Patek Cal. 10-200 Stud Holder vs. me

[mzinski]

So I’ve been cleaning and bringing back to life a Patek cal. 10-200 (you can see my very recent question looking to confirm the caliber since it’s unmarked). 
So far, everything has come together quite nicely until I oiled the balance wheel jewels. 
As you can see it’s the type in which the balance is removed from the c0ck to access the upper jewel. 

Upon reinstalling the balance I noticed the stud and stud holder is unlike anything I’ve encountered before. The stud slides into the stud holder and is clamped by the upper two screws. When not clamped, the stud can freely slide inwards, outwards, and rotate. At first I thought this was a clever way to allow watchmakers to adjust beat error without bending the spring or twisting the collet. But much to my frustration, I’ve found it to be an endless area of tweaks to try to locate the right spot and angle for the stud. 

Like I said, it looks like a clever design but maybe too clever for me. Can anyone recommend best working practices to incrementally adjust the stud into the right spot? 

[jdrichard]

45 minutes ago, mzinski said:

So I’ve been cleaning and bringing back to life a Patek cal. 10-200 (you can see my very recent question looking to confirm the caliber since it’s unmarked). 
So far, everything has come together quite nicely until I oiled the balance wheel jewels. 
As you can see it’s the type in which the balance is removed from the c0ck to access the upper jewel. 

Upon reinstalling the balance I noticed the stud and stud holder is unlike anything I’ve encountered before. The stud slides into the stud holder and is clamped by the upper two screws. When not clamped, the stud can freely slide inwards, outwards, and rotate. At first I thought this was a clever way to allow watchmakers to adjust beat error without bending the spring or twisting the collet. But much to my frustration, I’ve found it to be an endless area of tweaks to try to locate the right spot and angle for the stud. 

Like I said, it looks like a clever design but maybe too clever for me. Can anyone recommend best working practices to incrementally adjust the stud into the right spot? 

The stud should end up where the hairspring naturally rests. You should not twist the stud to adjust the hairspring.

[mzinski]

31 minutes ago, jdrichard said:

The stud should end up where the hairspring naturally rests. You should not twist the stud to adjust the hairspring.

Should I release the power in the mainspring, bring the pallet fork to neutral, bring the regulating adjustment to 0, then reattached the stud? 

Should I insert the hairspring into the regulator pins before or after I attach the stud? 

[nickelsilver]

Power off, stud cap screws loose, insert stud. HS in pins, wiggle watch a little so everything settles. Screw down stud cap screws.

 

From there, if you need to adjust anything adjust- beat error, move the hs collet. HS not centered in regulator pins, adjust. HS not flat, centered overall, adjust.

 

Ideally with everything "relaxed" and snugging up the stud cap it should all be good. But a watch this age has seen many watchmakers and probably needs some loving.

[mzinski]

37 minutes ago, nickelsilver said:

Power off, stud cap screws loose, insert stud. HS in pins, wiggle watch a little so everything settles. Screw down stud cap screws.

 

From there, if you need to adjust anything adjust- beat error, move the hs collet. HS not centered in regulator pins, adjust. HS not flat, centered overall, adjust.

 

Ideally with everything "relaxed" and snugging up the stud cap it should all be good. But a watch this age has seen many watchmakers and probably needs some loving.

Thanks! I followed that procedure - and - voila! Manageable beat rate and 0.1 beat error. However, the delta between hanging positions and flat positions is significant (max delta of 60-sec). I suspect the pins are a bit tight based on that result and observing the HS doesn't float between them. 

[JohnC]

Before you go adjusting the pins, I think the delta is in part caused by your hairspring being out of flat. You can see it in your last shot - the hairspring appears cupped, meaning the overcoil is naturally sitting too low and is being pulled up when you fasten the stud. You should be able to see this better with the balance out of the watch, and maybe the hairspring off the balance. Make sure I am not wrong before you go messing with it though.

But yes the pins may also be too tight. There are likely several small distinct problems. It is common on old pocket watches for the pins to be pushed together. I think at one point it was considered acceptable practice.

Edited September 20, 2021 by JohnC