Rebanking on JLC 889/929

[Knebo]

Hi all, 

I came back from holidays on Saturday early morning and put in a 6h watchmaking shift until 3.30am the following night. I really wanted to finish off that Jaeger-LeCoultre Master Geographic I had not finished before the holidays (because the mainspring hadn't arrived in time). 

Anyway, so I finished it and all seemed great. 

But now, I realised that it's rebanking/"knocking". 100% sure. Classical symptoms and I can even observe it visually (with the phone super slow-motion video). 

Here's a timegrapher picture (lift angle is correctly set to 50°). 

Movement diagram:

 

Please refer to this thread (which I'll eventually update, too) for more pictures of the movement:

https://www.watchrepairtalk.com/topic/31231-jlc-9293-master-geographic-base-jlc-8892-iwc-3253-ap-2124/?do=findComment&comment

 

Now, I know my most common options. 

- change mainspring to a weaker one: I don't want to do that because I'm using an original, new and calibre-correct JLC mainspring 

- re-oil the train and/or balance with thicker oils: I really want to avoid this because it would mean a hell of more work (disassembly of dial/hands, complication module, cleaning..). Furthermore, I already used 9020 instead of 9010 on the 4th wheel. 

To be honest, I'm looking for an "acceptable", but lazy way out (it's my own watch). 

I think I need to knock off (pun intended) about 15° of amplitude. 

Following ideas:

- add HP1300 to cental second pinion pivot. Currently, there's 9010 as instructed. Could I mix them without causing issues? 

- bend the centre seconds friction spring to be a bit tighter (the seconds hand is moving smoothly, so it seems to be correct as is) 

- add heavy oil or even 9504 grease to the pallet fork pivots 

Are these options likely to be effective (for at least 15° of amplitude reduction)? Any other lazy options? 

Thanks for your suggestions! 

Edited January 5 by Knebo

[RichardHarris123]

I don't know the answer but the lazy opinion is usually incorrect. 

[Knebo]

44 minutes ago, RichardHarris123 said:

I don't know the answer but the lazy opinion is usually incorrect. 

You are probably right 

[nickelsilver]

I would open the banking pins slightly to increase total lock. If it has solid bankings, move the pallet stones out about 0.005mm.

[VWatchie]

3 hours ago, nickelsilver said:

I would open the banking pins slightly to increase total lock. If it has solid bankings, move the pallet stones out about 0.005mm.

As always your input is always much appreciated! Would you say your suggested approach is the standard way to eliminate re-banking?

[nickelsilver]

10 hours ago, VWatchie said:

As always your input is always much appreciated! Would you say your suggested approach is the standard way to eliminate re-banking?

If possible I would put in a weaker mainspring as first choice. But that's not always possible, so yes, I would adjust the escapement.

 

In the event of not enough amplitude, I would first see if there is any room to move in the pallet stones/close the bankings. That's considering everything else is in top shape. A stronger mainspring would be a the last resort.

Edited January 6 by nickelsilver

[nevenbekriev]

Sorry for the question if the answer is somewhere in, but I am not following the  thread. There is a picture in the beginning with all the parts disassembled and there is a spring there, what happened to it?

[Knebo]

43 minutes ago, nevenbekriev said:

Sorry for the question if the answer is somewhere in, but I am not following the  thread. There is a picture in the beginning with all the parts disassembled and there is a spring there, what happened to it?

Thanks for the attention to detail. Unfortunately, I messed up the old mainspring in my attempt to wind it in my mainspring winder. I only have right-hand winders and the mainspring was left-handed. Furthermore, the inner coil for the arbor is very small in relation to the barrel size. Due to those two issues, I ended up distorting the old mainspring very badly. Can't reuse it. 

It's bizarre, though, because the mainspring I got from Cousins was supposed to be an original JLC spring for the calibre. 

Edited January 6 by Knebo

[AndyGSi]

27 minutes ago, Knebo said:

It's bizarre, though, because the mainspring I got from Cousins was supposed to be an original JLC spring for the calibre. 

This is an 899 not an 889?

[Knebo]

1 hour ago, AndyGSi said:

This is an 899 not an 889?

Oops, wrong screenshot. I double checked. I got the correct one, for 889. (but they are pretty much the same anyway) 

This is the correct screenshot:

[Neverenoughwatches]

5 minutes ago, Knebo said:

Oops, wrong screenshot. I double checked. I got the correct one, for 889. (but they are pretty much the same anyway) 

This is the correct screenshot:

I know the one that you removed and trashed Knebo may not have been the original, but how does the size compare to these two ?

