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Mechanical
Watch FAQ's
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Section
1: Watch / Movement basics
1.1.0 What is a mechanical
watch?
1.1.1
What is the difference between a movement, ebauche, and caliber
1.1.2
What is a "hack" seconds feature?
1.1.3
What does "17 jewels" mean?
1.1.4
Why do they use synthetic ruby?
1.1.5
Are more jewels better?
1.1.6
What is shock protection?
1.1.7
What is the "T", "T‹25", and the
lower-case Greek sigma on my dial mean?
1.2
What is a MecaQuartz?
1.3 What
is an Accutron?
1.4
What do I need to do to keep a mechanical watch running
for a lifetime?
1.5 Why
should I get a mechanical watch when a quartz watch is so
much cheaper and more accurate?
2.1
What's the difference between a "manual" and an
"automatic"?
2.2.0
How does an automatic mechanism work?
2.2.1
Are the Seiko Kinetic / Autoquartz therefore automatics?
2.3
What is a watch winder, and do I need one?
Section
2 : Brands & Accuracy
3.1
What is the best watch made?
3.2.0
How accurate can I expect an [insert brand here] to be?
3.2.1
What does "adjusted" vs. "unadjusted"
vs. "regulated" mean?
Section
3: Features
4.1
What is a chronometer? What is a chronograph?
4.2
What is a Rattrapante?
4.3
What is a Flyback?
4.4.0
What is a Column-Wheel?
4.4.1
Are Column-Wheel chronographs better than other types?
4.5
What was the first automatic chronograph movement?
5.1
What is a complication?
5.2
What's a Reserve de Marche?
5.3
What's a Perpetual Calendar?
5.4
What's a Tourbillon?
5.5
What's a Repeater?
Section
4: Materials
6.1 Should I be concerned
about radium on a vintage watch dial? How about Tritium?
7.1
What's the difference between acrylic, mineral, and
sapphire crystals?
7.2
How do I remove the scratches from an acrylic crystal?
8.1
If a watch is advertised as "18K", what does that
mean?
8.2
What do PVD, CVD, or PE-CVD mean?
8.3
What does Gold-Filled mean?
9.1
What are some other materials used as watch cases?
9.2
How do I remove scratches from my watch?
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PART I:
Watch
/ Movement Basics
 1.1.0
What is a mechanical watch?
A mechanical watch is a device for keeping time, which uses the energy
from a wound spring, and keeps time through the highly regulated release
of that energy through a set of gears (the wheel train) and an escapement.
It differs from the typical quartz watch in that it uses purely mechanical
components to keep time. Mechanical watches typically can run for
about 40 hours on one full winding of the mainspring, with a few designs
available with up to 8 days, or even 10 days, of power reserve.
A more in-depth
technical explanation, with photographs, of how a watch works can
be found in the Horologium article "The Anchor Escapement".
Also, it may be useful to peruse a diagram of watch parts residing
in the TimeZone archives to familiarize yourself with the lingo. Finally,
the Illustrated Glossary of Watch Parts is the definitive guide to
see schematics of parts in their natural habitat. (Like animals, they
are sometimes easier or more difficult to see in the wild.)
The basic design of mechanical watches has not changed very much in
the past fifty years. What has changed is the use of high technology
and modern materials in the design and manufacture of watches. Even
with the fusion of CAD/CAM, electrospark erosion in the manufacturing,
and titanium nitride cases; the pinnacle of watchmaking is still an
expression of elegance of design, attention-to-detail in finishing
and assembly, and the art of hand-tweaking movements for optimum performance.
A mechanical watch
is an anachronism, it is the ultimate refinement of "low"
technology; collectively they are an obsession shared by the enthusiasts
on TimeZone.
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| A
view of the self-winding movement with date and center seconds,
Caliber 315 by PATEK PHILIPPE. The latest generation
of renowned Patek Philippe self-winding movements, it features
a new, fast rewind mechanism powered by a 21-carat central rotor
for maximum winding efficiency. |
1.1.1 What is the difference between a movement,
an ebauche, and a caliber?
A movement is the completed, finished individual mechanism contained
inside the case of the watch, not including the case or dial itself,
which is responsible for keeping time. An ebauche is typically understood
to mean a "raw" or unassembled, unfinished movement, including
the major structural components (plates, bridges) and sometimes parts
of the wheel train and other moving parts. A caliber is the collective
name given to a series of movements of the same design.
Many watch
companies will purchase complete movements from a major supplier such
as ETA or Lemania, engrave their company's name and other information
onto them, and encase it with their own or even contractor-supplied
cases. This practice can be up-front - where the company acknowledges
that the movements are not of their own design or manufacture, or
it can be hidden - where the watch company claims to use "in-house"
movements when the movements are in no way designed or manufactured
internally.
Some watch companies
will purchase an ebauche from a major supplier, polish and decorate
the parts (i.e. finish the parts), and assemble it with standard parts
to create a higher quality-controlled movement than the stock ready-made
movement.
