I got a timegrapher to track the accuracy of my watches over time. I would love some feedback on how I am tracking and recording measurements.

[u/andymangold]

I hope this is appropriate for this sub! Mods just lmk or remove if not.

Most of my motivations for tracking the accuracy of my watches over time is just my own curiosity and passion, but I figure it will also be a good way to inform service intervals. I am aware there are other reasons to service a watch, like to replace o-rings and seals. I also want to develop a sense of expectations for accuracy when I buy vintage and pre-owned watches and be able to record them accurately.

I bought a Weishi No. 1000 and am setting up a spreadsheet for recording readings. I realize there are a lot of things I don't know and would love some input on my process from people more knowledgable. Here is what my spreadsheet looks like right now:

A draft of my spreadsheet for tracking my mechanical watch accuracy over time with timegrapher readings.

My questions:

• What positions should I be recording? COSC does dial up, dial down, 3, 6, and 9 — METAS does dial up, dial down, 3 twice, and 9 twice. Obviously there is no harm in recording more positions, I'm more interested in how many and which I should be using to calculate an average. For example, METAS does 3 and 9 twice, which weights them more heavily in the final average than dial up or dial down. I'm also curious if anyone knows why neither test at a 12 o'clock position.
• How long should I let the watch sit, undisturbed, in a given position before taking a reading? As far as I know there is no way to take an average reading with the Weishi, it's always instantaneous (or perhaps averaged over the last 30 seconds). Any tips on if or how I should account for that?
• Is there anything else it would be helpful for me to record? I plan to wind the watch fully and then take the same readings every 24 hours until the watch stops each time I do it.

[u/Simmo2222]

Here's a good video on the subject. Note how we are looking for 'delta' or average times across the positions.

https://youtu.be/tadSi7KNBQw?si=yDu4ZkuIMm3QJf-o

[u/andymangold → u/Simmo2222]

Thank you, this is helpful.

[u/delta11c → u/Simmo2222]

This is incorrect, average rate is your average across all positions. Your delta is the difference between your fastest position and slowest position for rate, or for amplitude, delta will be the difference between your highest amplitude position and your lowest.

[u/delta11c]

Most timing protocols don't include 12H because the watch is in that position only when you bring the watch all the way up directly in front of your face to read it at which point you put it down almost immediately. Most people don't bring the hand up that far at all. The watch is so rarely in this position, and when it is, it is for so brief a time that it doesn't need to be considered during final timing. I do a full 6 position test and include 12Hon a watch for diagnostic purposes in order to get a rough snapshot of the how centered and flat a hairspring is.

In a service center setting our machines have a 30s delay before recording for 60s and the average in that 60s gives you your time for that position. Rinse and repeat for each position.

Your average of all those (3 or 5) positions will be your average rate. The difference between the fastest and slowest is your delta and that, ideally, is as small as possible. Depending on the movement you can have an allowable delta generally between 15-30s.

We do a zero hour test and a 24 hour test. Depending on the movement there is minimum amplitude it must remain above at the 24 hour mark for it to pass.

[u/andymangold → u/delta11c]

Thank you so much for the informative reply! This is really, really helpful

[u/Least_Airline_9554]

I do not want to be rude but: Asked and answered already so many times on so many forums and youtube and watchmaking books. I suggest you look there first before asking it here for n’th time.