Press Release: GIRARD-PERREGAUX MICROVAR FREE SPRUNG BALANCE

[KokChoon]

Dear Horomundians,

Last week, I promised you an announcement of the technical advancement by the Manufacture and now I can start sharing some of the information that has been made available to me.

However, due to my limited access to the internet (traveling) as well as my extremely busy schedule this week, I will be sharing with you now the Press Release of this technical advancement - the new Microvar Free Sprung Balance by Girard-Perregaux.





Press Release:

GIRARD-PERREGAUX MICROVAR FREE SPRUNG BALANCE





Under its research in the field of chronometry and after years of development, Girard-Perregaux introduces the new Microvar free-sprung balance at the SIHH 2008.


The specificity of the Microvar is its combination of a a six-screw system and of two regulating weights positioned on the rim of the balance, which are used to respectively set the balance of the rim and the rate of the watch. In addition, a new cock is presented with a fine-adjuster for the adjusting mark.

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Dear Horomundians,

I will be back shortly for more detailed explanation of this excellent improvement by the Manufacture as soon as I have more time to post.

Meanwhile, please feel free to ask any question you might have so that I can also help to compile the answer in my following posts.

Cheers
KokChoon

[Jack Forster]

. . .right in line with Girard Perregaux's well known history of chronometric research- do you happen to know the balance diameter? A milestone for GP, thank you for sharing this with us!

Jack

[Monochrome]

Originally Posted by Jack Forster

.....A milestone for GP...

Uh me is simple watchlover... me don't understand...

Sorry to bother you guys, but could you please explain what the good thing is about this? I mean i've seen much more balancewheels with screws in them, so i don't see much difference. I can only deduct that if you (Jack) are impressed with this innovation, i must really be something...

Do i understand it right that this makes it possible to regulate a movement better and more precise?

[damien]

have this new free sprung balance? like jack says, i hope its a decent size diameter, unlike the calibre 3300s.

[HerrK]

I have to second monochrome. I am not a watchmaker either,
but as I understand the concept and term of "free-sprung"
balance the hairspring of the balance should be free, meaning
that the spring itself has no regulator. On the picture we can
see a swan-neck type of regulator, which seems to be attached
to the end of the hairspring!
On the other hand the two weights on the balance wheel would
make it a variable inertia/adjustable mass balance wheel. As far
as I know about the efforts in chonometry this has been the de-
vice of choice for the regulation of a watch.
Looking forward to learn more!

Cheers
Christian

[Jack Forster]

. . . the swan's neck regulator is, as you've noticed, attached to the hairspring stud (the end of the hairspring) not to a regulator- if you look at a non-freesprung balance:


(JR 1000 caliber from JeanRichard)

. . . you will see the hairspring stud and next to it the regulator. The moveable stud allows for putting the balance in beat- basically making sure the tick and the tock are equal.

Cheers,

Jack

[Jack Forster]

. . . in watchmaking, the rate of a watch can be regulated in one of two ways. The first is to use a regulator, which basically consists of two brass pins held in place on either side of the outer terminal curve of the hairspring. By moving the index pins along the length of the hairspring you can effectively shorten or lengthen the hairspring, which will cause the watch to gain or lose on its rate. The regulator index system however all other things being equal tends to magnify positional errors and also, depending on the watch, may tend to shift out of place during use, especially if the watch gets a hard jolt, which will of course change the regulation.

A freesprung balance on the other hand is regulated by the two meantime screws at opposite sides of the balance. Unscrewing them slightly increases the effective diameter of the balance and will cause a loss in rate, and vice versa. Such a watch is called "freesprung" because the spring is "free" that is there is nothing interfering with the natural oscillation of the balance spring (except gravity and the inner and outer attachment points.)

Freesprung balances are generally consider to be able to hold a rate better, and to offer less susceptibility to positional error. As a caveat of course, one should bear in mind that all generalizations about performance are just that- generalizations, and an enormous number of high grade watches both in the past and today used a regulator (and in pocket watches often in combination with meantime screws).

Cheers,

Jack

[Monochrome]

Thanx for explaining Jack Now i think i really understand... but let's check to be sure. The same certainty can be gotten from a swn neck regulator because this one also fixates the regulator so it can't move due to positionaly errors... right?
So if i understand it correct it's another solution for the same problem, although a swan neck also enables you to regulate a watch easier that with just a regulator....

Hope i'm right

[HerrK]

... a pleasure to get enlighted - even if it is about
the basics of watchmaking.

Cheers
Christian

[Jack Forster]

. . . the swan's neck spring is used to hold something in place.

Usually it's used to hold in place and allow fine adjustment of the regulator. The word "regulator" refers specifically to the movable device with two tiny pins, in between which the hairspring's outermost coil passes:


This picture, by Steve G (from his watch launchpad) shows the balance assembly of a Seiko chronometer. The regulator can be seen at the 3:00 position from the balance jewel. The other thing sticking out of balance cock at !:00 is the stud carrier which holds the stud, or end of the hairspring.

