Poise issue? Seiko 7625 with Renata 1594 balance

[steve1811uk]

8 hours ago, JohnR725 said:

in addition to looking for balance complete if you look at that list I gave you of other watches you can look for other Seiko watches that have the same balance complete. Although it's always disturbing when you find a complete watch just to steal one part from it. Seems like it be nice to find a broken watch the steal the part from.

then if you had a lathe not always 100% needed but nice to have if you are changing a balance staff. Then you can just change the balance staff in this watch. Of course you need a few more tools but this is watch repair you always need a few more tools don't worry you're never going to reach the end of when you need tools.

other options just because

this is an interesting video he's not using the classical bow to power the tool which is probably helpful. it's an interesting tool and it would help you with your problem but it takes a lot of practice to do it right. ey're broken

https://youtu.be/uktGMlwthlY

as usual in watch repair people are resourceful other tools like this one. Yes you can reduce the size the pivots with this and polish them. Not quite as nice as the above tool at least for burnishing but still works.

https://youtu.be/FRR9JSfUtCM

a variation of the above tool with a more practical way to drive it.

https://youtu.be/1uvc6yXBaqk

 

 

Hi John, I really appreciate it that you have taken the time to post such an informative reply. To cut a long story short I have just purchased a Jacot tool from eBay. The tool appears to be in very good condition with all parts and the price was reasonable. Looking forward to working with the tool to reduce the pivot diameter. I now need to look for a burnishing tool. Also would that same tool be able to reduce the diameter? I need to take off approx 0.01mm. Or something else with a fine abrasive quality? Thanks again.

[rodabod]

Hi Steve. A burnisher will allow you to remove small amounts like you describe. You can make a very sharp burnisher using a tungsten carbide D-bit and “make” the coarse flat surface by drawing it across a diamond stone. Another alternative is to make one from an old needle file - remembering to create a safe -edge with a slight back slope. 

[JohnR725]

3 hours ago, VWatchie said:

positional errors cannot be attributed to an unpoised balance wheel as long as the amplitude is at 220° at which point any positional errors originating from a heavy spot on the balance is cancelled out.

yes the magical amplitude as I call it should have zero positional errors showing up on the timing machine or the running of the watch. Of course the problem is keeping your watch running at 220°. Then running in all of the pendant/crown positions at exactly 220° is an issue.

3 hours ago, VWatchie said:

The movement is tested in four positions.

I'm guessing the problem when Mark does a video is time this means things have to be simplified. It's really hard to tell if you have a positional error if you only test in two positions that would show that. Ideally at least four pendant positions eight would be even better.

then for the rest of your question mark skipped over a lot of things in his video. Then if you're dealing with a modern watch you can probably skip static poising other than it doesn't cost you anything. Like for this discussion it made for a really good discussion. Because you cannot dynamic poise unless the watch is perfect and it was clear this watch was not perfect so wasting time dynamic poising would've been very bad.

I have two links below which might shed some light on things. The second one is a Greiner timing machine manual. What was really nice about their early manuals is they made the assumption that the watchmaker had no idea how their timing machine worked or anything related to precision timekeeping. This then gives us some really good manual on using your timing machine and how your watch works. On PDF page 23 it discusses dynamic poising. Greiner gets credit because it's in their manual and basically without a timing machine you can't dynamically poise.

the first link talks about timekeeping of course. Written by an obsessed former students of a Swiss school. I'm point this out because you'll see the influence of the school and an occasional reference to the American butcher watchmakers although I may be a bit harsh on my interpretation. I've seen his writing is in other discussion groups and he definitely does not favor American watch repair authors at all. The influence of the Swiss training.

Then he does comment that vintage like American pocket watches have gone through a lot of hands. This is why static poising in my view is a good way to start to see just how bad things are. If they were perfect from the factory you could conceivably go straight to dynamic poising. Kind of like Mark's doing in his video because on a modern watch it hasn't suffered at the hands of poor watch repair. plus typically is a screwless balance not bimetallic there's way less bad things that will happen to it. Or basically it's more likely to be cracked in the first place. At least up to a point remember Seiko does not typically make Rolex timekeeping watches and less were discussing the grand Seiko. Which means you can dynamically poise a Seiko and get it better up to a point.

https://www.historictimekeepers.com/documents/Watch Adjustment.pdf

http://www.historictimekeepers.com/documents/Micromat.pdf

 

 

 

[JohnR725]

1 hour ago, rodabod said:

A burnisher will allow you to remove small amounts like you describe

think about a burnisher like a file except it's teeth are superfine. Then to be technically correct they range from superfine to something that looks polished no teeth at all. you can remove a small amounts a metal than later basically polished by compressing the metal. If done right you end up with a really beautiful mirror finish black polish that's hard.

