Jaeger-LeCoultre 497 amplitude drop

[Jakub]

Good day!

Today I finished service of LeCoultre Futurematic. Once I’ve put movement together and let it run for while, it was about weishi time. Soon enough I’ve noticed new issue for me. 
There is significant amplitude drop between horizontal and vertical positions, but different horizontal and vertical positions have very close results. Same issue causes this movement to slow down. 
I don’t realize it would do before service, since the amplitude was in general low, so I didn’t pay attention to it (my bad). After I’ve found this, cleaned train, check end shake and hair spring.
Do anyone has this happened to them? Please let me know if there is something to be done. I feel I’m pretty close with getting this one right.

Cheers 

Jakub

[nickelsilver]

About a 40 degree drop from horizontal to vertical would be normal for many vintage pieces with relatively heavy balances and slow (18,000bph) trains. It's a matter of pivot size to balance inertia. You aren't too far off, and some older Lecoultre stuff is especially bad here- their smaller calibers can have a 70 degree drop in some cases. I've noticed that the escapement locks are often quite heavy on old Lecoultre calibers, and reducing that can help quite a lot. First of all it will boost the overall amplitude, but by reducing the lock you reduce the force needed to unlock, and this is especially helpful in the vertical positions where the balance is already dealing with increased friction.

 

As it is, have a look at the regulator pins; they should be very close, but with the spring bouncing evenly between them. About 2 hairspring thicknesses would be a max gap (so 1 thickness of freedom). If you can close them a little it will already improve the difference between H and V rates.

[Jakub]

2 hours ago, nickelsilver said:

As it is, have a look at the regulator pins; they should be very close, but with the spring bouncing evenly between them. About 2 hairspring thicknesses would be a max gap (so 1 thickness of freedom).

I can’t make picture clear enough, but you can take my word it is pretty much as you write. 

2 hours ago, nickelsilver said:

I've noticed that the escapement locks are often quite heavy on old Lecoultre calibers, and reducing that can help quite a lot. First of all it will boost the overall amplitude, but by reducing the lock you reduce the force needed to unlock, and this is especially helpful in the vertical positions where the balance is already dealing with increased friction.

Here I am very interested. I would love to explore this further, but I guess on cheaper caliber. I have some suitable CCCR watches with heavy locks. Correct me if I’m wrong, do I better own poising tool before this experiment?

Thank you for answer. I am happy to hear watch is actually behaving OK. On other side I have to resolve -26s/d. In this case I will regulate watch to V positions since there is more of them

Cheers

Jakub

[nickelsilver]

If you aren't experienced in adjusting escapements then definitely learn on something cheaper. There aren't too many Futurematics out there! I wouldn't recommend getting into poising on this one either. You will want to check it in 6 positions, 4 vertical and the 2 horizontal. An overall delta of 30 seconds would be normal for this watch. If you can set the machine to a time "window" where it averages over a set length of time, set it to 20 seconds. When moving to a new position give it 20-30 seconds to settle in, then take a reading. Take the average over the 6 and regulate to be about 5s fast per day.

 

Also, as you just finished it, you will likely find that it picks up some amplitude over the next few days. Not all watches do, but it happens quite often.

[Jakub]

I’m not experienced in adjusting balances, tho I went over some materials about it. I won’t do such a move on such a watch. For now I am happy with results on movement and power reserve. Poising tool is on the list and I have bunch of Soviet whole balances that I use for such a experiments.

I’ve noticed before increased amplitude. I assume it’s for better lubricant distribution. I expect “tick” and “tock” lines to be more parallel in next 24 hours.

Overall this 497, interesting experience. Specially unwind mainspring

[Knebo]

On 2/28/2021 at 3:48 PM, nickelsilver said:

some older Lecoultre stuff is especially bad here- their smaller calibers can have a 70 degree drop in some cases

Interesting! 

I just got a JLC Memovox 3151, calibre P489/1. The amplitude drops by 70° from horizontal to vertical. Good to know that this isn't too unusual. 

Btw, if anyone is ever searching: the lift angle on my P489/1 is 60° - as calibrated through visual (slow motion) inspection of the balance swing. This differs from the 40° lift angle found on various lists on the Internet. Makes a huge difference, obviously, in the timegrapher amplitude readings. 

Cheers