Usually, a swan's neck spring is used to control the position of the regulator (in Steve's picture you can see the ends of the two brass curb pins on the regulator, by the way.) but it can also be used to control the position of the stud (the bit on the end of the outer curve of the hairspring) if the watch has a movable stud carrier.

Changing the position of the stud carrier is done to put the watch "in beat" -basically to make sure the "tick" is of the same duration as the "tock."

Changing the position of the regulator (and its attached curb pins) is done to regulate the watch- that is adjust its rate- faster or slower.

Now both the regulator and the stud carrier (if there is one, not all watches have a movable stud carrier, in many watches especially vintage pocket watches the stud may simply be attached directly to the cock) can be held in place simply by friction fitting (which is usually the case.) If there is a fine adjustment device like a swan's neck usually it's there for fine adjustment of the regulator.

However, this new GP balance is freesprung- there is no regulator. In this case the swan's neck fine adjustment is for the position of the stud carrier NOT the regulator.

Hope this helps,

Jack

[Jack Forster]

. . . glad to be of assistance!

Jack

[KokChoon]

Dear friends,

Thanks for your comments and thanks to Jack also for his in-depth explanation on how the Free Sprung Balance works and helps in chronometry.

Girard-Perregaux has introduced this new free sprung balance, together with a fine-adjuster in its frame of research in the field of chronometry, and this, the result of several years of development according to my information.

Like Jack explained, I do believe that free sprung escapements are the most prestigious form of balances. In fact, some also confirmed them as one of the distinguishing elements of higher grade Horlogerie.

From the information shared with me by the Manufacture, YES, the free sprung escapements will progressively be introduced on the whole range of Girard-Perregaux movements. Well, an exception I guess, the famous Girard-Perregaux Tourbillons already have free sprung balance wheels (which itself is a classical construction).

I also understand that this Microvar Balance has actually been introduced to a new Haute Horlogerie piece that Girard-Perregaux will announce in SIHH 2008. I will try to find out more information about this new time piece and report here once I have the confirmed information.

In the following sub-threads to this one, I will share with you guys some details that I have received on this new technical advancement.

Cheers
KokChoon
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[KokChoon]

First of all, I would like to highlight some key points to the introduction of this new free sprung escapement as I found understanding these key points will help us better understand the Manufacture’s ideas and motivation behind this milestone creation.

As Jack has mentioned in his answer to some of the queries earlier, we can understand that adjustable inertial balance wheels allow more precise adjustments by the watchmaker, thus providing a greater stability of the adjustment over time and a better shock resistance.

The second point is that Girard-Perregaux’s Microvar actually combines both adjustable screws to poise the balance and weights to adjust the rate of the movement – i.e. precision of the timing.

Again, due to the great precision through the weights (which can be adjusted for +/- 40 seconds a day), and together with the cock integrating a fine-adjusting device for the balance spring stud for a perfect isochronisms, all these will result in the ease of after sales service operation – which can also benefits the consumer in both servicing duration and costs.

We will see in the future that this introduction will become a very distinctive element for Girard-Perregaux movements.

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[KokChoon]

I understand from some of the posts above that some of you guys are interested to know exactly how the mechnical movement of your watch works, and I also believe with a brief introduction of this mechanical functioning would benefit those who are interested.

I will try my best to explain and please pardon me should there be any mistake and I welcome anyone to correct me when I am wrong

I have got this simple picture below to illustrate very simply how movements got its power and hoe it in turn regulate that power to produce accurate timing….

Every watch needs a source of power and something (in most cases oscillator) to regulate its release.

In a mechanical watch, where do we get this source of power? Remember winding your watches? The source of power is actually a spring mounted in a barrel, and the oscillator is a balance wheel, which is mounted on a spring. Both are connected by a train of gears, which holds the hour and minute hands and an escapement – another important element in the regulatory function.

It would be very difficult to describe in words as one would need to see the movement to understand how this is done. The power is transmitted from the barrel through the wheel train and escapement and finally reaching the balance wheel. The energy distributed by the escapement gives an impulse to the balance wheel, making it turn on its axis. The balance-spring mounted on the balance wheel forces the balance to return to its initial position. When the balance swings back to its initial position, it unlocks one teeth of the escape wheel and keeps moving in the opposite direction. The balance-spring winds itself again and swings back in the opposite direction. This is how the balance wheel oscillates.

Thus, the balance wheel is the regulating organ of a mechanical movement, its heart!


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[KokChoon]

To help you understand better the difference between a normal balance wheel and that of the new Girard-Perregaux Microvar, I have put 2 balance wheels (a Glucydur annular balance wheel and the new Girard-Perregaux Microvar balance wheel) side by side in the picture below to better illustrate these differences.

We can see very clearly from the above illustration that adjustable-inertia balance wheels have weights and/or screws fixed on the rim, which allow watchmakers to regulate the rate of the movement.

One can distinguish two constructions of balance wheels:

In the case of the annular balance wheels, which are smooth, the adjustment of the watch can only be done by the regulator.

However, for the adjustable-inertia balance wheels having screws and “weights”, the poise of the wheel (balance) as well as the adjustment of the rate can be done with these screws or “weights”.

