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pmwas

Old, rusty verge watch from France - continued

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This time I'm facing a completely new chalenge.
I've already shown you this old rusty 19th Century verge watch, made in france circa 1830 - something told me the rust was NOT dealt with thoroughly, and I wanted to check myself.

Notice - I've NEVER yet worked on a verge watch, or on a fusee watch, so what I say here might be incorrect - this is no service manual
I'm always afraid - in such cases - of 'loosing' a working watch due to my error or just plain bad luck, but the look under the dial left no doubt...



Rust and mud...
The red circle points out a pin I just could not remove. I had to turn the plate around and break out the thin end, to remove the remains with a needle later...
Minor damage to the plate and pilar due to the attempts to remove the pin properly...



There are brown oil spots all over the paper I put the parts on!
There also was some ugly, green goo in the mainspring barrel.
It's my first verge job, so I got excited and forgot to take some inportant pictures, I'll make up for it next time.
So just two blurry pictures showing two ends of a fusee chain.
1 is the fusee end, 2 is the barrel end. The arrow pionts a corroded spot, where the chain broke at some point during servicing. Luckily it was just one link detached from the other, so I managed to re-connect and rivet the links together again. Still, this chain needs to be replaced, badly...

The plates cleaned up nicely, the stel parts - well... I just removed the red rust, I've not filed or polished them, because it already took a whole day this job...
Should be safe enough now.
The most work I had with the click and with the 3rd pinion which was quite bad. Center pinion also needed repeated cleaning.



To begin with - the dial side. I put this ock that holds the movement in the case (don't know the word). It consists of two steel parts joined with a screw and a spring mounted to the plate.
I also place two small bridges for 4th and 3rd pinios. They cannot be accidentally swapped as one has two pins and one a hole and a pin.

Then... the escape wheel bearings.
And I'll show you the escapement.



There. The verge escapement is of simple design - it has the crown shaped escape wheel and two pallets integrated with the balance staff.
The palets lock and unlock the teeth of the escape wheel, and the locked tooth of the escape wheel will push the pallet back keeping balance wheel in motion.
It's not a very accurate escapement, but certainly not bad as well.
Ave you can see how I assembled one of the bearings (the outer one), and you can also see the combined balance (1) and escape wheel (2) bearings all in one bridge placed on the underside of the top plate.
Below I assemble the inner escape wheel bearing.

I say inner, because the escape wheel pinion is placed horizontally in a verge watch and one bearing is right on the edge of the movement, and one deep, deep inside it.



Both escape wheel bearings are adjustable. The oter one has a steel cap as well.
The adjustment is done with two screws, just like in some furniture door hinges.
You adjust both bearings, so you get proper positioning of the escape wheel (God knows what's 'proper') and proper (that is low) endshake.

The green arrow points the factory made mark to ensure proper positioning of the bearing, which can be also moved sideways.

On top of the bridge, there is also this steel plate which is just balance bearing cap.
The bridge is screwed down to the top plate from the top side.
I think it's easiest to screw down the outer bearing, then place the escape wheel and then the bridge with the inner bearing, check there is some play between the bearings (if there's not, screwing down the bridge will damage the pinion!), screw down the bridge and then adjust the bearings. Seems logical...

As you can see the escape wheel spins nicely but with very little endshake - I think it should work fine...

Now. I've mentioned that the verge escapement is not very accurate.
Why is that? The ansewr is very simple. A balance on a hairspring has a fixed oscilation frequency when undisturbed. This is why detent escapements, like lever or chronmeter escapements, are so accurate.
They barely interfere with balance wheel's oscilations, allowing balance to keep it's constant frequency, even on different amplitudes.
Verge escapement, however, will have a tendency to interfere with the oscilation frequency, because when the pallet meets the tooth, the tooth will try to push it back, thus reducing the duration of the cycle.
If so, the cycle will end prematurely and the frequency will rise. And - of course - this will be very much dependent on the amplitude, so in verge escapement, the power transmitted from the mainspring will have a much greater effect on the beat than in your lever escapement watch.
As a remedy - fusee was installed in these watches, to equalize the power delivered by the mainspring.

Below - the barrel and the fusee connected by the 'notorious' chain.



Inside the fusee there is a ratchet on the 1st gear and ratchet wheel in the fusee cone. Thus, when you wind the watch, you just turn the cone, not the 1st gear, but when the barrel pulls, the whole assemby works as one piece.
A simple one direction clutch.

What does a fusee do? It's like a lever you use to lift heavy things - a longer lever will allow you to lift something heavier, but it's longer, so it's end will make a greater distance than an end of a shorter lever.
So here, when the mainspring is strong, it pulls the thinner end of the cone, so it's more 'difficult' for the mainspring. As the mainspring gets weaker, towards the end, the chain starts to pull the wider part of the cone, so it's 'esaier' for the mainspring to pull and the amplitude of balance's oscilations won't decrease.
Surely, the chain is quite a disadvantage...

Disassembling of a fusee might be confusing, especially in French watches, where it's less obvious than in most English ones.
The arbor is integrated permanently with the cone. Then you put the 1st gear on the arboe, make sure the click works, and place this ring on the arbor on a staking set, to join it all together:



To disassemble, you hold the first gear and tap the arbor until it all 'disintegrates'. Cool if it's all right, if jammed by rust - I think you're bound to bend the 1st gear, and so I like English pinned design (I've seen in the web) much better.

On the top of the cone there is this steel plate with a tooth:



That's meant to meet with this cleverly designed lever on the underside of the top plate.
This lever is a very clever design, it will be elevated by the fusee chain as it reaches the top coil of the cone, and there it meets the tooth to lock the fusee and prevent you from winding more.
So in a fusee watch it's not that you wind it untill the chain ends, but there is this lock to protect you from pulling the chain very hard. So clever!

The gear train traditionally has four gears, the 4th shaped in a way that it could drive a horizontal escape pinion.
You see that - you know it's a verge.

With the top plate on, I could place the fusee bridge (1), the 4th pinion bridge (2) and the Tompion's regulator on the movement.



Then the balance, balance bridge and it's pretty much done.
Wound - started ticking nicely in all positions, so I just finished assembling on the other side:



And re-cased the movement.
Cool!

Before my servicing, this watch would stop in certain oblique positions. Now there are some positions, where amplitude drops, but it keeps working in all of them.
I think re-adjusting the escape wheel bearings a bit more might help, but I've had enough for now.
The watch is also pretty accurate, so far way below 1 minute after 3 hours in center position, so not bad for an old, rusty verge.

I'm so very happy I managed to put this together! Huh... 1 level up !

Have a nice day!!!
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Updated 03-15-2017 at 04:30 PM by pmwas

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Comments

  1. Robert Gift's Avatar
    Thank you for the close-uphotos and explanations.
    Amazing the precision accomplished before modern machines.
  2. kinsler33's Avatar
    Very fine work. I'm jealous.
  3. sdowney717's Avatar
    The inside is lot more interesting to see than the outside.
    People don't think of the craftsmanship that goes into making things work. They just see the whole.
  4. pmwas's Avatar
    Indeed... it took quite some effort to make one of these. The precision is amazing no doubt, as is the fusee chain itself for example. So many tiny links riveted together with these tiny hooks on both ends - I enjoyed this work a lot