Search

LIV Search

All Hail the Mighty Mainspring

Contents

Part 1:
A mechanical watch is a thing of beauty

Part 2:
The mainspring: a brief history

Part 3:
The mechanics of a mainspring

Part 4:
Mainspring maintenance

Part 5:
Mainspring myths

Part 6:
In conclusion

A mechanical watch is a thing of beauty

Early development

Even the most modest mechanical watch houses a host of components in what can only be described as miniature feats of engineering excellence and creative daring. Yet one of its most critically important components is also one of its least hailed. That often overlooked component is the mainspring, which is unwarranted given how important it is to any mechanical watch. After all, the ‘magic coil’ that is a mainspring is at the heart of any mechanical watch.

There is a reason why Bloomberg referred to the mainspring as, “Watchmaking’s Most Essential and Underappreciated Component” in a February 2020 article. We here at LIV Watches are so enamored of mechanical watches that we thought it only right to pay homage to this most deserving component. This article will provide some insight into the brief history and basic mechanics of the mainspring. It will also look into some of the maintenance aspects thereof, as well as a few of the typical myths relating to mainsprings.

Keys of various sizes for winding up mainsprings on clocks.

Keys of various sizes for winding up mainsprings on clocks

The mainspring: a brief history

WWI and the interwar years

To understand the history of watches, one needs to delve into the history of clocks. It was weights, not mainsprings, that powered the earliest known clocks of Europe. Gravity did all the work to convert the torque needed to drive a clock’s gear train. The actual inventor of the ‘coiled spring’ that is the mainspring as we know it today is unknown. It is thought that the technology was developed from coiled springs first used in medieval locks made by locksmiths. What is known is the world’s oldest existing clock powered by a mainspring, which was a gift given to Philip the Good, Duke of Burgundy, in 1430. The clock is housed today in the Germanisches Nationalmuseum in Nuremberg, a testament to the complexity of timekeeping ingenuity already prevalent in the 15th century.


The sheer complexity of producing a mainspring at that time and in the centuries thereafter cannot be underestimated. The steel needed for a mainspring required very specific properties in order to be crafted into its unique, coiled shape, including its requisite tensile strength. Furthermore, the requisite thinness of the mainspring often proved an even greater challenge for steel-makers of the day. It wouldn’t be an exaggeration to conclude that the mainspring for an 18th century watch could take days of careful, hard labor. This immensely complex technique was described at length in 69 different sections in the book, The Art Of Making Watch Springs (or L’Art de Faire les Ressorts de Montres in its original French) by the English watchmaker, William Blakey, published in 1780.The mass production of mainsprings was only possible almost a century after Blakey’s book was released. The Industrial Revolution had ushered in milling machines that could mass-produce multiple, complex components. Carbon steel mainsprings were an improvement on former steel examples but were still flawed in that they lost elasticity over time. More metallurgically precise alloys emerged after World War II, which resulted in mainsprings that didn’t ‘set’ (lose elasticity) or break so easily. But they were still prone to excessive friction and wear. It was around 1965 that cold-rolled alloys that were less vulnerable to friction and wear replaced carbon steel in mainspring manufacture.

In five short years following Bleriot's flight, Europe and most of the rest of the world was plunged into the horror of WWI. Dirigibles and observation balloons were still in use but eventually succumbed to the rapidly developing airplanes. Watches and compasses now served to guide bombers to targets to deliver their ordnance as accurately as possible.

The airplanes of WWI were often hard to control. That meant the pilot was ill-advised to take his hands off the controls to retrieve his pocket watch. The same value that leads Santos-Dumont to seek a solution carried full force into combat.

Most aerial combat during WWI occurred during the day due to lack of proper instruments and lights. Bad weather almost always grounded the planes of the time. So watches did not need large quantities of luminescence. The just needed to be easy to read. Therefore, the iconic black dial and large contrasting Arabic numerals became standard issue.

As a result of experiences in WWI, U.S. Navy captain Philip Van Horn Weems designed an independently adjustable seconds ring. This feature allowed pilots to accurately synchronize their watch with a radio time signal without stopping the sweep seconds hand. Although "hacking" watch movements to allow everyone in a combat unit to synchronize their watches to the second, the practice could result in throwing pilots off course, ruin missions, and risk the airplane and crew.

