Watchmaking Excellence

This page is a visual dictionary of the standards expected of twenty-first century watchmakers. These images are intended to be used for watchmakers and consumers alike to be able to judge the quality of watch repair work. For each topic an exemplary example is presented along with some photos of unacceptable work and a short text description of the standard.

Cap Jewels

Hairspring

Screw Condition

Hand Alignment and Division

Applying Oil to Train Jewels

Oscillating Pinion Engagement—ETA 7750 and Similar Watches

Minute Counter Jumper Springs

Dial and Crystal Cleanliness

The Buckle or Bracelet Clasp

The Battery Well

Stem Cutting

Barrel Condition

The Escapement

Guard Pin Shake and Horn Clearance

Drop-Lock

Total Lock/Run to the Banking

Cleanliness and Condition

Lubrication

Shellac

Standards for the location and appearance of poising marks on modern balance wheels

Cap Jewel Preparation
Perfectly Cleaned Jewel The standard for oiling cap jewels includes perfectly clean jewels with oil expanding to fill an area with a diameter equal to between 1/2 and 2/3 of the diameter of the cap jewel. The oil circle should be perfectly round and concentric to the circumference of the jewel. If it is not, either the cap jewel is not seated parallel to the hole jewel, or there is some contamination drawing the oil away. The jewel should be disassembled, checked, cleaned, reassembled, and oiled to resolve the problem. Too little oil will result in the oil evaporating before the service interval is up. Too much oil will result in the oil contacting the edge of the jewel during a shock and “wicking” away, leaving a dry jewel that will become damaged and result in poor timekeeping of the watch.
Banana Shape Metal in Jewel Metal Flake in Jewel Oil Splash

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Hairspring
When adjusting balances with the Etachron regulating system, the hairspring should be centered perfectly between the two regulating pins when the balance is at rest at the dead point. The pins should be closed (by rotating the regulator block so that the outside pin moves away from the stud) until there is almost no deviation between the vertical and horizontal rates on the timing machine. The hairspring must be able to move freely between the pins, but the best rates are usually achieved when there is a very small gap.
Hairspring Perfectly Centered between the regulating pins when the balance is at the dead point. Hairspring should not be leaning against a regulating pin when the balance is at the dead point
Regulator block turned so that the inside pin is closer to the stud. Regulator turned the wrong direction.
Hairspring is flat, true, and centered. The gaps between the coils of the hairspring are even when the balance is at the dead point. Hairspring not centered.
Hairspring Expanding During the supplementary ascending arc of the balance wheel, the hairspring coils expand outwards. As it expands against the outer regulating pin the curve of the spring flattens, allowing a very small amount of hairspring to slide between the pins, effectively lengthening the hairspring. This lengthening is offset by the fact that the outside pin is positioned further from the stud.
Hairspring Contracting During the descending arc of the balance wheel, the hairspring coils contract inwards. As it contracts against the inner regulating pin, the curve of the spring tightens allowing a very small amount of hairspring to slide between the pins, effectively shortening the hairspring. This shortening is offset by the fact that the inside pin is positioned closer to the stud.

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Screw Condition
When watch servicing is complete, the condition of the screws in the watch should be as good as when the watch was received and, ideally, as good as when it left the factory. If the watchmaker damages the slot or head of a screw, it must be refinished or replaced. Using the wrong size screwdriver or using poorly prepared screwdrivers are the most common causes of screw damage. A screw showing no damage.
Burr raised on the corners. Typical damage caused by a screwdriver too narrow for the slot. A burr raised by a screwdriver that slipped. This piece of metal may come off and find itself in other areas of the movement. The well for the screwdriver has been scratched and a burr raised by using a screwdriver whose diameter is too large for this beveled screw.

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Hand Alignment and Division
Alignment:

The minute hand should point directly at the 12 o’clock (60 minute) marker when the hour hand is perfectly centered on any and every hour marker. This is typically assessed when the hands are at a right angle (90 degrees). A deviation of more than 30 seconds (3 angular degrees) does not meet the standard. Any deviation more than 1 minute (6 angular degrees) is considered poor workmanship.

Division:

All hands should be parallel to each other and the dial and the space between each hand should be even. The hands must not touch each other, the dial, or the crystal.

Perfect Hand Alignment
Perfect through Poor Alignment
Hands are parallel to each other and the dial with even spacing. Hands should not slope up or down and cannot contact other hands, the dial, or the crystal.

