Omega pocketwatch problems

[nlhatcher]

Hello,

After a long time collecting information,  tools, oils etc. I have been attempting my first watch service. For this I obtained an Omega pocket watch with a 38.5 LT1 movement - this was a non-runner but in otherwise good condition.

After several mis-starts and minor catastrophes, I have the movement back together, cleaned and lubricated, however I have a couple of issues; firstly the watch is reluctant to start after winding - is there anything obvious I should be checking for here?

Also, once it is running (with a little persuasion) it will run well, but only for 7 hours. I have run repeated tests, and it always stops after 7 hours. To me the obvious reason would be some kind of problem with the mainspring - which I replaced during the service - so I have had this out again, but I can't see any damage, either to the spring or the barrel. Can anyone suggest other reasons for this, what else I should be checking?

Any help/advice is much appreciated.

Regards,

Nick

 

 

 

 

[mikepilk]

According to Ranfft it should have a power reserve of about 38h.

 http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&Omega_38_5L_T1

Very little torque gets to the fork and balance. It takes very little to stop the watch. It could be that you have not got it completely clean, or have excess oil where it shouldn't be.

Not starting after winding is a sign that it's out of beat. Did you check that, do you have a timegrapher, and if so, could you post plots ?

 

 

[nlhatcher]

21 minutes ago, mikepilk said:

According to Ranfft it should have a power reserve of about 38h.

 http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&Omega_38_5L_T1

Very little torque gets to the fork and balance. It takes very little to stop the watch. It could be that you have not got it completely clean, or have excess oil where it shouldn't be.

Not starting after winding is a sign that it's out of beat. Did you check that, do you have a timegrapher, and if so, could you post plots ?

 

 

Hello Mike,

Thanks a lot for your answer, unfortunately I don't have a timegrapher (yet).

I was specifically wondering why it always stops after 7 hours? - can't be coincidence. 

Nick

[jdm]

23 hours ago, nlhatcher said:

unfortunately I don't have a timegrapher (yet).

It is an absolutely needed tool when working on mechanical movements. Without it you won't know how  well the movement.t is running. Exercised eyes and ears  helped with that, but one can't expect a beginner to have that.

 

23 hours ago, nlhatcher said:

I was specifically wondering why it always stops after 7 hours? - can't be coincidence. 

Only the barrel could make a revolution in approximatively 7 hours. But it takes something very wrong to stop it when it still has the most torque. Before taking it apart you could check if it happens in different positions too.

[mikepilk]

57 minutes ago, nlhatcher said:

Hello Mike,

Thanks a lot for your answer, unfortunately I don't have a timegrapher (yet).

I was specifically wondering why it always stops after 7 hours? - can't be coincidence. 

Nick

Do you have an estimate of what the amplitude is?  It's possible to do this using slow motion on you phone camera. Putting a dot on the balance with a marker pen can help.

If it's the barrel as @jdm suggests - have a close look at the teeth around the barrel for any damage or dirt.

[Nucejoe]

1 hour ago, nlhatcher said:

 once it is running (with a little persuasion) it will run well, but only for 7 hours. I have run repeated tests, and it always stops after 7 hours. 

I presume the movement in not cased. 

Furthure to above, check if the barrel lid rubs, the lid is to sit flush level in the barrel and not push on the spring, if tilted it might rub on barrel bridge or mainspring. 

[oldhippy]

Is there any sign of wear marks with the barrel and the barrel bridge or the barrel arbor holes. Sounds as if the main spring needs to be replaced it sounds as if it has lost its strength its tired as we say.  

[jdm]

1 hour ago, oldhippy said:

Sounds as if the main spring needs to be replaced it sounds as if it has lost its strength its tired as we say.  

Has been done already

mainspring - which I replaced during the service 

[oldhippy]

OK so is it the correct one? if it is then is the barrel cap level any signs of wear or marking inside as if the spring could be to high. Even though it stops after 7 hours I would  check from the center wheel backwards, is it doing this out of its case or cased up? 

[nlhatcher]

Hi,

Some answers;

I sourced the replacement spring from Cousins, and I understand(hope) that it is the correct one; 2.10 x .18 x 440 x 14.5

I have been testing with the movement cased, initially it seemed to be running ok, so I just went ahead and cased it.

There is no obvious damage/wear to the barrel, bridge or plate.

One point I should probably have mentioned previously; I swapped out the barrel from a donor movement before the service as the original had a disfiguring stain - I assumed that as the movements were the same calibre that they would be automatically interchangeable, but I have just compared them again and see that there is a slight difference in the shape of the teeth, so I'll reassemble the movement with the original barrel and test again.

Thanks again for the answers

 

 

[nlhatcher]

4 hours ago, mikepilk said:

Do you have an estimate of what the amplitude is?  It's possible to do this using slow motion on you phone camera. Putting a dot on the balance with a marker pen can help.

If it's the barrel as @jdm suggests - have a close look at the teeth around the barrel for any damage or dirt.

Hi Mike,

Once I have the movement back together I'll have a go at estimating the amplitude and report back.

[KarlvonKoln]

JDM has a good idea.  I have  encountered barrels with a  broken tooth before.

[JohnR725]

19 hours ago, nlhatcher said:

One point I should probably have mentioned previously; I swapped out the barrel from a donor movement before the service as the original had a disfiguring stain - I assumed that as the movements were the same calibre that they would be automatically interchangeable, but I have just compared them again and see that there is a slight difference in the shape of the teeth, so I'll reassemble the movement with the original barrel and test again.

Whenever working on older watches changing parts introduces typically new problems. People helping you on this discussion probably didn't grasp that you change the barrel. I think the only mentioned changing the mainspring and failing to disclose this little discrepancy well wasn't helpful

it's amazing what happens if things aren't exactly the size there supposed to be. I was once puzzled by an Illinois pocket watch I was servicing I like the pre-time on the timing machine but I couldn't get at the time so I just went ahead and cleaned. It still wouldn't time after cleaning? I only saw one thing that troubles me which was the mainspring barrel it just didn't look right but it was in the watch. Investigation revealed that somewhere in his life somebody changed the barrel and getting a proper barrel in solved all of my timing problems. If you didn't have a timing machine it's conceivable because I never put the hands on may be the thing did run don't know for the Time but it definitely look like crap the timing machine which is why they're very good diagnostic tools.

The problem with the early production watches are they tend to be made in batches and you tend to have parts variations a lot of times parts are actually fit per each watch. Always best to stay with what you have unless there's some reason you absolutely have to change to something else.

I'm going to attach an image the gear ratio will depend upon the particular watch there be some variation but it gives you a clue that the only thing revolving around For around your seven hours is the barrel.

 

 

[oldhippy]

Oh never mind its all part of learning. You won't make the same mistake next time.