Kai-Hylla.de  

Last Update: 03 Jun 2018
December 2017

Accuracy is a LibreOffice Calc document that identifies various properties of mechanical watches or movements. Over a longer period, a mechanical watch is observed. Ideally, the time on the watch to be examined and a time of the most accurate reference clock are recorded in the document on a daily basis. Likewise, any corrections to the time of the watch to be examined are noted.

The document then calculates various characteristics of the movement from the recorded data, such as, e.g. Accuracy, gait deviation, middle gait etc. This data is also shown in different diagrams. The values thus determined may then serve as a basis for regulating the movement, for example. Likewise, it can be determined for some properties of the movement whether they meet the quality requirements of some manufacturers, e.g. ETA or the COSC. Of course, this review is far from complete and not precise enough for an exact statement. But it gives a first impression of the quality of the work.

Basics

In order to understand how the document works, a few terms must first be defined. A holistic dictionary can be found in the Illustrated Professional Dictionary of Horology.

State

The difference between the time of the reference clock and the time of the watch to be examined. It describes how strong the watch to be examined fore- or pursues. If the score deviates from 0s, i.e. if the reference and the watch to be examined show different times, this fault can be eliminated by setting the watch to be examined to the correct time.

Daily rate

The difference between two states. It describes how quickly the deviation between reference time and displayed time changes. That is, how many seconds the watch to be examined gains or loses daily compared to the reference time. The value is normalised to one day i.e., to 24 hours.

The rate is typically dependent on the situation. That is, a different storage of the watch causes different rates. The daily rate can therefore fluctuate (see deviation). It is statistically considered over a series of measurements. Of interest are the maximum and the minimum daily rate, as well as its mean. The standard deviation describes how much the daily rate fluctuates around its mean. The smaller the standard deviation, the less the gear varies and the better it can be corrected by adjusting the movement.

Deviation

The difference between two daily rates. The deviation describes how much the rates change or the change of the state fluctuates. The deviation describes how uniformly a movement runs. A small deviation is thus a quality feature of the movement.

The deviation is recorded over all measurements and evaluated statistically. Relevant here are the maximum deviation and the mean of all deviations. The standard deviation of the gait deviation describes how much the rate fluctuates around its mean value. If a movement can be regulated in different positions, a position-dependent deviation can be corrected. A position-independent deviation can not or only with difficulty be corrected.

Position

The position in which the watch is stored. It is distinguished in which position the crown is located (top, right, bottom, left) or whether the dial is face up or face down.

Data acquisition

The data acquisition takes place manually by comparing the time of the movement to be examined with a reference time. For each measurement reference time, time of the movement to be examined and any corrections are noted. The measurements can be made at any time, but should be done about once a day to get meaningful data. Each measurement is automatically normalized to 24 hours for the evaluation in order to obtain comparable results.

The following information about the watch or movement necessary or optional:

Hersteller (manufacturer)
The manufacturer of the watch or the movement. The specification is optional.
Modell (model)
The model of the watch. The specification is optional.
Kaliber (calibre)
The calibre identification of the movement. The specification is optional.
∅ Uhrwerk (diameter of the movement)
The movements diameter in millimeter. This value is relevant for determining the COSC movement requirements.

The measurements are entered in a total of four columns:

Referenzzeit (reference time)
The time of the reference clock at the time of measurement. If a measurement at a time is not possible because the watch to be examined e.g. has stopped, the watch must be set to the time of the reference clock. This time is noted as usual in the Referenzzeit (reference time) column. The columns Zeit (Uhr) and possibly also Correction are left empty.
Zeit (Uhr)
The time on the watch to be examined at the time of measurement. If no measurement is possible because the watch to be examined e.g. has stopped, this cell is left empty. It is assumed that the watch is reset to the correct time, i.e. that their state is 0s. If the watch to be examined is not set correctly, the corresponding (incorrect) correction must be entered manually in the Kerrektur (Correction) column.
Lage (position)
The location in which the watch has been stored since the last measurement. The information is optional and is for documentation purposes only.
Korrektur (correction)
The correction of the watch to be examined after the measurement was made. If no measurement is possible because the watch to be examined is e.g. has stopped, this cell is to leave blank. It is assumed that the watch is reset to the correct time, i.e. that their state is 0s compared to the reference time. If the watch to be examined is not set correctly, the corresponding correction must be entered manually in the Korrektur (Correction) column.
Kommentar (comment)
A comment field. The information is optional and is for documentation purposes only.

