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Balance Hairspring swap


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I am messing about with a Slavia 1601 (part of my work rescuing watches for local charity to sell on).  The hairspring has broken at the collet.  I sourced a new balance complete for a 1601 but it turns out it is for a Slavia 1600 (a Renata 5095).  The main difference is that the 1600 has no shock system but the 1601 has.  Everything else seems to be the same.  I tried the new balance anyway but it does not work as the end shake is too high and disappears quickly if reduced.  On checking I see that the length and shape of the pivots are different, which I suspected would be the case anyway (I checked the staff dimensions on line and all the rest appear to be the same).

As this is an inexpensive movement I don't want to waste any more money on another balance complete, which are hard to get hold of anyway at a reasonable price.  My thought now is to transfer the hairspring from the new to old.  Both calibers have the same beat rate but the balance wheels are very different.  The non-shock wheel is smaller in o/d but has peripheral screws fitted, whereas the shock balance is a simple 2 spoke wheel larger in o/d (the overall o/d's are the same for both).  I acknowledge the implications of poise etc etc but is it likely that the non-shock wheel is heavier (I have no means to accurately weigh them) or has more rotational inertia and therefore has a stronger hairspring than the shock balance?  How would the effects of a stronger hairspring manifest itself in the running of the escapement?

Your comments would be appreciated before I mess about with a perfectly good new balance which I could resell if needs be.

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 Should you choose to , transfer the hairspring from 1601 to 1600, keep us posted on the rate. 

1-In case it runs slow, you can speed the oscilator by cutting some of the hairspring.

2-Running fast can be slowed down a little,  by moving balance screws outward.

Regs 

Joe

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Nucejoe, thanks for your comment.  I want to do it the other way, 1600 to 1601 so no screws to adjust in the balance.  The hair spring already has stud fitted, and the hairsping is very very delicate.  I doubt I could shorten it without destroying it !!  Would basically be limited to the regulator range at this point.

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the best way to do this is is just do it. After all it's hairspring hairsprings all look the same just go ahead and do it don't worry about it see what happens.

the short answer is it's a total waste of time.

For the most part each hairspring has been vibrated to that balance wheel. The exceptions are early watches with screws usually American pocket watches some Swiss watches. For the same watch with the same balance wheel a generic hairspring designed only for that balance wheel and eight no timing screws of various size and shape and weight and you can then match the balance wheel to the hairspring. But on a modern balance wheel without screws extremely problematic.

Then there's the other problem? They hairspring is a spring its energy is used to unlock the escapement. If you dramatically change the balance size or mass the hairspring may not have enough energy to unlock the escapement. Worse case you could end up with a watch that just doesn't run.

So the unfortunate reality of this is no you cannot change the hairspring but go ahead and do it anyway we love experiments.

Depending upon thing is it would be easier to try to repeat in at the collet. Because it only shorten it's a tiny bits you might still have enough length if you're lucky to get it to run and keep time perhaps depends on how much regulation space you have to move the regulator and how much to lose at the collet.

Probably the best thing the dubious see if you can find a scrap movement on eBay cheap

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JohnR725 thanks for your comments.  I am inclined to think that the h/s for the balance with screws (1600) would be 'stiffer' than the 1601 in order to handle the possible heavier weight and/or rotational momentum of the 1600, and would therefore tend to overdrive the 'lighter' balance (1601) rather than under-drive it.

As commented I may just wait for a reasonably priced suitable donor or balance complete for the original 1601 and sell on the perfectly good new balance complete for the 1600.  In the meantime I may have a go at refitting the original h/s to the original collar as you suggest. Can the bend for the spring at the collar be done cold or will this just over-stress it ??

The movement is from a ladies watch and is only 6.75 x 8 ligne, so everything is really tiny and delicate so completely destroying the collar and/or h/spring is a real risk for me !!

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On 5/9/2021 at 9:51 PM, canthus said:

Nucejoe, thanks for your comment.  I want to do it the other way, 1600 to 1601 so no screws to adjust in the balance.  The hair spring already has stud fitted, and the hairsping is very very delicate.  I doubt I could shorten it without destroying it !!  Would basically be limited to the regulator range at this point.

