Omega pocket watch, question abotu the calibre and mainspring.

[jpmort]

Ah, well, I am learning how to service watches, having completed about 4 now. And finally the outcome is one I am happy about.

But someone gave me an Omega pocket to see wht I can do with it.. And I do want to succeed in the challenge. The watch is of sentimental value to the person who asked me to look at it.
The serial no 4301181 dates it to 1912.
External case diameter is 47mm.
The issue is that I have this what I believe to be a 18 ligne movement, simply because the width of the movement is 40.5mm. Does this mean that I have a 40.6 cal watch, or 18"?
I have looked at the mainspring, and it certainly looks like it needs replacing. The confusion is, I am not quite sure what size to look for. I am used to having specific codes for watch movements, and this one has me stumped because I have read through several forum posts regarding this type of watch - that is in various sizes. And the mainspring type seems to be a question of trying and seeing. I am not sure if the old one is the original type.
Perhaps there are those here who could advise. The measured dimensions from the mainspring I removed seem to coincide with the ranfft description of the 18;
2.55 15.0 0.18 with a length around 440 - 450mm
The GR list links 18" to GR6774DBH 2.60 15 0.18 500
But I am not confident that my callipers are accurate enough to check the difference with some of the other similar mainspring sizes.
The Couzens catalogue seems confusing... Is 500 loo long?
So any help in identification of the watch and the mainspring, would be very welcome

[Neverenoughwatches]

9 hours ago, jpmort said:

Ah, well, I am learning how to service watches, having completed about 4 now. And finally the outcome is one I am happy about.

But someone gave me an Omega pocket to see wht I can do with it.. And I do want to succeed in the challenge. The watch is of sentimental value to the person who asked me to look at it.
The serial no 4301181 dates it to 1912.
External case diameter is 47mm.
The issue is that I have this what I believe to be a 18 ligne movement, simply because the width of the movement is 40.5mm. Does this mean that I have a 40.6 cal watch, or 18"?
I have looked at the mainspring, and it certainly looks like it needs replacing. The confusion is, I am not quite sure what size to look for. I am used to having specific codes for watch movements, and this one has me stumped because I have read through several forum posts regarding this type of watch - that is in various sizes. And the mainspring type seems to be a question of trying and seeing. I am not sure if the old one is the original type.
Perhaps there are those here who could advise. The measured dimensions from the mainspring I removed seem to coincide with the ranfft description of the 18;
2.55 15.0 0.18 with a length around 440 - 450mm
The GR list links 18" to GR6774DBH 2.60 15 0.18 500
But I am not confident that my callipers are accurate enough to check the difference with some of the other similar mainspring sizes.
The Couzens catalogue seems confusing... Is 500 loo long?
So any help in identification of the watch and the mainspring, would be very welcome

0.05 extra on the height as well. Could be your calipers. The ranfft size seems closest to what you have. How did the watch run with the spring you have ?

[RichardHarris123]

Looks like the 18" to me.  I have a  40.6 and it's different. 

[jpmort]

13 hours ago, Neverenoughwatches said:

0.05 extra on the height as well. Could be your calipers. The ranfft size seems closest to what you have. How did the watch run with the spring you have ?

Thanks for the advice. The mainspring was disconnected from the arbour, so I did not have a chance to kow how it ran. The mechanism is not worn, so I dont think it has been used much. And the spring has obviously been replaced sometime, but it has little tension left.

[Neverenoughwatches]

2 minutes ago, jpmort said:

Thanks for the advice. The mainspring was disconnected from the arbour, so I did not have a chance to kow how it ran. The mechanism is not worn, so I dont think it has been used much. And the spring has obviously been replaced sometime, but it has little tension left.

Ok. What is letting you think there is not much tension in the spring ? Is it quite coiled when relaxed ? I would still be curious to see what sort of performance you have with this spring. 

6 minutes ago, jpmort said:

The mechanism is not worn, so I dont think it has been used much. 

Ok just a question to ask how much inspection have you made regarding the rest of the movement ? Visually to the naked eye  it may look ok but under close inspection with a loupe or scope may very well tell a different story. If the mainspring is fatigued and this may not be the original as you say. So could be two mainsprings worn out then the rest of the mvt may well have a lot of wear, logically.

[jpmort]

13 hours ago, RichardHarris123 said:

Looks like the 18" to me.  I have a  40.6 and it's different. 

Ah thanks, thats helpful. And I think your cal is stated on the movement. Mine is blank...

[JohnR725]

23 hours ago, jpmort said:

The measured dimensions from the mainspring I removed seem to coincide with the ranfft description of the 18;
2.55 15.0 0.18 with a length around 440 - 450mm
The GR list links 18" to GR6774DBH 2.60 15 0.18 500
But I am not confident that my callipers are accurate enough to check the difference with some of the other similar mainspring sizes.
The Couzens catalogue seems confusing... Is 500 loo long?

