How to disassemble this English verge pocket watch movement?

[xyzzy]

I've been ask to take a look at an old pocket watch.  I estimate 1823 based on the hallmarks on the case.  It's a verge movement with a fusee, which appears to be intact.  However, I think the mainspring is broken and maybe the lower pivot on the balance staff or verge, I'm not sure what the right term is.

I am not entirely sure how to go about disassembling it enough to get the mainspring.

First I removed the hands, using a pesto #7 to remove the minute hand which had a square hold from the square cannon pinion, as this a key set watch.  The hour hand seemed loose on the hour wheel and came off with tweezers.  Then I  separating the joint between the movement and the case by removing the hinge pin.  I used a 0.7 mm screwdriver blade held backward in a pin vise as a driving tool to press it out.

The dial was held to main plate with pillars with tapered cotter pins.  I was able to grab these with small sturdy pliers and pull them out and remove the dial.

Now we get to the top of movement.  There a few pillars with cotter pins that hold the top plate to the main plate.  And above the top plate is a balance wheel with a hairspring, and this hairsping appears to be pinned to both a balance and to the top plate itself.  Under the balance wheel and above the top plate is a piece that appears to part of the regulating mechanism.  It's held down with three screws, has an engraved part next the balance, goes entirely under the balance, and has a hole in the middle for the balance and spring.  

The hole in this plate under the balance is smaller than the outer diameter of the balance.  So I see no way it could be removed without first removing the balance from above it.  Yet the balance spring is pinned to the top plate.  I see no way to remove it from the top plate without unpinning the spring, which seems like a somewhat drastic measure to take.  How will I ever re-pin it back correctly?

Here's a photo.  The various parts of the piece I'm trying to remove are labeled "A".  The three screws holding it in are labeled, S1, S2, and S3.  I've removed S2 and S3, but S1 is partially covered by the balance.  The pins holding the hairspring in are labeled 1 and 2.  The block pin 1 is in appears to be a single piece with the top plate.  The mainspring barrel, top, is trapped under piece 'A' as well as the balance.

I considered that I might be able to the remove the top plate, this part 'A' that is under the balance, and the balance and spring all together as a single unit.  However, notice the top of pillar 'P' protruding into the piece 'A' on the right side of the image?  Under the piece 'A' is a cotter pin in the pillar holding the top plate on!

It seems almost impossible to remove this tiny cotter pin in the narrow gap I'm able to make as I push up the right side of 'A' before it hits the balance.

 

Is it really necessary to unpin the hairsping to perform any kind of service on this movement?  Or is there some trick I'm missing?  Perhaps the stud the hairspring is pinned can be removed from the top plate?

[oldhippy]

You will have to unpin the hairspring take note of how much of the hairspring tail is left and mark or these days a photo. You say you think the spring is broken so are you saying there is no power? Are you sure the fusee chain is in tact. 51 needs to be unscrewed. Do you have the skills to undertake the balance work. Many watchmakers do not touch fusee P/Watches because they are very troublesome to work on and hardly any spares, chains and verge blanks are around, it is not that difficult to make a verge.

[xyzzy]

Indeed, no power.  The mainspring barrel just spins.  However, it might be a problem is the ratchet on the arbor might not be engaged.  It was under the dial, so I can't be sure what state it was in before I removed it.  But I see no spring to hold the click against the ratchet wheel.

It occurs to me that that mainspring arbor of a fusee movement need not spin.  So why even have a ratchet?  My theory is that one needs to "pre-wind" the mainspring so that there is still some tension on the fusee chain when fully unwound.  This could be done by winding the chain fully onto the barrel while the arbor spins freely, then engaging the arbor ratchet and winding the arbor a few clicks with the key.  This would tighten the chain and put some small wind into the spring.  The ratchet would keep the arbor from unwinding, while the taut chain's attachment to the fusee keeps the barrel from unwinding.

At this point, the arbor no longer needs to ratchet I think, so perhaps there is no spring and the "click" should be held engaged by tightening the screw it pivots on?

Judging by the marks on the plate, the pin holding the hairspring in has had a lot of fiddling with it over the centuries.  So perhaps it does need to be removed.

I noticed the square stud the hairsping is pinned to is the same size the winding key.  So tried giving it a turn, and it does turn easily!  One can imagine a T shaped pin on the underside that fits through a slot in the plate, then locks with a quarter turn.  Allowing the stud to be removed from the top with hairspring still attached.  But this doesn't appear to be the design.  

The fusee chain had become detached from the barrel, likely because of no tension on the hook at the end.  It also looked like the last time the watch was wound, the chain jumped some of the lower track on the fusee and reached the top too soon and then sort of jammed up as a wrap of the chain was wound between two earlier wraps.  I was able to gingerly pull it out and it seems intact.

There's some rust on the chain and some stiff spots.  I thought I give it some time in the ultrasonic in a bath of rust remover.  And then maybe oil it, if just to reduce the rate it rusts.

If the balance is broken, I can not repair it.  I'm not now entirely sure if it is.  The hairspring is so loosely coiled compared to a modern one that I was able to pull up the balance wheel and look at the lower pivot, and there is at least something still there.  Yet it seemed to have far too much side shake to not be broken.  The upper jewel is intact but I can't see the lower bushing/jewel or whatever is down there, maybe that is the problem?