Good chances are H/S would interchange, but I kinda wish they wouldn't and the thing runs slow and you let me work with you to vibrate a balance complete right in your watch without any dedicated or special tool. It will be rewarding in a real sense of the word because you can then fix many watches which now are tired of waiting in to do drawers. ?

Its only the case of anulare balance running fast that has to wait and only if you are not good at removing material off the balance rim. 

Regs 

Joe

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Nucejoe, thanks for your interest.  Could you give me a general outline of what you propose before I commit to possibly ruining a perfectly good new balance complete.  I am sure others in the forum would also be interested. I do like to learn and experiment but I am basically only an amateur and don't have the sophisticated tools many have at their disposal, and, my hands are ok but not as steady as they used to be (old age creeps on!!).  Regards

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Vibrating a hairspring without any tools is not an easy task to get it okay, if your satisfied to get it near enough in frequency then it is probably doable.
But just to get the feeling of how it is done with proper tools you could look at these notes from a watchmaking student. Without the tools I myself would have waited for the proper balance complete to turn up.
https://watchmakingjourney.com/2014/12/23/second-semester-final-project-vibrating-a-hairspring/
 

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 This is a standing offer to canthus or anyone willing to learn how to vibrate a hairspring right inside the watch without any special tool .

1 hour ago, canthus said:

  Could you give me a general outline of what you propose before I commit to possibly ruining a perfectly good new balance complete.  

Sure I,d be happy to.

On 5/9/2021 at 3:14 PM, canthus said:

 I tried the new balance anyway but it does not work as the end shake is too high and disappears quickly if reduced.  On checking I see that the length and shape of the pivots are different, 

  Lets first get the new balance complete working for you.

 Dr ranfft shows both 1600 and 1601 with just end stones, neither have shock system. Will you show a picture of the shock system on your watch or one like it. 

   You say "end shake is too high"    is end shake real small? 

All tasks to vibrate are;

1- R/R the H/S.

2- Detach and cut the H/S and reattach it to the stud, reinstal the balance complete.

            ,,,,,,, It might take you two or three tries to get to the right beat,,,,,,

Regs 

Joe

 

 

 

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3 hours ago, HSL said:

Vibrating a hairspring without any tools is not an easy task to get it okay, if your satisfied to get it near enough in frequency then it is probably doable.

Your link makes it looks so damn complicated is it really that complicated? when we have the offer below where it's really simple?

2 hours ago, Nucejoe said:

This is a standing offer to canthus or anyone willing to learn how to vibrate a hairspring right inside the watch without any special tool .

You really should do this as a walk-through lesson because it's a very necessary thing for people to vibrated hairsprings.

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Well, if you're going to vibrate from scratch and do it right there are quite a few steps. 1st vibration with a spring that seems close, then a calculation to get from its CGS to the correct CGS, second vibration, then calculate the pinning point, de-collet, remove the necessary spring length, then final vibration. In reality, with some experience, for a simple repair you can often hit a spring that will work 1st try, then often the pinning point is close enough, or if it's not a high grade watch you don't really have to worry about it too much. Having a Luthy tool is very nice (essential in my book), and of course having a varied stock of springs both steel and modern alloy- that's the really big trick.

 

But there are all kinds of work-arounds. I did a JLC 838 a while back for a manufacturer; needed a new hairspring, no balance completes available. They provided one from another balance; it was running like 300s slow with that, and the way it's made shortening the spring would be a last resort, so I drilled the balance rim carefully in opposing spots and ended up with a rate in original spec.

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1 hour ago, JohnR725 said:

Your link makes it looks so damn complicated is it really that complicated? when we have the offer below where it's really simple?

You really should do this as a walk-through lesson because it's a very necessary thing for people to vibrated hairsprings.

I do not have a TG or vibrograph to show how perfect the result is or that I did vibrate with success, but if work with canthus or someone else, then  he will be announcing the success.

Perosnally, I actually put the hands on the movement, let it run like 24hrs to get a ball park figure of the rate its producing, once its within regulating range I know full well a repairman with a vibrograph  can  accurately regulate the watch in less than a minute.

  I have a seiko 6309 ready to vibrate and post the walk through. A walkthrough shows bunch of pictures and at most explains thing in words, how would the reader know if success was acheived? 

I guess a walkthrough is in order. 

It may look laborious or rediculously rudimentary, but is really easy to understand, in fact there is nothing special about it. 