I really don't think you want that mainspring as you're going to have to modify it. Then did you actually measure 2.55 mm for the width of the spring? Brings up the problem of you want to go up in size or down in size the words maybe 2.50 mm?

I snipped out an image from the mainspring catalog and I mark the one that you like but notice those initials I wonder what they mean? DBH anything we should worry about?

Then the rest the dimensions? Any time you're dealing with a vintage watch your lucky to find a mainspring at all. Things you want to worry about art making sure it's not too wide because otherwise you won't builder close the lid and if you look at the existing barrel does it look like the barrels all scratched up because maybe the spring was too wide? Then there's the strength that's the thickness but that can vary a little bit because modern springs tend to be stronger than the blued steel Springs. Length not much you can do about unless you want to modify the end which you really don't want to do. Oh those initials again what the heck did they mean? You want to get a spring that doesn't have those initials after it as that's a specific type of end that you don't have. Let me see if I can find a picture from the beginning of the book? From your picture it looks like  normal type end  which looks bigger than usual because it looks  like somebody made a homemade end. The DBH Is commonly used in Elgin pocket watches and you don't have an Elgin pocket watch. So it wouldn't really be your best choice

 

 

 

[jpmort]

2 hours ago, Neverenoughwatches said:

Ok. What is letting you think there is not much tension in the spring ? Is it quite coiled when relaxed ? I would still be curious to see what sort of performance you have with this spring. 

Ok just a question to ask how much inspection have you made regarding the rest of the movement ? Visually to the naked eye  it may look ok but under close inspection with a loupe or scope may very well tell a different story. If the mainspring is fatigued and this may not be the original as you say. So could be two mainsprings worn out then the rest of the mvt may well have a lot of wear, logically.

I have cleaned and lubricated the train and balance, and they run really smoothly. The residue in the movement when I first opened it, is as you see in the pictures - they were taken on first opening.

I checked for end shake, and end play, and did not find any. I inspected the pivots quite closely, and I was surprised at the fact that they did not appear worn in the jewels. Inside the barrel drum, there was almost no black residue, and that really surprised me. So I concluded that the spring had not actually been used too much. I managed to bend the mainspring tighter so that it caught back onto the arbour, but that seems to me an indication that the spring-ness has reduced simply due to length of time.

However, any advice would be welcome. The main issue is that I want to ensure I order the best fitting mainspring, so I am looking to check the caliber correctly.

 

1 hour ago, JohnR725 said:

I really don't think you want that mainspring as you're going to have to modify it. Then did you actually measure 2.55 mm for the width of the spring? Brings up the problem of you want to go up in size or down in size the words maybe 2.50 mm?

I snipped out an image from the mainspring catalog and I mark the one that you like but notice those initials I wonder what they mean? DBH anything we should worry about?

Then the rest the dimensions? Any time you're dealing with a vintage watch your lucky to find a mainspring at all. Things you want to worry about art making sure it's not too wide because otherwise you won't builder close the lid and if you look at the existing barrel does it look like the barrels all scratched up because maybe the spring was too wide? Then there's the strength that's the thickness but that can vary a little bit because modern springs tend to be stronger than the blued steel Springs. Length not much you can do about unless you want to modify the end which you really don't want to do. Oh those initials again what the heck did they mean? You want to get a spring that doesn't have those initials after it as that's a specific type of end that you don't have. Let me see if I can find a picture from the beginning of the book? From your picture it looks like  normal type end  which looks bigger than usual because it looks  like somebody made a homemade end. The DBH Is commonly used in Elgin pocket watches and you don't have an Elgin pocket watch. So it wouldn't really be your best choice

 

 

 

Thanks for the info and I now recognise that I have to ensure it fits well, rather than be the exact size. The end is the normal bridle, and thats why the DBH one seems odd against the 18". And the catalogue extract you posted is the one I am looking at, and the one I think I might order is the normal bridle with the dimensions that are there. I was concerned that the length of 500 is quite a bit longer than the one that I am replacing.

[Neverenoughwatches]

6 minutes ago, jpmort said:

I have cleaned and lubricated the train and balance, and they run really smoothly. The residue in the movement when I first opened it, is as you see in the pictures - they were taken on first opening.

I checked for end shake, and end play, and did not find any. I inspected the pivots quite closely, and I was surprised at the fact that they did not appear worn in the jewels. Inside the barrel drum, there was almost no black residue, and that really surprised me. So I concluded that the spring had not actually been used too much. I managed to bend the mainspring tighter so that it caught back onto the arbour, but that seems to me an indication that the spring-ness has reduced simply due to length of time.

However, any advice would be welcome. The main issue is that I want to ensure I order the best fitting mainspring, so I am looking to check the caliber 

The spings ability to unwind itself is where its power lies. A worn spring would tend to be more coiled up when relaxed out of the barrel. The fact that it is not a tight feed onto the arbor would point to someone over prising it to fit it onto the arbor or possibly the incorrect spring. Generally a barrel diameter is also required as well as the height, thickness and length of the spring. 

