Chapter VII: Motion work
67. About the construction of this part of the movement not much needs to be said, because it is fairly independent of the design of the train. In Swiss watches the motion work is usually much smaller than it is necessary to make it. However, there is some advantage when using a free mainspring (Art. 48) in having very small motion work, because then the barrel cover does not need to have a shoulder for the hour wheel, so leaving the room required for such a mainspring.
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Figure 23.
Minute wheel mounted on a steel pin.
68. There are nevertheless some small points in motion work which permit improvement. In English watches, even of the best class, the minute pinion usually runs on a brass stud which is driven rather carelessly into the pillar plate, a construction which is completely unworthy of the character and the generally careful execution of these watches. In contrast, all Swiss watches, including the inferior ones (7), have a screwed-in stud on which the minute pinion fits. These studs are not easy to make, difficult to screw in and unscrew, and by cutting the screw hole into the plate they offer far less certainty of exact depthing than a round hole which can be drilled on depthing circles. I believe the solution lies between these two, one which is more easily executed, is firm and decreases friction. A hole is bored for the minute pinion in the pillar plate. A finely polished pin of hard of steel, rounded off at both ends, is driven into this hole so that it is flush with the inside of the plate and projects on the other side close to the dial. The minute pinion has a small projecting pipe which is left standing beyond the rivet and serves to hold the minute wheel a small distance above the plate; the other end of the minute pinion also has a small pipe which is turned down so that it has just the necessary shake under the dial.
69. Still another aspect could be improved easily. It is the way the minute hand fits on. In nearly all Swiss watches the hand fits on the end of the hand arbor (8), and we must support the square of the hand arbor or it may squeeze out of the pinion with the pressure. This is not the case if the hand fits onto the end of the cannon pinion, which must have a shoulder for this purpose. Besides, this arrangement has the advantage that the end shake of the hour wheel can be adjusted between the front surface of the cannon pinion and the lower end of the minute hand pipe so that it does not require the small spring washer which we normally use to hold the hour wheel in place.
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Figure 24.
Arrangement of the minute hand on the cannon pinion.
70. It remains to say a few words about hand setting which is usually done from the back, particularly with Swiss watches. Setting the hands from the dial is an inconvenience which is inevitable with full plate frames, while in bridge and three-quarter plate watches there is simply no necessity for it. Gradual replacement of the old-style fixed dome (double back) case, whose movement is only accessible from the dial side, also led to the demand to change the method of hand setting.
71. The dial of the watch, although made from a material which is difficult to work, is not open to much improvement. The possibility of damage to the enamel face led to many efforts to replace it by a more suitable material. But the main requirement of a good dial, clarity, has not yet reached such perfection in anything other than the enamel dial. A completely white surface with jet black figures on it cannot be excelled for this purpose. Silver dials, with which we have tried to replace enamel dials, can be nearly the same white colour, but they are prone to blackening by oxidisation or imprudent treatment. Gold dials have also been tried, but they are far less clear unless viewed under very bright light and cannot be recommended for persons who do not have good eyesight. It is strange, as we very often find with English watches, that a gold dial is used with gold numbers and gold hands.
For this reason the enamel dial, despite its fragility and greater thickness, is still in use and it will remain so with those who keep its main function in mind. But it cannot be denied that the invention of a suitable metallic or other material possessing the necessary characteristics would be a great improvement for the practical watchmaker.
There was a time when dials with a yellowish-grey colour were preferred in England and elsewhere. Naturally these are not as suitable as a white dial. In the same way a matt surface is regarded by some as a great improvement, since we can look at the watch from any direction without being disturbed by the reflections which a shining dial throws back. This is a strange mistake; because if the dial of a watch does not reflect light then the glass over it will surely do so; and anyway, it is very easy to look at a watch without disturbing reflections.
72. The attachment of the dial is done by pins or screws. The dial should not be fastened by two small screws (9) for which holes must be bored in the plate, because the dial is very easily damaged by the slightest side pressure when closing the case (since the holes are very close to the edge of the dial). This method of fastening the dial used to be preferred by the best Swiss and French makers and some beautiful dials were spoiled in consequence.
Another kind of fastening is with dial feet and pins, which is completely effective and has no risks; therefore it was preferred for English watches and, if the movement is accessible, nothing can be said against it. However, with today's movements, the majority of which cannot be opened by a hinge, attachment with pins would probably be quite cumbersome, because to remove the dial it would be necessary to take the movement from the case.
With all movements fitted in this way, the dial feet should be held by dog screws which allow the dial to be removed without taking the movement out.
73. A very good method of fastening a dial is to mount it on a thin rim of silver or gold which fits exactly onto the outside edge of the pillar plate.
74. In order to be clearly seen, the hands should be made a dark colour and blued steel is used for this purpose in preference to gold. The numbers and hands should be thicker than present taste prescribes. The most suitable form for hands are those of the so-called poker and spade; the Breguet and fleur-de-lis hands cannot be seen as clearly.
75. The seconds circle should have a longer and stronger line at each fifth second in order to facilitate reading off seconds.
In the past all dials had flat seconds, but for about thirty years sunk seconds have been generally used, even for inferior (10) watches. There is some advantage in flat watches because space for the seconds hand is obtained; but importantly the dial is weakened at the same time. This probably explains why some manufacturers make the sunk seconds bit smaller and paint the seconds divisions on the surrounding part. The seconds hand is then shorter and moves in the sink.
The dial should never be made larger than the pillar plate.
notes:
7 Or small ones. [Trans]
8 The taper pin running inside the hollow centre arbor. [Trans]
9 From the front. [Trans]
10 Or small watches. [Trans]