Other companies
purchase ebauches, finish them to a high standard, modify parts of
the movement, and add custom components like an upgraded escapement
assembly - to create what might be called a custom version of that
movement, much like how Carroll Shelby, AMG, or BMW's "M"
division re-engineer existing automobiles to produce something with
higher performance and exclusiveness. Many times, the company will
rename the caliber as its own to reflect the modifications and finishing
of the movement vs. an unmodified stock movement.
There is often
a debate on whether a particular company is being deceptive in renaming
a movement based on an outside supplier as an in-house caliber. This
debate is summed up quite nicely in the article "When a [Valjoux]
7750 ain't a 7750 any longer" by Time Flies and a host of regulars.
It should also
be noted that the largest supplier of ebauches in Switzerland, ETA,
can provide a wide variety of finishes on its products, from very
raw parts to fully finished movements complete with Geneva stripes
and other decoration. They even have a subsidiary, Soprod, that can
perform custom finishing and even modifications to the basic movement.
Therefore, there is by no means a single level of quality that one
can ascribe to an ETA movement - there are basic versions all the
way up to fully finished ones.
Finally, on TZ
it is common to see the word ebauche used to refer to any third party
movement, even if it is completely assembled.
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1.1.2 What is a "hack" seconds feature?
This is a military term referring to watches that stop the second
hand, to allow for more accurate synchronization between two watches.
In the most common type of hacking watch, when the crown is pulled
out to the time-setting position, a lever is moved which contacts
the rim of the balance, thus causing the movement to stop. There are
other methods used to stop the movement as well, including brakes
on the third or fourth wheel.
A. Lange &
Sohne have produced a watch that stops the balance when the crown
is pulled out and automatically moves the second hand to the "0"
position - to help facilitate setting against an accurate time reference.
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1.1.3 What does "17 jewels" mean?
Higher grade watches have traditionally used a jeweled movements,
which means that jewels (originally natural ruby, now synthetic ruby)
were actually used in the movement. These jewels are functional -
they are used as the bearings for the wheel trains and in high wear
parts such as the escape lever and impulse jewel.
A lower-end movement
from before 1970 would typically use 5 or 7 jewels; this end of the
market has pretty much been taken over by quartz. Nowadays, most manual
wind watches will have a standard complement of 17 jewels, which are:
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1:
Impulse jewel (the part of the balance wheel assembly which receives
a kick from the escape lever)
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2-5:
Balance staff pivot bearings (two pairs - in combinations of one pivot
jewel (i.e. jewel with a hole to receive the axle (pivot) of the wheel)
and one cap jewel (i.e. jewel without a hole outboard of the pivot
jewel, to prevent excessive movement of the balance staff), usually
shock protected)
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6-7:
Escape lever pallets (one pair)
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8-9:
Escape lever pivot bearings (one pair)
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10-11:
Escape wheel pivot bearings (one pair)
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12-13:
Fourth wheel pivot bearings (one pair)
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14-15:
Third wheel pivot bearings (one pair)
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16-17:
Center wheel pivot bearings (one pair)
Note that automatic
winding movements, and movements with additional functions such as
chronographs and calendars, can up the total number of jewels tremendously.
For example, the IWC Il Destriero Scafusia (claimed to be among the
most complicated wristwatches manufactured) has a total of 76 jewels
to accommodate the time, perpetual calendar, rattrapante chronograph,
repeater, and tourbillon functions - and this is a manual wind watch.
(Back
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Ruby
Jewel Bearings
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1.1.4 Why do they use synthetic ruby?
Ruby is technically known corundum, and is a crystallized form of
aluminum oxide. In pure form, corundum is white in color; trace impurities
are added to change the color - to red in the case of rubies. It should
also be noted that any other color of corundum (including clear) is
known as sapphire. Ruby is used because it is an extremely hard and
provides a slick surface for the wheel pivots (and other steel components)
to operate on. In a mechanical watch, there is a constant force applied
to the pivot of every wheel in the wheel train, which is applied by
the wound-up mainspring.
Without any jewels,
the steel wheel pivots would very quickly grind away the bridge and
plate material until the wheels came out of alignment, and the movement
would crash to a halt. In the inexpensive watch of yesteryear, the
pivot holes may have been provided with hardened metal bushings.
Ruby is significantly
better than steel in handling the forces involved, wearing long, and
providing a nice low friction surface suitable for both high-load
as well as high-speed motion. With modern production methods, they
are inexpensive.
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1.1.5 Are more jewels better?
Not necessarily. As noted above, a typical hand-wind movement today
will have only 17 jewels as a full complement. Some really high-grade
or ultra-thin movements will add a few extra jewels to further protect
against any wear, but even these top out at 21-23 jewels.
Only those pieces
of the movement which are between the mainspring and the escape wheel
are candidates for jeweling, as these are the movement parts that
experience the large forces or relatively high speeds of the mainspring
or escapement. Other components, such as the motion works (i.e. hour
and minute wheels), calendar mechanisms, and winding train are not
under this constant stress, and thus arguably do not need jewels.
