A strange one...if watches could talk!

[walkerwek1958]

Just started work on an ETA 2824 movement, the watch arrived last week. As usual I wound it up and put it on the Timegrapher to see what's going on. It's a big mistake to simply wade into a watch and take it to pieces, far better to get as much info as possible before stripdown.

Here's the trace:



The amplitude is way too low, that's consistent with a watch in dire need of servicing. However, what's strange is the high beat error, I`d expect no higher than 0.5, certainly not a value over 3. What's even stranger is the fact that the rate is good at +5, that makes me suspicious and I suspect someone has fiddled with this watch. The watch can`t talk, but I think I know what's happened , the beat arm has been moved in an attempt to get the rate to read correctly, that's thrown the watch way out of beat but made the rate look respectable. I`ll explain why I think this has happened, Here's a pic of the movement with the auto-winding in place:



and here's a pic with the auto-winding bridge removed


With the auto-winding in place the regulator stud (the small brass-coloured one) can`t be accessed, this is the part that needs adjusting if the fine adjuster hasn`t got enough range to correct the rate. When the watch is freshly serviced the rate should be set to between 0 and +2 (approx.) by moving the regulator, with the fine adjuster in the middle. The fine adjuster gives +/- 18 secs, one division equates to 6 seconds, so the fine adjuster should always be fairly close to the centre, it is used to fine-tune the rate during regulation after assembling the watch.

In this case, with an amplitude as low as 200°, the watch was never going to give the correct rate, I would've expected it to be at least 30 seconds out and I was surprised to see it at +5. Very strange, if the watch could talk it could confirm what's happened.

NEVER touch the beat arm (unless correcting beat error), that's the point where the hairspring stud is attached. Doing so will rotate the balance and hairspring, it'll change the relationship between the balance and the pallet lever and it will also affect the rate but it's the wrong way to adjust the rate.


H

If I find something unusual I get suspicious and inspect the watch v. carefully, this one was grubby inside suggesting it had been over-oiled in the past, but everything appeared to be OK. Here's the balance and hairspring


The hairspring is in good condition, so previous fiddling fingers haven`t done any damage. The spring was sitting nice and flat with the balance installed, I corrected the beat error and adjusted the spring to sit correctly in the Etachron stud. My fear was that doing so would introduce faults into the spring and cause it to lose concentricity by pulling it in one direction but fortunately this didn`t happen, the gaps between the spring coils are even so all looks well. The mainspring barrel is worn so that'll need replacement and there's a little wear on the winding pinion which suggests the watch has been hand-wound a lot. If I`m not happy with it I`ll replace it, they're not expensive.

Next step is to clean all parts and build the movement up with a new mainspring and barrel assembly, then see how it runs. I think it'll be fine.

[TheFixer]

Very interesting so please keep us updated.

[aamaci]

Thank you walkerwek1958, a most interesting, informative and educational post.
I love reading this kind of post.

A

[Mike2500]

Very interesting indeed and looking forward to the next instalment


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[markrlondon]

That was informative. Thanks!

[Mainspring]

Thanks Paul - always interested reading and seeing these threads/ stories.

[Pan16520]

Great post ….this brings an extra dimension to our hobby
Thank you


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[Griswold]

Very interesting Paul. Many thanks for taking the time to write it up.

[Darklel]

This is awesome, thanks for sharing

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