Watches and Winders: It's Not Only About Turns per Day

by Walt Arnstein

December 12, 2000

 
 
PART 1

1.0  Introduction

A commonly recurring topic on TZ forums is that of problems encountered with automatic watches that spend significant time on watch winders. Typical complaints involve some of the following:

  • Watches that inexplicably gain several minutes in a single day on the winder -- often in just a few hours -- but show exemplary behavior when tested on a watchmaker's bench.
  • Watches that stop while on a winder or shortly after being taken off a winder.
  • Watches that run measurably faster or slower while on a winder than they do on the wrist or while resting on the dresser.
All of these examples and quite a few others are very likely to be symptoms of unexpected aspects of the interaction between a watch and the winder on which it is regularly mounted for the purpose of keeping its mainspring wound. Alternatively, they can simply be the result of improper use of the winder and sometimes of merely not having read the instructions provided by the winder manufacturer. While the task of a winder appears on the surface reasonably straightforward, the coupling of a particular watch to a specific winder can in many cases be a marriage made in hell. In this article, we will examine in some detail the factors that influence the way a watch and a winder interact when connected together.

I have written on this subject before and TZers can refer to two of the articles, which can be found in "Articles from the TimeZone Community" in TimeZone's "Learning Zone".

More recently, however, I have been asked to wrap the somewhat disconnected and incomplete topics of these articles into a single document. Specifically, this article will address the question of why we need watch winders and what we need to do to maintain a peaceful coexistence between the watch and the winder. This will be discussed in the sections to follow.


1.1. Historical Background

The watch winder for mechanical self-winding watches is a relatively recent development as a consumer product. We can place its emergence in the mass market at around 1993. It began as a custom accessory, with a few high-end watch manufacturers building winders into presentation boxes for their perpetual calendars and other specialized watches. They were costly, to be sure (Patek's Perpetual Calendar came with a beautiful winder made by Scatola del Tempo, costing $2500 to replace!) but when you sell a customer a watch costing $50,000-plus, it should be reasonable for him to expect something more than a velvet-lined plastic or cardboard box.

Next, there appeared a few discreet advertisements in "International Wrist Watch" and similar magazines for high-end watch fanciers and marketers and aimed at the general market. The prices of these new devices were comparable to those of some respectable watches but the serious watch fancier found them to be worth the expenditure.

From this humble beginning, the product proliferated at an amazing rate until today, there are several dozen serious winder manufacturers and the market is in the many thousands per year some market analysts place it at well over 10,000 units annually. In fact, many serious watch collectors could also be considered winder collectors. No surprise there; quite a few of the top winders on the market display elegance and precision of construction that will not look out of place with a Breguet or a Lange, say, mounted on it.

What is behind this fast-growing trend? The simple answer is that watch owners, and particularly automatic watch owners, today own more watches than they can keep running without some outside help.

The history of the past 60 years offers a fascinating insight into the role of the watch in daily life. The 1930's saw the Great Depression, with unemployment running at 25 percent in the US and much higher in other parts of the world. As a result, watch ownership was a luxury far beyond the reach of most hourly workers, let alone the unemployed. A small proportion of low-to-middle income individuals inherited watches from parents or received them for some special occasion, but on the whole, they did not buy them.

World War II kept the watch market depressed as American companies like Hamilton, Elgin, Bulova and Waltham reoriented their manufacturing operations to the fabrication of timepieces and measuring instruments for the war effort. The flow of Swiss watches was also drastically reduced during these years.

With World War II over and millions of Americans yearning for consumer goods that had been denied them for many years, the watch market began expanding exponentially. Still, the wristwatch was not foremost on the consumer's mind, what with home mortgages, automobiles, washing machines and other burdensome expenses commanding a major part of the returning GI's budget. I am old enough to remember that period very clearly and can attest to the fact that the average man-in-the-street did not own a wristwatch. It was almost unheard-of for a high school student, say, to wear a watch. Adults who did own a watch usually owned only one and it was almost invariably a manual wind watch.

So uncommon was multiple watch ownership that watch repairmen routinely kept on hand loaner watches for their customers to wear while their sole timepieces were being serviced.

The automatic watch debuted as a consumer product around 1948. Sure, there were a few high-end automatics around before that time but most people had no idea what a "self-winding" watch was just like today.

