Hairspring troubles (I think?)

[Angrybear]

I recently bought a used watch on eBay as the basis for a project, I was after the ETA 6498 and the case it came with. It was completely unbranded and actually looked like someone elses old project they were getting rid of.

The watch kept pretty good time for a couple of days, so I decided it would be a good idea to strip it down and break it. All looked ok during strip down and inspection, but it was very dirty and pretty dry. After I had rebuilt and lubricated it I put it on the timing machine and initial results looked good. I rechecked after a few hours and instantly noticed it wasn't running right. Im not sure how to describe it but it just felt and sounded really weak. Amplitude was very low, and the timegrapher now thought the beat rate was 19800bph and not the 18800 it should be.

Upon inspection I noticed that the hairspring coils looked like they had clumped together. I removed the balance, demagnetised it and cleaned it again in essence of Renata. The coils had separated and I refitted the balance and started the movement. It sounded healthy gain and the timing results were good. I left it running for a number of hours and it was still fine, so I recased it in the watch. As soon as I had done this I noticed it was running really badly again. The hairspring coils once again were clumped together. I demagnetised the entire watch this time (in case another part was magnetised) and reinspected. The coils were still bunched up. I have now removed the hairspring and wheel from the cock and gently separated the coils. I have taken a photo of this stage and would really appreciate some feedback on what you guys see. I have a horrible feeling I may have damaged the hairspring during the first strip down, please let me know what you think? 

[Marc]

Obviously with only one pic from above it's not possible to comment on errors in the flat (it should be flat and parallel to the balance wheel rim when viewed side on) but the most noticeable problem is that the terminal curve appears to be a bit off. It should describe a perfect circle centered on the pivot with a radius equal to the distance between the gap between the curb pins of the regulator and the pivot hole in the balance cock. Yours looks like it is deformed inwards at the stud which will result in the coils being off center when mounted in the cock. This could just be a matter of tweaking the dog leg to correct it.

However you may find that the orientation of the stud isn't quite right either. Unless there is supposed to be a second dogleg at the stud (not the case here) the H/S should enter the stud tangentially to the same circle that forms the arc of the regulator. Looking at your pic I don't think yours will do that, although it's hard to be sure. I think that when you tighten the stud screw onto the stud it is going to cause the stud to rotate so that the screw goes into the slot in the stud, which in turn will push your coils even more off center. I could be wrong on this but it would be easier to see with the balance mounted in the cock with the pivot seated in the jewel.

[Nucejoe]

  Further to above, center circle doesn't look anything to be proud of.

  Following installstion, all geometric aspects of hairspring coil should be inpected again and if need be adjusted ,  namely it should be  ; concntric, centered, flat, level( parrallel to the cock, not fauling itself ) , so I make a habbit of checking and adjusting after installation even if its a brand new balance complete. 

Another point;  anybody might mess up a coil,  I practice sorting out a scrap coil, tens of times. 

Regs

 

 

[clockboy]

Looking at the spring there does not look like to much wrong apart from the areas I have highlighted. The blue area I have marked the spring is not following an equal distance (curve) of the next coil the red circle is where you adjust to correct the fault. The fault you seem to be encountering is the coils are sticking together. If it is not a magnetic issue then contamination is happening such as over lubrication from somewhere in the movement. It only takes the tiniest amount of oil/ grease to stick the coils together.  
 

[Angrybear]

Thank you Marc, Nucejoe and clockboy for such thoughtful, insightful and comprehensive answers. I appreciate the amount of effort that takes, especially to help out a stranger that has just joined.

The intention was to go away, spend a few hours manipulating the hairspring, and triumphantly return with photos of my now perfectly spaced coils.....

 

...well, that didn't happen!

I removed the hairspring from the wheel and spent a couple of hours trying to rectify the above areas. I actually got it to a point where I thought it might be ok. I attached the stud to the balance cock and threaded the spring between the index pins, and the collet pretty much lined up with the jewel on the balance. Excellent, lets get it fitted and try it I thought. So I removed the hairspring from the cock and fitted it to the wheel, trying to make sure I pressed it on correctly orientated with the impulse jewel. The collet went on pretty smoothly, but when I turned the wheel/hairspring assembly over and lined it up with the cock the spring was incorrectly positioned. No problem, ill just spin the collet round 90 degrees and it should be fine. 

You can probably guess what happened next. Just as I finished adjusting the collet the tweezers slipped. My beautifully adjusted hairspring is now a crumpled mess. Oh well, I won't make that mistake again!

Taking some time to think about the next course of action. After some brief research it appears that 6498-1 hairsprings are both thin on the ground and very expensive. I have a couple of Chinese clone 6497-2s in the drawer, but they run at 21600bph so I don't think their springs will work. I pretty sure I can't save the one I just ruined...

[jdm]

18 minutes ago, Angrybear said:

You can probably guess what happened next. Just as I finished adjusting the collet the tweezers slipped. My beautifully adjusted hairspring is now a crumpled mess.

Is this the first balance / hairspring you have manipulated? Chances of getting something like that right are extremely small for a beginner. There is virtually only one correct and safe way to work on balances, they are unforgiving. It may take quite a long time (not everyone is the same) to become proficient. Try to learn imitating good videos or reading books while practicing on some disposable piece, and of virtually no value.

[Angrybear]

Thanks JDM, I know you are right. This is my first attempt. What is frustrating is that it was all going pretty well! I have watched countless videos, including the ones from Mark. The chronoglide videos are particularly good. I was actually happy with the manipulation and was excited to see if it worked. I buggered it up during fitment! I should have known better and thought about it more carefully.

I just wanted to repeat my thank yous to everyone that has posted. The advice has been golden and I'm really quite moved by the amount of great advice you all provided. I just hope I can return the favour one day.

I have ordered a new balance complete from cousins, and will let you all know how fitment goes. Of course any extra advice is very very welcome.

[mikepilk]

18 hours ago, Angrybear said:

Just as I finished adjusting the collet the tweezers slipped. My beautifully adjusted hairspring is now a crumpled mess. Oh well, I won't make that mistake again!

Yes you will, it happens to all of us. I thought I was getting reasonably proficient at tweaking hairsprings - but I still have the odd accident. Still feel bad on wrecking the hairspring on an Universal Cal 267 a couple of years ago when I released one of the tweezers too early - still looking for a replacement 

Also made spaghetti out of an Omega Cal 455 hairspring - but as they are only 3 mm in diameter, I think even @Nucejoe would find those challenging !

If I'm working on a watch where there's little/no chance of finding replacement hairsprings, I'm not so critical in getting the hairspring perfect - especially for beat error.

 

[Angrybear]

The new balance complete arrived and I’ve noticed that the stud fitment is different from the old hairspring. The photo shows the new balance complete next to the old balance cock. Is there a way round this? Could I order a new stud holder and fit this to the old balance cock? Any advice greatly appreciated. 

[Angrybear]

I do have a spare balance from a 6497 that appears to have the correct stud holder. Unfortunately the 6497 cock doesn’t fit the 6498 movement. Could I possibly sway the stud holders over? Has anyone tried this?