Thanks very much for your comments. A few quick replies --
--to my knowledge the cal. 80110 does not have a free-sprung balance. --on the cal. 51010 Cinq is correct --the photo does show a free-sprung balance. In fact, I had written about this before in some detail; please see this prior post. --for everypone's info, my initial post yesterday is not an "official" post. I hadn't asked anyone at IWC to check it for accuracy and just dashed it off, thinking it'd be itneresting for the forum.
Michael, On this Forum we are often talking about "great movements" accurate timepieces, oscillations expressed in Herz, balance wheels and balance springs. As collectors, being no watch makers, as you state for yourself, technical explanations may be helpfull but often these are not understood. Watch makers on the contrary use so many technical terms that, although they try to transfer their knowledge to us collectors, they fail only because they do not use simple words and terms. From your analysis it is quite clear to understand the function of a balance spring and the balance wheel in classic watches and in those equipped with a free-sprung balance. It proves that writing about a technical subject is an art, mastered not necessarily by a technician, but by a person who can transfer thoughts and facts, using understandable language. And so you do! In Europe we say : "chapeau" (hats off). Kind regards, Adrian. (alwaysiwc).
And thanks Michael for the link to your older write-up. These two articles complement each other perfectly. I have a much better understanding of the mechanism now.
Hi Michael, After having studied your exellent article,allow me to ask you 2 questions. You state, that the regulation of the free-sprung balance is done by screwing in or out the few screws positioned on the balance wheel, changing the centrifugal forces in the wheel and by that the rating. But as you know the classic balance wheel is not only equipped with a regulator but also with a great number of screws, more than in the free-sprung balance wheel. These screws are often made from gold, to eliminate oxydation and magnetism. It seems to me, that when one observes such classic balance wheel, all golden screws have been screwed into the balance rim tightly. The head of the screws rest on the outer circumference of the balance wheel. But as in the free sprung balance, I can imagine that it is possible to "unscrew" opposite screws ( to prevent wobbling) for half a winding or more. In fact the same procedure as is used in the free-sprung balance. Is there an explanation why this is not used or is it effectively used? The second question if I may. It is well known that in watches with the classic balance wheel and balance spring, accuracy is affected by the position of the watch. This has to do with gravity. Gravity is pulling in a slightly different way on the balance wheel and the hairspring, depending from the position of the watch. This is why chronometer testing programs in the past were done in different postions : dial up, dial down, dial vertically and this for many consecutive days. Abraham Breguet invented the tourbillon to eliminate gravity forces in watches subject to different positions. Essentially, the free-sprung balance is in construction not very different from the classic balance wheel, only the classic index regulator fails. For me it is than difficult to understand why a watch with a free-sprung balance should behave differently, compared to a classic balance in terms of gravity and as a consquence in accuracy. Kind regards, Adrian, (alwaysiwc).
I've reached the limits of my technical expertise, and will defer to watchmakers for your questions. But let me try to reply to the second matter you've raised, aty least as an educated conjecture.
To me, a free-sprung balance is not simply dispensing with a classic regulator (index). As a result of that change, it also dispenses with a variable length hairspring. As a result, it is easier to use a Breguet overcoil with better results (since the function of the overcoil should be constant, without any slack or tightening of the hairspring).
While the Breguet overcoil does not directly affect positional accuracy, it does affect isochronism and does create a more constant affect on accuracy. That in turn minimizes the differences, including between various positions. Stated differently, a more perfectly formed hairspring should I think enhance all accuracy.
Thank you for your excellent post. I concur with Adrian that you have written about a subject of complex technical matter in easy-to-follow layman's words.
Allow me to chime in with a couple of points.
First, in answer to an inquiry, the Calibre 80110 does not have a free-sprung balance and relies on a micro-adjusted regulator (more about that below).
Second, the traditional type regulators that most watch manufacturers use come two ways:
with two parallel pins through which the hairspring passes through
a closed boot-shaped holder which, from the underside, can be swiveled to allow removal of the hairspring when necessary
These above type regulators can present problems if, for example in the first type, the twin pins are drawn together too close, moving the regulator can pull the hairspring with it and cause damage. If on the other hand, the pins are set too far apart they could have an inconsistent effect on the accuracy, beat error, and/or amplitude. In addition, an impact to the balance can cause the hairspring coil from coming out, under, and away from the regulator rendering the movement inaccurate.
The boot shaped regulator, at least, prevents the hairspring from coming out of place in case of a sudden impact. However, if the pin is too tight on the boot it, too, can cause similar problems described above.
A third type regulator not mentioned is one that has a micro-adjusting screw and which does not allow for sudden drastic changes to the hairspring. It takes much patience for a watchmaker to make the correct necessary turns to get an accurate rate. The calibre 80110 employs such a micro-adjustable regulator and so do many other calibres used by IWC.
In conclusion, the free-sprung balance avoids accidental occurrences mentioned but, as you Michael stated, takes time and skill to work with to set up properly.
Thank you for allowing me to add to your great post which I most enjoyed.
I've bookmarked this article to read it later and forgot about it. Today was finally the time I've found it again :o) Being it no news but technical explanations that do not fade out I hope it's not late to thank you for it even a few months later. Thanks, Michael. Informative and appreciated.