The arrival of the automatic watch was not accompanied by the emergence of the watch winder as a consumer product, as we well know. Why? Simply because the purchaser of an automatic watch in 1948 still ended up owning only one watch. After all, the base price of an Omega Seamaster Automatic in stainless steel was $105, as it was for a Tissot, Mido, GP, and a number of other popular Swiss self-winders. Rolex's Oyster Perpetuals began at $137.50. All this was a lot of money in 1948. Minimum hourly wage was 40 cents per hour, a new Ford cost about $1000 and a single-family dwelling could be bought with a down payment of $1000 and mortgaged with a GI loan for about $8,000. The resulting $75 mortgage payment every month plus the expenses of raising a new family still made an automatic watch something of a luxury and it is little wonder that the buyer of this timepiece didn't need to worry about what to do with the watch while wearing another watch. There was no other watch.

The 1950's were the "golden years" of the automatic watch. There was no competition from other technologies and prosperity brought the watch into the lives of an increasing number of "average" individuals. For the aficionados, we saw the advent of such great watches as the Omega Constellation, the JLC Memovox, the Rolex Submariner, etc. Had electronics not made their entrance around 1960, we would have seen a renaissance of the automatic watch and the watch winder would have been with us within a short time.

But with 1960 came the Hamilton Electric and shortly afterward, the Bulova Accutron. Not long after came the most serious threat to mechanical watch technology: Quartz.

Well, we TZers know the rest. The automatic watch made a miraculous recovery during the 1980s but not before the quartz watch became the standard item of wear for the Man in the Street. Still, the automatic watch has regained much popularity in a limited segment of the population and that segment includes a lot of people who own more than one automatic watch. With multiple watch ownership comes the problem and responsibility of keeping these watches running. Enter the Watch Winder.


1.2 The Wrist as a Watch Habitat

Before considering the benefits and the ordeals of using a winder, let's examine how an automatic watch behaves on a wearer's wrist. All modern automatics feature a rotor whose mass is unbalanced about its pivot. It is a comparatively heavy piece of metal, with most of its mass concentrated near its periphery in order to maximize its moment of inertia, a physical parameter that describes the rotor's tendency to preserve its rotational state. If it is stationary, it resists starting to spin; if it is spinning, it tends to continue doing so. For example, a bicycle wheel is an object with a high moment of inertia for its relatively low mass. Notice that most of its mass is concentrated in its rim and, of course, tire.

The energy of a spinning object varies directly with its moment of inertia (and the square of its angular velocity), so it is important that a watch rotor's moment of inertia be maximized. For this reason, the outer edges of rotors in fine watches are often thick and made of very dense precious metals.

The watch's rotor is a device for grabbing angular momentum provided by random motion of the owner's wrist and storing the associated rotational kinetic energy in its spinning state until it has the chance to transfer it to the watch's mainspring through the gear train provided for the purpose. The energy in the wound mainspring is accumulated in the form of potential energy, which is in turn gradually transferred to the balance wheel, where it is transformed once again into kinetic energy in the form of oscillation of the balance wheel.

The designers of the automatic watch had two major problems to solve from the outset:
  1. How to get enough energy into the mainspring to dispense with the need for manually winding the watch, and
  2. How to avoid overwinding the watch.
The first task is easy to accomplish: By maximizing the rotor's moment of inertia, minimizing friction and choosing gear ratios for optimum energy transfer efficiency, it is possible to convert a large amount of the owner's irregular and sporadic wrist motion into rapid gyration of the rotor. The source of the energy for the rotor is the momentum developed by inertial acceleration the many jerks, twists and thrusts performed by your wrist in the course of normal activity and gravitational acceleration, provided by Earth's gravity in that order. The role of these two sources represents the greatest difference between the nature of the wrist and that of the winder as energy sources. It is crucial and a cause of potential trouble for the watch. It will be discussed shortly.

The second task of the winding system in an automatic watch avoiding overwinding is accomplished by providing the watch with a means of slippage between the mainspring and its barrel once the mainspring reaches a predetermined state of tension, usually well below the maximum obtainable before encountering the "brick wall" resistance felt by the owner of a manual wind watch as he turns its crown. As will be shown, the winder is capable of taxing this overwind protection system to a degree rarely encountered on the wrist and never envisioned by the watch's designers. More on this later.

Let us now examine how a watch is worn and wound by the typical owner. He moves his wrist in a daylong series of irregular and sporadic motions that characterize the source of the momentum the rotor picks up as largely inertial. The Earth's gravity plays a very minor role in the functioning of the self-winding system. In fact, in orbit around the Earth, for example aboard a Space Shuttle, where the effects of Earth's gravity are totally absent, an automatic watch would continue to function perfectly, since inertial accelerations by the wearer's wrist are as plentiful as they are on Earth. This disproves, incidentally, the urban legend that the manually wound Speedy Pro "Moon Watch" was chosen by NASA for use in outer space because the ill-informed scientists from NASA thought that an automatic watch wouldn't work in the absence of the Earth's gravity. (In actuality, NASA's choice of a manual watch was made most likely because no automatic chronographs were readily available in 1960).

