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Poise issue? Seiko 7625 with Renata 1594 balance


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Hi, hope you guys can help. I have a Seiko 7625 in restoration. Old balance was working quite well in vertical and horizontal positions, similar rates in all positions but had a worn pivot causing dial up and down to differ more than I would like (around 15 seconds difference). Anyway, I couldn't find a Seiko balance but got hold of a Renata 1594 balance that is a compatible balance. First thing I noticed is that the hairspring was fitted 180 degrees out of phase. I fixed that by turning at the collet. I had to form the terminal curve which was successful. Dial up/down gave an amplitude of 273 degrees (beat error 0.1ms) but I had to move the regulator pretty much as far as it would go anti clockwise to speed up to +5 SPD (regulator arm nearly touching the bridge). Dial up and down amplitudes and rates were very bad, -32 and -65 with amplitudes 195 and 215, a huge drop. Any ideas? I am guessing that the balance is faulty and badly out of poise. It has numerous factory made poise holes that have been made on the back. Steve.

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Hi Steve

If you have checked and are sure of jewels on lower and upper balanace pivots, there remains the question of pivots bent, chipped or dirty as well as shakes on the staff.

I am affraid not much can be done to poise these anulare wheels as special tools are needed and I guess some skill  to poise em. 

 

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It’s not possible to fairly compare positional variation when the amplitude is much lower. 
 

So, if you want to move forward then you’ll want to correct the amplitude first. 
 

Given what you described about the hairspring orientation, do you believe that the roller position is correct? It’s slightly tricky to see where the impulse jewel should point as the balance arms are eccentric. If you have time to burn, then I’d maybe try moving it (and the hairspring to correspond). 
 

But firstly, best to check the simpler things like Nucejoe suggests like endshake and that the hairspring is breathing freely. 
 

 

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16 hours ago, steve1811uk said:

badly out of poise

 

14 hours ago, rodabod said:

It’s not possible to fairly compare positional variation when the amplitude is much lower. 

as you're running slow you can poise these balance wheels. If we knew the watch was running really well which it's not you could try dynamically poising it. Otherwise you can take the hairspring often statically poise. A carbide drill will takeoff weight on the bottom of the balance wheel. As you're running slow you're going to speed up if you go too far your going to need a new balance wheel.

I notice I'm not paying attention but did you tell us what the beat error of this watch is?

it would be nice to have a picture of the balance wheel in the watch.

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1 hour ago, JohnR725 said:

 

as you're running slow you can poise these balance wheels. If we knew the watch was running really well which it's not you could try dynamically poising it. Otherwise you can take the hairspring often statically poise. A carbide drill will takeoff weight on the bottom of the balance wheel. As you're running slow you're going to speed up if you go too far your going to need a new balance wheel.

I notice I'm not paying attention but did you tell us what the beat error of this watch is?

it would be nice to have a picture of the balance wheel in the watch.

Would you give a brief lesson on how to determine the amount of material to be removed for a poise? TIA

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2 hours ago, Nucejoe said:

Would you give a brief lesson on how to determine the amount of material to be removed for a poise?

one of the things really nice about the Internet is a lot of times you can look and somebody is already answered the question like at this link. then specifically were only looking at static poising.

as you're reading to the text at the link below you'll notice that a modern balance wheel from the factory should have been poised in the first place. But the question always is how closely is it anyway? Then he also makes a reference to other things can affect poise. This is why statically poising is a good way to start as we can see if it really is a poising issue or not. Because one of the concerns I have with the watch above is the amplitude is dropping below 200° and that's definitely a screw things up. Things like poising errors look much worse is amplitude drops.

then looking at the link you'll notice with his poising tool that the level can be placed on the jaws make sure that their level. you'll notice a lot of the tools will have the level built in the base and that's not the most desirable place to have it. Then you need to have a separate level to check the jaws.

then as to how much weight you need to remove that's going to be determined by how bad the balance wheel is. If you look at the example at the link he just takes off a tiny bit which is the most a modern balance wheel should  need.

unfortunately if you're dealing with a vintage pocket watches like I typically see. All sorts of strange things have happened to them over the years and it's possible sometimes with poising to take off so much weight that you have to put timing washers on to make up for the weight loss.

https://www.great-british-watch.co.uk/how-to-poise-a-balance-wheel/

 

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Thanks guys for all the input. The hairspring is off the balance now, please see picture attached. All looks OK there as far as I can see. I honestly think that the balance poising has gone wrong at the factory (it is currently sporting 11 poising holes!). I tried to get my hands on a poising tool on eBay last night but was thwarted in my attempt, just missed out. Anyway I am going to try and knock something up from a couple of Stanley knife blades glued onto a milled block of steel. I will need to get that perfectly level and then I will give static poising a go, wish me luck, nothing to lose. 0.5mm tungsten drill bits are on order. Give me a few days and I will post here. Steve.

