How the Bulova Precisionist Works

Maybe a cell phone can't replicate the aesthetics of a wristwatch, but in case you'd like to try, Bulova released a free iPhone and iPad clock/alarm app in December 2011 that features six watch face designs, including two Precisionists.
Photo by Lauren Vogelbaum/HowStuffWorks 2012

Time-telling tools are everywhere these days. Think about the number of mobile devices, clocks on computer sidebars and car radio displays you see before lunch on any given workday; there are plenty of ways to stay on top of the time, it seems.

But there's something about the face of an elegant wristwatch that just can't be duplicated in LEDs, liquid crystal or pixels. The three-handed watch face has served centuries' worth of explorers, businesspeople and users who simply want to mix high style with punctuality.

Of course, that's not to say that watch aficionados will tolerate lesser accuracy for the sake of a pretty piece of wrist jewelry. A watch is a tool first and foremost, and its ability to display reasonably accurate time is the key feature that differentiates it from a mere bangle. Some die-hards may stick to manual-wind watches or their automatic-watch cousins, citing the intricate beauty of their tiny mechanisms and the smooth sweep of their second hands as signs of high class, but most watch-wearers expect the relatively better accuracy and ease of use that come from a watch equipped with a quartz crystal movement.

A number of manufacturers have tried to combine the smoothness of a mechanical watch movement with the precision of the quartz crystal mechanism: Seiko's Spring Drive mechanism marries mechanical power with electronic regulation, while Citizen's Eco-Drive adds solar power and a tiny kinetic generator to the mix. But watchmaker Bulova took a different path in 2010 when it released its Precisionist mechanism: The company claims that this advanced take on quartz watch technology has raised the bar, creating the most precise watch to feature a continuous-sweep second hand [sources: Bulova; Seiko; DiFranco].

Bulova claims that the Precisionist strays from true accuracy 10 seconds or less per year, far better than the 15 seconds per month the company claims is standard for most quartz watches [source: Bulova]. But is that true? Does the Precisionist live up to the billing as a class-leading piece of technology? And how does this unique mechanism eke both smooth movement and high precision out of a quartz crystal mechanism? Take a few minutes to read on; it'll be well worth your time.

Some Background on Time and Timepieces

This isn't a Precisionist, but here you can see the inner workings of a quartz watch. The purplish bits are artificial ruby bearings, which create less friction and are longer lasting than metal bearings.
This isn't a Precisionist, but here you can see the inner workings of a quartz watch. The purplish bits are artificial ruby bearings, which create less friction and are longer lasting than metal bearings.
©iStockphoto.com/chasmer

Before we dive into the question of accuracy, let's take a second to get philosophical. Time measurement, after all, is something of an arbitrary construct. The seconds, minutes and hours we use to track duration are basically agreed-upon standards that humankind has employed to represent our march from the past into the future. Existence would not stop if we chose to stop tracking time in such a precise matter -- we could function just fine if our main time measurement consisted of sunrise, sunset and the position of the sun in between. A deep dive into the nature of time digs into such sticky wickets as multidimensionality, time travel and the nature of the universe. But for those of us inclined toward more concrete discussions, timepieces offer a more manageable topic [source: Biba].

Somewhere along the line, our ancestors decided that it was useful to track measured units of time. It may have been a pre-Egyptian noble or scholar who first noticed the steady march of shadows on a sunny day, but sundials -- the earliest timepieces -- have been recovered from archeological sites dating back to 800 B.C. [source: Gascoigne].

Modern watches and clocks work using principles that first came into widespread use in the middle of the 17th century: A resonator, which is a device such as a pendulum, spring-driven flywheel or electrified quartz crystal, oscillates, which means it vibrates or swings back and forth at a consistent, measurable rate. A timepiece will use gears, cams, electric circuits or a combination thereof to translate that oscillation into the measured movement of the clock's hands or a digital readout of the time [sources: Gascoigne, DiFranco].