I have also checked with the Manufacture and was told that the diameter of the Microvar balance wheel is 7.18 mm, compared to that of a GP 3300’s 7.50 mm. With this size, it can be fitted in most of the Girard-Perregaux calibres and I was also told that the Manufacture is also developing a version of the microvar balance for the bigger GP 4500 caliber.


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[KokChoon]

Sorry if this becomes too technical for you but for the benefits for those who are interested, I am going to cover in this sub-thread on how the 2 different types of balances can be adjusted for higher precision.

Below is a picture in which I have combined 2 balances (an annular balance and the Girard-Perregaux Microvar balance) side by side to show the differences between an annular balance and a Microvar free-sprung balance.

As mentioned above that there are few ways of adjusting the regulation of a watch and below are some of these methods:

Poising
Poising is balancing the wheel so that it turns regularly (as on car wheels).
Annular balances are pre-poised wheels and only small and irremediable corrections possible by deforming the rim – which from the sound of it tells us that this is indeed rarely done.
On the other hand, free-sprung balances’ can be adjusted with the screws on the balance. It allows watchmakers to eliminate residual poising errors compared to annular wheels.

Adjustment of the “Beat”
The beat is the difference between the duration of a “tic” and a “tac”. Both should be perfectly equal for the movement to be considered fine tuned!
In an annular balance, this adjustment is done through the stud holder.
For free-sprung balance on the other hand, is set once and can usually not be changed afterwards. However, with the Girard-Perregaux Microvar balance, it is still possible to do this fine adjustment through the eccentric screw for higher precision.

Adjustment of the Rate
The rate is the “speed” of the watch, i.e. whether it runs fast or slow.
In an annular balance, adjustment is done with the regulator by changing the active length of the balance spring.
For free-sprung balance, this adjustment is done with the weights on the wheel.


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[KokChoon]

It is believed that this distinctive shape of the Girard-Perregaux Microvar balance wheel, which is characterized by the poising screws on the external side of the rim and the adjustment weights on the top will soon be something a watch collector will look for when buying a Girard-Perregaux time piece….

The picture below explained where the screws and weights are located and how can they be adjusted to fine tune the regulating mechanism:

Also, we were told that in order to achieve the best aerodynamic flow possible, all screws and weights are integrated into the rim!

The material used for the balance wheel is “Glucydur”, an alloy of beryllium and copper, which has a very high hardness, is very stable over a large range of temperatures and is antimagnetic.



ADJUSTMENTS


1. ADJUSTING THE RATE

The screws on the top of the balance rim are used to adjust the rate of the watch!

As shown above, turning the pair of opposite weights with their mass closer to the center will speed up the rate. On the other hand, rotating the weights with their mass away from the center will slow the watch.

These rotations allow a variation of the rate of the watch by +/-- 40 seconds a day.

The slot within the balance wheel rim gives greater elasticity and is used to better monitor the weight positioning.


2. ADJUSTING THE BEAT

To reach a better precision and regularity in adjustment, an eccentric fine adjustment mechanism has been developed!

To have a perfect beat, the spring should be perfectly centered. Turning the eccentric adjustment screw in one direction or the other allows to move the fixation of the balance spring on the stud. The use of a fine adjustment system facilitates this operation. Thus, The watchmaker is able to make adjustments more easily and more precisely.


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[KokChoon]

A new fine adjustment cock (regulator / in combination with the annular balance wheel) will also be introduced on the whole GP 3000 caliber series from 2009, announced Girard-Perregaux.

The cock is actually the “bridge” holding the balance wheel, some called this the Balance Cock.

While Girard-Perregaux is planning to replace in the long run all in-house calibers with the Microvar Balance complete, it is also understood that this will take some times due to some production restrictions, especially the new hair spring used in the Microvar Balance. I believe this is due mainly to the difficulties to get production capacities from Nivarox

I was also told that the hair springs are different from those being used now. Among other specificities, the length, terminal curve and attachment points to the balance differ from the current one used. Girard-Perregaux has chosen to equip the new Microvar Balance with a flat hair spring to keep the complete calibre as thin as possible (the use of a Breguet hairspring would have added 0.3 mm height). One of the main characteristics of the GP3000 series is that this is an extra-flat movement.

However, the Manufacture might adapt Breguet hair springs on microvar balance for other movements when height is not really a problem there


Back to this new fine adjustment cock, with annular balance wheels, the adjustment of the rate is operated through the regulator, which shortens or extends the effective length of the spring. Shortening the spring speeds up the rate. Lengthening slows it down.

This operation is done by moving the regulator index. Adjustments by moving directly the index can be difficult to do with precision. The new cock (balance bridge) for the GP3000 series will allow a fine adjustment of the regulator through an eccentric screw allowing a much better regulation once the movement is in the case (like a swan neck regulator).

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[Jack Forster]

. . . those are wonderful images and I know I for one will be linking to them in other posts for years to come a great service to the GP/JR community and to Horomundi! Thank you!

Jack

[vlkcheng]

Thanks KC and Jack for your great info.
I wish I can change my current balance spring to the new microvar balance with my next service.
Bravo to the guys and gals at the GP manufacturer.