How to read the result from the machine that checks the

novacatz said:

So I am a bit of a perfectionist - and I noticed that my GMT Master II each week gains about 12 seconds (wearing about 2 days a week and otherwise in the winder)

I know this is in spec but bought it off to the rolex centre just to have a look see - and they tested it and they were convinced that the watch was as good as it was going to get and if I really wanted I could do the full timing check (which would take a week) but advised against it)

The person gave me a slip from the machine as attached... any person in the know that can help interpret all the numbers?

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First off, it is rare to find an automatic watch that performs as well as your watch. You should be very well pleased with the accuracy and precision your watch demonstrates. Further, if you asked for your watch to be regulated/adjusted to achieve better performance, it would most probably be worse after the attempt - best to leave it alone.

Now, here is what the numbers in your report mean:

The "Results and Statistics" side show the position the watch was tested in, the time gain/loss in seconds/day, the beat amplitude and the beat error. The positions tested were crown pointing down, crown pointing left, crown pointing up, dial facing up and dial facing down. The beat amplitude numbers simply show that the movement "swings" an adequate amount and can be an indicator of unusual wear or friction - your numbers are fine and show no problems. The beat error shows the difference in milliseconds between the "tick" and the "tock" of the movement - 0.0 is perfect (no difference), but small differences are usual as the watch position changes and your indicated errors are perfectly normal.

Your results in particular were as follows:

When Crown is pointing Down Gains 6 seconds/day Beat Amplitude is 281 Degrees with no error
When Crown is pointing Left Gains 1 second/day Beat Amplitude is 271 Degrees with no error
When Crown is pointing Up Loses 4 seconds/day Beat Amplitude is 267 Degrees with an error of 0.3ms
When Dial is facing Up No Gain or Loss Beat Amplitude is 289 Degrees with no error
When Dial is facing Down No Gain or Loss Beat Amplitude is 296 Degrees with an error of 0.2ms

On the right hand side of the report are the Range (difference from minimum to maximum) and Average values based on the measurements shown on the left. To wit:

Seconds/day Range is 9.9 seconds/day Beat Amplitude Range is 29 Degrees Beat Error Range is 0.3ms
Seconds/day Average is a Gain of 0.5 Seconds/day Beat Amplitude Average is 281 Degrees and Beat Error Average is 0.1ms

In the upper right hand corner of the report it shows that your movement beats at 28,800 vibrations per hour, it was tested with a lift angle of 52 degrees and the measurement period for each position was 20 seconds.

So, what does all this mean?

1. Your watch is performing very well - you should be well pleased.
2. On average, your watch will gain about a half second per day, but this will vary up or down based on your wear pattern and/or the position that your watch rests in while on the winder.
3. If you want your watch to gradually lose time to compensate for the fact that you are observing that it gains time, you should rest the watch in the Crown Up position.

I'm no professional, so all of the above is subject to correction/modification by those far wiser than I on this forum, but it should be substantially correct.

Any further questions?

HTH

novacatz said:

Hi Gaijin,

Thanks for the detailed reply above - definitely find it useful and thinking how I can place my watch so can get average of 0 gain a week (thinking 2 - 3 days out of the winder per week. just need to space it around the power reserve).

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Note that as the watch runs down, it may speed up or slow down a little bit, although I suspect Rolexes are pretty good this way. If you want to leave it out of the winder, do it for several short periods (e.g. overnight), not one long period.

A few things I want to understand more:

1.Beat Amplitude - you mentioned this measures the swing of the movement and is a sign of wear/tear/friction - can you let me know what is the range of 'good' 'concerning' and 'bad' etc.

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For the vast majority of movements, numbers around 270 degrees indicate a movement in perfect health. Much less than 240 indicates the lubrication is starting to lose its effectiveness, and much more than 300 suggests an incorrect (too strong) mainspring.

2. You mention the measurements were at a lift angle of 52 degs. - what is a lift angle?

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It is the angle through which the balance wheel turns while it is actively being propelled by the pallet fork and escape wheel. If you think of the balance wheel as a swing with a child on it, and you are the parent are pushing the swing to keep it going, the lift angle is the angle of swing during which you're pushing.

3. (not related to my watch) Are all the measurements above applicable to any mechanical watch? So in theory if I could put a non-rolex mechanical in the machine I should get some interesting comparative measurements?

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Yes. The machine that does this is called a timing machine. One puts the watch in the sensor, tells the machine the beat rate (e.g. 28800 bph for your watch) and lift angle, and the machine does the rest. It's all done via a sensitive microphone that listens to the movement and analyzes the sounds that it makes.

EDIT: PS. I'm a beginning amateur watchmaker, and also being an electronics hobbyist, am in the process of building my own timing machine.

Try searching ali express or the web for timegrapher. They should be around $100-150.

So i went to test my milgauss today... can someone comment on the results? in particular the angle and error... does this require regulation?



I am still facing the issue where my watch suddenly gain up to five seconds over a short span of one-two hours, and then stays relatively stable... I posted about it in this thread: https://www.watchuseek.com/f23/milg...thin-hour-two-normal-1038085.html#post7898216

Looks like a very healthy watch to me. Average of +2.4 seconds per day at 292 degrees amplitude. Minimal variation between positions.

Does your Milgauss gain a few seconds within an hour or two at the same time every day? Could it be that the reference time you're comparing against loses a few seconds in that time period. For example,

• if your PC clock is fast by 2 seconds per day,
• your PC resynchronizes its clock with the Internet at 5pm,
• you checked the Milgauss against the PC at 4pm and at 6pm,

then it will appear as if your Milgauss gained two seconds between 4pm and 6pm.

PC clocks are notoriously inaccurate (much more so than quartz watches) and can easily drift by seconds per day, which no one notices because most PCs these days resynch against Internet time every day or two.

Try checking your Milgauss against a decent quartz watch, which will at worst be +/- 0.5 seconds per day.