Automatic winding
movements will add about 4-8 jewels to help most efficiently transfer
the relatively small rotor forces into winding the mainspring. Another
factor has to do with how the watch is constructed - especially for
chronograph movements and perpetual calendars. Some chronograph movements
used today are modular in construction - meaning that a plate containing
the chronograph works is grafted onto a basic timekeeping movement.
Since the original timekeeping movements were not always designed
with this in mind, it becomes critical for the add-on module to add
as little "drag" as possible - which may indicate use of
jewels for their low friction properties.
You may occasionally
encounter a quartz movement with jewels in it - they technically aren't
necessary because a quartz wheel train is not constantly under stress.
As a historical
note, there was a "jewel craze" about 50 years ago, where
manufacturers, under the belief that the public thought more was always
better, came up with 75 or even 100 jewel movements. Most of these
jewels were not functional in any way, and the results looked ludicrous
to an informed eye.
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1.1.6 What is Shock Protection?
As is fairly obvious, a mechanical watch is made up of numerous tiny
parts, many of which are in constant motion. It would not do for an
accidental bump to interfere with the watch's ability to keep time
due to damaging of the balance pivots. So, watchmakers include "shock-protection"
in their watches in the form of a tiny spring that holds the balance
staff jewels in place, instead of being rigidly held. This gives a
slight amount of give - not enough to disrupt the operation of the
watch for more than a moment, but enough to prevent the balance pivots
or cap jewels from damage.
Shock protection
is usually only applied to the balance because the high speeds and
regular motion they are designed for - this kind of design goal leads
one to small, extremely hard pivots, with most of the weight concentrated
at the rim of the balance. These factors combine to make for a lot
of broken pivots.
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1.1.7 What do the "T",
"T‹25", and the lower-case Greek sigma on my watch
dial mean?
These are optional industry markings, found next to the inscription
'Swiss Made' on some watches, which signify what the markers on the
dial are made from.
The "T"
means that tritium (a low-level radioactive substance) was applied
to make the hands and/or markers glow in the dark. The "T‹25"
means the same thing, except it spells out that less than 25 milliCuries
of radioactive material is used. See section 6.1 for more information
about Tritium.
The lower-case
Greek sigma means that the markers are made of solid gold.
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1.2 What is a MecaQuartz?
A movement described as a "mecaquartz" is actually a quartz
movement that contains many mechanical components. An example is the
Jaeger LeCoultre (JLC) Caliber 631, which uses a quartz movement to
drive not only an analog hour/minute/second display, but also mechanically
drives a chronograph function (see 4.1, below). This differs from
a typical quartz chronograph, where the chronograph functions are
either digitally displayed in an LCD window (e.g. Breitling Aerospace),
or where the chronograph hands are individually driven by separate
motors (e.g. Seiko Flight Computer, with four separate motors).
A "mecaquartz"
movement as that term is commonly used is not a quartz movement with
a mechanical charging system, such as the Seiko Kinetic or Swatch
Autoquartz (see 2.2.1, below).
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1.3
What is an Accutron?
The Accutron is an electrically driven movement developed in the early
1960's by the Bulova corporation, and was a precursor to the quartz
revolution of the late 60's. Instead of having a mechanical balance
wheel, the Accutron used a mechanically resonating system very much
like a tuning fork to keep a constant vibration rate, and thus time
regulation, for the rest of the mechanical movement.
Accutrons have
a distinctive audible hum when operating, and their second hand is
driven at such a high frequency that it truly appears to move continuously,
unlike a mechanical watch (which vibrates at 10 Hz or less) or a modern
quartz watch. Accutrons were the first major advance using electronics
in timekeeping technology over mechanical watches.
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1.4
What do I need to do to keep a mechanical watch running for a lifetime?
Within reason, a mechanical watch can always be brought back into
good time keeping, and a jeweled movement can last for generations.
However, it is
important to periodically service a watch to ensure that the components
are well-lubricated, and that the mechanism is free from dust, dirt,
and moisture. Any water that gets inside a mechanical watch will wreak
havoc with the precision mechanism inside, especially the anchor escapement
and escape wheel which are typically made of steel.
The typical rule
of thumb is to have the water resistance (i.e., the integrity of the
seals in the crown, bezel, and caseback) of a watch checked every
year or so, especially if used for sports or diving. With the development
of modern synthetic lubricants, most manufacturers recommend a servicing
every four or five years.
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1.5 Why should I get
a mechanical watch when a quartz watch is so much cheaper and more
accurate?
Yes, a quartz
watch is cheaper and more accurate than a mechanical watch. A good
mechanical watch can typically be made no more accurate than 2-3 seconds
per day. Your typical inexpensive quartz is usually good to 0.5 seconds
per day or better.
But mechanical
watches are not about achieving the ultimate in accuracy. Craftsmanship,
aesthetics, and tradition are all part of the allure. Because the
wheel train of an analog quartz watch is not under constant stress
from a wound mainspring, it does not need to be as finely finished,
nor does it require painstaking skill and precision in assembly.
Mechanical watches
are good enough for most people's everyday lives, and they call to
our emotional side.
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2.1 What's the difference
between a "manual" and an "automatic"?
