Fusee Dismantling

[Profundus]

Hi everyone. I'm just in the middle of an English Fusee Lever Pocket Watch restoration & thought I might share the fusee dismantle so readers unfamiliar with them could see what's on the inside & how they work.

 

They really were an ingenious and elegant solution to early mainsprings varying in their power output depending upon how wound up they were causing variations in timekeeping ability over the overall timepiece. Modern, i.e. 20th Century mainspring steel was so much better quality that these variations eventually became null & fusees became redundant.

 

(Apologies for not great quality photos - I find my iphone is quickest for photos & uploading but have some blurring)

 

First here's the intact fusee, upright & bottom views.

 

 

 

There's a blued steel collar with a brass pin through it holding everything together & this pin needs pushing out - occasionally they need a bit of persuasion with some light hammer knocks but I try to avoid hitting anything unless I really have to:

 

Once the pin is removed the collar lifts off so the components can be separated:

 

First lift off the brass fusee cone:

 

 

Then separate the bottom brass main wheel from the steel wheel containing the two small steel paws (or "clicks") held by click springs. (note - fusee verge watches usually only have one paw/spring). The teeth of the brass ratchet wheel riveted to the underside of the fusee cone engages in the steel paws when it is together, the click springs providing the engaging pressure.

 

 

This fusee is in pretty good nick (no cleaning has been done)...normally the paws are filled with dried black oily gunk which needs cleaning out (carefully because the paws are very easily dislodged). Occasionally there is wear to paws or ratchet wheel teeth (causing slippage on winding the watch) which can often be sharpened with a file (the ratchet wheel can be removed from the fusee & then re-riveted on which is fairly easy with brass). Once I filed a new paw from some steel (a nail I think!) which was more than fiddly but satisfyingly worked afterwards. Click steel in a ready shaped rod can be bought but only if you can source it.

 

The bottom brass main wheel is fitted with a steel maintaining spring such that the working unit provides maintaining power.

 

As the chain is wound onto the fusee (tightening the mainspring at the same time), the ratchet wheel engages with the paws. The bottom brass mainwheel has teeth in it's edge which engage in a lever paw attached to the watch's mainplate. The fusee is shaped such that as the chain unwinds from it under the mainspring power, it exerts less power when fully wound than when the mainspring is at it's weakest ie almost unwound. At least something like that...I forget the details but there are some nice you-tube videos which explain a whole lot better than my ladybook version.

 

Reassembly is just a simple reversal, not forgetting lubrication. The last photo is just the mainspring in it's barrel - these are very strong when wound. Hope that was fun anyway!

 

 

 

 

 

 

 

 

[Geo]

Thanks for posting this David, it's good to see something a bit different. I have a couple of old fusee watches that could do with a service, and information is great to have at hand.

Are you going to do a complete walkthrough regarding the rest of the watch? It would be great if you could. :)

[bobm12]

Great pictures and refreshing new topic!

[clockboy]

Good post David. I have never worked on a Fusee so found it very informative.

[Profundus]

Hi, really glad you found it interesting & yes I'll happily do a future full walk-through...this one is completely dismantled so I might photograph the reassembly, then the dismantle with the next watch & then post in a few parts as it'll probably be rather long! :)

[MortenS]

Thanks for sharing and its very interesting if you photograph the reassembly.

 

Morten

[Mark]

Very nice post - thank you for sharing :)

[Nige]

Great post, I have an 1802 verge that really needs a clean, I have dismantled a cleaned my other watches but I'm a bit nervous about this one,are there any points I should watch out for,any info would be great.

[Profundus]

Hi Nige,

The fusees are a different breed from the later going barrel pocket watch movements (which could also include the wristwatch movements as they are generally the same, just smaller). In some ways the fusees are more awkward, in some ways easier and the verge is not that dissimilar to a lever in principle....heck, reading this back it is not helpful to you in the slightest! Have you worked on fusees at all before? If not, I'd pick up a lever & verge movement cheaply on ebay to dismantle & reassemble a few times before trying a nice watch....I ruined a couple of movements before I got the hang of it but better that than wreck a complete watch as buying interchangeable spares is not an option.

[mwilkes]

Hi

Any of you good folks know where I might pick up a replacement mainspring for a fusee watch? I could use a modern S-shaped pocket watch spring but they're designed to even out power transmission, presumably cancelling out the need for a fusee in the first place!

Thx

[Nige]

Thanks for your advice Profundas,I think I will do as you recommend,and practice a bit first,

[Nige]

Here are some pics of my Verge,it is by Down &Son of London.

[Profundus]

Wow that's a nice pair case, Tompion type regulator. Lovely!

[Profundus]

Hi, you could try here for a mainspring:

http://www.obsoletewatchandclockparts.com/index.htm

[Lawson]

Hi David

 

Your profile name is very apt indeed mate. 

This level of watchmaking is what I aspire to be able to accomplish with more practice and experience.

Simply magnificent illustrations of a lovely timepiece in very capable hands.

[Profundus]

Hi, that's very kind, thank-you! :)

[evn137BANNED]

Very nice write up. In my short experience ( newly found ) , I only ran across Fusee watches in literature as a historical reference. It essentially compensated for the shortcomings of metalurgy. Naturally when I saw this posting by Profundus, I had to look at it.

Bravo for posting it. Appreciation for such vintage piece can only be realized by the effort one dedicates to it.

Cheers.

Sent from my iPad using Tapatalk

[canthus]

I have a circa 1854 fusee pocket watch which I dismantled, cleaned and re-assembled including the fusee as shown in this post.  Care is needed when assembling the full plate as juggling a number of pinions into place is a delicate job.  I did this and then decided I would like to photo the processes, then managed to break a lever pivot !!!  I have found someone who is going to make me a new staff etc, but not yet got around to it. 

The other thing of note is how the mainspring is let down (not as mr bunn does it!).  The link below describes how to do it correctly.   Also the book 'The Pocket Watch (restoration, maintenance & repair)' by Christopher Barrow is excellent.

 

http://chestofbooks.com/crafts/mechanics/Cyclopaedia/Taking-Apart-And-Cleaning-English-Lever-Watch.html#.VTznepMasZY

[oldhippy]

Very good and informative, just one thing you forgot to mention the fusse is fitted with maintaining power, when winding the power of the spring in maintained in the train so the watch is still working. Someone has mentioned in Nige's post a Tompion type regulator. I think he is referring to the decretive balance cock. These were hand pierced and became a very decorative part of the watch. On the really early pocket watches with a verge escapement they were even more decorative with the pillars all pierced and fitted with a bulls eye glass.    

[tonystime]

This was great, thanks for the info