wrist action vs accuracy

[fwellers]

Hi,
I've often heard how much accuracy is affected by the different people wearing their watches differently. For me, this isn't making sense.

My limited understanding of the way mechanical watches work leads me to think that the only thing wrist action does is wind the mainspring.
The affects of the movement of your hand are blocked to the movement, except for the mainspring. The escapement translates tension on the mainspring into very precise and regulated clicks to the gears.

So this means that I can shake my hand like wild, or just walk regularly, and it means absolutely nothing to the movement except to wind it.

Now I have heard that a fully wound watch, has more tension on the mainspring, making it just a tad more presice, than an almost unwound watch.

But that being said, consider the myriad of people, who go through their day wearing the watch, keeping the mainspring fairly wound. It shouldn't matter whether one of them bowls all day, vs another who is a desk jockey, vs another who swims all day. As long as the mainspring remains on the upper end of wound, there should be zero affect on the watches accuracy or precision.

Ok, so correct my mistakes here please.

Thank you.

Floyd

[Tools]

Floyd,

It's the balance and it's delicate hairspring (as well as inherant friction of the mechanical parts) that are the basis of the accuracy and precision of your watch.

All those movements, gravity, friction, and centrifugal force affect the ralative speed that the balance wheel oscillates back and forth.. In a perfect world, a modern Rolex would swing the balance wheel at exactly 28,800 times per hour.. but these other effects make it imperfect..

[fwellers]

Thanks. But that's not the point I was addressing.
Assuming the imperfect watch, and assuming that different people wearing the same watch cause the balance wheel to oscillate at different rates, my presumption is that the watch will keep the same time on different people's wrists, with the only caveat being that both wear it enough to keep the mainspring near the top end of wound.

[Jedi]

I'd like to add the following to what Larry has said already:

- gravity is not constant all over the planet and depending on where you live, the effects vary accordingly. Rolex for example, adjust their movements in Geneva and then are shipped all over the world. Variations in altitude will also correspond to a variation in gravity. Therefore where you are in the world and how high up or low down you are changes the rate of the movement relative to where it was adjusted in the first instance.

- depending on the orientation of your watch on your wrist (eg. hand down by your side, flat on the desk when typing, folded across your arms) the location of the balance wheel and spring changes right? Therefore it oscillates differently in each position. The adjustment is meant to even out as best as possible each variation, hence on Rolex you'll find that their movements are adjusted in 5 positions.

- take all of the above and add variables like arm swing speed, some jarring movements (say knocking into things, taking a swing at a golf ball or your not-so-best-friend), then we have a set of conditions where differences in force applied help in changing the rate of a movement.

- shock absorbers like those from Incabloc and in Rolex's case, KIF, go some way to isolating the balance, but like all things mechanical, nothing is perfect.

[Jedi]

Originally Posted by fwellers

Thanks. But that's not the point I was addressing.
Assuming the imperfect watch, and assuming that different people wearing the same watch cause the balance wheel to oscillate at different rates, my presumption is that the watch will keep the same time on different people's wrists, with the only caveat being that both wear it enough to keep the mainspring near the top end of wound.

The people in question would have behave in an identical fashion if they were to keep the balance wheel oscillating at identical rates, not to mention carrying out the same activity.

[padi56]

As others have pointed out now in 24 hours, the escapement of a mechanical watch pushes the gears 432,000 times. Since a day has 86,400 seconds, even a watch that runs five minutes fast or slow each day has an accuracy of over 99.6 percent! A finer mechanical watch that gains or loses about nine seconds a day or about a minute a week has a breathtaking precision of over 99.99 per cent. This is very high precision, given the fact that the movement is constantly affected by the earth's gravity, metal expansion and contraction, temperature variations, subtle changes in lubrication and friction, shocks, and so on.The fact is that no mechanical watch made will keep perfect time, very close yes but perfect no.If you want spot on perfect then its one of the radio controlled or quartz hybrids watches.

[fwellers]

Originally Posted by Jedi

I'd like to add the following to what Larry has said already:

- gravity is not constant all over the planet and depending on where you live, the effects vary accordingly. Rolex for example, adjust their movements in Geneva and then are shipped all over the world. Variations in altitude will also correspond to a variation in gravity. Therefore where you are in the world and how high up or low down you are changes the rate of the movement relative to where it was adjusted in the first instance.

- depending on the orientation of your watch on your wrist (eg. hand down by your side, flat on the desk when typing, folded across your arms) the location of the balance wheel and spring changes right? Therefore it oscillates differently in each position. The adjustment is meant to even out as best as possible each variation, hence on Rolex you'll find that their movements are adjusted in 5 positions.

- take all of the above and add variables like arm swing speed, some jarring movements (say knocking into things, taking a swing at a golf ball or your not-so-best-friend), then we have a set of conditions where differences in force applied help in changing the rate of a movement.

- shock absorbers like those from Incabloc and in Rolex's case, KIF, go some way to isolating the balance, but like all things mechanical, nothing is perfect.

Thanks Jedi. I had forgotten about the different positions giving different rates. It does go to show that I still don't understand how the watch really works. Plus that is a real interesting point you brought up about the different gravity. Makes sense !!


PADI -- I just asked for purely speculative/understanding reasons. I have no issues with my watch being +11 to +15 in a week.

[Jedi]

You're most welcome Padawan Floyd... May the Force and Peace be with You...