temperature dependence?

[Doninvt]

I recently bought a Seiko  6R15 based Alpinist.  It keeps pretty good time if I keep it wound and sitting on a table in various positions, temperature in the mid 60's F.  On the wrist it goes to around +45 seconds/day.  Timegrapher shows similar results.. half or fully wound it runs way fast coming off the wrist or pocket and you can see it slide back to +/- a few seconds/day over the next 15 minutes as the watch cools off.  

I don't know what wrist temp means for the watch (skin on the back, ambient on the crystal), but guessing the difference is around 15 C, so the change would be 5 seconds/day/degree.

That sounds like a lot (COSC limit is .6).  What could cause this?  Are Spron hairsprings more sensitive?  Anything to do about it other than regulate for expected conditions?

 

[Doninvt]

18 minutes ago, Doninvt said:

, so the change would be 5 seconds/day/degree.

 

Correction... of course that's 3 s/d/d.

[jdm]

I handle many 6R15 watches and none shown to be very sensitive to temperature, so you would have to take timegrapher pictures taken at controlled temperature.

Anyway to help you with expectations I'm attaching the Technical Guide, like it or not Seiko specifies an acceptable accuracy on the wrist from -15 s/d to +25 s/day with temperatures between 5° and 35° C. But as mentioned with good regulation most pieces do better than that.

6R15B, 6R15C.pdf

[saswatch88]

Temperature has nothing to do with your watch running so fast. Seikos generally have higher fluctuations in accuracy in comparison to  non COSC swiss movements as just stated by JDM...what are the other TG readings? Amplitide? any beat error?

Fast running watch could be from dirty and/or sticking hairspring, movement being magnetized, or may simply just need to be regulated.

 

[yankeedog]

oils do change viscosity according to temperature..perhaps it has been over oiled?thin and runny at body temperature a little thicker at room temperature? Causing a drag.

Edited April 18, 2019 by yankeedog
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[saswatch88]

5 hours ago, yankeedog said:

oils do change viscosity according to temperature..perhaps it has been over oiled?thin and runny at body temperature a little thicker at room temperature? Causing a drag.

normally i would agree with this, but not in this case, i think motion would have more to do with watch speeding up at this point, temperature and gravity usually accounts to about +-5sec deviation together but +25 above the tolerances listed will not be be due to temperature unless he is running in 90 degree weather for a full hour but not from normal activity in 60 degree weather

[Doninvt]

Here are shots at 66F (ambient) and 89F (my only environmental chamber, a proofing oven),  both dial up.  On the 89F shot you can see that the rate starts at +41s/d and gradually drops as the watch cools off again.

 

[yankeedog]

Faster rate and smaller amplitude at higher temperature, check those lift angles, 52 and 53 as they will effect amplitude measurement. I don't think your hairspring is temperature affected.if it's effective length were changed by expansion or contraction it would show up in the beat error.Could it be that the action of self winding  could be the culprit?could the force generated by the swing weight be imparting more torque,generating more speed?

[jdm]

4 hours ago, yankeedog said:

Faster rate and smaller amplitude at higher temperature, check those lift angles, 52 and 53 as they will effect amplitude measurement.

Only by a very small amount, 1 or 2 deg,  does not affects rate which is the issue here.

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I don't think your hairspring is temperature affected.if it's effective length were changed by expansion or contraction it would show up in the beat error

No. Beat error is the time difference in the balance swinging in the two directions due to the center of hairspring not perfectly at the middle. It is true that timing changes when you adjust BE, but that is just because it makes the hairspring move relative to the regulator position.

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Could it be that the action of self winding  could be the culprit?could the force generated by the swing weight be imparting more torque,generating more speed?

You mean that pictures were taken in different state of winding? When you move around, swing the arm, etc the instantaneous rate changes a lot, as the balance is subject to varying acceleration vectors and shocks, but nothing can be done about that. 

[yankeedog]

not exactly... what I mean to say is this , the winding rotor produces torque. this torque is used the wind the mainspring. during the process of winding would not there be more rotational force transmitted to the the gear train accompanied by an temporary increase in rate? As I understand beat error, it is the difference in milliseconds between tick and tock, and that it is adjusted by centering the impulse jewel on the pallet fork, perfectly centered, no beat  error.It seems to me that if the hairspring is lengthened or shortened, it would cause the jewel to move relative to the fork and induce a beat error.

