Pocket Watches Advanced
Watchmaking 101
How does the balance wheel affect accuracy? What were stopworks used for? Where are the meantime screws?
Learn the basics of jeweling, configuration styles, railroad standards, watch mechanics, movement sizes, winding and setting, dial construction, types of adjustments, and more.
The Components
The Primary Components
These are the primary components in most pocket watches, though the visual layout may change between models:
The Mainspring
- Click - prevents the mainspring from unspooling
- Barrel Cover - traps the mainspring
- Mainspring - stores power to drive the gear train
- Mainspring Barrel - holds the mainspring and meshes with the center wheel
- Ratchet Wheel - meshes with the crown wheel and winds up the mainspring
- Mainspring Arbor - mounts the ratchet wheel and hooks the spooled mainspring
- Crown Wheel - transfers power from the winding stem to the ratchet wheel
The Gear Train
- Third Wheel - meshes with the center and 4th wheels
- Fourth Wheel - meshes with the 3rd and escape wheels
- Fourth Wheel Pinion - mounts the seconds hand
- Center Wheel - meshes with the barrel and 3rd wheel
- Safety Pinion - uncouples if the mainspring breaks
- Center Wheel Pinion - mounts the canon pinion, which mounts and drives the hour and minute hands
The Balance Assembly
- Escape Wheel - meshes with the 4th wheel and pallet
- Pallet Fork - receives impulse from the roller jewel
- Balance Wheel - oscillates to control accuracy
- Hairspring - sets the oscillation of the balance wheel
- Balance Staff - the pivoted axle of the balance wheel
- Collet - attaches the hairspring to the balance staff
- Hairspring Stud - anchors the tail of the hairspring
- Weights - controls the rate and positional accuracy
The Escapement
- Roller Jewel - provides the impulse to the pallet fork
- Pallet Cup - meshes with the roller jewel
- Pallet Arm - extends the reach of the pallet cup
- Exit Stone - temporarily locks the escape wheel
- Roller Table(s) - mounts the roller jewel and meshes with the guide pin
- Guide Pin - keeps the pallet and roller jewel aligned
- Banking Pins - limits the travel of the pallet arm
- Entry Stone - temporarily locks the escape wheel
- Escape Wheel - meshes with the 4th wheel and pallet
Balance Wheels
The Heart of a Watch
All watches from the railroad era used a balance wheel as a means of achieving accuracy. The earliest wheels were solid metal, while later models had expansion cuts to adapt for temperature changes and carried weights that added mass.
Its steady rate was controlled by an oscillating hairspring, and most models had some kind of regulator for fine adjustments.
Mean-Time Screws
These paired screws were used to quickly make bulk timing changes. They were usually found near the ends of the balance wheels arms and were made with a special interference thread to prevent them from turning without force. Any company that failed to install them on their watches (Elgin) invited a century of hacks to molest the other weights to make timing changes.
Ruining the Accuracy
When a watch inevitably slowed from thickening oils and had no mean-time screws to make adjustments, the lazy choice was to simply grind off the balance weights to gain time. At some later point the watch was cleaned properly, which then ran too fast because of the missing weight, so washers had to be added to increase mass - all of which ruined the positional accuracy.
Hairsprings
Flat
The hairspring is the balance wheel's rebound mechanism, oscillating in and out five times every second. The coils of a flat spring all lay on the same plane, anchored at either end. At the center is the collet, a brass split-ring that grips the balance staff, and at the tail is the stud, produced in many different styles.
Breguet
Prussian watchmaker Abraham Breguet is credited for inventing the overcoil hairspring, which put the final turn of the hairspring above all the other coils. While a flat hairspring applies lateral friction to the balance staff when it oscillates, the overcoil minimizes this effect by moving a much smaller distance.
Roller Tables
Single Roller
Any anchor or lever escapement requires a roller jewel, which is mounted in the roller table. On every cycle of the balance wheel this jewel gives an impulse to the pallet fork via the cup at the end of the pallet arm. A guide pin behind the cup prevented the pallet fork from drifting too early by meshing with a crescent-shaped cutout milled in the edge of the roller table.
Double Roller
Overbanking occurs when the roller jewel becomes misaligned with the pallet, which was possible with the single roller design. The double roller was developed to address this, using a smaller lower table with an indent to mesh with a horizontal guard pin. This allowed the pallet arm to swing only when the roller jewel was in the cup, virtually eliminating overbanking.
Mainsprings and Barrels
T-End Mainsprings
T-End Mainsprings
T-End Mainsprings
By far the most common.
