What are your experiences with the 7s26 movement?

[Deleted]

Maybe we could see what different folks experienced with the various versions; A, B and C.

My own experience with the 7s26A and 7s36A is quite extensive. I got to work on a 7s26C and I do have two 7s26B models.

What I have seen is that the 7s26A is prone to wide positional variance on timekeeping. This most often caused by improper adjustment of the regulator pins with most being too far apart allowing the hairspring to slop around in the opening.
The 7s26 B and C took care of this by using an etacron type regulator that can be easily adjusted for optimum regulator pin spacing.

The 7s26B regulator system was designed with the pins too short to handle the additional floppiness of the new hairspring materials and allowed the spring to become hung up on the pins if the watch was jarred. The 7s26C had the regulator pins extended so that this issue could no longer happen.

Aside from these differences; I am of the opinion that there is no inherent difference between the A, B or C versions. All should be able to perform to the same levels if carefully regulated.

I have a couple of watches with the 7s26A movement that date back to 1996 and 1997. The both still run perfectly and have a good solid reserve of about 40 hours.

Servicing and repairing these movements is dead simple...I can almost do it in my sleep; but it's better to be awake so I can spot any trouples before I put them all back together

[jringo8769]

well i have one ever had a 7s26c movement in my snk809 i had...it was amazing...kept perfect time...i just never wore it...so i sold it...i would buy one again 

[Adrian-VTA]

Awesome movement. Low part count and literally bugger all to go wrong. They do need servicing every 5-8 years though, as they experience an amplitude drop after that. But after service they pull 250-270. You can barely lose any parts off them too.

Compared to a base model ETA 2892 or something, the ETA has better rate recovery but is more complex and has annoying little click springs that fly off into the void, poor design choice if you ask me.

[stevenjohn]

I have them mostly in divers.  It's a tough movement with low part count.  It's easy to service, but I wish it had a standard date plate screw.  I usually get amplitudes in the 270-280 fully wound.  A larger diameter balance would also be nice, but that's a minor quibble.  I always worry about plastic parts going brittle too.

[Adrian-VTA]

I reckon the smaller balances have better rate recovery.

Apr 19, 2015 4:20:33 GMT -8 stevenjohn said:

I have them mostly in divers.  It's a tough movement with low part count.  It's easy to service, but I wish it had a standard date plate screw.  I usually get amplitudes in the 270-280 fully wound.  A larger diameter balance would also be nice, but that's a minor quibble.  I always worry about plastic parts going brittle too.

[sweffymo]

I have quite a few 7S26 watches, most of them using the newest C variation. They are all very accurate. They make my 4R37 powered watch seem inaccurate.

One of my Seiko 5s started gaining several minutes per hour after a shock and the balance looked screwy but the spring was still in the right place so I guess I actually managed to severely damage it, but that was after it slipped to the inside of my wrist and I basically slammed it full force onto a piece of steel...

Other than that issue which was clearly my fault, I have never had a single issue with any of my 7S26 powered watches. They're all within just a few seconds per day.

Sent from my Samsung Galaxy Note II using proboards

[stevenjohn]

Apr 19, 2015 5:19:22 GMT -8 Adrian-VTA said:

I reckon the smaller balances have better rate recovery.

Apr 19, 2015 4:20:33 GMT -8 stevenjohn said:

I have them mostly in divers.  It's a tough movement with low part count.  It's easy to service, but I wish it had a standard date plate screw.  I usually get amplitudes in the 270-280 fully wound.  A larger diameter balance would also be nice, but that's a minor quibble.  I always worry about plastic parts going brittle too.

Likely if you aren't fixing the moment of inertia parameter, but as with most engineering designs it's all about tradeoffs.  It's just my preference.

[69ChevelleSS]

Nothing technical to add but I can say that when I wear my SKX007 it's accurate all week.  Love that watch!

[thelias]

Apr 19, 2015 12:29:30 GMT -8 69ChevelleSS said:

Nothing technical to add but I can say that when I wear my SKX007 it's accurate all week.  Love that watch!

Yeah, my SKX009 keeps amazing time, actually better than my Baby Tuna which has the 4r36 movement. 

[Deleted]

What we have to remember is that all three calibres are machine built, assembled and regulated.
As such there will be variations in time keeping that generally fall within the printed spec. Seiko is not just being conservative with the specs; they are publishing what is technically possible with the equipment being used.

As many have noticed; these calibres can often be regulated to much tighter tolerances if they don't arrive already running with good timing.