Following his successful trans-Atlanic flight in 1927, Charles Lindbergh collaborated with Weems to develop the Hour Angle system which further enabled the wristwatch to determine longitude.

The German military specified a design that set the standard for what we think of as a classic pilot's watch today. By 1936, aviation advances allowed airplanes to fly at all hours and in foul weather (although grounding in severe conditions was common). The result was the Beobachtungsuhr (B-Uhr), or Observer.

Modern mainspring alloys include Nivaflex, made by the Swiss manufacturer Nivarox, which is owned by the giant Swatch Group. Nivaflex consists of 45% cobalt, 21% nickel, 18% chrome, 5% iron, and 11% other metals. Nivaflex mainsprings have many benefits, including being anti-magnetic.

Crucially important for a mainspring, they also have an extremely high tensile strength of up to 3,000 megapascals and attain values of 800 or greater on the Vickers hardness scale(see representation of the principle below). Just to provide a comparison that any watch enthusiast will appreciate, the 316L stainless steel used in the cases and bracelets of many better watches has a range of between 200 and 240 Vickers in hardness.

That means a Nivaflex mainspring is almost four times stronger than high-quality stainless steel! These mainsprings are also highly resistant to reverse bending and can retain temperature stability at anywhere between -58F and 660 degrees Fahrenheit (that equates to a range of -50 to 350 degrees Celsius). Importantly, they are also highly corrosion-resistant.

"Modern mainsprings are indeed far harder, stronger, and more durable than their carbon steel antecedents. The result is watches that are more durable and should last longer."

- Esti Chazanow

Co-Founder at LIV Watches

The mechanics of a mainspring

A mainspring is essentially a flat and thin, coiled blade made of a very flexible steel alloy. It is the ‘energy storehouse’ of the watch. This energy is generated each time the watch is wound, whether automatically or manually, since the curvature of the tightly coiled mainspring is increased, thereby allowing energy to be stored. The coiled shape allows for more even distribution of energy. This stored energy is transmitted to the oscillating section of the watch, known as the balance, via the gear train (or ‘wheel train’) and escapement. It is this fine balancing act between these components and released energy that control the proper timing of the watch.

A mainspring is all about the torque it can generate, being directly proportional to its width and which is why it needs to be so tightly coiled. Hence the reason why a mainspring has a maximum thickness of just 0.00295276 inches (that’s a mere 75/1,000 mm). The thicker the mainspring, the greater its torque, whilst the longer it is, the greater the watch’s running time. However, the snag is that torque is lost with each added millimeter of mainspring. And therein lies the greatest challenge for watchmakers regarding the mainspring: making it long enough to ensure longer running times for a mechanical watch, whilst ensuring that torque remain constant and strong. It’s no easy feat!

Typically, a mainspring is attached to a steel rod (an arbor), which is in turn attached to the crown. This allows the mainspring to be coiled each time the watch is wound. The arbor is held in place by what is called a click while the watch is running. It isn’t the arbor that rotates, but the mainspring barrel in which the mainspring is housed, which has gear teeth that engage the pinions of the gear train (also known as the ‘transmission system’ of a watch).

The gear train primarily comprises the four gears or ‘wheels,’ i.e. the center, third, and fourth wheels, as well as escape wheel and the pallet lever. Each wheel runs at a different speed or, more precisely, each wheel runs more quickly than the one preceding it. The first wheel after the mainspring barrel is the center wheel. It does one one full turn every 12 hours, to which is attached the hour hand. The third wheel is an intermediate wheel and is proceeded by the fourth or seconds wheel, which performs a full turn every 60 seconds and to which is attached the seconds hand. The final wheel, or escape wheel, is technically not part of the gear train but the escapement. Its function is to release energy to the pallet lever.

Bottom line: none of this energy in the gear train and its allied components would be possible without the energy being constantly released from the tightly coiled mainspring.

Mainspring maintenance

Something as thin, tightly wound, and requiring as much tensile integrity as a mainspring could run into problems, even when made with today’s far stronger, highly durable alloys. Since a mainspring is the energy powerhouse of a mechanical watch, so adequate power to or in the mechanism is all-important. Sometimes that intake or release of energy to or from the mainspring will fail for a variety of different reasons.

