Accuracy of your Quartz Chronometer?

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Watchamacallit
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Accuracy of your Quartz Chronometer?

Post by Watchamacallit » Fri Jun 22, 2018 7:15 am

Are others happy with the accuracy of their Chronometers, such as the C7, VW4, C30? My C7 Rapide Chronometer Mk 2 is not worn every day and has thus far gained about 1 second per month over the past 8 months. I have only been tracking visually using https://time.is/ so I need to get it entered into the WatchCheck App for better on/off wrist comparisons.

I am happy with the accuracy as well as with the looks/design of the C7 dial. Its appeal has held up well.

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Amor Vincit Omnia
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Re: Accuracy of your Quartz Chronometer?

Post by Amor Vincit Omnia » Sat Jun 23, 2018 3:22 pm

I set my Ascari COSC at the end of March. Currently between +2/+3.

That sounds OK. About +1 per month.
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The half minute which we daily devote to the winding-up of our watches is an exertion of labour almost insensible; yet, by the aid of a few wheels, its effect is spread over the whole twenty-four hours.
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Laird
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Re: Accuracy of your Quartz Chronometer?

Post by Laird » Sat Jun 23, 2018 5:06 pm

All my COSCs seem to perform pretty much as the Cert documents - altho I dont really use Lab techniques !
| Every CW C70 +EXCEPT+ the C70 US Cunningham Stripe & a DBR1 COSC| CW C7 Rapide COSC | CW C4 Phoenix | C60 316L 'Mellow Yellow | C8 UTC |
| Tag Heuer Calibre 16 F1 | Omega SpeedMaster HB-S1A | Breitling NaviTimer 01 |

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Re: Accuracy of your Quartz Chronometer?

Post by Watchamacallit » Wed Jun 27, 2018 7:54 am

Also my C3 mk2 (not a COSC) appears to have lost about 1 second per month over the past year. So it is performing nearly as well as my C7 Rapide Mk 2.

I am not totally certain of my memory and interactions with resetting time so I hesitate to post that as factual. I was resetting the watch before entering into the WatchCheck App and noticed that the time is 16 seconds slow. And the date wheel is 11 days behind, meaning the date would correspond to having been last set in Jan/Feb 2017. That sort of jives with my memory as I think I have only ever reset the watch once after noticing it get too far off (IIRC it was accurate from day 1, maybe off a couple of seconds per month during the time I was wearing it almost every day.) If the battery lasts I can get another reading.

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Re: Accuracy of your Quartz Chronometer?

Post by Watchamacallit » Fri Sep 14, 2018 9:56 am

Updating this thread since I am seeing a curious result with three of my favorite quartz watches. The results are nearly upside down from what one might expect. The hard data was measured with the WatchCheck app (which itself is subject to user error timing in pressing the measurement key) and is over a relatively short time period of 11 weeks. But I am taking into consideration how these watches have been performing over their lifetime and the watchCheck measurements are relatively correct/good.

The three watches from best performing to worst performing are:

1) C3 mkII chronograph. A limited edition Wimbledon with a 'regular' quartz movement. It has gained 0.9 seconds over the 11 weeks. So on pace for about +4 seconds/year. The watch sat in the watch box the whole time and sadly was not worn for even one day, even though the case size and style is great. When it was new it was worn a lot. It has always been accurate but I do not think it was this accurate when brand new and wearing it every day.

2) C7 Rapide Chronometer - Limited Edition (mkII). This is a COSC quartz advertised at +/- 10 second/year. It has gained 2.4 seconds over these same 11 weeks. So roughly 11 seconds/year at that pace which is within the margin of user measurement error. This jives with previous months were it appears this watch may gain about 10 seconds over the whole year. Which is fine considering this watch also has a quickset hour hand and has become one of favorite watches. It will be easy enough to hack the movement, or just know that it is reliably XX seconds fast. A fantastic watch. I really like the dial layout and overall look of this watch even if I prefer the smaller case size of the C3 mkII. I wear it frequently but not every day.

