ETA 2872

[arkobugg]

Cheers mates..

Have just cleaned and oiled and put toghter an ETA 2872 yesterday. The movment started just fine , but after a while it started to run like h......it when like 5 min gain in one hour.

And when I tried to adjust it with the speed stud while I had in he timegrapher, I did not get any change, nor either when I tried to adjust the beat error stud.

The timegrapher just show dots all over the screen, and sometimes the timegrapher did not show the imput on the screen, but I can hear the beat sound from the watch all the time. ( have tried it with other watches, so there is no error with the timegrapher)

Where to start adressing the problems???   Help!!

 

[Marc]

Have a look at the hair spring with a loupe. With that level of gain the odds are that you have a couple of coils sticking together, either due to magnetism or oil residue. Alternatively make sure that the hair spring isn't hitched up on anything and that it isn't touching anything that it shouldn't.

[arkobugg]

34 minutes ago, Marc said:

Have a look at the hair spring with a loupe. With that level of gain the odds are that you have a couple of coils sticking together, either due to magnetism or oil residue. Alternatively make sure that the hair spring isn't hitched up on anything and that it isn't touching anything that it shouldn't.

Thanks Marc, I will check later on today....

[arkobugg]

On 30.9.2016 at 9:13 AM, Marc said:

Have a look at the hair spring with a loupe. With that level of gain the odds are that you have a couple of coils sticking together, either due to magnetism or oil residue. Alternatively make sure that the hair spring isn't hitched up on anything and that it isn't touching anything that it shouldn't.

Hey Marc, Got some time yesterday, and looked at the hair spring with a microscop, (bought a new lomg arm stereo microscope)

could not see anything strange with the hair spring, is there anything else that I could check out?? still going fast as h........

Kind

Armand

[Marc]

Hi Armand,

Unless you have swapped any parts out from a different movement there are really only 2 possible causes for the excessive rate, one is the hair spring, and the other is the main spring.

If too powerful a main spring has been installed then over-banking can occur. This is when the amplitude of the balance wheel is so great that the impulse pin impacts against the outside of the pallet fork at the extreme ends of its oscillation and bounces back with greater energy as a result. This will result in an indecipherable timegrapher trace and can often lead to an increase in rate. Probably the easiest way to diagnose this is simply to listen to the watch. Over-banking is often referred to as "galloping" and if you listen to a watch that is doing this it is clear why; the regular ticking sound is replaced by a galloping horse sound. Another test to see if the main spring is too strong is to let the power down completely so that the balance stops and then just put on enough winds to start it going again and no more. If you get an acceptable rate with just the minimum of power then try increasing the level of wind incrementally, observing the behaviour of the balance at each stage. If the main spring is too powerful then at some point before you reach full wind the over-banking will start and the trace will go snow storm again and the rate will probably go through the roof.

I'm not sure that this is your problem though because in your original post you mentioned that it was fine to start with before going haywire. If it was a main spring issue I would have expected it to be a problem from the start.

The other possible cause is of course the hair spring. If anything happens that effectively shortens the hair spring then the rate will increase. This can be down to contaminated coils sticking together, magnetised coils sticking together, the outer coil getting hitched up on the regulator arm, an out of flat or out of parallel hair spring making contact with the under side of the cock or the top of the balance wheel, etc.

In my experience this is the most likely cause by far, which is why I suggested it to start with. Have you tried demagnetising the watch? With the watch running observe as much of the hair spring as possible to check that no part of it is touching anywhere it shouldn't as it breaths.

There are two other possible causes that could result in mad high rates. One is that with a screwed balance, screws have been removed from the balance rim and not replaced resulting in the balance being too light. This would give you an increase rate but you should still get a timegrapher picture. As the 2872 doesn't have a screwed balance you can discount this as an explanation.

The other is that the 2872 is the 28000bph twin of the 2873 which runs at 21600bph. If some 2872 train wheels had been swapped for 2873 train wheels then you would also get a crazy high rate. However, you would still get a t/g picture and the rate error wouldn't show on the trace, in fact the trace would look normal but the hands would move too fast. Again, the problem would be there from the start.

I'm pretty certain that you issues lie with the hair spring / balance wheel.

 

Marc

[arkobugg]

On 7.10.2016 at 2:30 PM, Marc said:

Hi Armand,

Unless you have swapped any parts out from a different movement there are really only 2 possible causes for the excessive rate, one is the hair spring, and the other is the main spring.

If too powerful a main spring has been installed then over-banking can occur. This is when the amplitude of the balance wheel is so great that the impulse pin impacts against the outside of the pallet fork at the extreme ends of its oscillation and bounces back with greater energy as a result. This will result in an indecipherable timegrapher trace and can often lead to an increase in rate. Probably the easiest way to diagnose this is simply to listen to the watch. Over-banking is often referred to as "galloping" and if you listen to a watch that is doing this it is clear why; the regular ticking sound is replaced by a galloping horse sound. Another test to see if the main spring is too strong is to let the power down completely so that the balance stops and then just put on enough winds to start it going again and no more. If you get an acceptable rate with just the minimum of power then try increasing the level of wind incrementally, observing the behaviour of the balance at each stage. If the main spring is too powerful then at some point before you reach full wind the over-banking will start and the trace will go snow storm again and the rate will probably go through the roof.

I'm not sure that this is your problem though because in your original post you mentioned that it was fine to start with before going haywire. If it was a main spring issue I would have expected it to be a problem from the start.

