A little bit of making.

[Dave S]

Evening all,
The patient - A French Mantle piece clock, which has a balance not dissimilar in size to a pocket watch.
Unfortunately its been dropped and the top pivot is now in 2 pieces.



A little bit of disassembly and the fun can begin :)



You can see the shorter pivot on the balance spring end.



So what to do?
Well, break out the lathe and a piece of blued steel and get going...



Grain of rice for scale.



Around this point I got hacked off with having to hand sharpen the gravers.
Maintaining the angle and flatness on them is tricky by hand, even with my makeshift jig.
So I took a day out from making the staff to make a grave sharpener (like you do).



This is 1/8 diameter micrograin carbide. took about 2 minutes to make into an acceptable graver.





Back to it - now more like a balance staff shape.
Of course I didn't read the accepted way round (roller table innermost) to make one until after I'd got a good way along.



Undercutting the rivet took some care, as did turning the top pivot.



I found a good way to stop the loss of small parts when parting off - a tube filled with grease over the part.



Having not lost my new staff I riveted it to the balance. I think I should make a smaller hammer...



And now it needs a little touch up of the pivot sizes on the Jacot tool:



Once I figure out how to use a Jacot so the balance and staff don't jump out all the time Ill post an update.
If anyone has any tips they would be gratefully received.

Dave

[Webwatchmaker]

Very interesting. Great to see traditional skills in use and enjoyed. I repivot platform escapement staffs when I'm bored !
Have you tried finishing the pivots in the lathe chuck with 3M papers stuck to lolly pop sticks ? 3M papers come in 6 grades from coarse (blue), which is Arkansas stone coarse, to mirror finish (white).

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[subseastu]

Didn't understand a thing in that but really interesting, thanks

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[Webwatchmaker]

Didn't understand a thing in that but really interesting, thanks

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I guess all watchymakery words are googleable ?

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[Dave S]

No, I’ve not tried in the lathe. I have some boxwood and diamond paste which would work I think.
The bottom pivot fits the jewel, but might be a bit tight. The top one is ~0.01mm to big. (The one I couldn’t measure until parting off)
I could use a wax chuck I guess to support the staff - the roller seat is tapered and would walk out of a normal collet I think.
But then I do have a Jacot tool with a bow and burnisher that I should probably learn to use.
The problem is that the staff is not very secure in the female centre and so it jumps out really easily. I wondered if there is some “secret” like a small blob of grease on the centre that I am missing?

Dave

[Webwatchmaker]

No, I’ve not tried in the lathe. I have some boxwood and diamond paste which would work I think.
The bottom pivot fits the jewel, but might be a bit tight. The top one is ~0.01mm to big. (The one I couldn’t measure until parting off)
I could use a wax chuck I guess to support the staff - the roller seat is tapered and would walk out of a normal collet I think.
But then I do have a Jacot tool with a bow and burnisher that I should probably learn to use.
The problem is that the staff is not very secure in the female centre and so it jumps out really easily. I wondered if there is some “secret” like a small blob of grease on the centre that I am missing?

Dave

The Jacot tool is fiddly and takes some practice to perfect it's use. Slight downward pressure on the bow and a small drop of oil on the pivot runner whilst keeping the burnisher in constant contact with the pivot should help to stop it jumping out of the runner bed. Depending on how well finished the pivot is initially, will determine the time needed to burnish it smoothly and to exact size. The advantage of the Jacot is that the pivot will have perfectly parallel sides. Runners need to be kept very clean as you can imagine to avoid scratching the pivot sides. Finishing the end of the pivot to a smooth round is done by passing it through the appropriate hole on the ends runner.
It's a lot quicker to finish the pivot in the lathe and with 3M papers but the Jacot art is then lost. The lathe doesn't do as good a job.
You are right that the coned roller end can slip out of the chuck, though a very slow speed reduces that risk. Substituting a wax chuck would certainly help.
*I have seen a thin open elastic band, attached at one end under the Jacot tool, used to turn the ferrule, instead of a bow.
Best wishes for a successful outcome.

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[Thewatchbloke]

I'm no expert in Jacot lathes but I do use mine occasionally!

What I can't see on yours is the forks on the drum that turn the wheel when you move the bow? You can see them on mine below.





I find it easier with the forks positioned nearer to the centre of the wheel but it's still a very tricky process to learn.

[Webwatchmaker]

I'm no expert in Jacot lathes but I do use mine occasionally!

What I can't see on yours is the forks on the drum that turn the wheel when you move the bow? You can see them on mine below.





I find it easier with the forks positioned nearer to the centre of the wheel but it's still a very tricky process to learn.

Yes. I noticed that too. Without the carrier on the ferrule the wheel would not turn. I presume it was left out for photographic clarity.

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[UMBROSUS]

That is superb

Just WOW


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[Webwatchmaker]

Congratulations ! That looks pretty damn good to me ! I will be very surprised if you don't get a superb amplitude when it's all reassembled.

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[Sausage]

My work is in precision turning so this kind of stuff is right up my street....In fact our Swiss type CNC's were originally developed by Citizen to manufacture components for their watches. However, there's nothing like some back to basics highly skilled lathe work.

Top stuff.

[Thewatchbloke]

Nice job Dave, I'm sure all the fork achieves is less backlash between direction changes with the bow. As you've proved it was just the lack of the actual burnisher that was causing the issue.

Now poise that balance!

[Dave S]

Finished. Wasn’t far out of poise, which I think is to be expected.
Apologies for the twitter link, it’s to a couple of second video of a ticking balance.
https://twitter.com/solutionsbydave/...197813760?s=21
I don’t have the rest of the clock, but this module is ready to go back to it and get fitted.

Should probably get on with learning Dial Enamelling now...


Dave

[Webwatchmaker]

Well done that man ! Congratulations on keeping these arts alive.
I shall be visiting an enamel dial maker in Switzerland this October and hope to add a couple of chapters on how to make them in my book.


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[Dave S]

Very small update on this.
The balance module is now installed back in the clock and ticking nicely.



The clock has three trains, one of timekeeping and two for the chimes. It now needs a service and re-casing but that’s not my job :)





There’s a short video on my Twitter:

https://twitter.com/solutionsbydave/...012129281?s=21

Dave

[Webwatchmaker]

Nice job Dave. It's great to get something working again.

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