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Jacot tool and pivot file burnisher question


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1 hour ago, Tmuir said:

The other gauge is part of the jacot tool, its for measuring the size of the pivot, I agree that the rubber bands are not for the jaccot tool

My eyesight lets me down again.:biggrin:My brain lets me down too.

Edited by oldhippy
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  • 9 months later...

I've got a Unitas 235 that has a cracked jewel that also damaged the pivot on the third wheel.

Cousins still has replacement third wheels for this movement, so safe with the knowledge I can order a repalcement wheel I decided it was time for me to try and polish the picot with my Jacot tool.

I've polished pivots on clocks no problem, but this is the first time I have tried on a watch pivot.

I'm amazed at just how much harder it is to polish the pivot on a watch.

I've butchered the pivot enough that I will be ordering the replacement wheel, but will continue to polish this pivot now just for practice.

The few things I have learnt from my attempts so far are.

  • Check the pivot dimension closely and select the correct diameter slot on the Jacot tool, don't just go 'close enough'
  • Ensure you have set up the tool so there is no slop in the way it is holding the wheel, else the wheel will tilt by a degree or 2 as you move the bow and burnisher backwards and forwards making it easier to end up with a tapered pivot
  • Take care on how you hold your burnisher to make sure its parallel to the pivot.
  • Get yourself a few wheels to practice polishing pivots from junk movements before touching an important wheel
  • Give yourself a break and go read WRT if you feel your pulse rising. :D

I may of done a crap job on polishing this pivot, but atleast I can say that I've started to learn how to use my Jacot tool now.............

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Working with such a tool for the first time, you are going to make mistakes. Just working with a bow is an art in its own right. Knowing where you went wrong and correcting is part of the fun. You will get there in the end so just keep it up.

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I went back last night and practiced some more. I got better results, but still not good enough.

I'm leaving it like that until I receive the replacement wheel and confirm it fits, because if it doesn't I will be taking it in to my night class and asking for help before I ruin it.

But once I'm sure the replacement wheel fits I will continue to practice on this one until I get it correct.

I also just received today a trashed English leaver fusee movemt that I only paid $20 for. Its too far broken to ever be made a working timepiece again, but will  prove me plenty of learning potential on a type of watch I've not touched before.

Far better to learn on a $20 wreck of a movement that a several hundred dollar good example.

 

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  • 2 weeks later...
  • 2 weeks later...

Hi folks. I just got a Jacot tool from eBay. I'm working through Practical Watch Adjusting by Donald de Carle which has been a brilliant guide. Just a couple of things I'm not sure on.

First, can anyone explain the scale on the pivot measuring tool? Why are the numbers on the left and right side different? I don't see how they relate.

Also, can anyone explain how to secure the work piece to the tool? The ones I've seen on YouTube have two "snake teeth" that clasp the wheel but this only has one. I can't see how it can hold anything securely.

Thanks all.

IMG_1033.jpg

IMG_1032.jpg

IMG_1034.jpg

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I have never used that type of gauge for pivots, so I don’t know about the measurements. I know you slide the pivot along on the inside until it stops and you read off the measurement.

 

Here is a good video about how to set up a Jacot tool and use it. Working with such a tool takes a lot of practice. Do not start on something you wish to keep, wait until you have the skill.

 https://www.youtube.com/watch?v=f-8Vd2m-WBs

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As you say, there are two sets of numbers on the gauge. 

I'm sure the left hand set of numbers is the diameter of the pivot in Dousiemes, and the right hand set is the appropriate Jacot drum notch that you should use when working with that pivot.  To check this, measure the gap of the gauge at the relavent numbers and see if it corresponds with the sizes I have given.

Here is a conversion of Dousiems to Millimetres.

1 = 0.19

2 = 0.38

3 = 0.56

4 = 0.75

5 = 0.94

6 = 1.13

7 = 1.32

8 = 1.50

9 = 1.69

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Ah. Actually the scale on the left is metric. But I think you're correct about the scale on the right showing which drum notch to use. Mystery solved. Now if I could just attache a balance wheel to the thing. I still can figure out how the "snake tooth" secures it. Thanks Old Hippy for the YouTube link. I had actually watched that one and it's super helpful. Although he doesn't demonstrate on a balance wheel which I understand should have rounded pivot ends. That seems to be a real skill which is going to require a lot of practice.

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The shaft is located between the hollow centre of the driving wheel and the shoulder of the pivot at the jacot end.  The driving dog sits between the the spokes of the wheel to impart the driving force.  Nothing is clamped in place.

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The little slotted gages are kind if sketchy, one of my teachers called them "pivot breaking tool". But for small diameters, say under .13mm or so, a micrometer poses a real threat of making tiny flats on the pivot even with a very light touch. Best is jeweled hole gages, available in .01mm, .005mm, and .0025mm increments. Without those you can get close using a micrometer and then use the actual jewel as a gage, look for about 5° of "tilt" for the correct freedom.

The drive finger is often a pair but a single one works fine.

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The little slotted gages are kind if sketchy, one of my teachers called them "pivot breaking tool". But for small diameters, say under .13mm or so, a micrometer poses a real threat of making tiny flats on the pivot even with a very light touch. Best is jeweled hole gages, available in .01mm, .005mm, and .0025mm increments. Without those you can get close using a micrometer and then use the actual jewel as a gage, look for about 5° of "tilt" for the correct freedom.

The drive finger is often a pair but a single one works fine.

Need to buy a jewel gauge ruler and a set of pin gauges.c09c8b255244f0ef7d63e38d2c4abf84.png574eae8cbc88d997ecdbe8e68c71a102.png


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