[oldhippy]

The ratchet is inside the fusee which is that cone shape. So you will have to take it apart to check.

If you followed what I said about the hairspring, that is the way to go about it. You will be able to lift the balance up enough after un pinning it to remove screw S1. After you have removed all that is under the balance you will be able to remove the barrel and then the top plate. Just be very careful how you go about it. Take note of the screws as they are all different and they properly will not fit snug in other places you can see how crude they are all individually made.  

[xyzzy]

Thanks for the help.  It's been disassembled.  I think I got a pretty good photo of where the hairspring should sit and the pin holding it in wasn't tight like some of the others have been.

The mainspring is broken.  This I can repair if I'm able to find a compatible one.  I've been careful to take pictures of all the screws before I remove them.  

There is a jeweled setting for the lower verge pivot.  I think maybe the jewel is broken, but it's inside the block the verge passes though, I don't know the term for it, and hard to see.

Here's the fusee and barrel with the top plate removed.

There's a ratchet inside the fusee.  There's a pin on the underside through the arbor that holds it together.  Looks difficult to remove.

However, there's a also a ratchet mechanism on the mainspring arbor, on the dial side of the watch.  It's here on the right.  I thought maybe there was a spring missing that held to ratchet tooth against the wheel, but perhaps it's just supposed to be held fixed with the screw tightened and not ratchet?  I see scratches on the plate that look like it's been pushed around with some sort of tool.

[oldhippy]

That ratchet is to set the tension for the chain on the fusee. The ratchet, the sort of thing you have on a clock is as I have said in the fusee cone. You expect to see all sorts of thing when you are working on on something as old as this. 

[JohnR725]

2 hours ago, xyzzy said:

It's been disassembled.  I think I got a pretty good photo of where the hairspring should sit and the pin holding it in wasn't tight like some of the others have been.

on a watch like this it's not supercritical as its timekeeping is going to be well not outstanding. The slightly earlier versions typically only came with one hand because that's the best it could.

2 hours ago, xyzzy said:

There's a pin on the underside through the arbor that holds it together.  Looks difficult to remove.

what does the pin look like it's made from?

2 hours ago, xyzzy said:

However, there's a also a ratchet mechanism on the mainspring arbor, on the dial side of the watch.  It's here on the right.  I thought maybe there was a spring missing that held to ratchet tooth against the wheel, but perhaps it's just supposed to be held fixed with the screw tightened and not ratchet?

18 minutes ago, oldhippy said:

That ratchet is to set the tension for the chain on the fusee.

the questions already been answered as he said before there's two ratchets. The small one that you can see visible in the played the only purpose of that is to set the tension so the chain doesn't fall off when it reaches the end basically you can go through a procedure to get things exactly righted even power but I usually don't worry about it so basically I think of this as you make sure that when it's all the way wound down there still some tension otherwise the chain falls off. That's why there is no spring that's needed because once it's set it stays word's.

Then a course is one inside the fusee that typically has springs or spring and unfortunately it does have to, parts.

20 minutes ago, oldhippy said:

You expect to see all sorts of thing when you are working on on something as old as this. 

yes the problem of vintage lots of people have repaired this watch or tried to repair this watch and that becomes a definite issue all by itself.

[xyzzy]

9 hours ago, oldhippy said:

That ratchet is to set the tension for the chain on the fusee.  

Thanks for the confirmation.  I theorized in my original post that this was the purpose of the mechanism, but I've never worked on a fusee before and there is little information online about them.

The underside of the fusee looks like this:

The ratcheting mechanism is entirely inside the fusee.  There's a brass cotter pin through the arbor holding it together.  It's in a recess below the bottom of fusee and it will be hard to get in with pliers.

9 hours ago, JohnR725 said:

yes the problem of vintage lots of people have repaired this watch or tried to repair this watch and that becomes a definite issue all by itself.

It's interesting all the work that has probably been done to this from when it was new until a fusee verge movement pocketwatch was no longer desirable to keep in operation compared to a lever escapement.

It looks like the mainspring arbor hole was worn considerably and then closed up with a punch:

Here we have quite a few scratches on the underside of the top plate.  While there are plenty of stray toolmarks from the errant screwdriver, these seem far too concentrated not to be intentional.  There's nothing here though to be adjusted, so I wonder why?  Maybe there was writing on the plate they were attempting to erase?

Here's the inside of the pivot for what I guess might be called the escape wheel.  I don't know that names for the parts of verge movement (other than the verge!).  The horizontal axis toothed wheel the verge interacts with.  It looks like someone decided the first hole, which might have a jewel, was bad.  They shifted the part to the right and made a new hole.  One can see what looks like an alignment mark that is offset to the right.

 

Edited August 23, 2023 by xyzzy

[oldhippy]

I would cut part of the pin off so that you can tap it out with a hammer and punch. I have marked on one photo that is where the ratchet is it is mounted on the steel pin.  Marks were made for all sorts of things on very old movements, its all part of the movements history there always nice to see.