3) Grand Seiko SBGF - Which has a 'highly' accurate quartz movement, but it is an earlier generation and not the current 9F movement. I bought this watch used because I liked the dial, smaller/thinner case size, high water resistance (at least when new), and most importantly because it has a quickset hour hand when compared to the newer 9F movement. It has gained about 4.6 seconds in 11 weeks. So about 22 seconds/year which is outside its advertised specifications of +/-10 and is thus the worst performer, even though it was the most expensive watch when new. I have worn this watch the most over the past 11 week period due to lots of international travel and wanting to wear a smaller lightweight watch in the summer. I wish it were as accurate as advertised but it is still a very nice watch with a great dial.
When the C65 was released it reminded me of this watch. (In a different thread I wished that CW could take up the mantle of creating a similar HAQ based on their C65, to get the best of all worlds....Great styling, go anywhere at anytime water resistance, extra timing function off the bezel, always accurate, small, thin, quickset hour for traveling, great brand, etc.).

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Re: Accuracy of your Quartz Chronometer?

Post by Watchamacallit » Sat Dec 01, 2018 10:07 am

A quick update (this will be the last one until years from now, and only then if the trend changes, as to not bore people).

After 5 months and wearing all 3 watches to various degrees, WatchCheck has recorded:

1) C3 mkII chronograph --> -0.3 seconds deviation. So on pace for recording less than 1 second of deviation over the whole year. This has not been exactly a straight line performance but has always tracked closely to time.is. It is remarkable performance and within the margin of error of using the smartApp (human variation of pressing button to record the current time). While this is a high quality watch I could not imagine it performing so well. Lucky for me.

2) C7 Rapide Chronometer Limited Edition (mkII) --> +5.1 seconds deviation. So about 1 second per month. So still a good chance that it will track within the 10 second/year COSC specification across a full year of temperature swings. Since I do not wear it every day, maybe that has been a negative factor.

3) Grand Seiko SBGF --> +32.1 seconds deviation. So averaging almost 1.5 seconds per week. This watch saw the most wrist time and spent time in the tropics (in 90F+ temps) and had the most variation between intermediate measurements. Though I did not take many intermediate measurements so I did not get a good gauge on when it runs slower or faster. But overall it has been very disappointing. I need to open the case back to see if the movement is real or fake. This is a used watch that when new was supposed to operate within +/-10 seconds per year, though the movement is known to "age" and drift beyond those specs after some years/decades like my example is. Still many basic quartz movements are accurate to within 1 minute/year. My old Timex Weekender probably tracks better but I have not explicitly measured it (I have not reset the time in 3-4-5 years and it is off by around 1 minute or so). I should go back to wearing my automatic diver when on vacation rather than this watch.

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Re: Accuracy of your Quartz Chronometer?

Post by hughesyn » Sat Dec 01, 2018 9:17 pm

Watchamacallit wrote:
Sat Dec 01, 2018 10:07 am

2) C7 Rapide Chronometer Limited Edition (mkII) --> +5.1 seconds deviation. So about 1 second per month. So still a good chance that it will track within the 10 second/year COSC specification across a full year of temperature swings. Since I do not wear it every day, maybe that has been a negative factor.
COSC average rate is ±25.6 seconds per year at 23°C, and
temperature sensitivity equivalent to ±73.1 seconds per year at 8°C or 38°C.
So still well within spec.

±10 spy should be achievable with a regular wearing.
It's strange that CW use the word 'certified' alongside the 10 second per year claim. Certified by whom? ETA probably say it will achieve 10 spy (with some caveats), but it will still get a COSC certificate at 25 spy.

Good to hear it performs as it should.
C8 Pilot Mk II Vintage; C5 Quartz Mk II; C4 'Phoenix', C5 MMXV FLE

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Re: Accuracy of your Quartz Chronometer?

Post by Watchamacallit » Sun Dec 02, 2018 11:04 am

Thanks @hughesyn for your comments. I must be the one who is conflating COSC with +/- 10spy. My C7 came with a COSC certificate noting the time deltas in various positions (as if it were a mechanical movement) and it was advertised on the website as having an accuracy of +/- 10spy, so those two attributes are probably distinct from each other. Various HAQ watches from Grand Seiko, Citizen, Longines, etc, got me to thinking that +/- 10 spy is readily achievable even though it does take extra effort and engineering.

While I have liked my C7 from day one, I appreciate it even more many months later.

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