Evaluation

The evaluation is performed automatically parallel to the data entry. The following values are calculated:

Stand (state)
The first diagram shows the corrected and the uncorrected state of the watch to be examined over the time. The state is the time that the movement to be examined is to fast or to slow in comparison to the reference time. The stand is given in corrective form. That is, a clock which goes slow has a positive status, since seconds must be added to get the correct time. This deviation can be easily corrected by setting the watch. The graph represents both the corrected and uncorrected levels. The slope of the grade of uncorrected levels represents the gait.
Gang (daily rate)
The graph shows the daily normalized to 24 hours per measurement. The corridor describes the change of states. That is, how much the rate increases or decreases compared to the reference time. It thus describes how much the movement is running too fast or too slow. If the individual rates are close together, the rate of the movement can be corrected by means of a regulation. The error bars show the std. deviation around the mean. The blue dashed line corresponds to this average of the daily rates. If it lies in the range between green lines, the watch to be examined fulfills the requirements of a very good movement with respect to the average rate. The area between the yellow lines describes the course of a good movement. The area between the red lines describes the movement of a movement that is just acceptable. If gears are outside the red range, it may be necessary to consider servicing the movement. The reference values for the green, yellow and red limits can be selected via the selection box below the diagram.

In addition to the diagrams, the individual data are also displayed in an overview:

Min. täglicher Gang (minimal daily rate)
The smallest of all daily rates in seconds per day. That is, the smallest increase in the deviation between the reference time and the time of the watch to be examined. The closer this value is to zero, the more accurate is the watch.
Max. täglicher Gang (maximal daily rate)
The largest of all daily rates in seconds per day. That is, the largest increase in the deviation between the reference time and the time of the watch to be examined. The closer this value is to zero, the more accurate is the watch.
Mittlerer täglicher Gang (mean daily rate)
The arithmetic mean of all daily rates in seconds per day. If the COSC requirement for the chronometer is met, this is signaled at the end of the line with a green check mark. If the hook is red, the requirements of COSC are not met.
Median des täglichen Gangs (median of the daily rate)
The median of all daily rates in seconds per day. That is, 50% of the rates are above this rate and 50% of the rates are under this rate.
Std. Abweichung des täglichen Gangs (std. deviation of the daily rate)
The standard deviation of all daily rates in seconds per day. Describes how much the daily rates scatter around their arithmetic mean. The smaller the value, the more stable the rates and the better the rate can be corrected by regulating the movement.
Mittlere tägliche Gangabweichung (mean daily deviation)
Mean change between the daily rates. Describes how much the rate changes on averages i.e. how much the change in the state varies. If the COSC requirement for the chronometer is met, this is signaled at the end of the line with a green check mark. If the hook is red, the requirements of COSC are not met.
Max. tägliche Gangabweichung (maximum daily deviation)
The maximum change between two daily rates in seconds. If the COSC requirement for the chronometer is met, this is signaled at the end of the line with a green check mark. If the hook is red, the requirements of COSC are not met.
Std. Abweichung der täglichen Gangabweichung (std. deviation of the daily deviation)
The standard deviation of all changes between the daily rates.
Max. Abweichung des täglichen Gangs zum mittleren Gang (maximal difference between daily and mean rate)
The maximum deviation of the daily rates in relation to the average daily rate. The smaller the value, the more stable the rate and the better it can be regulated. If the COSC requirement on for chronometer is met, this is signaled at the end of the line with a green check mark. If the hook is red, the requirements of COSC are not met.
Ganggenauigkeit (Accuracy)
Difference between the minimum and maximum daily rates in seconds per day.

Downloads