It’s worth noting that a watch movement may be in excellent condition, yet the watch may nevertheless not work properly simply because the mainspring can no longer deliver maximum energy needed to the gear train. For example, these are some of the signs that a mainspring could be in trouble in a manually-winding mechanical watch:

  • The watch simply doesn’t run
  • The watch runs slowly
  • The watch runs erratically, i.e. fast and then slow, and then fast again, etc.
  • The crown turns endlessly

The above could be due a broken or slipping mainspring, or, more specifically, to the mainspring barrel’s hook or arbor hook not catching properly when being wound.

It goes without saying that maintenance of any watch component is best undertaken by a professional. However undertaken, the maintenance of a mainspring should include the following factors:

  • The mainspring and its barrel’s diameter, height, thickness, length, and type will need to be known before maintenance can occur. The length will always need to be estimated due to the tightly coiled nature of the spring.
  • A thorough cleaning and lubrication with a good-quality mainspring lubricant may be necessary. Importantly, the lubricant or ‘grease’ should be appropriate for the caliber of the watch being serviced. For example, if the grease is too thick then it will prevent the spring from unwinding smoothly inside the barrel. This will result in intervals of irregular power distribution, which will almost certainly affect the performance of the watch.
  • Some of the most common greases used in the cleaning and maintenance of mainsprings, including the inside of the barrel, are Moebius 8217 natural grease, 8141 natural oil, and D-5 microgliss.
  •  

Some watch experts believe that the best form of mainspring maintenance is to simply replace it each time the watch is serviced, given that mainsprings are relatively inexpensive and simple to replace. This is also the consensus in online watch repair forums. Also, expensive mainspring winders won’t be needed when fitting a new mainspring. This saves a substantial amount of money because these tools are expensive. Furthermore, time and potential mishaps are avoided since a new mainspring means not having to clean, lubricate, and re-fit an existing mainspring.

Mainspring myths

Mainsprings may be razor-thin, tiny and tightly-coiled, but they’re not exactly fragile either. Nor are they made of porcelain (!) - remember, mainsprings are precisely made to be tough, durable, and flexible. This ‘fragility’ myth is just one of the factors that feeds the many myths that surround mainsprings. Here are just four of those myths:

1 • Watch winders are essential for vintage watches: Incorrect.
This myth results from the logic that self-winding or automatic movements benefit from being in constant motion, hence the need for winders. In fact, watch winders can be particularly problematic for vintage watches. The constant winding may put undue wear on the winding system of the watch, and it can also dry out the mainspring’s lubrication more quickly.

2 • It’s best to leave an old mainspring in for the ‘integrity of the movement: Incorrect.
As already explained above in the maintenance section, the replacement of a mainspring is usually the best solution when doing cleaning or maintenance on a watch movement. ‘Integrity’ of a movement is itself a myth of sorts. Like any mechanical device, a movement will invariably require replacement of certain of its parts during its lifetime. Ask any car collector about that! The same goes for watches.

 3 • Replacement of a mainspring will devalue a vintage watch: Incorrect.
See point 2 above. Any watch expert will confirm that assessing the exact ‘provenance’ of a movement is far more difficult than one would think. And nor does replacing a mainspring in any way devalue the worth of a good watch.

4 • You must be careful not to wind a mechanical watch too much: Incorrect.
This is actually one of the most enduring myths of all regarding mechanical watches and, by extension, mainsprings. Watch experts will categorically state that ‘over-winding’ of a decent-quality modern mechanical watch is not actually possible. The winding mechanism of a mechanical watch, whether manual or automatic, simply ‘decouples’ from the mainspring when it is fully wound. It can literally be wound to infinity thereafter without any damage to the mainspring.

There is an important caveat however: an old or poor quality watch can result in a damaged mainspring if over-wound. So keep that in mind when winding your vintage or inexpensive mechanical watch!

In conclusion

Perhaps now one can better appreciate why we thought it necessary to dedicate an entire article to a tiny, coiled piece of metal found in any mechanical watch. Think of it as ‘the little engine that could,’ and without which a mechanical watch is no more.