[jdm]

27 minutes ago, yankeedog said:

As I understand beat error, it is the difference in milliseconds between tick and tock, and that it is adjusted by centering the impulse jewel on the pallet fork, perfectly centered, no beat  error.It seems to me that if the hairspring is lengthened or shortened, it would cause the jewel to move relative to the fork and induce a beat error.

We're probably saying the same thing. Centering the impulse jewel is done (on mov.ts having this feature) by moving the endstud of the hairspring, that will make the balance staff and impulse jewel to rotate accordingly. In doing this, the total HS length stays the same, but the since the regulator arm didn't move, the effective HS length changed, and so the timing. Once that is done you would then regulate rate, at this during which error should not change at all, or by 0,1 Ms perhaps.

[Doninvt]

On the winding, I hand wound about 30 turns of the crown, then let it run about 15 minutes before the 66 degree timegrapher run.  Then about 20 minutes in the oven to bring it up to 89 degrees, then that session on the timegrapher.  Not much opportunity for self winding during all this as I wasn't wearing it.

I didn't realize the timegrapher would reset the lift angle to default when powered down, which is why the first run showed 62 degrees instead of 63.

The couple of times I've let it run down, the reserve was over 60 hours by a few.

On every count it seems well within spec, except for the temperature thing.  The previously posted technical guide (thank you) indicates the -15 to +25 spd should hold on the wrist at ambient of 5 to 35 C, and I've been well within that temperature limit, but as I said generally getting around +45 on the wrist.  Even with diashock, I switch to a quartz watch when doing high shock activities like racquet sport or hammering etc.

 

 

[yankeedog]

I have that same timegrapher, it resets to default of 52 degrees whenever you shut it down. You are probably going to have to live with this temperature problem. and yes hammering nails is not the best thing for a mechanical watch.

[CaptCalvin]

Try giving it a wind of about 10 clicks or so after the watch settled down. I suspect the bridle might be binding on the barrel wall. If it's not that then it's lubrication. Seikos tend to be overoiled out of the box. Can't see any other reason it takes 15 minutes to stabilize.

[Nucejoe]

 

Correction... of course that's 3 s/d/d.

I presume you bought the watch brand new and dirty HS and such dosn,t apply.

I suppose seiko made this to stay on wrist. 

 

[Doninvt]

Yes, purchased new and recently.  As it came, I'd say more made to stay sitting on a table, since that's where it keeps good time if I keep it manually wound. (That may change as we move into summer and the ambient temperature goes up 10 or 15 degrees C)

In the ways I can observe through timegrapher, this 6r15 seems to do better than my Seiko 5 (7s36) in things that can be attributed to care in assembly or materials:

Position variation, beat error, regularity of beat, time to recover from changed position.

Yet, the 7s36 shows nowhere near that temperature dependence.  As an engineer, I'm wondering what the cause is, maybe spring stiffness changes with that Spron alloy?  I haven't heard of this being a general thing with 6r15's (D version if that matters).

Being well out of Seiko's specification, is there any recourse through the dealer, given that it's a Japanese Domestic Market model and I'm in the US?  If not, any other solution (maybe  a new balance?)  I could regulate it "for the wrist", but if the basic T dependence is there, there would still be seasonal variation that I don't see on my cheaper Seiko.

 

[Doninvt]

10 hours ago, CaptCalvin said:

Try giving it a wind of about 10 clicks or so after the watch settled down. I suspect the bridle might be binding on the barrel wall. If it's not that then it's lubrication. Seikos tend to be overoiled out of the box. Can't see any other reason it takes 15 minutes to stabilize.

It seems to be the temperature of the watch returning to ambient.  The rate difference is observable both fully wound and a day into the reserve.  For the graphs I posted, the ambient was about 10 minutes after winding, then 20 minutes in the oven to stabilize at 89F before that graph was taken.  I can try winding a few clicks to see if there's a difference

Edited April 25, 2019 by Doninvt
more detail

[Doninvt]

For completeness, here is the result after putting the watch in the refrigerator (37F) for half an hour.

Only a small fraction of the sec/day/deg difference that the warm (89F) gave compared to 65F ambient.

I also note that my 7s36 based watch has just a very few seconds difference between 65 and 89 deg F.  

I'm thinking maybe there's an irregularity in the hair spring that goes critical (touching an adjacent turn of the coil?) at a particular temperature.

[Doninvt]

To put a wrap on this story, I sent it back to the dealer's service.  They were unable to fix this and I got a refund.  I just found another Alpinist which doesn't show the problem.