Any ideas what could cause a wildly fluctuating rate?

M'Bob · Feb 20, 2021

So I ponied up and got one of these inexpensive timegraphers. I tested about seven watches, the results were mostly within normal limits, but this one has me stumped: it’s a cal. 321 Speedmaster. The amplitude and beat error look okay, but check out the way the rate dramatically changes:

Any idea what is a typical reason for a rapidly changing and widely fluctuating rate? I would add that I tried demagnetizing it about four times, without a change. Thanks.

michael e · Feb 20, 2021

Could it be dirt on the hairspring?

M'Bob · Feb 20, 2021

michael e
Could it be dirt on the hairspring?

I have no idea. But it does sound like a hairspring problem, doesn't it?

michael e · Feb 20, 2021

M'Bob
I have no idea. But it does sound like a hairspring problem, doesn't it?

Or a loose pallet fork jewel?
Im just guessing here.

Temprus · Feb 20, 2021

Looks to be mainspring issue.
Very stiff mainspring.

Dan S · Feb 20, 2021

I wonder if the timegrapher is reliably picking up the sound of the movement. Have you experimented with the pick-up to make sure it's locking in?

masteroftime · Feb 20, 2021

That is really odd...also I'm unsure whether that is necessarily a good amplitude. Has the watch been serviced somewhat recently? It strikes me as a little high, if that is the true amplitude.

I would also question whether it is reliably picking up the sound of the movement.

M'Bob · Feb 20, 2021

Dan S
I wonder if the timegrapher is reliably picking up the sound of the movement. Have you experimented with the pick-up to make sure it's locking in?

masteroftime
That is really odd...also I'm unsure whether that is necessarily a good amplitude. Has the watch been serviced somewhat recently? It strikes me as a little high, if that is the true amplitude.

I would also question whether it is reliably picking up the sound of the movement.

The watch has been serviced within the last year.

Regarding whether it’s picking up the movement sound: can’t say for sure, but this didn’t happen to any of the six other watches I checked at the same time.

M'Bob · Feb 20, 2021

masteroftime
That is really odd...also I'm unsure whether that is necessarily a good amplitude. Has the watch been serviced somewhat recently? It strikes me as a little high, if that is the true amplitude

Could be mistaken...thought 270-315 was okay.

Archer · Feb 20, 2021

What is the state of wind?

What is the lift angle set to?

What position is the watch in?

Without knowing that and assuming full wind, with correct lift angle, in a horizontal position, I would say it’s possibly rebanking.

If you turn the watch to a vertical position, assuming it is horizontal, what happens?

M'Bob · Feb 20, 2021

Archer
What is the state of wind?

What is the lift angle set to?

What position is the watch in?

Without knowing that and assuming full wind, with correct lift angle, in a horizontal position, I would say it’s possibly rebanking.

If you turn the watch to a vertical position, assuming it is horizontal, what happens?

40 degrees, dial-up only, and at full wind. I can try it again moving the watch from horizontal to vertical, and report back. If it were rebanking, would the amplitude reading be outside (higher) than the normal range? Thanks.

Archer · Feb 20, 2021

What “normal range” is varies. Some movements rebank at lower amplitudes than others. I’ve had 321’s rebanking at slightly over 300 before...

Canuck · Feb 20, 2021

I recently had a friend bring me an Omega 30t2 because it ran poorly in one pendant position. He was certain it only required a minor adjustment. I noticed the endshake on the balance wheel appeared to be excessive, and even though the watch ran while I was examining it, the wheel “wobbled” noticeably. Close examination disclosed that one balance pivot was quite scored, and worn. Someone (not me), had been trying to compensate for the too short and scored balance staff, by scoring the pillar plate to lower the balance cock. Whether the watch was running face up, or face down, the upper (or lower) pivot moved out of the jewel hole on the pillar plate, or the balance clock, just enough to cause the wheel to wobble. But not enough to stop the watch. I had a NOS 30t2 balance staff on hand, so I fitted it, tidied up all the butchery done by some previous goon, and that solved many of the problems. Next challenge was to rectify a number of “modifications” done to the Breguet overcoil hairspring. Very often, erratic watches behave the way they behave for more than one reason. There are times that many causes add up to erratic performance, and it is necessary to identify and cure each problem in order to solve an erratic performer.