An "automatic" wristwatch is a mechanical wristwatch with
a self-winding mechanism. In other words, one does not have to wind
the crown periodically to keep the watch running. A "manual"
or "manual wind" watch must be wound by hand, using the
crown, usually every day, to operate continuously.
If one were going
to own only a single watch, and wear it every day, an automatic would
be a good choice, since the watch will be worn consistently enough
to stay wound - the owner would never need to manually wind the watch,
and would only need to adjust the time to compensate for drift and
at changeover to daylight/summer time and back. (In fact, several
early automatic movements dispensed with the crown and moved the time-setting
mechanism onto the back, under the theory that the mechanism would
only be accessed infrequently. This turned out to be a marketing flop
- people liked the look and easy accessibility of the crown.)
For this reason,
most commonly seen watches with more than a simple date window use
automatic movements - this includes "triple date" calendars,
annual calendars, perpetual calendars, and any of these combined with
moonphases (see 5.3 for more information about calendars). With few
exceptions (oddly enough, these seem to be more expensive watches),
most manual wind watches have simpler calendars, although they may
include other complications like chronographs (see section 4.1).
One caveat about
automatics - if you have more than one watch that is worn regularly,
the automatic winding advantage is lessened - the automatic may stop
if not worn often enough. With some calendar mechanisms, this is can
be an increased inconvenience when the watch is reset.
Finally, since
frequently worn automatics are usually at or near a full state of
wind most of the time, one may get the impression that they can be
adjusted to be more accurate and consistent over the course of many
days. This, in fact, is not necessarily the case, as a manual-wind
watch that is wound consistently once per day can be tweaked so that
the day to day variation is very small. In short, there is no definite
performance advantage to an automatic - it is mostly a convenience.
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2.2.0 How does an automatic
mechanism work?
All self-winding watches work on the principle of converting arm motion
(kinetic energy) into the winding of the mainspring (potential energy).
Usually, this is performed by a half-disc of metal weighted at the
edge called a rotor, which spins when the wearer's arm is accelerated
unpredictably (that is, when moved normally in the course of everyday
life). This rotary motion is then geared down to wind the central
arbor of the mainspring.
All automatic
watches have an overwind protection mechanism of one sort or another,
to prevent breaking the mainspring once fully wound. In a typical
system, the mainspring, which is wound at the central arbor of the
barrel, is not rigidly attached to the outside of the barrel. Instead,
there are a series of detents along the outer edge of the barrel that
allow a stiffly constructed mainspring part called the bridle to slide
along when an attempt to overwind is made. On some watches, a faint
click can be heard when this happens, on others, it cannot be heard.
It should be noted that this overwind protection is critical to avoid
damage to the watch, and is reported to be one of the more tricky
things to get right during a watch service because of the special
lubricant needed to ensure proper operation.
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2.2.1 Are the Seiko
Kinetic / Autoquartz therefore Automatics?
Not quite, but close. The Seiko Kinetic and ETA Autoquartz movements
are quartz movements. However, they use a rotor system similar to
those used by automatics. The difference is that the rotor's motion
is converted to electricity, which is then used to charge a capacitor.
The quartz movement then draws current from the capacitor as if it
were a battery.
It should be noted that the latest generation of autoquartz movements
can store enough power to run the watch for several months (or even
years in the case of the Seiko Auto-Relay); a mechanical automatic
can only store as much power as contained in the mainspring - which
is usually only 40 hours or so for most automatics.
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2.3 What is a watch winder,
and do I need one?
As noted in section
2.1, collectors who have more than one automatic watch may have "difficulty"
keeping any one watch going continuously. This leads to increased
inconvenience if calendars and moonphases must be reset. A solution
has been invented - the automatic watch winder.
The idea is quite
simple: strap the automatic watch to a motor, which then moves the
watch enough to keep it wound when not worn on the wrist. That way,
one can choose to wear any watch at any time, and not have to reset
the time or calendars. In theory, this device should be simple and
cheap.
In practice, it's
not as easy as it sounds. First, while an automatic watch has an overwind
protection mechanism to avoid damage to the movement, if the overwind
mechanism is constantly used for hours at a time (i.e. though constant
turning, rather than the unpredictable movement of the human wrist),
the lubrication of the mechanism is worn out faster. This means that
watch winders must be designed to only make so many turns per day,
and to let the watch sit. Furthermore, since automatic winding mechanisms
vary from watch model to model, the winder must be designed to have
an adjustable number and direction of turns per day. Finally, mechanical
watches are considered luxury items, which means watch winders are
doubly so - due to the small number of people who would actually want
one.
All of this means
that manufacturers for the consumer market must not only make their
winders mechanically foolproof to avoid damaging watches, but they
often construct the winder comparably to a jewelry box. The upshot
of all this is that most consumer watch winders with programmable
winding are expensive - often costing several hundred or thousand
dollars.
While cheaper professional models exist, these often do not come with
programmable settings, as the maker assumes that they would be used
in a watchmaker's shop.
Lastly, winders
are not a necessity, they are a convenience. You should decide whether
they are worth it based on whether you feel inconvenienced resetting
your automatics occasionally, and whether they are worth it to you
as a luxury item.