8 hours ago, VWatchie said:

As always your input is always much appreciated! Would you say your suggested approach is the standard way to eliminate re-banking?

I also had questions H, thinking about how folk sometimes move banking pins as a lazy/not understanding alternative to moving pallet stones. I decided not to ask having assumed Nicklesilver would suggest that the escapement's safety would be assessed first before moving the banking pins .

[Knebo]

53 minutes ago, Neverenoughwatches said:

I know the one that you removed and trashed Knebo may not have been the original, but how does the size compare to these two ?

Unfortunately, I can't compare it anymore since the new mainspring is in the barrel. But the difference can only be small. It's a remarkably small spring, barely taller than the metal retention ring (it was hardly protruding from the ring, which even made it difficult to align it on the barrel to press in). 

[mikepilk]

Omega Working Instruction 81 suggests putting HP1300 on one, or both pallet pivots.

13 hours ago, nickelsilver said:

I would open the banking pins slightly to increase total lock. If it has solid bankings, move the pallet stones out about 0.005mm.

I did wonder about moving the pallet jewels out. I recently had severe rebanking after fitting a new mainspring. Thicker oil did not help, and even after fitting a much weaker spring, it was still close to rebanking. 

[Knebo]

7 minutes ago, mikepilk said:

Omega Working Instruction 81 suggests putting HP1300 on one, or both pallet pivots.

I like this idea because it's easy and unlikely to cause any harm, right? (if anything, further prevent wear on the pivots). And it's easy/accessible. If it's even in the Omega instructions (thanks for sharing that), it can't be too bad, right? 

Changing the pallet stone depth or banking pins is quite a "serious" intervention... 

[mikepilk]

I've just re-read it, and now I have doubts. I took it to mean the pallet pivots, as I have seen this advice elsewhere.

It says "Replace the lubrication on the bridle facing the dial".  I assumed "bridle" was a mis-translation and meant pallet. But, it says "Replace", when you normally would not oil pallet pivots. Could it mean balance jewels?  
I've searched through my Omega service sheets and can find no reference to "bridle".

[Knebo]

40 minutes ago, mikepilk said:

I've just re-read it, and now I have doubts. I took it to mean the pallet pivots, as I have seen this advice elsewhere.

It says "Replace the lubrication on the bridle facing the dial".  I assumed "bridle" was a mis-translation and meant pallet. But, it says "Replace", when you normally would not oil pallet pivots. Could it mean balance jewels?  
I've searched through my Omega service sheets and can find no reference to "bridle".

thanks for sharing!

This is rather unclear indeed. I only know "bridge" for the mainspring bridle. It could make sense to replace the breaking grease with HP1300 to cause premature slipping. But that would also affect the power reserve. It also doesn't make much sense in the context of the Omega text ("bridle facing the dial" ??).

So they must mean something different. Balance jewels also makes sense. But I guess, replacing it only on one side would lead to some differences between dial up vs dial down timekeeping. But maybe not too dramatic.

 

 

[nickelsilver]

I tried to find that Omega doc in French, as it is in English I have no idea what they mean by bridle.

[VWatchie]

3 hours ago, Knebo said:

I like this idea because it's easy and unlikely to cause any harm, right?

I can’t imagine it would cause any harm as long as the oil doesn’t spread to the teeth of the escape wheel. Unfortunately, I don’t think it will help much, but it might still be worthwhile.

3 hours ago, Knebo said:

Changing the pallet stone depth or banking pins is quite a "serious" intervention...

I used to feel the same way but was determined to try and learn it, which eventually led me to start the following thread that will hopefully be helpful in moving forward.

 

[Neverenoughwatches]

3 hours ago, mikepilk said:

It says "Replace the lubrication on the bridle facing the dial".  I assumed "bridle" 

What does the afore and after text say Mike ? could the word dial be mixed up with wall ? That would make more sense in relation to adjusting amplitude on an automatic. 

[LittleWatchShop]

I am way out of my league here, but I feel a little punchy this morning.  Oil the pallet fork pivots--something I never do, but ¿Quien sabe?

[fellerts]

For what it's worth, D5 on the pallet fork pivots robbed around 30 degrees of amplitude on an ETA 2472 I worked on a while ago. I also played with D5 on the balance pivots which had less of an effect.

I'm wearing that particular watch right now and it's at ~340 degrees in the horizontal positions today compared to ~300 degrees 2 years ago, so this migth not be a viable long-term solution. Your mileage may vary.