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12 minutes ago, rodabod said:

I’m not convinced that a poise issue alone would lead to a drop in amplitude such as what is described in the original post. 

I can't think of anything else to blame as the jewels and lubrication are good. Pivots are definitely not bent. Also dial up/down shows very good amplitude. I am thinking that this balance should have gone to the reject bin. Anyway, I will attempt static poising and see how far I get with that.

Edited by steve1811uk
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 To check the balance wheel for poise, just put the balance and cock back on mainplate( without the fork and preferably no other parts), then in vertical position heavier side comes to rest at 6 oclock( bottom of the hour), ink- mark the spot.

My experience is, having always removed too much material on first try, I say shoot for half the amount you think should be removed.

Good luck.

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I do still wonder if it was the roller which was 180 degrees out of phase. There are more poising marks on the opposite side of the rim which can sometimes correspond with counteracting the weight of the roller and impulse jewel. 

However, I also don’t see how poising it will significantly increase the amplitude. When you timed it in opposite positions (pendant up and pendant down) both showed a loss in rate, rather than one being fast and the other being slow. 
 

 

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2 hours ago, rodabod said:

I’m not convinced that a poise issue alone would lead to a drop in amplitude

I definitely agree with the above statements. I deal with vintage watches that have greater poise error than your demonstrating and is not an amplitude issue. 

2 hours ago, steve1811uk said:

I can't think of anything else to blame as the jewels and lubrication are good. Pivots are definitely not bent. Also dial up/down shows very good amplitude. I am thinking that this balance should have gone to the reject bin. Anyway, I will attempt static poising and see how far I get with that

having said the above statement statically poising isn't going to hurt anything. It's a easy way to find out if it really is the problem. Has a advantage that your balance wheel will be lighter and will run faster.

 

1 hour ago, Nucejoe said:

My experience is, having always removed too much material on first try

this is where using an actual poising tool should help with that problem. Then make sure the jaws are clean free of oil and also the pivots. any kind of residue or oil on the jaw's or the pivots will show up and interfere with getting a perfect poise. Then it doesn't have to be super perfect. Initially the heavy spot will show up very dramatically. As you get closer and closer to poise will take longer and longer to finally come to rest of the heavy spot. You go far enough it eventually will just continue to rotate and come to a stop.

 

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19 minutes ago, rodabod said:

I do still wonder if it was the roller which was 180 degrees out of phase. There are more poising marks on the opposite side of the rim which can sometimes correspond with counteracting the weight of the roller and impulse jewel. 

 

Good point.

19 minutes ago, rodabod said:

However, I also don’t see how poising it will significantly increase the amplitude. When you timed it in opposite positions (pendant up and pendant down) both showed a loss in rate, rather than one being fast and the other being slow. 
 

 Imbalance weight is a load on balance wheel to be moved around. There is no such extra load on a poised ( balanced ) wheel.

In vertical position, when that extra load( imbalanced weight) heads downward, it accelerates the whèel and decelrates it when heading upward, you see the difference here is about the same.

In horizental position, that extral load doesn't head up or down.

Hope this helps.

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I think there is some confusion here. All of the pendant positions are slower than the dial positions. A “heavy spot” corresponds with a relatively speaking “light spot” on the opposite side. None of the other pendant positions show a faster rate. 

There is a 60 - 70 degree drop in the pendant positions which in my opinion is not simply the result of a poising issue as the positional variation is not horrendous.
 

 

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18 minutes ago, rodabod said:

I think there is some confusion here. All of the pendant positions are slower than the dial positions. A “heavy spot” corresponds with a relatively speaking “light spot” on the opposite side. None of the other pendant positions show a faster rate. 

There is a 60 - 70 degree drop in the pendant positions which in my opinion is not simply the result of a poising issue as the positional variation is not horrendous.
 

 

I guess we will not know until I try poising. I could in theory adjust the rate by say +50 seconds and that would give us approx +55 DU/DD, +15 PU/PR, -15 PD/PL. I tried the balance on its own by the way and couldn't really identify a heavy spot but it wouldn't spin for very long in a vertical sense. In horizontal it would spin for a long time.

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58 minutes ago, steve1811uk said:

I tried the balance on its own by the way and couldn't really identify a heavy spot but it wouldn't spin for very long in a vertical sense. In horizontal it would spin for a long time.

attempting to use the watch as a substitution for poising tool is very bad.  while casually it might seem like the right thing balance wheel resting on the poising tool has almost 0 friction as in a watch there's going to be more friction.