But there is a situation in which a watch's winding is totally dependent on the Earth's gravity: On a winder. And therein lies the source of lots of potential problems.


2.0 A Watch's Winding Characteristics

On a typical wearer's wrist, the automatic watch receives its winding torque via a continuous series of brief -- we have used the terms "irregular" and "sporadic" impulses on its rotor, each giving the rotor a small increment of angular momentum. The nature of this sort of energy delivery is such that no single action by the owner forces the rotor and its attached winding gear train to move a sizable angular distance. That is, in fact, is the intention of the manufacturer.

When a watch receives its angular momentum impulses in the above way, there is a significant degree of self-limitation, or overwind prevention, built into the system. As the mainspring winds, its resistance to torque impulses from the rotor grows accordingly and the rotor begins to "bounce" from a semi-hard resistance, transferring less and less energy to the mainspring. Since there is backlash ("dead zone") in bidirectionally winding watches whenever the rotor reverses direction, excess energy in the rotor is dissipated by a series of back and forth bounces within this dead zone. In unidirectionally winding movements, like the Valjoux 7750, the first bounce of the rotor from its winding direction sends the rotor spinning rapidly in the freewheeling direction, again dissipating the extra energy. In some watches, this behavior is fascinating to observe. The rotor of Cartier's Tank Française, for example massive despite the ETA 2000 movement's diminutive size sometimes spins for 30 seconds or more at speeds that make its vibration and gyroscopic precession strongly felt if the watch is held in the open hand. The momentum developed by this rapid rotation prevents added impulses from being applied during most of this process.

The useful self-limitation just described is not available to a watch on a typical winder, by which we mean a winder that rotates a watch about the axis of its hands in a steady, semi-continuous manner. Here, the main, and only, source of torque is the Earth's gravity, which keeps the rotor at the bottom of its arc of swing while the watch revolves about it. Accordingly, the rotor exerts a steady torque on the mainspring through the winding system's gear train and the mainspring is wound until it reaches the slippage point designed into its barrel. Then it continues to turn, this time with the outer end of the mainspring slipping against the inner wall of the barrel. Excess energy is dissipated in the only way available, i.e., heat developed by the slippage. And even beyond this effect, the inevitable consequence is added torque on the watch's main gear train and escapement.

The situation becomes even more significant if the watch's lubrication inside the mainspring barrel (a very special grease) begins to dry out, or the grease was not properly applied in the first place, or the wrong grease has been used, or the mainspring has been replaced with one having the wrong spring constant, or any combination of the above. In such a case, the slippage may not begin to take place when expected and the winder can keep increasing the tension in the mainspring to the point that overbanking begins. This refers to the condition in which the swing amplitude of the balance wheel goes well past its normal bounds and begins to bounce from its "crash stops", so to speak. The result is a drastic increase in rate of minutes per hour, lasting until the mainspring has a chance to relax to a normal level again and exposing the escapement parts to the risk of permanent damage. It is the equivalent of winding a manual-wind watch right to the "brick wall" resistance that signals the mainspring's reaching the limit of its capacity and then simply continuing to force the crown against the stop instead of letting go and allowing the mainspring to back off a few degrees as it was designed to do.

Interestingly, the above excess torque is far less likely to develop on the wrist, even if the watch's lubrication is less than perfect, simply because the impulses on the mainspring are short and sporadic as described earlier. Here, the situation is equivalent to a manual-wind watch being wound to its full capacity and then the crown being given sharp but short twists against the "brick wall" resistance, allowing a couple of seconds to pass between these attacks. The effect on the watch's rate in such case will be very minor.

For a final illustration of the contrast between wearing a watch and winding it on a winder, let's consider something all TZers know, i.e., that you can manually force a watch to wind quickly for short periods by forcing the rotor to turn continuously. This is done by holding the watch face up and swirling it in circles of just the right rhythm, the same motion used to swirl a drink in a glass. It is the technique recommended for starting stopped automatics that lack provision for manual winding through the crown (e.g., Seiko divers using the 7S26 movement). But such motions are rare in the course of daily life and are not an expected phenomenon. If they were, the watch manufacturers would have made specific provisions to deal with them. Yet this is precisely what happens when a watch is on a winder.

The inevitable conclusion from the above considerations is that the watch is subjected to a wholly different treatment on the winder than it is on the wrist.


Click here to continue to Part 2


 
 

Back to top of page | Return to Time Zone Home Page
Copyright © 2001-2004 A Bid Of Time, Inc., All Rights Reserved
E-mail: info@TimeZone.com