[jpmort]

1 hour ago, Neverenoughwatches said:

The spings ability to unwind itself is where its power lies. A worn spring would tend to be more coiled up when relaxed out of the barrel. The fact that it is not a tight feed onto the arbor would point to someone over prising it to fit it onto the arbor or possibly the incorrect spring. Generally a barrel diameter is also required as well as the height, thickness and length of the spring. 

I did not reply to your previous question properly. The spring is quite coiled when free, nothing like the springs I have come cross before. When I first opened it, and saw that the spring had come away from the arbour, it was open and quite clear from the arbour. I had to bend it quite a bit to get it to sit well an the arbour again. Your point abotut he barrel diameter is a good one, I will use that as a guide to selecting the new spring.

[Neverenoughwatches]

1 hour ago, jpmort said:

pring is quite coiled when free, nothing like the springs I have come cross before. 

It is probably worn out then and would provide little power. I can only suggest using the ranfft guide and match up with what you had in the barrel. A slightly under size would be better than an over size if you cannot get the exact match.

[jpmort]

16 minutes ago, Neverenoughwatches said:

It is probably worn out then and would provide little power. I can only suggest using the ranfft guide and match up with what you had in the barrel. A slightly under size would be better than an over size if you cannot get the exact match.

Thanks, that makes sense. And I suppose I have an 18".

[Neverenoughwatches]

2 hours ago, jpmort said:

Thanks, that makes sense. And I suppose I have an 18".

Let us know when you you have it i stalled so we discuss the outcome. 

[JohnR725]

6 hours ago, jpmort said:

Your point abotut he barrel diameter is a good one, I will use that as a guide to selecting the new spring.

 

8 hours ago, Neverenoughwatches said:

Generally a barrel diameter is also required

Barrel diameter size is only specified for modern mainsprings. Typically on older mainsprings it's never mentioned at all unless? Unless it's made for a specific watch in other words the only time you care about barrel diameter is if you're going to shove the spring in from the holder it's in.

Otherwise with holder packaging especially when it's the older blued steel Springs a lot of times they would be in holding rings much much larger than the barrel. Then I have a image here for you here's a sampling of a whole variety of mainspring packages how many of them have the barrel diameter?

Then I also have a picture of what the mainspring ring looks like if you're not familiar with it springlike that it billed to just push it right into the modern barrel which is why a lot of hobbyist watchmakers never end up with mainspring winders because they typically buy brand-new Springs and just shove in

Microphone off lights in them lot of how to live in by the spring strangely enough it is a spring but it will line of not being used to set spring take them out of the barrel much bigger circular route there's nothing that Mister them back

Then the third image mainspring is when their brand-new the top one that some modern white spring you'll notice the back curve it has. Some modern Springs website which back curve they have more back curve the front curve it just depends on who manufactured which watch was manufactured for etc. the spring below strangely enough is a good spring but in my mind borderline on not being good least it opened up. Usually when you take out blued steel Springs their circular they have zero resemblance of the taken aback curve and there's not much bigger than the barrel. They will work they will run the watch but not for very long because it just no energy left is no spring left in the spring.

[jpmort]

12 hours ago, JohnR725 said:

 

Barrel diameter size is only specified for modern mainsprings. Typically on older mainsprings it's never mentioned at all unless? Unless it's made for a specific watch in other words the only time you care about barrel diameter is if you're going to shove the spring in from the holder it's in.

Otherwise with holder packaging especially when it's the older blued steel Springs a lot of times they would be in holding rings much much larger than the barrel. Then I have a image here for you here's a sampling of a whole variety of mainspring packages how many of them have the barrel diameter?

Then I also have a picture of what the mainspring ring looks like if you're not familiar with it springlike that it billed to just push it right into the modern barrel which is why a lot of hobbyist watchmakers never end up with mainspring winders because they typically buy brand-new Springs and just shove in

Microphone off lights in them lot of how to live in by the spring strangely enough it is a spring but it will line of not being used to set spring take them out of the barrel much bigger circular route there's nothing that Mister them back

Then the third image mainspring is when their brand-new the top one that some modern white spring you'll notice the back curve it has. Some modern Springs website which back curve they have more back curve the front curve it just depends on who manufactured which watch was manufactured for etc. the spring below strangely enough is a good spring but in my mind borderline on not being good least it opened up. Usually when you take out blued steel Springs their circular they have zero resemblance of the taken aback curve and there's not much bigger than the barrel. They will work they will run the watch but not for very long because it just no energy left is no spring left in the spring.

Thank you for your long answer. Very helpful. I thought it is time to post my old spring,a nd you can see how exhausted it appears...

[JohnR725]

Yes that's definitely a set mainspring. Then it looks like a standard tongue end. The critical dimensions are the width you don't want to go to wide or you won't feel the close the lid and it won't work at all.  Then the thickness and the length can vary a little bit because you may not actually Billy get an exact spring.