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PART
II:
Brands
& Accuracy
3.1. Who makes the
best watch?
The answer to this question depends almost exclusively on what is
important to the person asking it. Consider the following qualities
that a watch can have, any of which can be the most important factor
in some people's minds:
Accuracy
- how well does the watch keep time?
Features - can the watch act as a analog or digital calculator?
a calendar which never needs setting? keep important phone numbers?
can be used when diving to hundreds of meters? double in a pinch as
an altimeter, depth gauge, navigation system, and emergency locator?
can it be used as a stopwatch? - the variations these days are endless!
Status - will
the other person, whether in a business or social setting, be unconsciously
impressed and swayed by the fact that I'm wearing a recognizable symbol
of status and success on my wrist? This is a legitimate question for
some people.
Ruggedness/Dependability - can I wear this watch in combat? can
I wear it near strong magnetic fields? will it need a battery replacement
at an unacceptable moment?
Aesthetics - is this watch a work of art? does it fit with my
personal sense of taste?
Craftsmanship - what do the dial, case, and movement say about
the skill and care of the watchmakers who made it?
Cost -
how cheap can I get it for?
Decide what is
important to you in a watch, then find out whether the watch you're
looking for has it.
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3.2.0 How accurate
can I expect a [insert brand here] to be?
This is truly
a Frequently Asked Question, in that people will post that they have
just bought a new IWC/Rolex/JLC/Revue Thommen/Omega/etc., and it gains/loses
X seconds per day - they then ask whether this acceptable for this
brand.
After
reading several articles on this subject, I've come to the following
conclusions:
-
Just
about any current production watch is capable of running overall
within 1-2 seconds/day - this includes relatively inexpensive brands
like Hamilton and ORIS, as well as high-end brands like Patek, JLC,
and Lange.
-
The
stability of a given rate can be quite ephemeral, with the instantaneous
rate even in a single position varying constantly. This means that
the rates for a given watch are constantly drifting - although for
higher grade movements the amount of drift tends to be much smaller.
-
The
question of accuracy is more subtle than it appears on the surface.
The reason is that, due to the limits of how small components can
be, forces will act on the components differently when worn on the
wrist vs. when resting in any particular position. In other words,
even a watch which has a daily error rate of 4-5 seconds/day in
any single position can be made to show zero overall drift though
the combination of wearing the watch and letting it sit overnight
in a particular position to compensate for drift obtained during
wear.
- A higher quality
watch may or may not be more accurate than a lower quality watch at
any given instant in time, but it has the potential to be more accurate.
The reason is that a higher quality watch has been adjusted to minimize
the variation in error in several positions, and has less drift in
the rate over time.
It is a relatively
simple operation for a watchmaker to adjust a watch that runs consistentlyfast
or slow to near zero error. This operation, which is called regulation
- merely increases or decreases the overall rate without compensating
for rates in positions.
Also, the
conventional wisdom is that a typical new watch needs to be run-in -
in other words, while sitting unused in the jeweler's shop, lubricants
pool in certain locations. It takes a couple of months for the lubricants
to be properly redistributed, and for the motion to wear away some of
the microscopic imperfections that all parts have. Bottom line - let
a new watch run for about 2 months before taking it in to be re-regulated.
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3.2.1 What does "adjusted"
vs. "unadjusted" vs. "regulated" mean?
These are terms
to be used in conjunction with the discussion in section 3.2.
An "unadjusted" movement is a movement where no attempt
has been made to ensure that the daily error rate in several orientations
(positions) have been minimized across the positions. An "adjusted"
movement, therefore, has had some extra care in ensuring that the
variance in accuracy between several orientations is minimized.
Watches are typically adjusted to 2, 3, 4, 5, and 6 positions. Traditionally,
they are ordered as follows:
1.
Dial Up
2. Crown Down
3. Dial Down
4. Crown Left
5. Crown Up
6. Crown Right
For example, a watch adjusted to two positions include positions 1
& 2 from the above list (i.e. face up and crown down). Similarly,
a watch adjusted for 4 positions has been adjusted in positions 1-4,
and so on. Watches can also be adjusted for isochronism (i.e. constant
time across varying states of wind) and temperature. Some manufacturers
(Franck Muller, some Patek Phillipe) adjusts to 8 positions (the above
six plus two half-way orientations).
A "regulated" movement is a when the overall rate of the
entire movement (either adjusted or not) is brought into correct absolute
timing. Unlike adjustment, this is a simple tweak, which moves the
daily rates of all of the positions up or down without intentionally
changing the relative rates in positions.
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Section 3:
Features
4.1 What is a chronometer?
What is a chronograph?
These two terms are commonly confused among new watch aficionados.
They actually have very little to do with each other.
