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Jacot tool: Does Direction of rotation matter?


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Hello All;

I have this Jacot tool and for several projects it gets time to learn the skill(s) of burnishing pivots.

Jacot-tool.jpg.b4437c0039881da1606132b836d8f381.jpg

Traditionally (probably before everybody had electricity) these tools are bow-driven, occupying one-hand/arm to operate the bow.

But I like to have both my hands free to concentrate on the job and therefor like to have the tool belt driven by a small, speed adjustable 12Volt DC motor. To adjust the speed (RPM) I'm planning to use Pulse Width Modulation via a 555-chip, but this doesn't allow me to mimic the bow-action; changing constantly & frequently the direction of rotation.

But does that matter? Has this constantly & frequently change of rotation direction any influence on the end-result?

If not, my plan was to let the top of the pivot to turn towards me.

Any metallurgical thoughts? 🤔

 

 

 

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I've pondered over this question for many years and come to a conclusion that it does matter. 

If you subscribe to the idea that burnishing is able to move atoms by shearing of the metal lattice structure, then a bidirectional approach would be able to move atoms into a scratch from both sides of the scratch. Makes sense?

I recently got a Jacot tool but have yet to master the coordination of working both the bow and burnisher simultaneously in both hands.

I am thinking of constructing a PWM controlled motor with an additional board for directional change. Maybe just a simple 555 in bistable mode controlling a relay to change polarity to the motor every 1 - 2 seconds. 

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Interesting thought and it does make sense.

Somehow, I knew that I wouldn't get away with it that easy 😬

Using a relay (via a 2nd 555?) isn't a bad idea either or a kind of electronic switch (Arduino?)

Back to the drawing-board 😉

 

Edited by Endeavor
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I like shortcuts. Maybe a ready made board like this would work.
https://a.aliexpress.com/_mMgDqxi

It's probably cheaper than building it yourself. But a PWM motor controller would still be required.

The same setup could be used for a DIY cleaning machine with auto reverse function. 😉

Perhaps Prof @LittleWatchShop could review the concept and comment?

 

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As you know, to feed the beast, we get financially squeezed empty (import-duties, "handling"-fees etc) for anything coming from outside the EU, so an as simple as possible DIY solution is preferred.

The beauty of the 555 is its operating voltage 4.5 - 16V. The DC motor I had in mind is 12V, so a 12Volt adapter feed can be used for both.

I'll start digging too and any suggestions are very welcome 😉

 

Edited by Endeavor
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I've practised quite a bit to get the hang of the Jacot tool and I'm now feeling fairly confident using it and looking at a successfully burnished pivot through my stereo microscope is actually one of the most satisfying aspects of repairing.

I don't have a bow (or a motor) but use a Yoyo keychain. The most common error, in the beginning, was being too light-handed and this made me slip with the burnisher up onto the wheel arbor. This very quickly damages the arbor but as I was operating it manually I could stop the rotation as soon as I discovered or felt that something was wrong. This made the arbor look ugly but still usable. Using a motor I would expect things to go really bad and quickly should the burnisher slip. And, when you're new, it isn't obvious that you've involuntarily moved the burnisher onto the arbor.

After a lot of practice, I made the following personal note in my "horological notebook". Please note that this is a note that was originally intended only for myself so I hope it is understandable.

"When burnishing on the Jacot tool, the burnisher should of course be placed perfectly flat on the pivot bed. However, make sure you're leaning in a bit extra (don't be afraid to do it quite heavily) on the edge of the burnisher placed in between the pivot and the pivot shoulder. Like you're pushing a bit extra on that edge. This mitigates the risk of slipping with the burnisher up onto the wheel arbor creating "an extra heel" on the arbor."

 

Moving the right and left hand in the same direction could possibly make it easier as shown here. I move my hands in opposite directions and I'm now used to it and feel comfortable doing it, but I'm thinking the approach shown in the video might be easier when you're getting started.

 

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The proper action using a bow is the backwards  & forwards motion. When I burnish clock pivots in a lathe the action is just one way. I don't think you are going to do any harm. The trick is not to put too much pressure on the pivot and burnish is an art which you will learn, it is different to turning down a pivot.  