 

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2 hours ago, JohnR725 said:

Your link makes it looks so damn complicated is it really that complicated? when we have the offer below where it's really simple?

Well, everything is simple if you know the theory behind it, just like @nickelsilver said there are two options to go with, it is either playing around with the length of the spring or the mass of the balance.
In nickelsilvers example he solved it by drilling away mass from the balance, wouldn't say that is what a novice would be able to do without proper tools. 
Adjusting the length of a hairspring when one never done it before, well if you have a good hand to eye motoric it might work. 

I wait with anticipation on the tutorial.
Meanwhile I can contribute with a small illustration of the theory I think is in play here ?

Hairspring.thumb.png.a4a6aa4609c9ed9fdf2636f992b33007.png

Edited by HSL
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 This being my first walkthrough I can only wish to make a presentation as good as VWatchie but will try my best and post one within two weeks.

I will be using a vintage Oris calender pointer calib 704kif as I have plenty of parts and have not seen a walkthrough on this calib on the forum. I can always use help with my broken English so correct me to make this a useful walkthrough and understandable for all.

Once again if you know what H/S is compatible with the balance at hand or its matching CGS, vibrating is simpler than guessing a used mainsprings strength.

Regs 

Joe

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12 hours ago, HSL said:

Well, everything is simple if you know the theory behind it, just like @nickelsilver said there are two options to go with, it is either playing around with the length of the spring or the mass of the balance.
In nickelsilvers example he solved it by drilling away mass from the balance, wouldn't say that is what a novice would be able to do without proper tools. 
Adjusting the length of a hairspring when one never done it before, well if you have a good hand to eye motoric it might work. 

I wait with anticipation on the tutorial.
Meanwhile I can contribute with a small illustration of the theory I think is in play here ?
 

No analytical calculation will be involved, its simple fitting of hairspring on balance and see what rate you get at the end and begining of terminal curve, decide what length of H/S to leave free and inch-in towards the beat the movement requires.

Nothing advance, just basic common sense.

I have tons off vintage manual wind Oris to fix, if a H/S didn't vibrate a balance I just tried it on another Oris balance of same calib.

Its simple, once you browse this walkthrough you probably say what is the big deal, anybody can do that.

Regs

Joe

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Nucejoe, just finding a spot for the stud is something rather different than vibrating a hairspring correctly, as described by nickelsilver or by the link above. 
You don't mind the pinning angle, essential for isochronism. And there are totally different rules for PW and WW.

Frank

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This is a great thread. I  tried to swap a hairspring to a different balance wheel and staff yesterday and found while the watch would run and it seemed the amplitude was pretty good my timegrapher gave me a reading of +++++ secs/day even though the line seemed to be going down. A watchmaker told me that the hairspring I used would have been calibrated to the balance wheel I pulled it off, so it's not so easy as to simply swap hairsprings. I guess that's why the proper thing to do is swap balance staffs. That is the next thing I will learn to do. All this information about vibrating a hairspring is very interesting and sounds really hard. 

 

IMG_5344.jpg

Edited by Rowbear23
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This is a great discussion and very informative. Due to lack of proper tools and a bit too shaky hands, I have now decided that I will wait out and try and source a 1601 balance complete or one with broken pivots that I can remove the h/s.  This will enable me to resell the good NOS 1600 balance to pay for a 1601 balance or whatever.  I have a lot of other items to work on at the moment so will have a quick try with the old h/s on the 1601, and leave it be for now if I can't sort.  Thanks for everyone's input.

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On 5/14/2021 at 2:24 PM, praezis said:

Nucejoe, just finding a spot for the stud is something rather different than vibrating a hairspring correctly, as described by nickelsilver or by the link above. 
You don't mind the pinning angle, essential for isochronism. And there are totally different rules for PW and WW.

Frank

Hi Frank, is pinning angle the bend in H/S close to the stud.  I take that into account but don't know what pinning angle is by its name. 

Regards

Joe

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Hi Joe,

no, something different.

- draw a line from center through the spot where the hairspring leaves the collet.

- draw another line from center through the spot where you grip the hairspring on vibrating and where you get zero rate error. 

Angle between these lines is the pinning angle, it shall be around zero on wristwatches. See "Caspari effect".

Frank

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