For example, a grandfather clock may have a pendulum designed to swing from one side to the other every second. That motion momentarily releases a spring in the clock's mechanism, allowing the second, minute and hour hands to progress by their respective distances around the clock face. Suppose, now, that your clock has a pendulum that swings every half-second, doubling its oscillation. Your clock can now track half-seconds, giving the hands a smoother motion and allowing you to adjust it with a finer degree of precision. Take this concept, replace the pendulum with an object that oscillates at an extremely high frequency -- multiple times per second -- and you have the makings of a modern timepiece.

How precise can clocks be?

Check out these videos to learn more about clocks, from ancient cultures' timepiece inventions to how machines help mass produce watches today.
Science Channel

High-end watches can vary in accuracy depending on their mechanisms. Watch manufacturer Seiko claims its Spring Drive -- an electrically adjusted automatic mechanism -- varies by no more than one second per day, for example. Breitling, which markets its watches as pinnacle-of-performance timepieces for aviators and sailors, bills its automatics as meeting the Swiss Official Chronometer Testing Institute (COSC) standard for daily variation: no more than four seconds fast or six seconds slow per day. Quartz watches -- even relatively inexpensive ones -- can be expected to vary or drift by one second or less over the course of 24 hours [source: Lombardi].

The Bulova Precisionist has a claimed accuracy of 10 seconds of variation per year, drifting less in one month than a decent quartz watch might vary in a day. That may sound very accurate, and may be totally acceptable for most users. But wristwatches as a whole can't hold a candle to the mother of all accurate timekeepers: atomic clocks.

Forget pendulums; these precision machines use a variety of methods to measure the inherent oscillation of individual atoms. Working as tiny resonators, atoms vibrate at extremely high frequencies; Cesium atoms, for example, resonate at 9,192,631,770 hertz, or cycles per second. Atomic oscillation is also very consistent: Researchers behind a London-based clock using the so-called Cesium fountain process say that their machine is accurate to within two 10 million billionths of a second. Granted, the clock suffers from the inherent problem with atomic clocks from a consumer standpoint: they're large, sterile arrays of chambers, tubes, wires and scaffolds -- not something that would look nice on your wrist, and not exactly an affordable item available at the corner drugstore [source: Loftus]. But it's nice to know the gold standard when you're talking about time. (Learn more about atomic clocks in our article, How Atomic Clocks Work.)

The Bulova Precisionist is nowhere near as accurate as an atomic clock, but it does hold its own against other wristwatches in its price range. Read on to learn how the watchmaker squeezes this level of precision out of what is essentially an accurized quartz movement.

How the Precisionist Mechanism Works

At its heart, the Precisionist mechanism uses tried-and-true quartz crystal technology: A carefully measured electrical current energizes a quartz crystal shaped like a tuning fork, which begins to oscillate at a particular frequency. This vibration creates electrical pulses at a consistent rate; the watch's integrated circuits use those pulses to trigger the watch motor. The motor, in turn, moves the gears, and thus the hands, a tiny distance with each pulse. (To learn more about the process, check out our article on How Quartz Watches Work.)

This mechanism overcomes a number of the problems faced by manual and self-winding watches, most notably the dependence on a delicate balance of wheels and springs. These precise components can be affected by gravity and strong electromagnetic fields, and they lose accuracy if not regularly cleaned and tuned. But quartz watches aren't invincible; beyond the need to replace the battery over time, the mechanisms hinge on the integrity of a tiny quartz tuning fork. Change the fork's temperature or contaminate its surface with even a little dirt or dust, and its oscillating frequency can change, throwing off the entire system [source: DiFranco].

The Precisionist uses a pair of tech tricks to overcome the quartz mechanism's weak points. First, its crystal is unique: most quartz watches use crystals shaped into two-pronged tuning forks, but the Precisionist literally goes one better with a three-pronged fork that the company claims can oscillate at 262.144 kilohertz (or 16 beats per second), about eight times faster than the 32.768 kilohertz (about 1 to 2 beats per second) that is the typical frequency for quartz oscillators. For comparison, the balance wheels of most mechanical watches oscillate at frequencies of 8 to 10 beats per second. Like a microscope being able to show more detail at 100X magnification than at 20X, the higher-frequency oscillation means the watch's processor can measure smaller fractions of each second, giving it more precise data to translate into the hands' movement [sources: Lombardi; Arnstein].

