-up, The Microstella screw screwed outward will slow the balance wheel down.

The very fine adjustment on the small screws = 1 second/day for each turn and an adjustment on a larger screws = 2 seconds/day

Any adjustment on one Microstella screw requires the same adjustment on the opposing Microstella screw. If you did not balance the two it would be adjusted out of poise similar to a spoke in a bike wheel it would not run true.

[chowkanhung]

In high school, we have learnt that the period of oscillation for Simple Harmonic Motion is directly proportion to the square root of moment of inertia.

If we want to regulate the watch running at a faster rate, we can turn the tiny screws in such a way that they move a bit towards the centre of the balance wheel. In this way, its moment of inertia decreases and thus the period also decreases. The watch runs more faster.

On the other hand, if we want to regulate the watch running at a slower rate, we can turn the tiny screws in such a way that they move a bit away from the centre of the balance wheel. In this way, its moment of inertia increases and thus the period also increases. The watch runs more slower.

Am I correct ? Please educate me if I am wrong.

Chow.

[Darlinboy]

You are correct sir!

[padi56]

Originally Posted by chowkanhung

In high school, we have learnt that the period of oscillation for Simple Harmonic Motion is directly proportion to the square root of moment of inertia.

If we want to regulate the watch running at a faster rate, we can turn the tiny screws in such a way that they move a bit towards the centre of the balance wheel. In this way, its moment of inertia decreases and thus the period also decreases. The watch runs more faster.

On the other hand, if we want to regulate the watch running at a slower rate, we can turn the tiny screws in such a way that they move a bit away from the centre of the balance wheel. In this way, its moment of inertia increases and thus the period also increases. The watch runs more slower.

Am I correct ? Please educate me if I am wrong.

Chow.

Yes thats basically correct the Microstella system is considered much better to the regulators used on other watches. As it does not introduce beat errors when the tick is slightly longer that the tock. But we are only talking with this type of adjustment just over a minute either way.