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30 minutes ago, HectorLooi said:

burnishing

Thinking of burnishing have a couple of PDFs attached. True it same that clock pivots but it should work for watch pivots. Although traditionally the watch pivots were polishing will go in the jeweled bearings versus brass bearings which conceivably will cause some of the concerns of clocks with brass bushings are brass bearings not to be an issue.

35 minutes ago, HectorLooi said:

I recently got a Jacot tool but have yet to master the coordination of working both the bow and burnisher simultaneously in both hands.

A long time ago a watchmaker showed me how to use the thing he commented that basically you have to practice every single day otherwise you going to break a lot of pivots.

Then thinking about how you could drive your. This isn't quite what has looking for their something a little different basically I've seen one that holds the tool and has a drive similar to this but for right now is this picture where obviously it only goes probably in one direction you could treasure in the other direction but do need to? Oh minor advantage to these tools is you don't have to hold on to the burner.

https://www.nielsmachines.com/en/pivofix-jacot-tool-watchmakers-lathe.html

https://www.worthpoint.com/worthopedia/rollifit-steiner-jacot-tool-rudolf-276432917

9 minutes ago, VWatchie said:

but use a Yoyo keychain

Something like this?

https://www.nielsmachines.com/en/sold-wit-swiss-jacot-pivot-lathe.html

Conveniently what we want to see is just off the edge of the picture

https://youtu.be/OkWAQbhfeKk

 

 

Pivots finishing burnishing electron microscope.pdf LaBounty-Burnishing Pivots finishing burnishing.pdf

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1 minute ago, oldhippy said:

The proper action using a bow is the backwards  & forwards motion.

Not sure if this was in response to the video I linked to, but even though the hands are moving in the same direction it still makes the burnisher and the wheel go in opposite directions.

2 minutes ago, JohnR725 said:

A long time ago a watchmaker showed me how to use the thing he commented that basically you have to practice every single day otherwise you going to break a lot of pivots.

It feels like that statement is a slight exaggeration. Personally, I would rather liken it to learning to ride a bike. Quite a lot of practice is needed, but as soon as you get the hang of it, it sticks. Regardless of that, I always take an extra practice round on a scrap wheel before starting for real.

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17 minutes ago, VWatchie said:

It feels like that statement is a slight exaggeration

It's an age-old problem some people are just incompetent they need to practice a lot other people just look at the tool And the first pivot is the most beautiful black polish you've ever seen and  never practice at all. The reality is everybody is probably in between. I'm just telling you the experience that I had vintage watchmaker shows me how to use the tool. Makes the most beautiful polished possible I do have to agree it was a very beautiful polish.  

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Okay, the original question was: Does the direction of rotation matter?

Personally I do subscribe to HectorLooi's bi-directional idea;

3 hours ago, HectorLooi said:

If you subscribe to the idea that burnishing is able to move atoms by shearing of the metal lattice structure, then a bidirectional approach would be able to move atoms into a scratch from both sides of the scratch. Makes sense?

 and that has now become for me one of the design criteria's.

With the Bow or a Yoyo keychain, one hand / arm is still busy doing the driving, something, as I mentioned in my openings question, I want to get rid off. I like to have both my hands free & available to concentrate on the burnisher. This also to avoid problems as VWatchie describes.

My design criteria's are now;

1) Hands-free driven, preferably with the available material I have (12V DC motor with belt and electronics)

2) Pulsating Bidirectional

3) Adjustable RPM

If we were to go into the "how-to" achieve this, it would deviate too far from the original question and perhaps best is that I open a new threat for that.

Thank you all for your valuable contribution 👍 😉

 

 

Edited by Endeavor
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1 hour ago, VWatchie said:

Not sure if this was in response to the video I linked to, but even though the hands are moving in the same direction it still makes the burnisher and the wheel go in opposite directions.

It feels like that statement is a slight exaggeration. Personally, I would rather liken it to learning to ride a bike. Quite a lot of practice is needed, but as soon as you get the hang of it, it sticks. Regardless of that, I always take an extra practice round on a scrap wheel before starting for real.