The other possible cause is of course the hair spring. If anything happens that effectively shortens the hair spring then the rate will increase. This can be down to contaminated coils sticking together, magnetised coils sticking together, the outer coil getting hitched up on the regulator arm, an out of flat or out of parallel hair spring making contact with the under side of the cock or the top of the balance wheel, etc.

In my experience this is the most likely cause by far, which is why I suggested it to start with. Have you tried demagnetising the watch? With the watch running observe as much of the hair spring as possible to check that no part of it is touching anywhere it shouldn't as it breaths.

There are two other possible causes that could result in mad high rates. One is that with a screwed balance, screws have been removed from the balance rim and not replaced resulting in the balance being too light. This would give you an increase rate but you should still get a timegrapher picture. As the 2872 doesn't have a screwed balance you can discount this as an explanation.

The other is that the 2872 is the 28000bph twin of the 2873 which runs at 21600bph. If some 2872 train wheels had been swapped for 2873 train wheels then you would also get a crazy high rate. However, you would still get a t/g picture and the rate error wouldn't show on the trace, in fact the trace would look normal but the hands would move too fast. Again, the problem would be there from the start.

I'm pretty certain that you issues lie with the hair spring / balance wheel.

 

Marc

Hi Marc,

First of all, sorry for very late answer. I have been lot of other thing ta take care of...building on to the house, prepering the garden for winter and stuff...

Thanks for doint this for me, Im very gratfull... Very good decription to how to try to solve problem. I had some time to work on this watch in the weekend.

When I did service on this watch, the original main spring was broken, so I got I new on from a this company http://www.elisabeth9679.com/

I have no reason to belive that the spring is the wrong type, but that can of course be the case. Anyway, a put this in. And it when well like I said befor for some weeks after that like I wrote before...

I have not demagnetising the watch, and in the weekend I was looking at the watch while it was running, and I noticed that some of the spring coils was going togheter like you said. I took the apart. Winded uo the watch, not 100% but maybe 70 / 80 % hard to tell ...and had on my hand, then it when okay, for 2 hours., and then it started to go faster...the day after I looked at the coil spring, and they where still apart...What is happining???  Can it be magnetized while running??   Later on this day ore tomorrow I will wind it up 10 % and measure on the timegrapher, and see if there is a variation if I wind some more....

Thanks again

Armand

 

 

[clockboy]

It could be some sort of grease on the coils. If the coils stick together for any reason the watch will run fast. 

[arkobugg]

51 minutes ago, clockboy said:

It could be some sort of grease on the coils. If the coils stick together for any reason the watch will run fast. 

Can that be like that the watch runs okay for 2 hours, and the start to go faster?  I thinking the main spring will drive the movment with a constant speed, and the balance wheel is the regulator, and if the the spring coils are sticking the movment goes faster. But if the spring coils are not touching the other it should be okay. It douse not matter how long the distance is as long there is air between them or?

[swordfish]

My advice: Put a cheap compass close to the ticking watch. If the ticking watch makes the compass needle sway back and forth, the hairspring is definitely magnetized. If the compass needle does not sway, no firm conclusion can be made. 

[clockboy]

In your last post I understood that some of the coils were sticking together. I was therefore wondering if it was grease causing this issue. If I have read your post correctly that is. If so how did you overcome the coils sticking together. If you are absolutely sure it is not the hairspring  I would then measure the strength of the old spring to check it is comparable with the new. I know that it is a pain to remove the new spring but it is a case of elimination.

If it is not the hairspring & not the mainspring then it must be the canon pinion.

 

[arkobugg]

23 minutes ago, clockboy said:

In your last post I understood that some of the coils were sticking together. I was therefore wondering if it was grease causing this issue. If I have read your post correctly that is. If so how did you overcome the coils sticking together. If you are absolutely sure it is not the hairspring  I would then measure the strength of the old spring to check it is comparable with the new. I know that it is a pain to remove the new spring but it is a case of elimination.

If it is not the hairspring & not the mainspring then it must be the canon pinion.

 

About the main spring, so was the old one broken almost ine the nearby with the arbor, but how can we explain that it runs okay the first 2 hours or so, and then start gaining speed....

Pls explain what it is, if its the canon pinion?

[clockboy]

If the canon pinion is loose then the watch will run fast & it will be impossible to regulate. If the hands have no resistance & feel very loose when you turn the crown it is almost certainly the canon.
The mainspring for a 2872 is GR 3315X
1.30x.12x400x10.5


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[jdm]

6 hours ago, clockboy said:

If the canon pinion is loose then the watch will run fast & it will be impossible to regulate.

Sorry, how and why a watch could run fast with lose/slipping cannon pinion ?

Edited October 24, 2016 by jdm

[clockboy]

The cannon pinion operates like a clutch. It must have enough friction to drive the hands but not to much to stop the watch. Also if very loose the movement will be very difficult to control & also the hands do not turn. 
However I have worked on watches where the cannon was too loose & the hands were still turning.
See below an explanation of how the cannon pinion works & how the friction is adjusted.

 

http://www.timezone.com/2002/09/16/the-motion-works/

[arkobugg]

On 25.10.2016 at 8:56 AM, clockboy said:

The cannon pinion operates like a clutch. It must have enough friction to drive the hands but not to much to stop the watch. Also if very loose the movement will be very difficult to control & also the hands do not turn. 
However I have worked on watches where the cannon was too loose & the hands were still turning.
See below an explanation of how the cannon pinion works & how the friction is adjusted.

 

http://www.timezone.com/2002/09/16/the-motion-works/

Cheers mates!!

Sorry for late answer...

Thanks all for great help from you all !!

I will take out the canon pinion during the weekend, and see how it looks...

to be continued ...