Throughout the site you may discover many terms that are unfamiliar or confusing when applied in the vernacular of watchmaking. To remedy this I’ve excerpted several terms from the glossary in Henry B. Fried’s book The Watch Repairer’s Manual which I would recommend for the novice watchmaker along with Donald De Carle’s Practical Watch Repairing. Although De Carle’s book is considered superior by the professional community, Fried’s is the one I own so it is his terminology that I’ll reference here.
Those interested in taking watchmaking a step further must pick up George Daniel’s Watchmaking.
Alum: A whitish mineral salt used by watchmakers to dissolve steel screws that have broken off in plates of other metals such as brass or copper.
Amplitude: The amount of arc or swing of the balance. This can also be measured by certain types of oscilloscope.
Annealing: The act of heating and slowly cooling a metal or substance to render it softer or to relieve internal stresses.
Arbor: The axle of a wheel or shaft that turns in a bearing; commonly referred to as the barrel arbor, pallet arbor, winding arbor.
Arkansas stone: A white marble-like stone used in various shapes and sizes as a grinding stone to sharpen gravers and tools. Used in powdered form as an abrasive with grinding laps.
Automatic: A self-winding watch using a rotor or oscillating weight.
Banking pin: Two pins that limit the motion of the pallet fork. They also control the amount of slide of the pallet jewels.
Barrel arbor: The axle of the barrel around which the mainspring is coiled.
Barrel hook: A hook or slot in the inside of the barrel wall upon which the last coil of mainspring is attached.
Beat: The tick of the watch or one swing of the balance wheel. In Beat: when on beat or vibration of the balance receives its impulse at the same distance from the line of centers as the other.
Benzene: A coal-tar product used as a cleaner and rinse in watch and clock cleaning. Highly volatile and inflammable.
Beryllium: A metal used in minute quantities with nickel and steel to produce nonmagnetic, non corrosive balances and springs capable of good temperature adjustments.
Bezel: The top part of a watch case that contains the crystal.
Bimetallic: Made up of two metals. In watchmaking, this refers to the split balance having a brass rim and steel frame.
Bluing: To change the color of polished steel by heating it to approximately 540° F.
Brace: The hook or connection attached to the outer end of the mainspring.
Brake spring: The extension to the regular mainspring in an automatic watch which supplies the slip-clutch effect to prevent tight winding.
Breguet: Abraham Louis, 1747-1823, horological genius and inventor. The name applied to the type of hairspring which has its last outer coil raised above the body of the spring and curved inwards.
Bridge: The upper plates in a watch movement that contain the bearings for the wheel pivots and have pillars at both ends, such as the train or barrel bridges.
Bridle: Another term for the brake spring. Also called slip-clutch, safety for mainspring, safety-spring, slip-spring, slipping attachment.
Broach: A tapered steel tool, with flat cutting edges used to enlarge holes already drilled.
Burnisher: A hard polished piece of steel used to polish softer metals by rubbing it along the surface to be finished.
Calibre: The size or factory number of a watch movement.
Caliper (balance): A tool shaped like a caliper but with a hole in the top of each leg to hold the balance so that it may be observed for true running in the flat and round.
Cannon pinion: A thin, steel tube with pinion leaves at its lower end and carrying the minute hand on its upper end.
Cap jewel: The flat solid jewel upon which rests the pivot end. Also called the endstone.
Carbide: The type of cemented carbide tools used as gravers to cut very hard metals. Excellent in cutting out balance hubs.
Carbon Tetrachloride: A non-inflammable solvent of good cleaning qualities but highly toxic.
Cavitation: The process during ultrasonic cleaning in which minute bubbles are created and collapsed to dislodge dirt from parts to be cleaned.
Cement: Stick shellac or sealing wax.
Charged: To have imbedded in a lap of metal or wood, particles of abrasive or polishing powders.
Chronograph: A watch with hour and minute hands and a center sweep-second hand which can be controlled by a special button. A watch where the second hand may be started, stopped, and made to return to zero.
Chronometer: A watch or clock adjusted to keep exact time. Usually a large mounted watch with the detached spring detent escapement.
Cleaning solution: A dirt, tarnish and grease-dissolving liquid composed mostly of ammonia, oleic acid, and water.
Click: The pawl used to prevent the ratchet wheel from turning back after the mainspring has been wound.
Clutch wheel: The cylindrical winding wheel with ratchet teeth on its upper end, a slot-neck in the middle, and curved teeth on its lower end. Also called the castle wheel.
Cock: An overhanging support for a bearing such as the balance bridge. A bridge having a support at one end only.
Compensating balance: A bimetallic balance of brass and steel split near the arms and constructed so that its effective diameter will contract or expand in temperature changes to compensate for these changes to itself and to its hair-spring.
