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Deafboy
··His Holiness Puer SurdusI will have a micrometer next week to measure the thickness of the mainspring. 👍
Need advice on servicing Longines 23M
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ChrisN
·The plots are quite typical of the vintage watches I service (I've had much worse in some very old Elgin wristwatch movements). Youtube videos of watch adjustments of modern movements look much cleaner on their timegrapher. Is it because of my timegrapher software, old movement design and manufacturing, worn movements, too much lubrication, wrong lubrication, noisy environment, etc I don't know.
Still, not sure what actual amplitude you have but, good luck.
Chris
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Archer
··Omega Qualified WatchmakerThe plots are quite typical of the vintage watches I service (I've had much worse in some very old Elgin wristwatch movements). Youtube videos of watch adjustments of modern movements look much cleaner on their timegrapher. Is it because of my timegrapher software, old movement design and manufacturing, worn movements, too much lubrication, wrong lubrication, noisy environment, etc I don't know.
Can you adjust the gain on the timing machine or software? If so, adjust it to be slightly less sensitive and see if that cleans up the plots. I have no idea what machine/software you are using here or how much it picks up from external sources, etc. so it may just be a gain issue. In the video you posted earlier I do see what appears to be debris on the escape wheel, and in the larger photos you posted of the pallet fork and escape wheel lock, they don't look particularly clean to me. So for now I would be cleaning up the escapement, and if that is indicative of the cleanliness of the rest of the movement, that's something to work on going forward.
Looking at those photos the angle isn't the best to see it clearly, but the lock doesn't look particularly uneven or shallow to me. Shallow lock can certainly contribute to higher amplitude - in school we moved pallet stones and observed the direct relationship between their depth and the amplitude, and you can fine tune the stone depth to make the amplitude equal on both sides and make it lower or higher. That is not easy work for an amateur though, and requires some equipment to do accurately that I'm guessing you won't have (escapement meter). Also messing around with the stones without taking into account other effects can be a bit tricky (these things don't happen in isolation), and you would likely end up in a worse situation than you are now.
By the way I checked a few sources I have and the lift angle for the 23M appears to be 46 degrees, rather than 47. This would mean it was rebanking at an amplitude as low as 310, which would be unusual (not unheard of, but unusual). Have you tried letting the mainspring down, and rotating the balance by hand (tweezers) to estimate the number of degrees required for the roller jewel to strike the outside of the fork horn?
I would verify the strength of the mainspring when you are able, and if it is what it's supposed to be, then we can move forward from there. If I were you I would already be looking for a slightly weaker mainspring of the same general dimensions.
As Chris has mentioned in a previous post, there are things you can do to scrub off amplitude, but these are last resorts, and all other avenues should be looked at first.
Cheers, Al
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Deafboy
··His Holiness Puer SurdusCan you adjust the gain on the timing machine or software?
Yes, this is something I do. The software runs on Windows and I adjust the sound card "volume" for cleanest signal.
It could be dirt on the escape wheel and pallets but my basement is quite noisy (a few fans - inside a computer and scientific instrumentation) and other sources of noise.
By the way I checked a few sources I have and the lift angle for the 23M appears to be 46 degrees, rather than 47. This would mean it was rebanking at an amplitude as low as 310, which would be unusual (not unheard of, but unusual). Have you tried letting the mainspring down, and rotating the balance by hand (tweezers) to estimate the number of degrees required for the roller jewel to strike the outside of the fork horn?
I actually did this yesterday, following-up on Chris' comment on amplitude measurements. I did it two ways: static and dynamic. Static is the way you describe i.e. pushing the the balance wheel at either end of travel (and taking pictures). The dynamic way was to wind the watch so it operates in re-banking and take a movie using the slo-mo feature on an iPad (120 fps). I measured the angles of the balance wheel on the images using an image analysis software. Both methods concurred: from equilibrium position I obtained 330 degrees in one direction and 337 degrees in the other. The timing software shows about 315 degrees on the onset of rebanking. My guess the discrepancy between the software amplitude and imaging methods is due to way the software calculates amplitude and produces error onset of rebanking. That said I use the dynamic imaging technique to determine the lift angle of a movement.
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Archer
··Omega Qualified WatchmakerBoth methods concurred: from equilibrium position I obtained 330 degrees in one direction and 337 degrees in the other. The timing software shows about 315 degrees on the onset of rebanking.
If I were you, my next step would be to put dial and hands on the movement, fully wind it (to the point where you indicate it is rebanking) and see if it's actually gaining time.
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François Pépin
·So first question is what is the size and type of end on the mainspring you installed? Based on Bestfit books, the spring should be 1.20 X .10 X 343. Not sure if you simply ordered one from a supplier and asked for a spring for that movement, but you should note that when suppliers don't have the spring you need, they will often send the "closest available" and even a small change in strength in particular can make a huge impact on amplitude. This is why when I email a supplier and ask for pricing, I always tell them that if they don't have the exact size I'm looking for, let me know what they are proposing as a substitute.
