Accuracy possibilities on more common/less expensive movements

[jwolfe16]

Hi All,

I am curious as to what  I could realistically expect from a more common/inexpensive movement (such as the Orient F6922 or the  7S26 in my Seiko 5's) in terms of accuracy. I am considering on either tackling this myself or sending it off.  I've just noticed alot of variance between my 2 Seiko 5's with the 7S26 movement as well as   +10  - +35 with my Ray II (Orient F69). I've heard alot of contradicting feedback and would just like to get someones opinion on the matter. 

[qhartman]

It's probably possible to get movements in that class to be more accurate. I have a Hamilton that consistently hits COSC specs. I've heard of someone (maybe here?) getting a Seiko 5 to run around +2.
But, numbers like that aren't normal. The accuracy of a particular movement is largely a function of the accumulation of tiny flaws in manufacturing of all the parts. Lower end movements that haven't been painstakingly gone over will have more tiny flaws and will be less accurate.
As long as my variance is within spec for the movement, or if you can't find that, within +- 20 with good amplitude, I wouldn't worry about it much.

Also, how are you measuring? If you're not using a timegrapher, the results are going to be suspect. I was using an app (toolwatch) to track the accuracy of my watches, and it was all over the map. Turns out, that was mostly due to user error. I borrowed a friend's timegrapher to get a real look at how they were doing, and they were all fine. I'm probably going to get one for myself soon here, they've gotten to be fairly cheap. More info: http://www.wristtimes.com/blog-1/2014/6/24/how-to-use-a-timegrapher

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[qhartman]

Oh, so my point is, if it's something you want to table for fun and learning, do it! See how well you can get them running. I probably wouldn't pay to have them worked on though.

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[rodabod]

One of the issues with the Seiko 5 is that it won't tend to reach as high an amplitude as a similar Swiss movement, and this leads to greater effects on timing variations due to balance poise. So, for starters, you want that movement running a good 270 degrees + if possible.

[JohnR725]

for the Seiko watch we've covered this kind of in a similar discussion found at the link below

precision timekeeping is more than just moving the regulator there are some things you can do but your somewhat limited no matter what with the quality of the watch. For instance when you look at the link below there some time plots that show gear train fluctuation. Specifically the power through the gear train is fluctuating and there's nothing you're going to do to fix that. Then the low amplitude causing positional errors if you are really obsessed you can attempt to fix these with static then dynamic poising. but no matter what is a limit of what you can do with the low grade watch no matter how much time and effort money you throw at the problem unless a course you replace the low grade watch with a high grade watch or better grade watch.

 

so you still can try a timekeeping experiment. First let's eliminate amplitude variations? When the watches not on your wrist you need an auto Winder this way the watch is always kept wound up. Then setting the watch to a accurate time standard and using only that time standard look at your watch every 24 hours and see what it's doing. If you're lucky it will have a consistent timekeeping error in other words it's fast or slow a certain amount every 24 hours if that's the case you can attempt to regulate that out. If it's inconsistent fast one day slow another there isn't much you're going to do with that.

then a timing machine in watch repair is really a must Chinese machines at less than $200 considering everything they do is totally insane not to have one. especially when just touching the regulator can sometimes have some very dramatic effects you need something to tell what you're doing.

So watching a watch over several days consistent error? Put it on the timing machine it's probably not going give you the same number that you're seeing but you can use the timing machine as a gauge. In other words you want to speed up by four seconds see with the timing machine says add four seconds and regulate to that. Then back to watching the watch with  the time standard you can usually get reasonably close to doing this.

https://www.watchrepairtalk.com/topic/9079-seiko-movement-regulation-and-fixing-positional-accuracy/#comment-86439

[jwolfe16]

Thanks for your responses. I think  I've come to realize why people spend thousands on  Swiss Watches  (i.e. Omega's, Rolex's, e.t.c.)

[rodabod]

Well, you can get exceptionally good performance from a common ETA.

[qhartman]

Honestly most of those mass produced luxury watches use the same movements, they are just the ones that have been finished better and have been tested to be more accurate. ETA produces the same movement in many different grades, and the higher grades will go in the more expensive watches. But even so, if you shop for just the movements, even high grade ETA movements aren't a ton more expensive than lower grade ones. Think $100 vs $80. That kind of scale.

What folks are really paying for there mostly are Superior finishing and brand.

When you get into bespoke and highly modified movements though, then you're talking about something else.

If accuracy is your goal, get quartz, especially high accuracy quartz (HAQ).

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[JohnR725]

I'm attaching a PDF that you find interesting it's a couple of pages out of a eta documentation. ETA is interesting they have their service manuals but they also have their manufacturing information guide which I always find really fascinating. Because this is where you get all the nice little technical specs like these. so what you see is therefore different crates but in real life there's only two grades. There's a difference in the material in the balance wheel hairspring in the higher end so they are going to be better temperature compensation. In each grade is regulated higher and higher regulation which is why there's four of them. Which means you can take the lowest one and if you understood precision timekeeping regulated into the next category and conceivably into the chronometer category except the temperature problems which probably aren't going to really be that much of a problem.

ETA-2824-2-Manufacturing-Info-Fr-Gr-En page 6 and 7.pdf