 

[praezis]

@VWatchie
Seems some videos produce more questions than answers - compared to reading books by proven expert authors (the old fashioned way, I know).

To your initial question: Dynamic poising is to be handled with care. Conclusions are valid only, if the watch is in perfect technical condition!
The mentioned watch differs by more than 50 degrees in those two vertical positions. Here the rate difference can come from isochrone effects (rate dependent on amplitude) - in that case, poise conclusions are not valid at all!

Also a TM amplitude measurement can be unreliable, the real lift angle may differ from that listed in tables. So keep far away from 220 degrees for poise testing, best 180 degrees or lower (lower will magnify the error).

Frank

[Nucejoe]

On 11/16/2020 at 9:59 PM, VWatchie said:

You got me completely wrong joe! I'm not judging you. I appreciate you, for many reasons, one of them being your honesty, which is sort of rare. 

 Thank you for your patience and understanding and please accept my apology.

 Wishing you health.

 

 

 

 

[steve1811uk]

Well, I have the Jacot tool and have made a burnisher (3mm x 3mm graver with one side rubbed against a 600 grit diamond stone, held in a pin vice). I need to take the pivot diameter down from 0.088mm to 0.078mm (measured with a mitutoyo 0.001mm micrometer). That's a hundredth of a mm reduction. I have watched the various videos on YouTube regarding Jacot use and I am making an appeal for help to you guys with experience of using that tool.

1) Did I do right using the 600 fine diamond stone to make the burnisher finish, or should I have gone finer? 1200 grit?

2) How much burnishing will be required to remove just 0.01mm? A few seconds, a minute, more? What would you do? Is it a case of burnishing for say 5 seconds and then measuring to see the effect that had?

Thanks in advance.

[JohnR725]

A extremely long time ago somebody showed me how to use the tool so as far as practical use goes it's too long to remember other then? Like everything else in watch repair you really should practice on something first. It's always a nice fantasy that the first time everything is going to work perfect and you can start practicing on alive watch. But the unfortunate reality is it's usually something different I would find some practice balance wheels to practice on get a feel.

[rodabod]

Hi Steve,

Grits are always a bit subjective as abrasives wear down in use, and some are more effective than others. I reckon 600 grit sounds about right. It should have what looks like a grained finish, a bit like what is seen on some watch cases.

When it comes to burnishing, make sure the surface is always wet with oil. Any oil will do. On larger pieces, the oil will turn slightly grey or dirty looking as material is removed - if you mop it up with a white tissue then you may see. Your small pivot may not produce much debris though. You need to use relatively high pressure to burnish - but remember your pivot surface area is tiny, and it's also liable to snap!

Repeatedly measure to assess how much material you are removing. There is no ballpark figure for how fast it will cut. Keep the burnisher face parallel to the pivot, and if you have not already, it is worth making the edge which is perpendicular to the burnishing side have a slight back-slope to give better access and lessen the chance of this "safe edge" from damaging anything.

[steve1811uk]

Thanks guys for the input. I do have some old Ricoh balance wheels minus hairsprings that I can use for practice. I will report back on how it goes.

[nickelsilver]

For resurfacing my carbide burnishers I use a 45 micron / 280 grit diamond plate for my finest one, my regular burnisher is done with an 80 micron resin bond diamond wheel. I think 600 grit is too fine.

 

To take off about 0.01mm at that diameter should take anywhere from 10 seconds to a minute depending on the burnisher and pressure. Thin oil is good, many here use almond oil, some use lavender oil.

 

The Mitutoyo 0.001 reading mics I've seen have been digital and are even more unwieldy and have less feel than their simple brothers, I bet a coke you've squished your pivots a bit. I'd be very surprised to see a sub-0.08mm pivot in a commercial grade Japanese watch.

 

To measure these pivots you really need a jewel gage.