I'm still in favor of you doing static poising just because it's easy to do as long as you don't get carried away with your drill and turn your balance wheel and the Swiss cheese there isn't going to be much harm. But if you don't have a poising tool. Is something else we can do the only reason I did not recommend it is because I still think you're having an issue and it's not a poising issue so using this next method the fixed an issue that's not a poising issue is going to have problems

there's another way to poise a watch or verify that the watch is poised that's something called dynamic poising. This is where the watch is all back together the balance wheels in the watch you adjust the amplitude to about 180° you want it low ideally because everything gets magnified as the amplitude goes down. Then you time the watch in eight pendant or crown positions. some people only do for positions but it's much better if you would actually do eight positions. Then you write all the numbers down and we might build get a clue whether you really have a poising issue or not.

 

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5 hours ago, JohnR725 said:

attempting to use the watch as a substitution for poising tool is very bad.  while casually it might seem like the right thing balance wheel resting on the poising tool has almost 0 friction as in a watch there's going to be more friction.

 

This probably has been a major cause of my failure to poise.

Thanks for taking the time to respond and explain things.

Regards joe

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3 hours ago, Nucejoe said:

This probably has been a major cause of my failure to poise.

while static poising in the watch is not good dynamic poising is. So providing you are not trying to adjust for watch that really should be statically poise and just doing the final poise or you're really obsessed with timekeeping then you can go with dynamic poising. But I found typically with pocket watches statically poising gets me so closer is no point in doing dynamic poising.

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Well I've started on my knocked up poise tool that seems to be going quite well. I think I have identified at least two heavy spots.  I think the blades might be slightly magnetised as the balance can get pulled towards the blades, so I will address that later before I start taking any weight of the balance.

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11 hours ago, rodabod said:

I think there is some confusion here. All of the pendant positions are slower than the dial positions. A “heavy spot” corresponds with a relatively speaking “light spot” on the opposite side. None of the other pendant positions show a faster rate. 

There is a 60 - 70 degree drop in the pendant positions which in my opinion is not simply the result of a poising issue as the positional variation is not horrendous.
 

 

I see.

There already are too many holes on the rim, we might end up with a useless balance digging more holes on it, I mean there is little margin left. How about data in eight vertical positions? Increases certainty.

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If the wheel is effectively too heavy overall for the spring (it is running slow) then you could remove material. But the most simplistic way to do this would be to achieve something akin to moving meantime screws - ie. remove material from two spots, directly opposite, and perhaps preferably at the ends of the balance arms. 

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Well, I did some static poising tonight and I made some progress with that, taking out some heavy spots. Rate overall has increased with the lightened balance. However...... the amplitude in vertical positions is still dropping off the face of a cliff, down to 190 degrees (-80 SPD) from 260 degrees (2 SPD) in horizontal. One thing I have noticed is that horizontal amplitude quickly drops from 270 to 250 after full wind, within a space of about 20 seconds. Scratching my head now.

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31 minutes ago, steve1811uk said:

Scratching my head now.

outstanding progress has been made.

You'll notice in this discussion you asked the question sort of? So when you start the discussion off is I have a poising issue and that is not really a question it say I have a problem and it's the poise issue. So now that the balance wheel conceivably is more poised you found that it didn't fix the issue. You will note that I did not discourage you from fixing the poise issue because it's a good learning exercise but it probably isn't the reason you have a loss of amplitude.

in a somewhat random order of where the problem could or could not be as far as timekeeping issues go look at sure regulator pins how far apart are they? If you have dramatic amplitude changes and unless you were free sprung balance like Rolex typically has you have regulator pins a necessary evil. the problem is the farther the pins are a part the greater the effect will be with amplitude variations. This is usually the most likely thing that causes a timekeeping issue is the regulator pins and amplitude.

Now amplitude a variety of things can be going on here especially with the new balance staff. Especially one that had issues. Ideally balance pivots on the end are supposed to be barely curved and of course polished the entire pivot needs to be shiny and polished. The reason why it's not a nice round shape is you want to equalize the resistance so the end of the pivot that would have the least now has more to hopefully make it more equal when the staff is resting on its sides. So conceivably your NZ are pivots are two round but before we worry about that we need to actually figure out what the real problem is.

Then I believe in the very beginning you set a pivot was worn and if you have a worn pivot conceivably you have jewels that have issues. As hard a sapphire is they're not perfect you could have a cracked jewel or some other issue. That would cause a dramatic decrease in amplitude.

Then? Just as I thought I'm repeating something that was already suggested you way up above by nice job. So you could have pivot and or jewel issues and seeing as how you had a warning pivot originally it makes it very likely.

Other things that affect amplitude is of the hairspring isn't perfectly flat if it's touching the balance arms and it won't always touch consistently somet.mes only touch when it's in one position or something.

So now we have to go back to being a detective and figuring out what the real problem is it was very likely not poise but it still had a nice lesson and hopefully it keeps better time once we figure out what this amplitude problem is

 

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