Last Updated on Monday, 26 April 2010 19:46 Written by GoldSmithWatchWorks Wednesday, 14 April 2010 10:27

Most vintage mechanical wristwatches tend to be accurate to within 30 seconds per day, no vintage watch, no matter how carefully regulated, can rival the precise accuracy of contemporary quartz watches.

In addition, vintage automatics will tend to differ in timing when taken off the arm and stored.. whether for a few hours or an entire night.

Another major item is POSITIONS. Gravity affects the operation of a watch. Depending on the position,-- dial up, crown up, 9 clock up, face down--- gravity will effect the balance. In many cases a watch will run perfect on the arm, but lose or gain time when taken off.

UNADJUSTED means that only the balance SLOW/FAST mechanism can be adjusted. There are no further adjustments.

If your watch has the capability for adjustments, like a Rolex, it can be from 1 to 8 position adjustments which allow for more precise adjustment. (please read our section on adjustments)

Further, no one replaces all wheels and staffs et al on a vintage watch. It is nearly impossible. A good watch restorer will replace main spring and worn parts. BUT ALL parts have NORMAL wear. This normal wear combined with the changing of positions when on arm or off arm means that the average loss or gain can be anywhere from 10 to 40 seconds a day.
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We at GSW are happy with the average of 20-30 seconds a day for all of the above facts on a vintage watch. THOUGH MOST WATCHES WE OFFER ARE ACTUALLY TIMED WITH IN 2 TO 6 SECONDS PER DAY.

Multiple adjustment vintage watches, which are generally several hundred dollars higher than non adjusted movements ( 700.00 Vs 400 ), are 5 to 10 seconds a day average -- depending on age of movement.

****************************************************************************************************************** Unadjusted
Unadjusted movements are those with no means or provisions made for the adjusting the watch to temperature or position.  Whatever variation in the timekeeping rate results from a change in temperature, or the position in which the watch is carried, exists as a result of the way that the particular watch was built. Jurst about all of the mass-produced, jeweled unadjusted watches could keep time within a few minutes a day.

Adjustment
watches marked "Adjusted" may have a variety, or combination, of features. A catalog description or repair manual for the specific watch would have  the level of adjustment is being claimed. High grade watches built after 1905-1908 may be marked with specific adjustments; especially railroad time service. The balance that sets the time keeping rate of the watch should be adjusted. The purpose to keep the balance (wheel) oscillating at a consistent rate. The consistency of the rate of oscillation of the balance (wheel) thus determines the timekeeping quality of the watch.

Temperature Compensated Balance
A temperature compensatedA balance has the rim made of two dissimilar metals. There are usually two arms (spokes) from the hub supporting the rim and there is a slot cut in the rim just past each arm. This forms two rim segments having one end supported by the arm and the far end free to move. These slots, and the two colors of metal in the rim, are identifying characteristics. As the temperature increases, lessening the power of the hairspring - the spring coiled inside of the balance (wheel) - the far ends of the rim segments deflect inward. As temperature decreases, the segment ends relax, moving outward, as the hairspring strength increases. The action is much like an inexpensive thermostat in the home. This movement of the rim segments changes the moment of inertia of the balance (wheel), compensating for the alteration in the hairspring strength.

Adjustment to Temperature
Adjustment to heat and cold requires a temperature compensated balance. After all of the other adjustments have been made, one would adjust the balance by way of specific pairs of screws (180 degrees apart) set into the rim. These give the balance mass, which sets the basic rate at which it oscillates. One pair may be the meantime screws which can usually be identified  by being longer than the other screws, and are used to bring the rate deviation to minimum with the regulator in its center position. The locations of most of the pairs of screws are 180 degrees apart on the balance rim, they are chosen to provide the best match of change in moment of inertia to change in hairspring strength ...extra pairs of holes are available so the screws can be moved to the best possible positions. The object is to keep the balance oscillating at the same rate over the specified temperature range.

Adjustment to Position
This is adjustment maintains the same rate of balance oscillation regardless of which of the position the watch is in. There are a six positions. The number of  positions to which the watch is adjusted is specified for most watches built after 1905-1908. Unspecified adjustment means adjustment to three positions, but there are a number of instances in which it means five positions. Adjustment to three positions most likely means stem up, stem at the 3 o'clock position and stem at the 9 o'clock position.

Adjustment to four positions: dial up, stem up, stem at the 3 o'clock position and stem at the 9 o'clock position.

Adjustment to two positions: dial up and stem up, while adjustment to one position was stem up with watch inclined 45 degrees to the rear

Adjusted to five positions:

1) the three positions of stem up, stem at the 3 o'clock position and stem at the 9 o'clock position + the dial up and dial down positions.

2) (1) dial up, (2) dial down, (3) stem up, (4) stem at 9 o'clock and (5) stem at 3 o'clock.

There can be a 6th position which is stem down at the 6 o'clock position.

NOTE: Temperature variation is greater than positional variation, adjusted to position includes adjustment to temperature. A high grade Swiss watch marked adjusted usually implies adjustment to all positions

Adjusment to 8 positions means:

1) adjustment to temperature, isochronism and 6 positions.

2) adjustment to heat, cold, isochronism and 5 positions.

Adjustment to Isochronism:
The adjustment of the hairspring is required to compensate for a reduction of main spring strength as it winds down. The power output of the mainspring will decrease as it unwinds over the course of the day. A watch adjusted to isochronism allows the oscillation the balance to be at the same rate throughout the specified length of run between windings of the mainspring, regardless of how far in each direction the balance (wheel) rotates. This length of run is typically 30 hours for earlier watches and 42 hours for post World War I watches.