 

 

 

 

Edited January 3, 2021 by nickelsilver

[JohnR725]

9 hours ago, nickelsilver said:

To measure these pivots you really need a jewel gage.

Yes if you're not careful measuring something is fine as this will be an issue. Micrometers are better than veneer calipers but there like a little tiny vice and you're going to put a lot of pressure on your pivots just because it's going to be really easy to do. They do make holders for the micrometer or bench micrometers where micrometer sits on the bench it makes it a little easier to use but that's a lot of pressure conceivably you going to put on a tiny pivots.

But there is a micrometer that does work well I'm attaching a picture unfortunately it's pricey. Then there's the jewel gauge which is nice because it's lightweight so like if the staff is in a lathe you could use it there without bad things happening.

Of course the best gauge of wall to use is whatever your putting it in. Because that's where it has to fit.

 

[clockboy]

As John highlights to measure pivot a pivot gauge is the safest and IMO the most accurate way to measure.

[steve1811uk]

Well I have an update. Gave up with the jacot. I soon realized that it would take more time and spare balance wheels than I had available. I think it is one of those tools that you would need to spend 100s of hours in order to master it, especially for small watch pivots. I did manage to get a donor movement however. After a lot of work on the hairspring, centering, flattening, demagnetising I have the watch running really well. It's now within +-10 in all positions with 275 degrees amplitude in horizontal and a small beat error. Regulator pin spacing was left a bit wider than I would normally aim for. If I made that very narrow it had the effect of making the vertical positions too fast and also lowered amplitude.

[steve1811uk]

Well I have an update. Gave up with the jacot. I soon realized that it would take more time and spare balance wheels than I had available. I think it is one of those tools that you would need to spend 100s of hours in order to master it, especially for small watch pivots. I did manage to get a donor movement however. After a lot of work on the hairspring, centering, flattening, demagnetising I have the watch running really well. It's now within +-10 in all positions with 275 degrees amplitude in horizontal and a small beat error. Regulator pin spacing was left a bit wider than I would normally aim for. If I made that very narrow it had the effect of making the vertical positions too fast and also lowered amplitude.

[nickelsilver]

In the Swiss schools in the early-mid 20th century they did indeed spend 100s of hours on the Jacot. It's a great but funny tool, if you don't get it straight away then it takes time. But as a former teacher I can say that in 5 hours you can get it. Unfortunately there's literally not one YT video I've seen that explains its use correctly. Best I can recommend is buy "steampunk" lots of wheels off Ebay and practice.

 

Great job on that watch!

[steve1811uk]

23 minutes ago, nickelsilver said:

In the Swiss schools in the early-mid 20th century they did indeed spend 100s of hours on the Jacot. It's a great but funny tool, if you don't get it straight away then it takes time. But as a former teacher I can say that in 5 hours you can get it. Unfortunately there's literally not one YT video I've seen that explains its use correctly. Best I can recommend is buy "steampunk" lots of wheels off Ebay and practice.

 

Great job on that watch!

Thank you for responding. I actually sold the jacot, it's gone to a good home, the British school of watch making based in Manchester of all places. I've just purchased a staking set instead with the cash (Bonelli, made in Italy, looks decent and complete). Should me much easier to replace a balance staff rather than burnish a tiny pinion, for me at least.

[VWatchie]

On 1/2/2021 at 1:45 PM, steve1811uk said:

2) How much burnishing will be required to remove just 0.01mm? A few seconds, a minute, more? What would you do? Is it a case of burnishing for say 5 seconds and then measuring to see the effect that had?

I've been practicing a bit with my Jacot tool and was able to successfully take down a few pivots to the smallest diameter allowed by the Jacot tool, 0.04 mm I believe (or 0.07, can't remember exactly). Not that I needed it, it was just for fun and practice. Anyway, in my limited experience the time spent burnishing isn't all that relevant as long as you keep burnishing until you've reached the diameter determined by the currently selected bed in the Jacot tool. That, is you can't really overdo it. I believe an experienced repairer/watchmaker develops a feel (felt in the burnisher) for when the currently selected diameter has been accomplished.

I did learn the hard way that if you burnish a train wheel pivot and slip from the shoulder to the arbor, the burnisher will grind it down in fractions of a second. So, if this happens (which can be a bit hard even to detect when you're new), stop immediately, and reset the edge of the burnisher to the shoulder.