Another and _very_ frequent cause of the lower center pivot cutting, particularly in new watches, is the neglect to remove the polishing material from the cannon pinion where the center arbor is solid.
A small portion of oil should be applied to the bearings of the minute wheel, (where its pinion, or the pivot on which it revolves, is steel), hour wheel, and cannon pinion where the center arbor is solid, and to the set hands arbor where the center arbor is hollow. The safety pinion should always be oiled, as it may not otherwise be of much service.
~50. The Third Pinion Pivots~ are sometimes the source of mischief. When the center wheel is placed above or below the barrel, the upper or lower pivot of the third pinion receives such great stress that the oil is forced out in many cases. By increasing the length of the pivot this could be obviated. The minute wheel is sometimes so close to the lower bearing of this pinion as to absorb the oil. This can be remedied by cutting a recess in the lower side of the minute wheel. Where it is possible to do so the wheels should be so placed on their pinions and arbors, and at such a distance from the bearing surfaces of the latter, that the stress on each pivot--the combined result of the weight of the wheel and the forces acting on it--will be equal.
~51. The Fourth Pinion Pivots~ should follow the same general laws as that given for the rest of the train; but it should be borne in mind that fluid friction acts as a retarding force much more perceptibly in the lighter parts of the train; consequently if no second-hand is to be carried, very small bearing surfaces should be the rule in this case.
~52. The 'Scape Pinion Pivots~ as well as the shoulders should not be too large, while there should be sufficient back taper to insure the oil remaining at the pivots. A very small quantity of oil should be applied, as, when too much is used, it is liable to work up into the pinion where the latter is short, as in very thin watches, thus producing, when very fine dust is added, a mixture that acts much like oil stone power and oil, which cuts away the leaves of the pinion.
~53. The Lever Arbor Pivots~ should also be small, with small shoulders so as to reduce fluid friction to a minimum.