Conical pivot: A pivot which curves back into the main body of its arbor, such as those used with cap jewels. (Balance staff pivots)
Countersink: A chamfered or concave cut.
Crown: The winding button on top of the stem.
Curb pins: The two regulator pins almost pinching the hairspring.
Demagnetizer: An electric coil connected to an AC power supply through which a magnetized movement or part is passed to diminish its magnetized condition. Newer models of this device use capacitors, electronically for greater efficiency.
Dennison gauge: A mainspring gauge composed of a thick strip of brass with numbered and graduated notches or slots used to designate the width of a mainspring. The system uses the millimeter as its unit. 1.00 mm equals No. 1 Dennison; 1.10 mm equals No. 2 Dennison, etc.
Depthing tool: A tool which will accommodate two wheels or a wheel and pinion between their centers and, by means of a screw, bring them into correct pitch; this distance may then be transferred to the plates for comparison or verification.
Detent: the setting lever. Also that part of the chronometer escapement that locks the escape wheel. A detainer or pawl.
Dial train: The train of wheels under the dial which motivate the hands. The cannon pinion, hour wheel, minute wheel and pinion.
Diamantine: A powdered, crystallized boron used to give the dead flat black polish to steel.
Discharging pallet: The exit pallet jewel. The pallet jewel from which an escape tooth drops as it leaves the pallet.
Double roller: Two discs mounted on the balance staff, the smaller, crescent disc set above the larger which contains the impulse roller jewel.
Draw: The force which keeps the pallet against the banking pins. The result of the combined angles of the escape teeth and the pallet locking surface.
Drop: The free, unrestrained motion of the escape wheel as it leaves one pallet jwel before it drops upon the locking surface of another pallet jewel.
Dynamic Poise: Poising a balance by observing its errors on a timing machine while the watch is running; poising while the balance is in motion.
Ébauche: A term used by Swiss manufacturers to denote the raw movement without jewels, escapement, plating, engraving.
Elinvar: An alloy of nickel, steel, chromium, manganese and tungsten used in balances and springs, capable of close temperature adjustments.
Endshake: The free up and down space of pivoted wheels or arbors in their bearings.
Entrance jewel: The jewel first contacted by an escape tooth before it enters between the pallets.
Fork: The upper end of the pallet containing the slot, horns, and guard finger.
Fourth wheel: Usually the wheel upon which is mounted the second hand.
Guard pin: A thin finger emerging from a boss below the slot in the pallet fork and working in conjunction with the safety roller to aid in preventing overbanking.
Hairspring: The spiraled spring attached to the balance to govern the speed of the balance oscillations.
Headstock: The main part of the lathe resting on the bed and carrying the spindle and chuck.
Horology: The science and study of time measurement.
Hour wheel: A flat, brass, toothed wheel mounted on the tube which fits over the cannon pinion and supports the hour hand.
Impulse pin: The roller jewel.
Incabloc: Trade name for a shock-resisting arrangement of balance jewels and staff design.
Index: The regulator.
India stone: A fast-cutting artificial abrasive.
Invar: An alloy similar to Elinvar.
Isochronism: Quality of keeping equal time during the normal run of the mainspring, usually the qualities of a well-formed overcoil (Breguet) hairspring.
Jacot tool: A small hand lathe or turns used to shape pivots by burnishing.
Jasper stone: A red-brown quartz containing iron oxide capable of polishing steel, gold and other metals to a high finish.
Lever: Usually referred to as the pallet.
Lift: The motion given to the pallet during contact with the tops of the escape wheel.
Line of centers: A line drawn through the escape wheel, pallet, and balance centers.
Locking spring: A spring used to lock the setting lever while it is in the setting position.
Marine chronometer: A boxed watch clock set in gimbals utilizing the spring detent escapement; used on shipboard to determine longitude.
Meantime screws: The adjustable screws in a better grade balance used to bring the watch to close time without the use of the regulator. Sometimes called timing screws.
Micron: One thousandth of a millimeter (0.001mm).
Milling machine: A machine used to cut gears and perform milling for contouring operations.
Minute wheel: The wheel in the dial train that connects the cannon pinion with the hour wheel.
Movement rest: A platform or vise upon which the movement is placed while it is being repaired.
Nonmagnetic: A balance and spring composed of alloys that will not retain magnetism after being put through a magnetic field.
Oilstone: Generally, the Arkansas white stone used with oil.
Oscillating weight: The swinging weight on self-winding watches. Generally referred to those which swing between bumper springs and not a full 360°.
Overbanking: The malfunction of the pallet fork in which it shifts from one banking pin to the another without being released by the roller jewel.
Overcoil: The Breguet type of hairspring.
Pallet: The jeweled lever working in conjunction with the escape wheel: the frame containing the pallet jewels.
