weird stop-and-go timegrapher readings after balance staff change and pallet stone refitting -- Vostok 2414

[Klassiker]

10 hours ago, JohnL said:

if it's only the hairspring and balance wheel that are synced

The hairspring is matched to the wheel and staff assembly, but it is variations in the wheel portion of the assembly which significantly affect the moment of inertia. The MoI is proportional to mass and to the square of the radius around which the mass is rotating. That means dimensional differences between staffs have hardly any effect, but the tiniest differences between the mass and dimensions of wheels, especially at the rim, puts them outside the range of any individual spring.

[LittleWatchShop]

6 hours ago, RichardHarris123 said:

The staff will affect the moment of inertia but the tolerance of a new staff means it's negligible.  Yes the density of the new staff has an effect but basically diddly squat. 

"Diddly squat" is not a term of art in the watchmakers lexicon, but accurately conveys the fact that a change in staff has an infinitesimal effect on resonant frequency of the balance/hairspring oscillator. Assuming the pivots are properly dressed.

It is a common term here in Texas. "I don't give a diddly squat about your bob wire fence, those are my cows and I am commin to get them."

[Knebo]

On 2/20/2025 at 3:08 PM, VWatchie said:

You certainly have a right to be! Congrats!

I've been trying this many times but never really succeeded. For some reason, Archimedean spirals confuse my brain. I know they have an absolute centre, but I can't find it for some reason. The only time I truly succeeded in manipulating a hairspring was by @nickelsilver helping me out by drawing arrows in an image of where to push. I feel very envious that you are ahead of me! 

It seems you got it just right! In my experience, however, there's such a thing as too little end-shake especially when working on these Russian movements where the tolerances are pretty crude. It's a bit like shoes, just right is the best but if that's not possible it's better with a little too large than too small. Anyway, it sure looks like you nailed it!

And should very much be so. I've probably had nearly a hundred Vostok movements on my TM, even brand-new movements, and have very rarely seen results like that. A bit of roller coaster is simply the norm for these movements. So again, congrats! 

Yes, they are great to learn with, but let's not forget these movements were never meant to be marvels of Swiss precision, but inexpensive and practical enough to be afforded by the masses. For this reason, and IMO it would be unfair to call them anything derogatory. A few decades ago these movements were manufactured by the many millions every year. It's a general misconception that the Russians are unable to produce quality in anything. The quality level is a very deliberate choice, and there are plenty of examples where Russian technology far exceeds Western technology.

Håkan, thank you very much for your kind words! 

A few small responses to your points:

1. I'm certainly not ahead of your regarding hairspring manipulation. Knowing you a little bit, you probably set yourself targets of perfection. I try the same, but with hairsprings I just want them to be fully functional, not necessarily aesthetically perfect. In the case of this Vostok, my "fixed" hairspring is now as ugly as it could be -- while still fully functioning. The terminal curve is not nice at all and the hairspring is only central between the regulator pins in this particular position... if I had to regulate it again, I'd have to bend to, too. 

2. Endshake: very true. It took me a few attempts to get it just right. In fact, I over-shot once by a tiny margin. The last half-turn of the screws on the train bridge caused the train to lock up. But the next go (pushing the jewel back ~2/100th) brought it to "just right". 

3. Yes, you are right about the very respectable functional quality of these movements -- when considering the (high) quantity and (low) cost of these movements. So no offence to them. But if you forget about quantities/costs and just compare them to e.g. a ETA/Selitta (I know that this is an unfair comparison regarding costs!!)... then they're pretty shitty