Hook Mainsprings
T-End Mainsprings
T-End Mainsprings
Used in barrels with internal hooks.
Brace Mainsprings
T-End Mainsprings
Brace Mainsprings
Used inside slotted barrels.
Going Barrels
Hanging Barrels
Brace Mainsprings
GOOD
A watch barrel contains the mainspring, and a going barrel has a cover that snaps on tightly, leaving a very confined space for the mainspring to uncoil. Newer alloy springs have sharp edges that will snag on any ridges or serial numbers stamped inside this type of barrel, making for an occasionally erratic letdown.
This is the most common design, using a slotted or T-end spring.
Hanging Barrels
Hanging Barrels
Hanging Barrels
BETTER
A hanging barrel consists of a barrel and cover that never touch each other, rotating on a common arbor and giving the spring more room. Waltham used this design on several of their models. The mainspring is allowed to unspool at a much smoother rate, producing more consistent torque.
Hanging barrels have an internal hook to anchor the mainspring.
Motor Barrels
Hanging Barrels
Hanging Barrels
BEST
A motor barrel has a pair of internal jewels between the winding arbor and the barrel and its cover. This increases accuracy by letting the mainspring unspool without friction, and when used with a hanging barrel makes for the smoothest letdown.
External jewels on the plate are entirely for show and to inflate the count, and do not reduce friction or improve accuracy.
All About Stopworks
The Geneva Cross
The stopworks, or Maltese Cross, originated in Switzerland in the 1700s as a means of limiting mainspring travel in watches.
A single-tooth drive cam was mounted on the arbor that mated with a driven wheel with a single closed spoke and several open ones. After a given number of rotations the closed spoke would lock the drive cam and prevent the mainspring from turning.
Achieving Isochronism
The intent of stopworks was isochronism, the ability of a watch to run at the same rate despite any changes in its power source. The red line in this graph represents the drive torque of any mainspring, and the paired stopworks allowed the watch to run only in the middle two-thirds of its linear force, shown in green.
Most stopworks have been tossed by lazy hacks as unnecessary.
Configuration Styles
Open-Face
Open face was by far the most common, with the winding stem at the 12:00 position, and was available in every size that American watch companies had to offer. This configuration eventually became one of the primary railroad criteria.
There are four styles for open-face cases: threaded covers, snap-on covers, internal swing-ring, and hinged clamshell.
Hunting
Hunter (hunting) placed the stem at the 3:00 position, and was not railroad approved. The cases have a front lid to protect the dial and glass crystal, which opens by depressing the crown.
There is no such thing as a double hunter or a half hunter.
A case is either hunter or it's not, though demi-hunters have numerals on the front lid and a small crystal to view the hands.
Sidewinder
Sidewinders are hunter movements in open-face cases. Seldom purchased this way historically, this arrangement means the original gold-filled hunting case has likely been melted down.
Most collectors believe this configuration to be incorrect.
Conversion
Conversion dials allowed hunter movements to be used in an open-face case by moving the seconds bit to the 3:00 position, returning the winding stem to 12:00. These began showing up after WWI, were usually made of metal or porcelain, and could be railroad acceptable.
Reversible
Reversible cases had a center ring that rotated within the frame, displaying the movement in either hunting or open-face style. This does not convert the movement, since its winding pinion doesn't change positions. For example, an open-face movement used as a hunter profile will simply be aligned as a sidewinder.
These were also called a Muckle case, after inventor E A Muckle.
Winding and Setting
Pendant Set
Pendant, or stem-set, was the most common, though the design required twice as many parts as a lever-set variant. The hands are set by popping up the crown, which did not meet railroad standards because the hands could accidentally be reset. The watch is wound by twisting the crown in a ratcheting motion.
Lever Set
Lever-set watches did meet railroad standards, as long as it was an open-face model. Setting the time meant removing the bezel and pulling out a lever, which could be in several different spots around the dial. The watch is still wound by twisting the crown.
Key Wind / Key Set
Key-wind and key-set watches also didn't meet railroad requirements. The watch was wound with a small square key through the back and the hands were set by removing the bezel, although a few were able to also set the hands from the back.
Pin Set
Pin, or nail-set, was largely a Swiss innovation and was seldom used on American brands. It was a clumsy design, requiring the pin to be held in while turning the crown to set the hands.
Plate Layouts
Full Plate
Bridge Plate
Full Plate
All American companies offered full plate designs, with the balance wheel being the only visual component of the gear train. The balance wheel was recessed on some models, but was always located above the upper plate.