 

 

[Neverenoughwatches]

2 minutes ago, fellerts said:

I'm wearing that particular watch right now and it's at ~340 degrees in the horizontal positions today compared to ~300 degrees 2 years ago, so this migth not be a viable long-term solution. Your mileage may vary.

My thoughts also that it would thin out over time with so much quick movement from the pallet fork. D5 is more designed for slow revolutions. As far as i can figure the pallet fork would be the fastest moving component in a watch.

[Jon]

@KneboIf the knocking starts early, no amount of HP1300 on the pallet fork pivots or anywhere else will make much difference.

What I mean by knocking early, is when the movement knocks way before getting to full wind. So, if a movement just knocks for the first five to ten minutes after reaching full wind, it is knocking late and if the movement knocks between half to three quarters wind, then it knocks early. A late knocking movement can have the amplitude dropped by greasing the pallet fork pivots and maybe every other pivot with HP 1300. But if the movement starts to knock around three quarters wind, no amount of grease is going to alleviate that in my experience.

Some vintage watches I work on such as JLC's can knock with the mainspring that is meant for it, so a weaker spring needs using. Don't hold onto the idea that because the mainspring is apparently the correct size that it works. It isn't always the case.

I think this is a gift to you!

Now you need to be able to find out what spring you need and what works to the optimum.

Find out at what point the spring knocks. With no power on the watch, wind the movement to full wind and count the turns of the mainspring (count how many turns of the ratchet wheel), then take the power off and wind the movement on the timegrapher and see how many turns until knocking occurs. This gives me an indication if the mainspring is way over strength or just a tad.

If the spring knocks at half wind, then it is way over strength and may need to come down at least 0.01 mm in thickness, maybe more.

If the movement knocks very close to full wind, you may want to bring the spring down half a strength by 0.005 mm

Personally, I would change the spring rather than resetting the escapement, but that's just my personal choice.

Pity it doesn't have a sweep second pinion and brake spring, as setting the spring tighter will reduce quite a lot of amplitude. I use that in vintage Rolex's to remove any knocking issues

[mbwatch]

3 minutes ago, Jon said:

But if the movement starts to knock around three quarters wind, no amount of grease is going to alleviate that in my experience.

@Jon This is such a helpful answer. I recently had a 1 jewel brac (of all things) that was still knocking 8-10 hours after full wind and this explains why I could not calm it down.

[Knebo]

24 minutes ago, Jon said:

@KneboIf the knocking starts early, no amount of HP1300 on the pallet fork pivots or anywhere else will make much difference.

What I mean by knocking early, is when the movement knocks way before getting to full wind. So, if a movement just knocks for the first five to ten minutes after reaching full wind, it is knocking late and if the movement knocks between half to three quarters wind, then it knocks early. A late knocking movement can have the amplitude dropped by greasing the pallet fork pivots and maybe every other pivot with HP 1300. But if the movement starts to knock around three quarters wind, no amount of grease is going to alleviate that in my experience.

Some vintage watches I work on such as JLC's can knock with the mainspring that is meant for it, so a weaker spring needs using. Don't hold onto the idea that because the mainspring is apparently the correct size that it works. It isn't always the case.

I think this is a gift to you!

Now you need to be able to find out what spring you need and what works to the optimum.

Find out at what point the spring knocks. With no power on the watch, wind the movement to full wind and count the turns of the mainspring (count how many turns of the ratchet wheel), then take the power off and wind the movement on the timegrapher and see how many turns until knocking occurs. This gives me an indication if the mainspring is way over strength or just a tad.

If the spring knocks at half wind, then it is way over strength and may need to come down at least 0.01 mm in thickness, maybe more.

If the movement knocks very close to full wind, you may want to bring the spring down half a strength by 0.005 mm

Personally, I would change the spring rather than resetting the escapement, but that's just my personal choice.

Pity it doesn't have a sweep second pinion and brake spring, as setting the spring tighter will reduce quite a lot of amplitude. I use that in vintage Rolex's to remove any knocking issues

Thanks @Jon, helpful as usual!

I had already tested the "early" vs "late" knocking. And it is indeed "late". That's why I'm looking at alternative options to the weaker mainspring.

In fact, it doesn't knock at all when fully wound MANUALLY (max 335°). However, there seems to be a bit of extra tension coming when it is AUTOMATICALLY winding. Then it goes to 345 and the next reading is snowstorm/knocking. 

The movement DOES have a sweep second with tension spring. I actually mentioned that option in my original post. 

I think I'll now replace 9010 with HP1300 on the upper balance jewels and see what happens. 10-15 down would suffice, I think. If not enough, I'll bend the sweep second spring a bit.