Contents

Part 1:
A mechanical watch is a thing of beauty

Part 4:
Mainspring maintenance

Part 2:
The mainspring: a brief history

Part 5:
Mainspring myths

Part 3:
The mechanics of a mainspring

Part 6:
In conclusion

Early development

A mechanical watch is
a thing of beauty

Even the most modest mechanical watch houses a host of components in what can only be described as miniature feats of engineering excellence and creative daring. Yet one of its most critically important components is also one of its least hailed. That often overlooked component is the mainspring, which is unwarranted given how important it is to any mechanical watch. After all, the ‘magic coil’ that is a mainspring is at the heart of any mechanical watch.

Given the fact that Santos-Dumont was a regular participant at the airshows of the day, other pilots exhibited one of the earliest known examples of wrist envy. As a result, the pilot's watch soon became a "must-have" instrument in the cockpit. And, not just for "keeping up the the Santos-Dumonts" reasons. Advances in powered flight were enabling planes to fly further and faster. With a reliable watch and a compass, pilots had the tools they needed to calculate time-speed-distance, determine when to move to the next leg of a flight, judge how much fuel was left, and generally be safer in the air.

Pilot Louis Bleriot wore a Zenith wristwatch when he made aviation history being the first to fly an airplace across the English Channel in July of 1909. Taking advantage of the feat for marketing purposes, Bleriot commented upon landing that he was very satisfied with his Zenith and would recommend it to others. The records are unclear on the point of Bleriot's comment being spontaneous or rehearsed.

WWI and the interwar years

"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."

- Chaz Chazanow

Founder at LIV Watches

Advances during WWII

French watchmaker Zenith continued to manufacture their pilot's watches. Striking a neutral stance, Zenith sold its watches to both the Allies and the Axis. They used their 1939 Type Montre d"Aeronef design as the basis of their wristwatch. It featured the black dial and white arabic numerals with the large onion-style crown at 3 o'clock.

The United States did not produce a purpose-made pilot's watch. One of the most widely produced models supplied to American forces was the A-11. Manufactured by Bulouva, Waltham, and Elgin, the watch featured the required high-visibility black dial with white Arabic numerals. The manually wound movement featured a hacking function for synchronization. Some A-11s were waterproof, some were dust proof, some had luminous hands, , and some did not. All had a larger crown at 3 o'clock, but not in the onion style.

Postwar evolution

Keys of various sizes for winding up mainsprings on clocks

There is a reason why Bloomberg referred to the mainspring as, “Watchmaking’s Most Essential and Underappreciated Component” in a February 2020 article. We here at LIV Watches are so enamored of mechanical watches that we thought it only right to pay homage to this most deserving component. This article will provide some insight into the brief history and basic mechanics of the mainspring. It will also look into some of the maintenance aspects thereof, as well as a few of the typical myths relating to mainsprings.

The mainspring: a brief history

To understand the history of watches, one needs to delve into the history of clocks. It was weights, not mainsprings, that powered the earliest known clocks of Europe. Gravity did all the work to convert the torque needed to drive a clock’s gear train. The actual inventor of the ‘coiled spring’ that is the mainspring as we know it today is unknown. It is thought that the technology was developed from coiled springs first used in medieval locks made by locksmiths. What is known is the world’s oldest existing clock powered by a mainspring, which was a gift given to Philip the Good, Duke of Burgundy, in 1430. The clock is housed today in the Germanisches Nationalmuseum in Nuremberg, a testament to the complexity of timekeeping ingenuity already prevalent in the 15th century.


The sheer complexity of producing a mainspring at that time and in the centuries thereafter cannot be underestimated. The steel needed for a mainspring required very specific properties in order to be crafted into its unique, coiled shape, including its requisite tensile strength. Furthermore, the requisite thinness of the mainspring often proved an even greater challenge for steel-makers of the day. It wouldn’t be an exaggeration to conclude that the mainspring for an 18th century watch could take days of careful, hard labor. This immensely complex technique was described at length in 69 different sections in the book, The Art Of Making Watch Springs (or L’Art de Faire les Ressorts de Montres in its original French) by the English watchmaker, William Blakey, published in 1780.The mass production of mainsprings was only possible almost a century after Blakey’s book was released. The Industrial Revolution had ushered in milling machines that could mass-produce multiple, complex components. Carbon steel mainsprings were an improvement on former steel examples but were still flawed in that they lost elasticity over time. More metallurgically precise alloys emerged after World War II, which resulted in mainsprings that didn’t ‘set’ (lose elasticity) or break so easily. But they were still prone to excessive friction and wear. It was around 1965 that cold-rolled alloys that were less vulnerable to friction and wear replaced carbon steel in mainspring manufacture.