Andy F · Feb 21, 2021

Is the hairspring captured in the regulator properly? Is the hairspring well formed - with all coils equally distanced from the next inner or outer coil? Is the hairspring binding on itself?

M'Bob · Feb 21, 2021

A Andy F
Is the hairspring captured in the regulator properly? Is the hairspring well formed - with all coils equally distanced from the next inner or outer coil? Is the hairspring binding on itself?

Great questions all, but can’t answer them as a haven’t opened the watch nor can I. And, I probably wouldn’t be able to give you an answer if I was indeed inspecting it. Thus, I was trying to get some diagnostic ideas from just the timegrapher, if possible.

michael e · Feb 21, 2021

M'Bob
Great questions all, but can’t answer them as a haven’t opened the watch nor can I. And, I probably wouldn’t be able to give you an answer if I was indeed inspecting it. Thus, I was trying to get some diagnostic ideas from just the timegrapher, if possible.

You big tease! 😁

S.H. · Feb 21, 2021

So, assuming is is demagnetized.

Did you check that the watch keeps reasonable time? Because if the mainspring is only slightly too strong, rebanking can happen only dial up or dial down, at full wind. As soon as friction increases and the spring unwinds, it can disappear. Impact on timekeeping may be slight.

Of course if the mainspring is really too strong, it happens on all positions and not only at full wind. Big impact on timekeeping if it is regularly rebanking.

If the hairspring is sticky, deformed, out of the regulator, or if a small hair is tangled in it, you can have all sort of weird stuff happening, but usually on all positions, full wind or not. Two coils touching, in particular, may induce weird rate variations if they come in contact and stick at high amplitude. Usually, also a visible impact on timekeeping.

So, you may check what happens at full wind, half wind, dial up and on the side. But without opening it you may not be able to know much more... had to diagnose anything remotely.

M'Bob · Feb 21, 2021

S.H.
So, assuming is is demagnetized.

Did you check that the watch keeps reasonable time? Because if the mainspring is only slightly too strong, rebanking can happen only dial up or dial down, at full wind. As soon as friction increases and the spring unwinds, it can disappear. Impact on timekeeping may be slight.

Of course if the mainspring is really too strong, it happens on all positions and not only at full wind. Big impact on timekeeping if it is regularly rebanking.

If the hairspring is sticky, deformed, out of the regulator, or if a small hair is tangled in it, you can have all sort of weird stuff happening, but usually on all positions, full wind or not. Two coils touching, in particular, may induce weird rate variations if they come in contact and stick at high amplitude. Usually, also a visible impact on timekeeping.

So, you may check what happens at full wind, half wind, dial up and on the side. But without opening it you may not be able to know much more... had to diagnose anything remotely.

Thanks for these suggestions. I'm going to try them and report back.

SkunkPrince · Feb 21, 2021

I'd be finding the guy who serviced it and asking him to make it right.

M'Bob · Feb 21, 2021

So I measured the timekeeping at 24 hours past full wind, and here’s what I found:

Then, wound it fully and it looked better than previous, almost like something became “unstuck.”

But after putting in the vertical position, it showed this, but then dial up, went back to the crazy high rates.

So: better rate at 24 hours vs full wind, and better rate vertical than dial up (generally). Hairspring intermittently sticking?

Any ideas what could cause a wildly fluctuating rate?

M'Bob

michael e

M'Bob

michael e

Temprus

Dan S

masteroftime

M'Bob

M'Bob

Archer

M'Bob

Archer

Canuck

Andy F

M'Bob

michael e

S.H.

M'Bob

SkunkPrince

M'Bob

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