3/4 Plate
Bridge Plate
Full Plate
A 3/4-plate design protected the balance wheel between the plates. Some models split the upper plate between the barrel (mainspring) bridge and the gear train bridge, while others had a single plate to cover both areas.
Bridge Plate
Bridge Plate
Bridge Plate
A bridge movement also stacked the balance wheel inside the gear train, with as many as four separate upper plate bridges. A "false" bridge model was actually a single piece with shallow milling cuts to mimic the real thing.
Plate Finishes
Gilt (Gilded)
Gilt (Gilded)
Gilt (Gilded)
Gilded plates were the most common prior to 1880, chemically transferring a thin layer of gold onto bronze plates.
Nickel
Gilt (Gilded)
Gilt (Gilded)
Nickel-plated bronze was an ideal choice into which dazzling patterns could be milled or turned, called damaskeening.
Two-Tone
Gilt (Gilded)
Flashed Gilt
Two-toning required the initial step of masking of areas of the plates with wax and then gilding to achieve this look.
Flashed Gilt
Flashed Gilt
Flashed Gilt
This effect was similar to two-toning, except the patterns were milled before the plates were gilded.
Frosted
Flashed Gilt
Acid-Etched
American Waltham pioneered this look, with the patterns milled after sand or bead-blasting the plates.
Acid-Etched
Flashed Gilt
Acid-Etched
US Watch of Waltham was the first factory to etch a pattern with acid on mirror-smooth plates.
All About Fusees
Verge Escapement
The verge dates to the 1200s and used a pair of steel paddles mounted 90 degrees apart on the balance staff to alternately lock and release the crown wheel. It was bulky and the mating surfaces wore quickly, although they could be made very small. Combining the verge with a fusee made small watches possible.
Fusee Cone
The fusee was a very simple yet effective method of equalizing drive torque as the mainspring unspooled and lost power. The design dates back to the 1400s, with the earliest versions using gut or wire. When the watch is fully wound, the chain is coiled entirely around the fusee cone, and the mainspring is applying the largest force with the smallest amount of leverage. As the mainspring unwinds, the chain begins to wrap around the mainspring barrel, and its weakening pull is applied to the expanding spiral radius toward the bottom of the fusee cone.
Achieving Accuracy
Verge fusees inevitably speed up over time because of the wear of the mating surfaces. The soft brass teeth of the crown wheel become worn out against the steel paddles on the balance staff, reducing the travel of the balance wheel. This decreases the amount of time between impulses, causing the watch to gain.
Adjusted to Positions
Accuracy
Accuracy was the most important aspect of any watch, so high-grade movements were adjusted to keep better time. These adjustments offset the effects of friction, gravity, temperature, and the fading torque in a spent mainspring by fine-tuning the balance, and getting a watch to run accurately took hours of work by a skilled watchmaker.
Isochronism
The word is Greek for same time and is the accuracy of a watch whether the mainspring is fully wound or almost spent. Barrel stopworks, counter-balanced pallet forks, and hairsprings with overcoils all helped to equalize mainspring torque in pocket watches.
Temperature
Changes in temperature affected the hairspring and the oils in a watch, altering its accuracy. Factory adjustments took days, with the watches kept running in cold boxes near freezing and hot boxes at 90°F. Bi-metallic balance wheels with expansion cuts and the invention of alloys like Elinvar in hairsprings in the 1920s helped to offset this.
Positions
A watch can be oriented pendant up or down, pendant left or right, or dial up or down. There are nine total adjustments - the six positional ones, isochronism, plus one each for heat and cold. When a movement was marked with a given number of positions it meant certain orientations, although this was not universal, and it was assumed that isochronism and temperature adjustments were included. Some factories milled the word "Adjusted" on the plates with no explanation of what that meant, while other firms inscribed the total number of adjustments to which the watch was timed against.
Railroad Standards
What Made A Watch Railroad Grade
The growing country moved nearly everything by rail in the 1880s, so an accurate timetable between freights became increasingly important. For decades the railroad companies had generally accepted any 18-size 15-jewel watch for service, but in 1891 the Kipton, Ohio crash killed several people because an engineer's watch had stopped, and the rules changed.
Webster C Ball, a successful jeweler and store owner, was given authority as Chief Time Inspector, overseeing thousands of miles of track. New standards were adopted, and by the turn of the century a Railroad Grade watch was American-made, open-face, lever-set, either 16 or 18-size, had a minimum of 17 jewels and was adjusted for temperature and positions. It had to be equipped with a steel escape wheel, a micro-regulator, and a bold Arabic dial. Railroad workers were required to submit their watches for regular inspection, and the most important criteria was that any watch had to be accurate to within 30 seconds a week.