Modern mainspring alloys include Nivaflex, made by the Swiss manufacturerNivarox, which is owned by the giant Swatch Group. Nivaflex consists of 45% cobalt, 21% nickel, 18% chrome, 5% iron, and 11% other metals. Nivaflex mainsprings have many benefits, including being anti-magnetic.

Crucially important for a mainspring, they also have an extremely high tensile strength of up to 3,000 megapascals and attain values of 800 or greater on the Vickers hardness scale(see representation of the principle below). Just to provide a comparison that any watch enthusiast will appreciate, the 316L stainless steel used in the cases and bracelets of many better watches has a range of between 200 and 240 Vickers in hardness.

That means a Nivaflex mainspring is almost four times stronger than high-quality stainless steel! These mainsprings are also highly resistant to reverse bending and can retain temperature stability at anywhere between -58F and 660 degrees Fahrenheit (that equates to a range of -50 to 350 degrees Celsius). Importantly, they are also highly corrosion-resistant.

"Modern mainsprings are indeed far harder, stronger, and more durable than their carbon steel antecedents. The result is watches that are more durable and should last longer."

- Esti Chazanow

Co-Founder at LIV Watches

The mechanics of a mainspring

A mainspring is essentially a flat and thin, coiled blade made of a very flexible steel alloy. It is the ‘energy storehouse’ of the watch. This energy is generated each time the watch is wound, whether automatically or manually, since the curvature of the tightly coiled mainspring is increased, thereby allowing energy to be stored. The coiled shape allows for more even distribution of energy. This stored energy is transmitted to the oscillating section of the watch, known as the balance, via the gear train (or ‘wheel train’) and escapement. It is this fine balancing act between these components and released energy that control the proper timing of the watch.

A mainspring is all about the torque it can generate, being directly proportional to its width and which is why it needs to be so tightly coiled. Hence the reason why a mainspring has a maximum thickness of just 0.00295276 inches (that’s a mere 75/1,000 mm). The thicker the mainspring, the greater its torque, whilst the longer it is, the greater the watch’s running time. However, the snag is that torque is lost with each added millimeter of mainspring. And therein lies the greatest challenge for watchmakers regarding the mainspring: making it long enough to ensure longer running times for a mechanical watch, whilst ensuring that torque remain constant and strong. It’s no easy feat!

"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."

- Esti Chazanow

Co-Founder at LIV Watches

Typically, a mainspring is attached to a steel rod (an arbor), which is in turn attached to the crown. This allows the mainspring to be coiled each time the watch is wound. The arbor is held in place by what is called a click while the watch is running. It isn’t the arbor that rotates, but the mainspring barrel in which the mainspring is housed, which has gear teeth that engage the pinions of the gear train (also known as the ‘transmission system’ of a watch).

The gear train primarily comprises the four gears or ‘wheels,’ i.e. the center, third, and fourth wheels, as well as escape wheel and the pallet lever. Each wheel runs at a different speed or, more precisely, each wheel runs more quickly than the one preceding it. The first wheel after the mainspring barrel is the center wheel. It does one one full turn every 12 hours, to which is attached the hour hand. The third wheel is an intermediate wheel and is proceeded by the fourth or seconds wheel, which performs a full turn every 60 seconds and to which is attached the seconds hand. The final wheel, or escape wheel, is technically not part of the gear train but the escapement. Its function is to release energy to the pallet lever.

Bottom line: none of this energy in the gear train and its allied components would be possible without the energy being constantly released from the tightly coiled mainspring.

Mainspring maintenance

Something as thin, tightly wound, and requiring as much tensile integrity as a mainspring could run into problems, even when made with today’s far stronger, highly durable alloys. Since a mainspring is the energy powerhouse of a mechanical watch, so adequate power to or in the mechanism is all-important. Sometimes that intake or release of energy to or from the mainspring will fail for a variety of different reasons.

