AS1903 train assembly problem

[tonydagee]

Hello all,some help greatly appreciated with the assembly of the going train for this AS 1903please.

having carefully checked the pivots in their jewels, and making sure train is free, on  fitting the bridge  the assembly jams when screwing down.

I  checked again leaving out the 4th wheel and the escape wheel alternately,  and then I could screw down both times. 

wheels are not damaged  and pivots not bent.  Jewels  also look fine.What the deuce is going on?!

 

 

 

 

[AndyGSi]

What condition was the movement in when you started?

Can you post a photo of the bridge and are you sure the pivots are engaged before screwing it down?

[RichardHarris123]

Could be an end shake problem, as @AndyGSisaid, was it running before? 

[Jon]

1 hour ago, tonydagee said:

having carefully checked the pivots in their jewels, and making sure train is free, on  fitting the bridge  the assembly jams when screwing down.

I'm not 100% sure what you are saying. You made sure the train is free. How, if when you screw down the bridge and everything jams?

 

1 hour ago, tonydagee said:

I  checked again leaving out the 4th wheel and the escape wheel alternately,  and then I could screw down both times. 

If that is the case that when the 4th and escape wheel are not there you can screw down the bridge and you get the freedom of the train, then try only the escape wheel in place and fit the bridge. If this isn't the problem, then just fit the 4th wheel and try with the bridge. It's about finding out what works and slowly adding more wheels until you find the offending part. Try checking the endshake of every wheel as well

[Nucejoe]

 There is no need to try/eliminate each suspect wheel individually.

When all train gear are in and secured by bridge/bridges,

Check end shake on each arbour. Zero end shake on any wheel's arbour = jam in gear train

 So a jewel has to be moved to create some end shake. Ideal end shake .01mm on each side of the arbour. 

You also ought to decide which jewel ( on  mainplate  or bridge) to move to ensure no pinion leave and gear teeth rub. 

 Excessive end shake or poorly adjusted jewels can let adjacent gears rub on each other. 

Good luck

 

 

Edited Wednesday at 09:05 PM by Nucejoe

[tonydagee]

Hi Jon and all,

 I meant the wheels are freely engaging with each other on the the pillar plate.

I have a train bridge from a donor movement, that may help if it’s a Jewell problem 

thanks Tony

[Jon]

15 hours ago, Nucejoe said:

There is no need to try/eliminate each suspect wheel individually.

When all train gear are in and secured by bridge/bridges,

I agree and that is what I would do and as I screwed the bridge down and it jammed I would check the endshake of the wheels at that point and instantly I would see the problem, but @tonydageesaid as he screws down it jams, so as I understood it he is inferring he hasn't managed to fully screw the bridge down before the wheels jam and if there is less than zero endshake on one of the wheels it might crack or damage one of those jewels on the bridge or mainplate. Unlikely, but it could happen. If only the offending wheel is in place and he screws down the bridge, he'll know instantly it is that wheel, which I reckon it is either the 4th or escape wheel by what he has said.

@tonydageewas the watch movement working before you worked on it? Jewels can move whilst being cleaned. I have had this happen a couple of times and when assembling a movement that previously worked well before cleaning, I found that there was zero endshake of a wheel when I screwed down the bridge.

By telling us that he has a donor bridge, strongly suggests that he might not be adept or confident at moving jewels to suit the correct endshake rather than reaching for a different bridge.

I would leave the donor bridge alone for now and work on the endshake issue, if that is what it is. 

Have you replaced any of the wheels from a donor movement?

@tonydageedo you know how to set jewels to the correct endshake?

If you are going to set the jewels on the escape wheel, remember that the endshake of the escape wheel and pallet fork has to be roughly the same, because the escape wheel tooth should ideally make contact with the same spot on the impulse face of the pallet jewel in both dial up and dial down positions.

Edited Thursday at 12:32 PM by Jon

[VWatchie]

17 hours ago, Nucejoe said:

Ideal end shake .01mm on each side of the arbour.

Are you sure about that? In my limited experience, end-shake < .02mm hasn't worked well at all, affecting the overall performance to become more or less erratic. If we're talking Rolex movements, I guess .01mm would work well, but a Vostok movement would more than likely jam. Here is a thread I started about it three years ago:

https://www.watchrepairtalk.com/topic/23280-can-end-shake-and-or-side-shake-ever-be-too-small

 

I just re-read the thread I linked to, and in a picture published by @JohnR725 not even Rolex would accept an end-shake < .02mm for any of the train wheels.

[Nucejoe]

21 hours ago, VWatchie said:

Are you sure about that? In my limited experience, end-shake < .02mm hasn't worked well at all.

 Acheiving optimum overall performance is the aim, which you achieved with bigger than .02mm end shake in your  Russian  movements.   

23 hours ago, Jon said:

I agree and that is what I would do and as I screwed the bridge down and it jammed I would check the endshake of the wheels at that point and instantly I would see the problem, but @tonydageesaid as he screws down it jams, so as I understood it he is inferring he hasn't managed to fully screw the bridge down before the wheels jam and if there is less than zero endshake on one of the wheels it might crack or damage one of those jewels on the bridge or mainplate. Unlikely, but it could happen. If only the offending wheel is in place and he screws down the bridge, he'll know instantly it is that wheel, which I reckon it is either the 4th or escape wheel by what he has said.

By telling us that he has a donor bridge, strongly suggests that he might not be adept or confident at moving jewels to suit the correct endshake rather than reaching for a different bridge.