A chronometer is a watch which has passed a test given by the Contrôle
Officiel Suisse des Chronometres, or COSC. The COSC is an official
Swiss government agency which tests watches to ensure that they fit
within a narrow-but-usually-obtainable window of acceptable error
(i.e., the rate in all positions falls into the range of -4 seconds/day
to +6 seconds/day). While some watch companies tout their products
as having a COSC certificate, it really is not that difficult to pass
the test, and over 95% of the watches submitted pass. Another factor
to consider is that the COSC does not test watches as they are sold
in the store, but movements fitted with a temporary case, dial and
hands. In addition, the COSC certificate cannot say anything about
how the movement was handled after testing. For more information on
COSC testing and the meaning of the results reported on the COSC certificate,
see Mike Disher's article "Reading and Understanding a COSC Certificate".
Several watch manufacturers actually put more stringent tests than
the COSC procedures on all of their watch production (the JLC Master
Control 1000-Hour series is probably the most well known.)
A chronograph
is a watch that tells the time of day and also allows the user to
time events of short-to-medium durations (i.e. from a few seconds
to a few hours, typically). This is usually done in a mechanical watch
through the central seconds hand, and one or more subdials (the regular,
or continuous seconds, is also located on a dial). Chronographs are
of varying usefulness, and are an interesting complication to put
on a watch, as they often give the watch a sporty image. In addition
to elapsed time, chronographs are often fitted with several scales
designed to measure other things, such as pulse rate or units manufactured
per hour. Mike Margolis has written a short discourse on chronograph
scales.
A typical modern
chronograph is operated with two pushers: one to start and stop the
timing, and a second to reset the hands to zero when the timing is
stopped. (In some older chronos with only one-button for control,
the sequence of pushes was start-stop-reset - there was no provision
to continue timing once the mechanism was stopped.)
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4.2 What is a Rattrapante?
A "Rattrapante" is a chronograph with an added second hand,
to allow, for example, lap times in a multi-lap event to be read off
without stopping the chronograph. A chronograph is usually started
with one pusher, which starts both second hands moving (one superimposed
over the other). When the operator desires to read an intermediate
time, he/she pushes a second pusher. On the dial, one of the second
hands stops (the "split" hand), while the main second hand
continues. If the second pusher is pressed again, the split seconds
hand "catches up" with the main second hand, and is ready
to be used again.
Interestingly,
three languages describe this function in different ways: "Rattrapante"
is the French term for "catch up" (describing the motion
of the split hand); the German term for this function is "Doppelchronograph",
or double chronograph; the English term is "Split Seconds"
(describing the appearance of the second hand when the function is
activated).
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4.3 What is a Flyback?
A "Flyback" or "Retour a vol" is a function which
allows the chronograph to be reset to zero without having to stop
the chronograph first (recall that a normal chrono requires one to
stop the timing before resetting). This is useful for aviation, where
several segments or legs of a route are flown for specific periods
of time in sequence; the act of stopping, resetting, and restarting
leads to a short delay in the beginning of timing the next leg. This
delay, reportedly, can be a factor in some precision military operations,
for example.
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4.4.0 What is a Column-Wheel?
Constructing a chronograph is fraught with the potential for inadvertently
stopping or damaging the entire movement. For example, if the reset
mechanism was somehow activated while the chronograph was running,
large destructive forces would be applied to the entire movement train,
which would at the very least jam the movement, and would likely destroy
several components.
The column wheel
was one of the successful early designs to ensure that none of the
above happened. If you can visualize the top of a castle turret, with
tooth-like battlements, this is what a column wheel looks like. The
pushers that control the chronograph rotate this wheel, and the various
parts of the chronograph are controlled by fingers that fall into
and out of the spaces between the teeth. This ensures that each of
the chronograph parts is coordinated properly.
Because producing
and finishing a column wheel is labor-intensive, a simpler, easier
method of producing chronographs was needed to keep this complication
from appearing only in very expensive watches. The most common method
is to use an oscillating pinion to coordinate the chronograph start,
stop, and reset (i.e. a cam shaped device that rotates back and forth
as the various functions are activated.) This allows for reliable
operation without nearly as much fiddling and hand adjustment as a
column wheel requires, and the pinion can be built using pieces of
stamped metal.
These days, relatively
few column wheel designs are still being produced - the Zenith El
Primero, some Lemania and F. Piguet movements, and (interestingly)
a F. Piguet rattrapante mecaquartz are examples. The most common movements,
such as the Valjoux 7750 and various Lemania movements (1874, 5100),
are not of column wheel design.
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4.4.1 Are Column-Wheel
chronographs better than other types?
Certainly column wheels are a traditional method of coordinating the
chronograph components, and tradition counts for a lot.
On the other hand,
the newer, non-column wheel movements have certainly proved themselves
in a variety of demanding situations. Both the column-wheel and non-column-wheel
version of the Omega Speedmaster were certified for space flight by
NASA. And the non-column-wheel Lemania 5100 has been one of the few
mechanical movements to be accepted as sufficiently rugged by modern
military forces.
So, much like
the question of which watch is best, I suggest that one think about
which factors are personally most important in a chronograph, and
make the decision from there.
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4.5 What was the first
automatic chronograph movement?
The late 60's saw a race among three sets of manufacturers (two Swiss
groups and Seiko in Japan) to create the first automatic winding chronograph
movement. Interestingly enough, they all succeeded within a few months
of each other.