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Applying Oil to Train Jewels
Properly Oiled Train JewelTrain jewels must be perfectly clean before any lubrication is applied. It is preferable for lubricants to be applied directly to the oil cup after installing the bridge, but they can be applied directly to the pivot of the component before installing it when applying lubricant to the oil cup is not practical or there is a high risk for oil to be applied in areas where it critically should not be. Both methods of applying oil must be precisely and cleanly performed. When the component is installed, the oil should fill the space between the jewel and the pivot and extend out into the oil cup with sufficient reserve to last the full service interval. In many watches this means the oil will extend to a height of about half the depth of the oil cup. Too little oil will cause premature wear of the component over the service interval, and too much oil introduces the possibility that oil will contact the bridge and be drawn away from the pivot, run down the arbor to the pinion, or contaminate nearby components. No oil should be present on the flat top of the jewel, and there must be no contaminants on the jewel or in the oil.
    To assess the quantity and condition of oil, it is important to move the watch movement around so that the light is reflected in different directions. This will help you see where the oil is located and if it is clean. Moving the wheel and pivot as though testing for endshake or side shake will force the oil to move, making it easier to see and assess the quantity of oil.
QR-Code
CorrectQtyofLubrication SmallPieceofDebris OilonFlatofJewel

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Oscillating Pinion Engagement—ETA 7750 and Similar Watches
The engagement of the oscillating CorrectEngagementpinion on the ETA 7750 is a topic of its own because it has a clutch mechanism for the chronograph that is not widely used in other calibers. Engagement of this wheel and pinion does not follow the normal rules for wheel and pinion engagement.  Because its construction follows a different pattern than traditional horizontal clutch mechanisms, it is not possible for the teeth to make contact on the pitch circles. Proper engagement of the oscillating pinion and seconds counter wheel ensures smooth operation of the chronograph without excessive loss of amplitude or disengagement during shocks. As with all wheel engagements, the depth of engagement is measured on the line of centers (the imaginary line connecting the center of the arbors of both wheels). The teeth of the oscillating pinion should penetrate two-thirds of the depth of the teeth on the seconds counter wheel (chronograph wheel). This must be checked for all teeth on the chronograph wheel with the chronograph running and with tension on the clutch lever to accommodate for sideshake of the wheels and manufacturing tolerances. The apex of the pinion tooth should align with the transition between the dedendum and addendum of the teeth of the seconds counter wheel. The arm of the clutch lever should rest firmly against the eccentric for adjusting its depth.
Illustration EngagementTooDeepEngagementTooShallowShouldNotBeGap-TooDeep  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Minute Counter Jumper Springs
In a chronograph with an instantaneous or semi-instantaneous minute counter, the minute counter wheel is independent of the other gear trains of the watch and only has tension during the short period when the minute-counter finger is advancing the minute-counter train. The role of the minute-counter jumper is to keep the minute-counter wheel stationary at all other times and to position the wheel so that the hand can align consistently with the markers on the dial.
The positioning of the jumper spring is usually adjustable with an eccentric post. The spring will position the wheel such that two teeth maintain contact with the spring when there is no tension. It is important that the wheel maintain the same position when the reset-to-zero hammer is in contact with the heart cam of the minute counter. The position of the spring should be adjusted when the hammer is against the cam. When the hammer lifts away from the heart cam, the wheel can shift slightly due to sideshake but should not rotate due to the tension of the jumper.
The tension of the spring needs to be sufficient enough to prevent movement of the hand when the watch receives a shock, to limit its advance to a single tooth when it receives an impulse from the minute finger, but weak enough that it does not significantly impact amplitude during the advance of the counter.
In the ETA 7750, the base of the spring should be flat, flush to the edge of the chronograph bridge, and the eccentric post should be in the slot. Be sure to use the correct tool when adjusting the eccentric.
Correctly-Adjusted

 

 

 

 

 

Illustration-ETA7750

 

JumperOnTopEccentricPost

 

JumperSpring

 

 

VerySmallGapAcceptable

 JumperSpringNotFlush

 

 

 

LargeGapX

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Dial and Crystal Cleanliness
The cleanliness and condition of the dial and crystal of the watch are extremely important. These areas are constantly viewed by the owner and are the first and sometimes only impression the customer gets of your workmanship. The standard for these components is that they should be perfectly clean and free of dirt and debris, without smudges, and undamaged. One or two pieces of lint or debris that are only visible under magnification are acceptable. Multiple pieces of lint or debris visible to the naked eye under the crystal or on the dial are not acceptable and should be removed. No damage to the dial hands or luminous markers that is visible with weak magnification is acceptable. Any significant residue under the crystal, on the dial markers, or hands is not acceptable.Perfectly_Clean_DialLgPiecesLintSmudgeOnUnderside   MultiplePiecesofLint  DebrisOnDateDamageDateDisc DamageToDial