I would say that all depends on the person you are. Some children will get on a push iron for the first time and be able to ride it within minutes others may take days and some weeks. You never forget how to ride a bike even after many years, but some amount of practice is needed to become proficient again. Same applies to playing an instrument,  practice every day and you become the best you can be. A while away from practice and your skill becomes rusty but quickly regained when resuming practise. We all have different muscle and activity memory retentions. So maybe a bit of exaggeration the old watchmaker stated but certainly some truth in that periodic rests from practice could result in incidents of damage. A lengthy stint of practice would be a good place to start when initially learning and should iron out most of your faults and raise a good portion of your list of questions go ask.

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57 minutes ago, Endeavor said:

Okay, the original question was: Does the direction of rotation matter?

Personally I do subscribe to HectorLooi's bi-directional idea;

 and that has now become for me one of the design criteria's.

With the Bow or a Yoyo keychain, one hand / arm is still busy doing the driving, something, as I mentioned in my openings question, I want to get rid off. I like to have both my hands free & available to concentrate on the burnisher. This also to avoid problems as VWatchie describes.

My design creteria's are now;

1) Hands-free driven, preferably with the available material I have (12V DC motor with belt and electronics)

2) Pulsating Bidirectional

3) Adjustable RPM

If we were to go into the "how-to" achieve this, it would deviate too far from the original question and perhaps best is that I open a new threat for that.

Thank you all for your valuable contribution 👍 😉

 

 

One thought that springs to mind that is having the abilty to stay manually in sync with the bi directional motor. The motor drives the balance one way while you push the burnisher against that direction, in regard to the traditional way of burnishing with a jacot.  Or even if that opposite action is still required ?

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When using a normal hand held burnisher it makes sense to do the back and forth motion. If you don't want to use a bow, there are options like: some folks attach some elastic line to the back of the bench, with some monofilament to go around the pulley terminating in a ring (like a keyring). Pull down, let up, back and forth. The built in spring drive that's an option on Steiner and was a bolt on accessory for others works similarly. There's still a string that goes around the pulley and you pull down, let up. In school we used the elastic with key ring setup; I also acquired a Steiner with the spring drive at some point, but last 20 years or so I just stick with the bow.

 

If you want to motorize, with it unidirectional, during half the burnisher motion nothing will really be happening. I think it would be good to let up on the burnisher pressure on the "return" stroke, but maybe it makes no difference. If you try to get a system that reverses it would be necessary to synchronize the burnisher motion with the motor direction change. Easier when you are the motor. Also, you would need to have your burnisher in position before starting the motor, or the pivot will jump out of the bed and possibly break. That's kind of addressed on:

 

-systems like the Pivofix, or similar tools that work with a normal Jacot tool, where a wheel is used to burnish and everything moves in a continuous direction- industrial pivot burnishing machines work the same way. An upside to those tools is they can avoid some of the issues that come when you don't have dozens of hours of practice using a hand held burnisher. I haven't used them very much, but I think it could still be easy to break a very tiny balance pivot if you aren't super careful.

 

It isn't super complicated to make a setup to use a carbide wheel, but still a fair bit of labor. I've seen some examples on Instagram, a fellow Steamlainer made a pretty nice one a while back. The carbide wheels can be bought from Horia or Eternal Tools, or commercial ones sometimes found on auction sites. Though, I think if you look at the price of the raw materials, plus the carbide wheel, and count your time at a fraction of minimum wage, secondhand units don't look so expensive anymore! Pivofix excepted. Last one I saw on Ebay went for like 3500 dollars...

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18 minutes ago, Neverenoughwatches said:

One thought that springs to mind that is having the abilty to stay manually in sync with the bi directional motor. The motor drives the balance one way while you push the burnisher against that direction, in regard to the traditional way of burnishing with a jacot.  Or even if that opposite action is still required ?

With the electronic board that I linked above, a pause can be programmed between direction changes, so that should cue you to prepare to change the direction of the burnisher.

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45 minutes ago, nickelsilver said:

f you want to motorize, with it unidirectional, during half the burnisher motion nothing will really be happening. I think it would be good to let up on the burnisher pressure on the "return" stroke, but maybe it makes no difference. If you try to get a system that reverses it would be necessary to synchronize the burnisher motion with the motor direction change. Easier when you are the motor. Also, you would need to have your burnisher in position before starting the motor, or the pivot will jump out of the bed and possibly break.