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5.1 What is a complication?
A complication is anything that is above and beyond simply telling
time. A basic watch is a three hand timepiece - hour, minute and seconds.
Anything more, even a day or date display, is a complication. Most
complications are modules place on top of and integrated with the
base movement. A chronograph (timer) is an example of one of the most
useful complications and a dual time display is another very practical
complication. Some more complicated watches are designed from the
ground up.
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5.2 What's a Reserve
de Marche?
A Reserve de Marche, or Power Reserve, is an indicator that displays
the approximate number of days or hours left on the current state
of mainspring wind. This typically cannot be done by a simple gear
train, since a watch is wound from the center arbor of the barrel,
and the power is removed from the outer rim of the barrel. Therefore,
a gear train that can act as a differential is required to read out
the difference between the arbor position and the barrel rim position.
This can be a very useful complication, as it lets one know whether
a watch is wound before putting it on. This is true for automatics
(which may be in any state of wind) or long power reserve watches
(such as the Eberhard 8 days, Lange 1, or the Patek 5100 ten-day reserve).
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5.3 What's a Perpetual
Calendar? How is it different from an Annual Calendar or Triple-Date?
A perpetual calendar
is the most developed form of the simple date window on a typical
watch. It keeps track of date, day-of-the-week, (sometimes weeks),
months, year, leap years, and sometimes even centuries. Because of
the relatively complex rules governing the Gregorian calendar, including
the varying lengths of months, and leap years every four years, a
typical perpetual calendar has wheels turning from several times per
second (e.g. balance wheel) all the way to once every four years.
Because of the complexity of the Gregorian calendar, some perpetual
calendars will require an experienced watchmaker open the watch to
make an adjustment at AD 2100, or later.
Some less complex
calendars are also available:
-
Semi-perpetual
calendars (e.g. the Breitling Montbrilliant 1461), which requires
an adjustment on leap year day only.
-
Annual
calendars (of which the Patek Philippe 5035 is an outstanding example),
which only require a user adjustment once every February
-
"Triple
date" calendars, which contain month, day, and date - but need
to be manually advanced at the end of each (short) month
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5.4 What's a Tourbillon?
A Tourbillon is a device that is designed to counteract the effect
of gravity on the movements balance, thereby increasing the movement's
accuracy. A tourbillon features a small cage that holds the balance
and the escarpment, and the cage turns independently of the watch,
usually at a constant rate of once per minute. The tourbillon, which
means "whirlwind" in French, is one of the watchmaking art's
most involved and elegant complications.
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5.5 What's a Repeater?
How is it different from a Sonnerie?
A repeater, or "Repetition Minutes" is a variety of chiming
watch. Unlike a striking clock, repeaters do not automatically strike
the hour, quarter, or minutes in passing - they must be activated
by the user, usually through a slide or push button.
Watches which
do strike "en passsant" (in passing) automatically are called
Petit or Grande Sonneries.
Repeaters currently
come in several varieties, based on the smallest unit of time which
they can indicate:
Quarter Repeater: Chimes the hour, followed by the number of
quarter-hour intervals at the current time. (example: 4:21 would have
four chimes for the hours, then 1 chime for passing the first quarter-hour.)
Half-quarter
Repeater: Chimes the hour, followed by the number of half-quarter
hours (i.e. 7.5 minute intervals) past the hour. (example: 4:21 would
have four chimes for the hours, then two chimes for two half quarters.
Note that it would chime three times once getting past 4:22:30)
Five-minute
Repeater: Chimes the hour, followed by the number of five-minute
intervals (example: 4:21 would have four chimes for the hours, then
four chimes for passing 20 minutes past the hour.)
Minute Repeaters:
Chimes the hour, followed by quarter-hours, followed by minutes (example:
4:21 would have four chimes for hours, 1 chime for passing the first
quarter-hour, and six chimes for minutes into the second quarter hour.)
These again are
very high-priced items, with one exception - the Kelek five-minute
repeater at $5,300 list. More typically, they are in the $20,000 and
up range.
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6.1 Should I be concerned
about radium on a vintage watch dial? How about Tritium? What is Luminova?
The short answer is not to worry about it.
Radium was used
after about 1900 as a means of illuminating watch hands and markers
at night. It was widely used until the 1940's or so, when the hazards
of radiation were - belatedly - understood. Since them, a less powerful
radioactive source, tritium (a kind of hydrogen) has been used. Tritium
is also being phased out of watch dials, partially due to availability
of tritium, and partially due to the development of non-radioactive
luminous compounds like Luminova which "hold their charge"
of light better.
The main victims of radium were the watch dial painters, who were
encouraged to keep a fine point on their paint brushes by licking
the brush end. The wearers of the watch receive only a small dose
of additional radiation per year, much less than the natural background
radiation.
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7.1 What's the difference between acrylic, mineral,
and sapphire crystals?
An acrylic watch crystal (i.e. the see-through window above the dial)
is a kind of plastic, which has the advantage of being resistant to
shattering, but can be scratched easily. Fortunately, scratches can
be easily removed from acrylic.