Pegwood: Small wood stick whose sharpened end is used to clean jewel holes.
Pillar plate: The lower or main plate of the watch.
Pin pallet: The lever escapement wherein the pallet has upright pins instead of horizontally set jewels. Used in alarm clocks and non-jeweled cheaper watches.
Pinion: The small geared arbor of a wheel pushed by a larger wheel.
Pivot: The thin end of a moving axle or arbor.
Poising: An operation to adjust the balance so that all weights are counterpoised.
Position timing: Adjusting a watch so that it keeps precise time when the watch is placed in a given position.
Ratchet: A wheel usually placed over a mainspring arbor and working with a retaining click or pawl.
Receiving pallet: The entrance pallet jewel.
Recoil click: A click designed so that it will not permit the mainspring to be wound dead tight, recoiling a bit after any winding.
Regulator: Part of the balance bridge which resembles a racquet (racket) and contains vertical pins which straddle the hairspring. When the regulator moves towards the stud, the effective length of the hairspring is made longer and the balance slows in speed; when the pins are moved farther from the stud, the hairspring is made shorter and the watch goes faster.
Rotor: The swinging weight in self-winding watches which turns fully in a complete arc of 360°, as differentiated from the term, “oscillating weight” whose arcs are restricted by bumpers.
Run: A term applied to the action of slide caused by draw. The action of the pallet toward the banking pin after lock takes place.
Safety roller: The small, crescent roller disc planted above the impulse roller. The upper part of the double roller.
Screwed file: A knife-edged file for slotting the screwed.
Screwplate: A steel plated with holes of many sizes threaded with cutting edges for the forming of watch screws.
Setting lever: the detent which fits into the slot of the stem and pushes down the clutch lever.
Shake: The distance the escape wheel can be moved backward (manually) before the back of a tooth contacts a pallet jewel when the opposite jewel is at the very moment of unlocking.
Slide: See Run.
Snailing: Decorative abrading of wheel and plates in pattern form.
Split chuck: The modern lathe collet or chuck partially “split” or cut in three equally spaced parts through the front of the chuck to give it resiliency and some tolerance.
Spotting: To decorate a plate or wheel by a series of equally spaced spots or whirls made by a revolving abrading rode.
Springing: The active of coordinating a hairspring with a balance so that the vibrations will equal a given number per hour; also called vibrating.
Sprung: The term applied to a lathe chuck that has lost its resiliency as a result of being used to grasp metal that was too large or too small. A lathe chuck that is spring is inaccurate because only one or two of its sections may be sprung and thus any metal thereafter inserted will be pulled out of center.
Staff: A pivoted arbor or axle usually referred to as the axle of the balance; as the “balance staff”.
Stake: A metal die holder or anvil or rest.
Stem: The squared shaft going through the winding pinion and the clutch wheel.
Step chuck: A lathe chuck with steps of graduating diameters used to hold wheels or other flat, round objects.
Stud: The metal piece anchored to the balance bridge into which the outer end of the hairspring is attached.
Sunk seconds: The small second dial which is depressed to avoid the second hand from interfering with the progress of the hour and minute hands.
Tailstock: The body on the lathe bed opposite the headstock used to support work held between centers or long rods. Also may contain drills or other attachments.
Tempering: Preparing metal for a desired hardness by heating or hammering.
Third wheel: The train wheel between the center and fourth wheel.
Timing screws: Adjustable balance screws used to decrease or increase the effective diameter of the balance in order to retard or hasten its vibrations.
Total lock: The distance of lock upon the pallet jewel after slide when the pallet rests against the banking pin.
Tourbillion: A watch in which the escapement, mounted on a cage attached to the fourth pinion, revolves around the mounted and stationary fourth wheel.
Train: A set of wheels geared or connected together.
Tripping: A malfunction caused by the failure of the escape tooth to lock upon the locking surface of the pallet jewel. Instead, the tooth enters directly upon the lifting surface with the result that the pallet may have an action like an alarm clock hammer.
Ultrasonics: Cleaning watch parts by very high frequency sound waves (over 18,000 vibrations per second) traveling through a liquid in which the parts are immersed.
Up-and-down indicator: The semi-circular dial on chronometers that tells how much the mainspring has been unwound and thus indicates when the spring should be wound. Also called Reserve power indicator in automatic watches.
Wax chuck: A cement chuck on which objects that cannot be held accurately in the split chuck are cemented to a brass rod held in this chuck.
Winding pinion: The first winding wheel through which the stem enters. A wheel with two sets of teeth. One is set to radial to its center and the other is set upright, crown style with ratchet teeth. The wheel above the clutch wheel.
Yoke: Part of the setting mechanism which holds down other setting parts. Also called the setting bridge.