Good points and in the same line as the question of @Neverenoughwatches

What I learn from this is to start the motor slowly. The duration of a certain rotational direction is "programmable" / adjustable. It should be possible to adjust the duration of a certain direction to be fairly in sync with the frequency of the burnisher strokes, of which the operator is the driver / pace-maker. I guess the frequency of the burnisher movement can be fairly slow and let the electro-motor do the work. It's probably more important to burnish in both rotational directions, not the frequency thereof.

I'm left-handed and fairly steady with it, but on delicate jobs I really like to us both my hands, hence my wish to get the Jacot tool motor diven.

 

Edited by Endeavor
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I made this many months ago and posted about it.  As I recall nobody commented. I had a geared down motor and I just applied power. No pwm control. I 3D printed the mount and pulley. I am away from the shop now. When I get home I can take better pictures.

YouTube video https://youtube.com/shorts/9TpAIyitI2Q?feature=share

As I said in my original post, I am not moving the burnisher because I am concentrating on holding my phone steady.

Edited by LittleWatchShop
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I hope nobody minds if i diverse a little but while on the subject of pivot polishing/burnishing i have some things to add. I have read about some old ideas regarding the polishing of pivots with abrasive compounds. And recently a discussion we had here about using pin polishers. My first thought is compound abrasives would charge the pivot with the abrasive thereby making the pivot itself an object with a grinding/cutting ability. Might this also apply when using a rubber compound abrasive like the eveflex pin polishers . An abrasive file or stone is going to remove material leaving a grain as opposed to burnishing which evens out the surface by compressing the peaks into troughs making the material more compressed structurally so harder.

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2 hours ago, Endeavor said:

Please, we are deviating from the topic !

Well, it's not like we've deviated to talk about crochet, right? 😉 So far, all posts have at least been about how to achieve a good result on the Jacot tool. And yes, I believe most of the posts have tried to reply (directly or indirectly) to your initial question "if changing the direction of rotation matters", and my impression is that there is a consensus that it does, although not super critical.

Before constructing a motor-based solution I'd say give the Jacot a day or two of practice and then I'm not so sure you'll find a motor-based solution all that necessary. Even so, knowing you are an engineer, you'd (unlike me) probably find it quite interesting to build a motor-based solution, and of course, in that case, you should definitely go for it! For me, that's just not an option. To me, it would be a daunting task and would probably take me weeks or even months.

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9 minutes ago, Neverenoughwatches said:

I hope nobody minds if i diverse a little but while on the subject of pivot polishing/burnishing i have some things to add. I have read about some old ideas regarding the polishing of pivots with abrasive compounds. And recently a discussion we had here about using pin polishers. My first thought is compound abrasives would charge the pivot with the abrasive thereby making the pivot itself an object with a grinding/cutting ability. Might this also apply when using a rubber compound abrasive like the eveflex pin polishers . An abrasive file or stone is going to remove material leaving a grain as opposed to burnishing which evens out the surface by compressing the peaks into troughs making the material more compressed structurally so harder.

The Eveflex abrasive as seen in this thread uses silicon carbide as the abrasive. It is harder than aluminum oxide, (9.5 compared to 9 on MOHS scale) another common abrasive known as Diamantine in the watchmaking world, and what ruby/sapphire is. It takes some effort to embed abrasives into any substrate, and most laps are made from softer material like cast iron or bronze for that reason. But it's conceivable that a small amount could embed in a pivot, and in that event even a tiny amount over time could wear a jewel. Even if using aluminum oxide, that can wear aluminum oxide. Diamonds are faceted using- diamond abrasive.

 

I know everyone is terrified of the Jacot tool, but it really is the best thing ever. The pivot is laying securely in a bed, the work is done between centers, and there are no abrasives involved. When I was teaching I would start students on larger pivots, like 0.20mm, and have them work them down as far as possible, going from bed to bed on the tool. There's a bit of a limit to how far you can go depending on the bite of the burnisher, but with a nice carbide burnisher I've taken 0.10mm pivots down to 0.05mm without breaking as a demonstration.

