Impulse jewel gets stuck on pallet fork

[ColinC]

I have a watch with an AS1700/01 movement which runs great dial down but when I turn it dial up it stops. Turns out that that the Impluse jewel is able to get stuck on top of the pallet fork.  The issue seems really similar to this post but the cause is not the same 

There is quite a bit of endshake on the balance and at the extreme end of that movement the balance jewel can pass partially over the pallet fork and get stuck.
 

Here is a photo of the balance wheel / roller table - it doesn't appear to have the crushed roller table problem from the other post 

As an experiment I tried moving both the jewels the pallet fork pivots sit in up a bit but that didn't make enough difference.

The impulse jewel seems to be intact.  It does look like a longer jewel would prevent the problem but it does not appear that this jewel, which I assume hasn't been changed, was once just fine

Any ideas what I can do or should look at next?

[caseback]

5 minutes ago, ColinC said:

There is quite a bit of endshake on the balance and at the extreme end of that movement the balance jewel can pass partially over the pallet fork and get stuck.

Any ideas what I can do or should look at next?

 

You mention endshake on the balance?

[nickelsilver]

The upper pivot of the balance is very suspicious. A tiny piece of dust at the balance end of the balance cock could also bring this about. Endshake on a balance should be 0.02mm-0.03mm, 0.05 is a lot. If your pivots are good, and endshake is excessive, it must be corrected.

Edited November 6, 2024 by nickelsilver

[JohnR725]

15 minutes ago, ColinC said:

There is quite a bit of endshake on the balance and at the extreme end of that movement the balance jewel can pass partially over the pallet fork and get stuck.

 

2 minutes ago, nickelsilver said:

endshake is excessive, it must be corrected

 

16 minutes ago, ColinC said:

It does look like a longer jewel would prevent the problem

The most important thing when fixing a problem in the watch is to identify the problem and fix that. I agree with @nickelsilver The End shake issue has to be addressed first. Fixing of the symptoms of the problem without fixing the problem will not solve the problem. For one thing a longer jewel introduce other problems to be dealt with.

Elite nice to have a side view picture the balance staff so we can see both pivots. In addition you need to check the balance jewels and make sure they're fine and not broken or some other issue with them

[ColinC]

I agree that the excessive endshake seems to be the problem - but what causes it and how can it be adjusted?

I know what to do with wheels on the train of wheels where the endshake is too big or too small - but what do you do with the balance and incabloc settings?

Both the jewels in both incabloc settings appear clean and undamaged (just recleaned and oiled them) 

[praezis]

Measure the length of the balance staff, it looks suspicious. And not like a Incabloc staff.

[ColinC]

The balance staff is 2.75mm long.  Where can I see what is should be?

Ranfft has a couple of staffs listed on this page.
This is one of them and it is the same length as the one I have

[Nucejoe]

 Remove the fork, put balance & cock assembly back on mainplate, if the balance oscilates freely in both DU & DD position, pivot is not short, adjust balance settings.

In case balance doesn't oscilate freely in DU position, pivot on cock side is short, in which case good repair is to replace the balance staff. If its incabloc you can flip the end stone in the setting upside down, so its dome side faces the short pivot. Which  is not good watch repair, but works.

 This test should be done before re-asembly. When you have only balance&cock assembly on mainplate, you have clear all around  access  to balance complete.

Rgds

 

 

[tcolgate]

6 hours ago, Nucejoe said:

If its incabloc you can flip the end stone in the setting upside down, so its dome side faces the short pivot. Which  is not good watch repair, but works.

(sorry to interject, but was curious)...

Presumably oil would not hold in the correct place in this case? I can imagine the spring would be pretty difficult to fit to?

[VWatchie]

Not sure what it brings to the table in this particular case, but the linked thread created by @Jon contains one of the most appreciated posts on WRT:

 

[Nucejoe]

3 hours ago, tcolgate said:

(sorry to interject, but was curious)...

Presumably oil would not hold in the correct place in this case? I can imagine the spring would be pretty difficult to fit to?