 

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The Buckle or Bracelet Clasp
ButterflyClaspWe often focus on the watch movement, but the case and bracelet are just as important. The case and bracelet should always be thoroughly cleaned before returning the watch to the customer. Depending upon the customer’s request and the brand’s Standard Operating Procedures (SOP), they may also undergo a complete refinishing and refurbishment. Extra care should be taken to ensure no polishing compound remains anywhere on the clasp or bracelet if it undergoes refinishing. It’s easy to overlook some important elements of the bracelet clasp, including spring bars, friction pins, rivets, button operation, and components that should be lubricated.
Watches with a button-operated butterfly-style clasp should be perfectly clean and well finished when returned to the customer. Both sides of the bracelet should snap securely without depressing the buttons and remain closed unless the button is depressed. If the clasp needs some adjustment, no tool marks should be visible. Screws should be secured with a thread-locking compound, friction pins should be tight, and friction points should be treated with a heavy lubricant that can withstand the elements, such as beeswax.
https://youtu.be/8HfyIRjDJnc—Video from Gevril Group showing proper function of clasp.LubricationPoints

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The Battery Well
BatteryWell-Correct

 

 

 

When replacing the power cell in an electric watch, it is extremely important to pay attention to the battery well. The battery well often provides direct access to the gear train of the watch. There should be no debris (lint, dust, etc.) anywhere in the watch, including the battery well. The battery should be clean, with no corrosion, fingerprints, oil, or debris attached to it. The insulator (when required) should be clean and properly placed to prevent a short to ground. The battery clamp (when present) should be properly positioned to retain the battery in the event of a shock. All electrical contacts should be clean and in good condition. If there is any corrosion present or if the plating is coming off, they should be cleaned or replaced.

 

 

 

BatteryLeak

SmAmtLint

Crystal-Deposits

Damaged-Insulators ScratchedBridges

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Stem Cutting

 

 

When cutting and preparing a stem to be fit to a crown, the stem must be handled in a way that no damage is done, especially to the threads, hubs, and other working surfaces. The end of the threads that will be attached to the crown must be clean, not have any raised burrs, and must not come to a sharp point. A thread-locking compound is usually applied to the threads to help secure the crown to the stem. The threads inside the crown must also be clean and free of any debris.

 

 

 

 

 

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Barrel Condition

 

The barrel complete with mainspring is the power source for the watch, and its condition is very important. The barrel should be completely clean and free of any scratches or damage, especially in the hole for the arbor and on the surfaces where the mainspring will slide. A barrel with damage or excessive wear must be replaced. The arbor must also be clean and damage free. The teeth must be clean and not distorted or damaged in any way.

 

 

rustyarbor

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The Escapement
Proper adjustment and handling of the escapement is absolutely critical to the function of the watch. It is quite complicated and many books have been written on the topic. We will be focusing on the Swiss lever escapement made with traditional materials (steel and synthetic ruby) and covering the standards for adjustment in multiple parts.

  • Endshakes and Division
  • Guard Pin Shake and Horn Clearance
  • Drop
  • Lock and Run to the Banking
  • Lubrication
  • Shellac

Endshakes and Division
The amount of proper endshake in the escapement depends on many factors, including the total thickness of the movement and the level of manufacturing precision of the components. You should refer to the manufacturer’s specifications, if they are available. Generally speaking, the endshake in the escapement should be small but present (0.01 to 0.05mm). Typically, the endshake of the balance staff and pallet arbor are the same. The escape wheel can have a little more endshake than the pallet fork or balance staff.
All components should operate freely without rubbing or contact except where necessary. The fork slot should contact the impulse pin (roller jewel) at their center and should not be able to touch the roller table, mainplate, or shock setting in any position. The guard pin should be centered on the safety roller and safely clear the impulse pin. The escape wheel teeth should slide across the center of the pallet stones and should remain in full contact with the stones in all positions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Guard Pin Shake and Horn Clearance
dec2016-watchmakingexcelThe guard pin and fork horns are essential components for providing safe action of the escapement when the watch receives a strong shock. The escapement will function normally without them in a stable environment. In most modern watches the guard pin and fork horns are not adjustable, but their function is essential and can be affected by damage, wear, or the installation of replacement parts and therefore must be checked.
Guard pin clearance must be smaller than the clearance of the fork horns at their extremity (the point where the impulse pin first passes the horns when returning to the dead point); otherwise, the impulse pin may not be able to enter the fork notch during the moment when a shock has forced the guard pin against the roller. Guard pin shake should be equal on both sides of the dead point (i.e., for both the ascending and descending supplementary arcs of the balance wheel) and is measured at multiple locations on the safety roller.
Horn clearance must be equal on both sides of the dead point and is measured at the point where the impulse pin passes the fork horns. Horn clearance must be greater than guard pin clearance, present along the entire length of the horn, and less than total lock. The tooth of the escape wheel must not transition from the locking face to the impulse face when the fork horn is pressed against the impulse pin.dec2016-escapewheel-incorrect