Bulova engineers tackled the problem of temperature fluctuation by adding temperature regulation to the Precisionist's circuitry. The circuitry in the watch essentially senses temperature changes and adapts to corresponding changes in the quartz crystal's electric pulses. It's a small adjustment that might seem too miniscule to bother with, but tiny changes in pulse strength at the crystal's high oscillation frequency can add up to accuracy-killing deviations as the temperature changes [sources: Lombardi; DiFranco].

Precisionist Materials and Bulova's History

The clock atop Denver's Coors Field is a Bulova timepiece.
The clock atop Denver's Coors Field is a Bulova timepiece.
George Rose/Getty Images

As of Spring 2012, Bulova offered the Precisionist movement in six style collections ranging from sporty to dressy with prices ranging from about $300 to $900. For the most part, the collections target fashion-conscious consumers, with the major difference among the styles involving face shapes, engravings, colors and material selections. These range from slim stainless steel cases with leather straps, mother-of-pearl inlays and diamond accents to chunky titanium cases with ballistic fabric straps and carbon fiber inlays.

Most of the watches are water resistant to about 100 feet (30 meters) -- although one might find it hard to imagine taking the diamond-studded designs anywhere near a pool, let alone an ocean. The Champlain collection incorporates screw-back cases and extra gaskets to push the water resistance to about 900 feet (300 meters), making them suitable for use by divers [source: Bulova].

The Bulova Watch Company is employing new-to-the-market ideas in the Precisionist mechanism, but the company itself is no spring chicken. It has been in existence since 1875, and launched its first line of wristwatches in 1919 to respond to the demand of soldiers in World War I, who needed easier access to an accurate timepiece than could be had from a pocket watch. Bulova's wrist-mounted option caught on, and veterans brought the idea home from the battlefield.

Over the years, Bulova has had other firsts that go beyond watch making. In 1941, the company made advertising history when a commercial for its wares aired during a baseball game. Legend has it the company paid a whopping $9 for the commercial (for more on Bulova's commercial first, see our article 10 TV Moments that Changed the World). And the company's Accutron quartz-tuning-fork–regulated technology, which has been used everywhere from NASA satellites to the first moon walk to Air Force One, remains a solid contender in the watch market today.

Author's Note: How the Bulova Precisionist Works

This one's gonna cost me.

As I spent my research time studying the inner workings of various high-end watches, I realized how much work goes into making an accurate timepiece. Think about it: When the various parts in a watch are measured in microns, something as small as a misplaced drop of lubricant or a stray eyelash can be the difference between a useful piece of jewelry and a dud just waiting to be returned to the manufacturer. Even microscopic bits of dust can do a number on a watch's precision. And then there's temperature, magnetic fields, imbalances not aligned with the expected gravitational pull ... but I digress.

My paranoia came from studying my own watch, a well-loved, off-brand automatic I got a few years ago as a gift. I still get a kick out of its skeletonized mechanism that lets me watch the balance wheel flicker back and forth as the second hand ticks around at 4 beats per second.

But it's drifting, or at least that's the way it seems. Maybe it's simply in need of lubrication and a little cleaning. Or perhaps it's bounced off the floor one time too many in my early-morning fumbling to get dressed for work. Either way, all it took was this article to get me paying attention to the watch's accuracy.

It's true that automatics are less precise than quartz watches. And I have to admit that some of the Precisionist models are quite attractive. My brain's now working, and I can see it: a well-earned paycheck from writing about watches will arrive just in time ... to plunk down for a nice new watch.

Funny how those things go, isn't it?

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Sources

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  • Connor, Sean. "The amazing Bulova Accutron." (March 9, 2012) http://www.elektron.demon.co.uk/accutron.html
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  • Loftus, Jack. "This clock won't be late for another ten million years, give or take." Gizmodo." Aug. 28, 2011 (March 10, 2012) http://gizmodo.com/5835138/the-worlds-most-accurate-timepiece-resides-in-london
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  • Seiko. "Mechanism: The genius of Spring Drive." 2008. (March 9 2012) http://www.seikospringdrive.com/flash.html