 

It's well worth getting some job lots of wheels and pinions and just spending some time with the tool. Most of my students were comfortable after a couple of hours of work, maybe a day at most. True, back in the day Swiss schools would spend weeks to months on pivotage, but that included many hours of turning work (between dead centers usually) making stems, plug gages, and balance staffs. I've noticed the youngsters that come to the workshop the last few years from Swiss and French schools are also terrified of the Jacot, and might sit there for an hour trying to work down 0.01mm off a pivot. But they just were poorly instructed. Out comes the box of wheels and pinions, and a 5 minute demo, and an hour later they got their mojo going.

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After what ever you have done to the pivot such as turning it down, polishing you should always burnish the pivot. That is why I said in my other post it takes practice to burnish a pivot correctly, because if you do not you will be left with marks still on the pivot and you know what that can lead to.  If you do not know the answer then you should not be playing about with pivots. 

Edited by oldhippy
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24 minutes ago, Neverenoughwatches said:

I hope nobody minds if i diverse a little

Not at all, sir! 😉

35 minutes ago, Neverenoughwatches said:

Might this also apply when using a rubber compound abrasive like the eveflex pin polishers .

Well, I would refer to @nickelsilver's excellent reply.

One thing I'd like to add though is that EveFlex does in no way replace the Jacot tool. I don't think you or anyone else on this thread believe that but there might be future readers who do. I do use EveFlex but only to thoroughly clean the pivot and pivot shoulder and most of the time that's all that's needed. However, all grits of EveFlex are indeed abrasive, so one must be careful not to deform the pivot into a tapered shape. I only use the soft fine grit EveFlex, and I'm always careful not to go for too long, but I'm still pretty sure a few microns of deformation and removal of material take place, so not sure I'd use this method on my (imaginary) Philippe Dufour movements.

If a pivot is scored or deformed, the Jacot tool is just phenomenal, and in my experience, provided the damage isn't too severe, it removes less than 1/100 mm of material (provided you find the perfect pivot bed on the runner for the job at hand).

3 minutes ago, nickelsilver said:

I know everyone is terrified of the Jacot tool, but it really is the best thing ever.

3 minutes ago, nickelsilver said:

Out comes the box of wheels and pinions, and a 5 minute demo, and an hour later they got their mojo going.

Great post @nickelsilver! And as I mentioned in my first post, looking at a successfully burnished pivot through a stereo microscope is one of the most satisfying feelings there is. The mirror shines on the pivot and the black polish on the shoulder. Is there anything more beautiful on this planet!? 😎 The price paid is of course practice and some failures (but hopefully just on those scrap wheels).

11 minutes ago, oldhippy said:

it takes practice to burnish a pivot correctly, because if you do not you will be left with marks still on the pivot and you know what that can lead to.  If you do not know the answer then you should not be playing about with pivots. 

Friction and Armageddon! 😉

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2 hours ago, nickelsilver said:

The Eveflex abrasive as seen in this thread uses silicon carbide as the abrasive. It is harder than aluminum oxide, (9.5 compared to 9 on MOHS scale) another common abrasive known as Diamantine in the watchmaking world, and what ruby/sapphire is.

I love these kind of discussions that twist and turn just a bit. Ideas pop into heads, i have one to put to Nicklesilver after reading this part of his post. Your combination of words here Nicklesilver  Ruby / sapphire and abrasives made my ears prick up or is that eyes pop out 😄.  Impulse/pallet stones to be used for pivot burnishing/ polishing etc.  A handy managable size in scale with a staff pivot. Any application to be had this idea ?

1 hour ago, VWatchie said:

One thing I'd like to add though is that EveFlex does in no way replace the Jacot tool. I don't think you or anyone else on this thread believe that

Definitely not Watchie, thats why i just didnt get the idea of this Galaxy pro pivot polisher. It just feels like a gimmicky naff gadget in all honesty. There's a reason that the jacot tool and its variations  has been used predominately since it was invented. A well manufactured staff turns out as good a pivot as you can get, it makes sense to mimic that process as close as we can with the tools that we have available. 

Edited by Neverenoughwatches
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