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Drop-Lock
Drop-lock occurs at the instant when the drop ends and the escape wheel tooth contacts the pallet stone. It is measured as the distance between the corner of the pallet stone and the heel of the escape wheel tooth at the instant the escape wheel tooth contacts the pallet stone. Drop-lock, like total lock, is often expressed in terms of a fraction of the length of the impulse face of the pallet stone. Drop-lock must occur on the locking face of the pallet stone. Drop-lock must be equal on the entry and exit stones; or stated another way: drop-lock must occur at the same distance from the corner on both the entry and exit stones. The drop must not end on the impulse face of the pallet stone because that could cause the watch to have poor amplitude.

 

 

 

 

 

 

 

 

 

 

 

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Total Lock/Run to the Banking
Total lock is the sum of drop and run to the banking. It must be equal on the entry stone and exit stone. The design of the escapement determines how deep total lock should be. As a general rule, it should be equal to approximately 1/3 the length of the impulse face of the jewel for slow-beat watches, and approximately 1/6 of the length of the impulse face for high-beat watches.

 

 

 

 

If drop and total lock are equal for the entry and exit stones, so will be the run to the banking.

 

 

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Cleanliness and Condition
All components must be perfectly clean and in good condition. No particles of dust, debris, or lint are acceptable. The parts should be inspected for damage or wear. Some items, such as a bent guard pin or fork horn, should be detected during the check of their function. If missed in a visual inspection, chipped or worn pallet stones, fork horn slots, or other damage may not be detected until the watch is on the timing machine.

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Lubrication

 

 

The ideal quantities of lubrication on the escapement vary widely by manufacturer and depend on factors such as size and rate of the escapement, as well as whether or not epilame is applied. In all cases, lubrication must be present and must be cleanly applied only in functional areas. No lubricant should be present on the top or bottom of the pallet stones, deep in the gaps between escape wheel teeth, or so far down the locking face that it contacts the body of the pallet fork.

 

 

 

 

 

 

 

 

 

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Shellac

Proper shellac is essential to maintain the position of the pallet stones in the fork. Poorly applied shellac can interfere with the operation of the pallet fork or fail prematurely.

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Standards for the location and appearance of poising marks on modern balance wheels

The poising of balance wheels is typically performed at the factory. Re-poising of the balance wheel is often necessary when a balance staff is replaced or there are other changes to components. The object of poising the balance wheel is to locate the center of gravity at the center of the staff. This is accomplished by removing weight from locations at the greatest diameter until the weight is evenly distributed. Static poising is performed on a balance that is clean, true in the round and flat, and with hairspring and collet removed. Fine adjustments can be made via dynamic poising with the balance installed in the watch. Care must be taken to ensure the hairspring is properly adjusted so as not to remove material from the balance wheel to compensate for errors in hairspring adjustment.

When poising a balance wheel (either statically or dynamically), it should be performed in a clean and neat fashion. As little weight as necessary should be removed; and when possible, weight should be removed from only one point on the balance wheel. Any burrs raised during the drilling operation should be removed.

On modern balance wheels without screws, weight is removed by drilling a hole in the underside of the balance rim. This hole MUST NOT penetrate beyond either edge of the rim.

On modern free-sprung balance wheels with regulating devices (Micro-Stella, Gyromax, etc.), care must be taken to insure the weights are distributed evenly before undertaking poising. Sometimes this is best accomplished by moving them to their extreme inner position. Regulating screws or nuts should NOT be used for adjusting poise.

If marks are made with ink to mark the location of the roller jewel or hairspring collet when replacing the staff, they must be removed before installing the balance in the watch.

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