It’s worth noting that a watch movement may be in excellent condition, yet the watch may nevertheless not work properly simply because the mainspring can no longer deliver maximum energy needed to the gear train. For example, these are some of the signs that a mainspring could be in trouble in a manually-winding mechanical watch:

  • The watch simply doesn’t run
  • The watch runs slowly
  • The watch runs erratically, i.e. fast and then slow, and then fast again, etc.
  • The crown turns endlessly

The above could be due a broken or slipping mainspring, or, more specifically, to the mainspring barrel’s hook or arbor hook not catching properly when being wound.

It goes without saying that maintenance of any watch component is best undertaken by a professional. However undertaken, the maintenance of a mainspring should include the following factors:

  • The mainspring and its barrel’s diameter, height, thickness, length, and type will need to be known before maintenance can occur. The length will always need to be estimated due to the tightly coiled nature of the spring.
  • A thorough cleaning and lubrication with a good-quality mainspring lubricant may be necessary. Importantly, the lubricant or ‘grease’ should be appropriate for the caliber of the watch being serviced. For example, if the grease is too thick then it will prevent the spring from unwinding smoothly inside the barrel. This will result in intervals of irregular power distribution, which will almost certainly affect the performance of the watch.
  • Some of the most common greases used in the cleaning and maintenance of mainsprings, including the inside of the barrel, are Moebius 8217 natural grease, 8141 natural oil, and D-5 microgliss.
  •  

Some watch experts believe that the best form of mainspring maintenance is to simply replace it each time the watch is serviced, given that mainsprings are relatively inexpensive and simple to replace. This is also the consensus in online watch repair forums. Also, expensive mainspring winders won’t be needed when fitting a new mainspring. This saves a substantial amount of money because these tools are expensive. Furthermore, time and potential mishaps are avoided since a new mainspring means not having to clean, lubricate, and re-fit an existing mainspring.

Mainspring myths

Mainsprings may be razor-thin, tiny and tightly-coiled, but they’re not exactly fragile either. Nor are they made of porcelain (!) - remember, mainsprings are precisely made to be tough, durable, and flexible. This ‘fragility’ myth is just one of the factors that feeds the many myths that surround mainsprings. Here are just four of those myths:

1 • Watch winders are essential for vintage watches: Incorrect.
This myth results from the logic that self-winding or automatic movements benefit from being in constant motion, hence the need for winders. In fact, watch winders can be particularly problematic for vintage watches. The constant winding may put undue wear on the winding system of the watch, and it can also dry out the mainspring’s lubrication more quickly.

2 • It’s best to leave an old mainspring in for the ‘integrity of the movement: Incorrect.
As already explained above in the maintenance section, the replacement of a mainspring is usually the best solution when doing cleaning or maintenance on a watch movement. ‘Integrity’ of a movement is itself a myth of sorts. Like any mechanical device, a movement will invariably require replacement of certain of its parts during its lifetime. Ask any car collector about that! The same goes for watches.

3 • Replacement of a mainspring will devalue a vintage watch: Incorrect.
See point 2 above. Any watch expert will confirm that assessing the exact ‘provenance’ of a movement is far more difficult than one would think. And nor does replacing a mainspring in any way devalue the worth of a good watch.

4 • You must be careful not to wind a mechanical watch too much: Incorrect.
This is actually one of the most enduring myths of all regarding mechanical watches and, by extension, mainsprings. Watch experts will categorically state that ‘over-winding’ of a decent-quality modern mechanical watch is not actually possible. The winding mechanism of a mechanical watch, whether manual or automatic, simply ‘decouples’ from the mainspring when it is fully wound. It can literally be wound to infinity thereafter without any damage to the mainspring.

There is an important caveat however: an old or poor quality watch can result in a damaged mainspring if over-wound. So keep that in mind when winding your vintage or inexpensive mechanical watch!

In conclusion

Perhaps now one can better appreciate why we thought it necessary to dedicate an entire article to a tiny, coiled piece of metal found in any mechanical watch. Think of it as ‘the little engine that could,’ and without which a mechanical watch is no more.