How to oil a watch
Before final assembly of the movement, balance endstones should be mounted on balance cock and pillar plate and respective capped jewels oiled.
For the purpose of retaining a sufficient amount of oil in the pivot holes, we take advantage of a natural phenomenon, which is called capillary action. This action, roughly stated, is the tendency of liquids to run in between surfaces which are nearly in contact, and also to run upwards, quite rapidly, in very small tubes, against the force of gravity.
Capillary action is strikingly illustrated in the wick of a lamp in which the close proximity of the fibres, acting like capillary tubes, causes the oil to run upwards through the wick as fast as it burns at the top. In view of these facts, we shall endeavor to explain why a pivot sometimes will run dry in a short time because of too much oil in the pivot hole. Looking at Figure 18, we find that the hole jewel is convex on the side towards the endstone. Also, there is a certain distance between the two jewels. This space is usually made about .02 to .03 mm., and is for the purpose of providing a reservoir for the oil.
The convex shape of the hole jewel tends to keep the oil around the pivot, being attracted by the close space nearest the hole through the capillary action referred to above.
To lubricate a capped jewel place a small drop of oil in the oil cup and feed it into the space between the jewel and the endstone with a pointed wire. The amount of oil is determined by the size of the bubble that should cover approximately % of the jewel diameter. If the size of the bubble is too small, the supply will lubricate for a short time, because it is subject to drying and oxidation. If the bubble covers too large an area, the oil will be drawn away between the metal surfaces, leaving pivot and jewel bearings dry and subject to wear.
After winding the mainspring into the barrel, a sufficient supply of oil should be applied to the surface of the coils and the bottom of the barrel. Before replacing the barrel arbor, the bearings should be lubricated with a thin film of oil.
Winding arbor square and clutch teeth should be lubricated with a very thin film of white petrolatum. Setting and minute wheels need no lubrication.
After final assembly, all train jewels and bushings should be carefully oiled. The point of the oiler should contact the bottom of the jewel or bushing oil cup and the pivot simultaneously. This prevents any lubricant from spreading onto the surface of the jewel or bushing. When oiling center lower bearing, a small drop of oil should be placed on the cannon pinion friction groove assuring smooth setting friction.
After assembling the escape, a small drop of oil should be placed onto the impulse surface of the pallet exit stone. The pallet should then be moved back and forth until the escape wheel has made one revolution, thus lubricating each escape wheel tooth with a thin film of oil.
Do not oil the jewel pin nor the safety action.
It is difficult to prescribe an accurate quantity or oil drop size to lubricate a watch bearing. Experienced watchmakers will determine the amount they will use in providing a correct film on any bearing or surface that needs lubrication.
CLEANING AND OILING EQUIPMENT
CONTAINERS FOR SOLUTIONS — Wide-mouthed, one gallon glass containers with tight fitting glass stoppers should be used for all solutions. They should be filled about halfway in order to avoid any possible spilling when the basket of the cleaning machine is set in motion.
LUBRICANT — Supplies of watch cil should be stored hermetically sealed in a dry, cool place and protected from direct light. It should comply with the following essential qualifications:
- It shall lubricate.
- It shall not spread.
- It shall not easily evaporate or become gummy with age.
- It shall not oxidize or corrode any metal it contacts.
OIL CUP — A drop of oil should be placed in a conventional transparent glass oil cup, provided with a cover. The oil should be renewed daily to eliminate contamination by dust, or other foreign matter.
OILER — It is advisable to use a plain oiler made from steel wire, flattened out on the end and notched lightly in order to hold a small drop of oil at the tip. Such wire oilers are sold by watch supply houses. The pointer, used to feed oil between hole and cap jewels, can be made from a fine needle or pivot broach. It should be shaped to a fine, polished flat point and all burrs removed. At all times, the oiler and pointer should be cleaned by pushing the tip into a piece of featherwood or elder pith.
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