Mineral crystal
is a kind of glass, which is more scratch resistant than acrylic,
but not as as good as sapphire. Mineral crystals are also somewhat
better at shatter resistance compared with sapphire. Unlike acrylic,
scratches in mineral glass are more difficult to buff out; and unlike
sapphire, mineral glass will scratch. The mineral crystal seems to
be a poor compromise between the two extremes.
A sapphire crystal
is indeed made of synthetic sapphire, which is a transparent form
of corundum, or aluminum oxide. It is extremely hard (Moh's scale
9), and will resist scratching by most substances short of diamonds.
However, if struck sharply and from the correct direction, sapphire
will shatter. Despite the relatively large size compared with sapphire
gemstones, sapphire crystals aren't very expensive.
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7.2 How do I remove the scratches from an acrylic
crystal?
Good old-fashioned
toothpaste is a good start. Start by buffing a little bit onto a clean
cloth over the area of the scratch. Rub lightly, and rinse with a
very slightly damp cloth. Repeat until gone.
Note that there
are also purpose-made polishes for this purpose, such as Polywatch
or Crystal-Kleer
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8.1 If a watch is advertised as "18K",
what does that mean?
The term 18K refers to solid gold. Pure gold is very soft; gold is
made in several "karats", or 1/24th proportions of gold,
to make it harder and stand up to daily wear.
9K = 9/24 purity of gold = 37.5% purity (sometimes seen in vintage
and/or UK market watch cases, along with 10K gold)
14K = 14/24 purity of gold = 58.3% (sometimes marked 583 or 585 in
gold hallmarks)
18K = 18/24 purity of gold = 75% (sometimes marked 750 in gold hallmarks)
24K = 24/24 purity of gold = 100%, which I'm guessing you'll never
see in watch cases.
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8.2 What do PVD, CVD, or PE-CVD mean?
Physical Vapor Deposition is a method of plating
gold or other substances to a thickness of several microns (1/1000ths
of a millimeter) over a base metal surface. Other methods include
Chemical Vapor Deposition (CVD), or Plasma
Enhanced Chemical Vapor Deposition (PE-CVD).
This allows the watch to look like a gold watch, but it won't last
for more than a few years of normal wear. When it does finally show
through, it cannot be repaired.
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8.3 What does Gold-Filled mean? How about Rolled-Gold
Plate?
Gold-filled means gold bars are soldered to a base metal, then rolled
into sheets to give a somewhat higher thickness of gold than any plating
method. The resulting layer of gold is slightly thicker than a sheet
of paper. Gold-filled cases were originally warranted to last a certain
number of years in normal wear - e.g. 25 years, and are somewhat more
durable than modern gold plating.
This practice
was common until the 1960's, but has been largely replaced by plating
processes.
Rolled-gold plate
was another vintage method of plating gold, except the gold was rolled
out flat before being bonded to the base metal. This process has been
supplanted largely by electrochemical plating and PVD.
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9.1 What are some other materials used as watch
cases?
Aside from the standard gold and stainless steel, high-end watches
are often made of platinum or titanium.
Platinum is a
very heavy metal, and gives a shiny white metal appearance. Unlike
gold, pure platinum is fairly hard and resistant to scratches (similar
to hard stainless steel). For this reason, it is often used in 95%
purity (i.e. Pt 950). However, raw platinum is more expensive to use,
not only because of its rarity, but also because it is used in higher
purities and requires more effort to work into a final shape.
Titanium is a
relatively light-weight metal, with a hardness exceeding that of most
steels. It also has a poor heat transfer capability, which means that
it won't carry heat away from your skin as quickly as steel or aluminum
(i.e. it will feel warmer to the touch - sometimes you'll see claims
that titanium "remains at skin temperature" - this is technically
incorrect, any more than a small piece of wood stays at skin temperature).
Several varieties of titanium are available. Titanium has some interesting
mechanical properties: it can "rip" when cut so it is difficult
to machine, and two pieces of titanium pressed together can "weld"
themselves together. This latter property is why it is important that
watches with titanium cases and backs have the casebacks removed periodically
- the threads can actually rip out of the case if left undisturbed
too long.
Other case materials
which one will run across occasionally (especially on the vintage
market) are Sterling Silver (92.5% purity silver), Coin silver (80%
purity silver), nickel silver or silveroid (not silver, but 66% copper,
24% zinc, and 10% nickel), nickel, and nickel plated steel. Also,
more recently, one can even find watch cases made of ceramic (zirconium
oxide, as used recently by IWC) and aluminum (used in conjunction
with other metals, as currently used by Porsche Design and BVLGARI.)
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9.2
How do I remove scratches from my watch?
Depends on the finish. For gold or platinum, use the appropriate polish
from a jewelry store, keeping in mind that a brushed gold/platinum
finish will be harder to match than a glossy finish (see the stainless
steel article for pointers on matching the pattern.)
For gold filled
or gold plate, it is recommended that you leave them alone - you don't
want to remove any more of the finish than already exists.
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