Second is, are you sure what you are getting is rebanking? If you have a timing machine, has the lift angle been set properly, and if so what is the amplitude like before you get what I assume is a very fast rate? Have you demagnetized the movement as part of the service? I typically demagnetize twice - once before cleaning and again when the movement has been reassembled. Is the balance spring free of oils and dirt? All this need to be checked.
As an aside, although most of the time you fight to get more amplitude on a vintage watch, there is nothing quite as frustrating in my view as fighting too much amplitude, if that's what this really is...
For the regulating pins, they needs to be parallel and properly spaced. What you have done in bending the one pin up high will cause dial up and dial down rate differences. So you need to put a double bend into the pin so that you can close up the gap if needed, and also keep the pin parallel to the boot that can turn. Here's an example of the opposite, where someone bent the pin out at the bottom:
And it had to be bent back to be parallel again to eliminate the large positional variance from dial up to dial down:
So in your case it's tough to see in the photo you have posted, but you may need to bend it in towards the boot up high, and then put a second bend in just under the first bend in order to keep them parallel.
As for the balance spring shape, can you post a clear photo of the spring at rest? I've not serviced a 23M (although I have a 23Z in the shop right now) so I'm not sure what the spring is supposed to look like on this one specifically, but I really need to see a shot of the balance at rest to see what is going on here.
As I've said before on the forum and to you in PM's as well, learning how to fix things like automatics and chronographs should only come after being able to really get a proper job done on a simple manual wind watch. 90% of the skills you need are used on a manual wind...
Cheers, Al
Great stuff as usuall, Al. But how do you manage to take pictures like these??
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François Pépin
·Great thread, thank you all!
By the way, I can confirm that playing with pallets is kind of tricky fo an amateur! I have tried this game several times, not always winning...
By the way, I can confirm that playing with pallets is kind of tricky fo an amateur! I have tried this game several times, not always winning...
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Deafboy
··His Holiness Puer SurdusHello All,
Here's a long overdue update on servicing the Longines 23M movement.
I did get a micrometer and the thickness of the new spring was 0.100 mm +/- 0.003), which is what is recommended for this movement.
To reduce amplitude I considered replacing the spring with another spring of lesser thickness. For instance the Longines 8L movement uses a spring of 0.090 mm, but the height of the spring is less so I was concerned about not holding well in the barrel. I drew a scaled drawing of the two springs inside the barrel (see below), where the barrel floor and cap are in light blue. We see the spring's tabs are of marginal height to hold in the barrel in the case of the 8L spring inside a 23M barrel. In addition this spring is somewhat shorter so that might affect the power reserve and perhaps even watch accuracy.
Then it occurred to me that the original "blue steel" spring might still be good. I usually replace the blue steel springs in old watches as a matter of course because they are known to lose their elasticity (they become "set") and can also break. The picture below shows that the blue steel spring doesn't have the "S" shape of the new white alloy spring, but compared to other blue steel springs I've seen it is actually quite nice. So I carefully put the original spring back in the 23M barrel and the watch is now running well! 😁 Amplitude in horizontal position is about 290 degrees when fully wound and drops to about 255-260 degrees 24 hours later.
To finish off I dynamically poised the balance wheel to minimized positional variances and obtained a 13 s spread of rates in the vertical positions at full wind, and I also did a final regulation.
The watch is now running about 4-5 s/day fast when worn.
I want to thank all those who offered advice and look forward to servicing another vintage watch!
Here's a long overdue update on servicing the Longines 23M movement.
I did get a micrometer and the thickness of the new spring was 0.100 mm +/- 0.003), which is what is recommended for this movement.
To reduce amplitude I considered replacing the spring with another spring of lesser thickness. For instance the Longines 8L movement uses a spring of 0.090 mm, but the height of the spring is less so I was concerned about not holding well in the barrel. I drew a scaled drawing of the two springs inside the barrel (see below), where the barrel floor and cap are in light blue. We see the spring's tabs are of marginal height to hold in the barrel in the case of the 8L spring inside a 23M barrel. In addition this spring is somewhat shorter so that might affect the power reserve and perhaps even watch accuracy.
Then it occurred to me that the original "blue steel" spring might still be good. I usually replace the blue steel springs in old watches as a matter of course because they are known to lose their elasticity (they become "set") and can also break. The picture below shows that the blue steel spring doesn't have the "S" shape of the new white alloy spring, but compared to other blue steel springs I've seen it is actually quite nice. So I carefully put the original spring back in the 23M barrel and the watch is now running well! 😁 Amplitude in horizontal position is about 290 degrees when fully wound and drops to about 255-260 degrees 24 hours later.
To finish off I dynamically poised the balance wheel to minimized positional variances and obtained a 13 s spread of rates in the vertical positions at full wind, and I also did a final regulation.
The watch is now running about 4-5 s/day fast when worn.
I want to thank all those who offered advice and look forward to servicing another vintage watch!