 

If you are going to set the jewels on the escape wheel, remember that the endshake of the escape wheel and pallet fork has to be roughly the same, because the escape wheel tooth should ideally make contact with the same spot on the impulse face of the pallet jewel in both dial up and dial down positions.

 

 

 

Edited yesterday at 11:55 AM by Nucejoe

[JohnR725]

12 hours ago, tonydagee said:

I have a train bridge from a donor movement, that may help if it’s a Jewell problem 

Always best in watch repair to diagnose and determine the problem or problems before implementing a solution. Versus mixing and matching hoping to somehow the problem will go away. Because often times mixing and matching from donor movements will introduce new problems especially if it was a vintage watch. 

On 4/2/2025 at 11:24 AM, AndyGSi said:

What condition was the movement in when you started?

Yes always one of my favorite questions are we fixing a pre-existing condition or are we dealing with a new problem after servicing?

On 4/2/2025 at 11:15 AM, tonydagee said:

 checked again leaving out the 4th wheel and the escape wheel alternately,  and then I could screw down both times.

Why don't you try putting the fourth wheel and escape wheel in only and see what happens.

 

4 hours ago, VWatchie said:

22 hours ago, Nucejoe said:

Ideal end shake .01mm on each side of the arbour.

Are you sure about that? In my limited experience, end-shake < .02mm hasn't worked well at all, affecting the overall performance to become more or less erratic. If we're talking Rolex movements, I guess .01mm would work well, but a Vostok movement would more than likely jam. Here is a thread I started about it three years ago:

1 hour ago, Nucejoe said:

Acheiving optimum overall performance is the aim, which you find to be bigger than .02mm end shake with Russian  movements.   

interesting I wonder if there is a confusion of terminology here? For instance from the Swiss watch repair manual it appears to be end shake of 0.01 might actually be side shake specification? which if you notice changes with the diameter of the pivot

typically the only place I've ever seen end shake is with Rolex. Although I'm doing a quick search on something

here's something interesting Omega watch and they'll accept a worse case of 0.03 for the balance wheel. Continuing down my search results I see another Omega watch with the same specification. I wonder if that means Omega is making poor quality watches if the tolerance is greater than a

what I find interesting is looking at various books on watch repair and digest really isn't any specifications for end shake. Even though when I was in school we spent a lot of time adjusting it don't actually remember what it was at all. Of course some of that's because I typically work on American pocket watches where it cannot be adjusted it is what it is. Which seems to be the philosophy for just about all the watches out there except Rolex. Then even Rolex based on the tolerances of

2 hours ago, Nucejoe said:

Acheiving optimum overall performance is the aim, which you find to be bigger than .02mm end shake with Russian  movements. 

so apparently anything worse than 0.02 mm would be horrible but I'm not finding that specification out there may be you can find be the reference book? then Rolex the only company that seems to really get obsessed about it and actually published numbers based on this discussion apparently sucks for tolerances. Which suggests there must be a confusion over specifications in this discussion

 

 

[Neverenoughwatches]

On 4/2/2025 at 7:15 PM, tonydagee said:

Hello all,some help greatly appreciated with the assembly of the going train for this AS 1903please.

having carefully checked the pivots in their jewels, and making sure train is free, on  fitting the bridge  the assembly jams when screwing down.

I  checked again leaving out the 4th wheel and the escape wheel alternately,  and then I could screw down both times. 

wheels are not damaged  and pivots not bent.  Jewels  also look fine.What the deuce is going on?!

 

 

 

 

To clarify....the train spins when the bridge is on but not when it's screwed down fully.if you leave out either the 4th wheel or the escape wheel, the wheels that are installed will then all spin when the bridge is screwed down fully. This suggests to me that the endshakes are fine and there is actually an engagement issue between the 4th wheel and the escape wheel.

As all the wheels will spin freely when the bridge is fastened down, but not when they are all installed together.

Edited yesterday at 05:44 AM by Neverenoughwatches

[Klassiker]

10 minutes ago, Neverenoughwatches said:

This suggests to me that the endshakes are fine and there is actually an engagement issue between the 4th wheel and the escape wheel.

I came to the same conclusion.

9 hours ago, JohnR725 said:

Why don't you try putting the fourth wheel and escape wheel in only and see what happens.

That's what I'd do.

[Nucejoe]

 Let me rephrase my previous response to VWatchie's  findings.  

As far as I am concerned ;  " whatever end shake you get best overall performance with, is the ideal end shake " which mainly applies to balance shake and entire escapement.  

 Though VWatchie only mentions erratic graphical display !   I presume the word "overall  includes ,  timekeeping, minimum amp drop after 24 hrs run, smallest delta " positional amplitude drop"  etc. 

When we get optimum performance, I can't care less what  books recommend. 

The issue OP is facing is a problem in gear train, which I think this thread will well cover all possible faults and approaches to correct the problem.  

Regs

 

 

 

Edited yesterday at 11:58 AM by Nucejoe

[VWatchie]

20 hours ago, Nucejoe said:

As far as I am concerned ;  " whatever end shake you get best overall performance with, is the ideal end shake " which mainly applies to balance shake and entire escapement.

Yes, that's a more reasonable approach 

[Jon]

22 hours ago, Nucejoe said:

When we get optimum performance, I can't care less what  books recommend. 

I'm with you there brother!

[Neverenoughwatches]

23 hours ago, Nucejoe said:

When we get optimum performance, I can't care less what  books recommend. 

The classic - Practical over Theory -  A book doesn't cover every situation.