 Your presumptions are both correct, but to both are non classical  solutions .

   Epilame the lubed end stone, so oil stays on dome top.

 Flipping end stones Usually leaves it  loose inside the setting housing, you can streighten the shock spring , even bend it , usually  minimal bending  would suffice, way before reaching the springs fatigue threshold.                                                                         This trick is an alternative approach for  repairers who don't  have a staking set, yet unskilled to restaff  a balance wheel or build and poise  balance completes or can not  find or make a balance staff.

Mostly for beginners/ hobbyist.  

I doubt if its thaught in any class or mentioned in any watchrepair book, however,  worth knowing when it works & you get ten more years out of the old balance staff.

Rgds

Edited November 7, 2024 by Nucejoe
Typo

[ColinC]

6 hours ago, VWatchie said:

Not sure what it brings to the table in this particular case, but the linked thread created by @Jon contains one of the most appreciated posts on WRT:

Thanks for surfacing this one for me - I think it is exactly what I needed.

I was not sure if you could push the incabloc settings or what tool to use - looks like you can and that I have the right tool!   I will practice on a scrap movement this weekend.
 

[Jon]

17 hours ago, ColinC said:

I agree that the excessive endshake seems to be the problem - but what causes it and how can it be adjusted?

It can be caused by many things, but don't assume how you found the settings is how it is meant to be.

If there is too much end-shake of the balance, look at the safety roller and see if the guard pin is in direct line with that safety roller in both DU and DD and that the impulse jewel isn't too deep or shallow into the notch in DU and DD. The end-shake of the balance should be about the same as the pallet fork for the reason I just said and the escape wheel should be the same end-shake of the pallet fork so the escape wheel will hit the same point (Middle to top 3/4) the impulse face of the pallet stone in either DU or DD. Once you understand these basic parameters you have to adhere to it will be a lot easier to alleviate the problem. 

By what you have said and let's presume the balance staff is the correct size, I would first ensure the IncBloc setting on the balance is seated properly and that there isn't any 'birds feet' under the balance cock or that it has been bent to increase the end-shake of the balance. Once you know that is right, I would move the IncaBloc setting in the mainplate towards the balance to decrease the end-shake of the balance, but be very careful when fitting the cock after doing this just in case the shake is now too little and you crack a cap jewel doing up the cock.

Once the end-shake feels better check the guard pin is in line with the safety roller in DU and DD. You may then want to adjust the shake of the pallet to suit the balance now and then the escape wheel in turn

Don't assume that any of the end-shakes of the escape wheel, pallet fork or balance is correct to begin with

[nevenbekriev]

@praezis has pointed to something... Is actually this balance (on the pictures) for shock proof movement??? I am not sure, and this is something that matters.

OP, balance end shake may be a problem, but what You think (that "the Impluse jewel is able to get stuck on top of the pallet fork in DU position") sounds very suspicious. Did You ever do the free oscillations test in DU position?

[JohnR725]

It was a nice to have a better picture. Specifically not at any angle as the roller jewel doesn't look quite right it does look like perhaps it's short or it could just be loose and has relocated farther in but from this angle it looks angled and doesn't look quite right. So a better picture would be nice.

22 hours ago, ColinC said:

AS1700/01

I'm attaching of the parts list which also has a pretty decent service manual don't see that very often. But brings up an amusing problem? On the first page the picture the movement very clearly shows a Incabloc Jewel assembly on both the front and the backside. But all the rest the pictures the movement in the manual that seems to be missing? Plus a careful look at the parts list indicates that that is also missing. Which brings up as we already know a suspicion of a watch that was made over a time span which obviously has lots of variations. Like balance staffs variations I found this on one of the popular parts site. Is also looking at the best fit site online and it's showing the same thing lots of variations the balance staff and balance complete.

Do we know anything about the service history of this watch? The problem with parts variations is that of someone is changed you the balance staff or more likely the balance complete and was unaware of all the variations that would be a problem.

 

3903_AS 1700, 1701_Smaller.pdf