Adjustments made to a watch is what keeps your time piece as efficient and as valuable as possible. By making certain adjustments to the watch, the movement of the watch will show little fluctuation or variation in keeping accurate time.
A watch that is unadjusted means that no efforts have been made to adjust for position or for fluctuations in temperature. In the case of a watch that is not adjusted, the temperature of where you are as well as the position in which you are carrying or placing your watch when not being worn will affect its accuracy.
Generally, the more adjustments a watch movement is capable of having made to it the stronger the dependability and the more accurate it is. Often, a watch is marked with the number of it has so that the owner knows exactly how the watch is destined to perform and if claims made about the watch are actually true.
Watches that were made after 1908 are generally marked and watches that were specifically made for use on the railroads were most assuredly adjusted. The key to an adjustment, particularly to an accurate time piece like a railroad watch, is the balance wheel. That is the small wheel like mechanism that oscillates quickly back and forth and is the actual device that keeps the time. The time keeping quality of any watch depends on the consistent movement of the balance wheel.
Over all, a rule of thumb is that if there are no markings on the watch movement indicating how many adjustments it has then the watch was not adjusted which means it will be a much lower grade time piece. If it does have a marking that reads “adjusted”, the vagueness could mean just about anything. Was it just adjusted to temperature? What about six positions or isochronism? When looking at a watch that is rather vague with regard to markings it is best to do your due diligence before making any commitment to buy it if you are a collector who is desiring to own quality movements.
ADJUSTED TO TEMPERATURE
Adjusting a watch for temperature simply means that adjustments made to the workings of the watch have taken into consideration certain temperature fluctuations so that the watch will remain accurate regardless of the temperature that it is exposed to.
The balance wheel must be compensated for both hot and cold extremes. The balance must be compensated. The balance wheel has screws set into the rim. They come in pairs and are normally 180 degrees apart from each other. This allows the balance wheel to obtain a certain mass which in turn can set the particular rate at which the balance wheel will move and oscillate.
The longer screws are meantime screws and are used to bring a minimum rate deviation with the regulator in its regular center position. The screws are there to detect and adjust to even the slightest change or alteration of hairspring strength. The mechanical watch uses a hairspring to basically keep the time. The strength, or stiffness, of the spring will vary according to the current temperature conditions.
One of the technological advances in temperature compensation was a bi-metallic compensating balance. It is usually constructed from steel and brass with the steel being fused onto the brass itself. This balance may also be known as a “cut balance” because it doesn’t have a continuous rim. It is cut at two particular points to allow the bi-metallic balance to fluctuate, or breathe, with the changes in temperature.
When the temperature of the balance increases, the watch’s rate will move up. This happens when the small “arms” of the balance slightly begin to curl in an upward direction. In colder temperatures, the balance will be much more contracted or stiff and the tiny “arms” will curl outward a bit to make the adjustment thus decreasing the rate of the time piece. The skill of the watch service technician can change the positions of the balance’s weight screws thus enabling the increase or the decrease of temperature compensation aimed at a wide range of temperatures.
ADJUSTED TO POSITIONS
The balance and the hairspring run differently according to the positions they are adjusted to. When a watch is at rest on its back side, the balance is basically operating on one pivot. When the watch is in a more upright position with the pendant upwards, the balance will be running on the sides of both of the pivots. This, of course, creates a whole different situation with regard to the friction that is produced. The position of the watch greatly affects how the mechanism operates with regard to both the changes in friction and the force of gravity when the watch is moved to different positions.
Time keeping errors of a positional nature will occur when there is any error in the poise of the watch. The adjusting to positions was established so that, like with temperature, the time keeping precision of the watch will remain intact and unaffected regardless of where the watch is positioned.
For position adjustments, the highest quality watches are adjusted to six standard positions. The six standard positions are dial up (DU), dial down (DD), pendant up (PU), pendant down (PD), pendant left (PL), and pendant right (PR). Quite often only five positions were adjusted for. There could be a mechanical problem with the watch if you are suffering from some significant position errors.
Positioning timing can be a tricky thing and there are many contributing factors that can affect the timing such as overcoil shape, hairspring pinning point or the shape of all the balance pivots. These can all be vital factors in ensuring that your watch has excellent and effective positional timing.
ADJUSTED FOR ISOCHRONISM
Isochronism has to do with the tension of the spring and how the watch will operate differently depending on spring coil tension. When the main spring is fully wound, it will have far more strength and tension than one that has been allowed to run down. It will be the difference in spring tension that will cause the isochronal errors.
While isochronism affects all watches regardless of type, it seems to have a greater affect on watches that are older and more used. It will happen in the older watches that have time trains that have been rendered inefficient as well as with watches that have steel mainsprings. The addition of jewels to watches, as well as the addition of alloy made mainsprings, have reduced the chances of isochronal errors. For the most part, the design has to be made at the original point of the watch. To fix and adjust for isochronal error after the watch had been designed and produced is almost impossible.
Two mechanisms, the Fusee and the stop-works, are implanted into the watches to try and keep isochronal errors to a minimum. The stop-works essentially limits the mainspring to a middle range of operation while the Fusee works to equalize the mainspring’s overall pull. The Fusee mechanism became obsolete as pocket watches improved in their design just as carburetors in cars became obsolete when a fuel injection system was created.