Seiko 7005n loosing lots of time + problem with hairspring terminal curve

[Daimon]

Hi,

Patient - Seiko 7005n after motorcycle crash, overall in pretty good condition internally but not running.

After closer inspection it turned out roller jewel was missing.

After searching it turned out new balance complete is cheaper than roller table - so to make work faster and avoid posing problems, ordered part 0310020.

After installing it turned out that terminal curve is way off, see 

My own conclusions (pretty obvious):

 - overall spring shape looks okay except for terminal curve

 - terminal curve looks ok near regulator pins (at position when taking a photo) but gets worse and worse closer to the stud

 

Timegrapher results show that watch is loosing lots of time

 

So I guess there are 2 questions:

 - where exactly should I slightly bend hairspring to fix terminal curve shape? Near stud?

 - does this kind of terminal curve shape could cause that this timing problems or do I need to look into more places?

[JohnR725]

the best way to do this would be to remove the balance wheel from the bridge. Then you Both balance wheels side-by-side and figure out where the bands need to be so that they both match each other.

Then the next probably have is they look nice outside of the watch but how do they look in the watch? Often times people centering hairsprings out of the watch do not realize the hairspring has to be flat and it can't be touching the balance itself or the bridge. This is a maximum loss of amplitude when the hairspring is not flat and it's rubbing on things. Only seen when the balance wheel and bridge or in the watch.

then you do have the right part number but did it come in the original brand-new package? I'm wondering because the shape of the balance wheels a little bit different and the material it's made up of is definitely different

 

[Daimon]

4 minutes ago, JohnR725 said:

then you do have the right part number but did it come in the original brand-new package? I'm wondering because the shape of the balance wheels a little bit different and the material it's made up of is definitely different

Int came in packaging which looks proper but no way for me to really verify that

[AndyGSi]

Terminal curve looks OK.

Have you tried rotating the stud?

[Daimon]

6 minutes ago, AndyGSi said:

Have you tried rotating the stud?

Unfortunately that's not possible. Stud has v-shaped cut so once screw is tightened it self positions itself to that cut

[caseback]

If and when the balance is mounted on the main plate and everything is flat and parallel and the only issue is a deformed terminal curve, you could adjust that in situ.. But the hairspring seems to be rubbing against something.

So the tried, tested and thorough method is to take the balance wheel and hairspring off the cock and check if the hairspring is flat and parallel to the wheel. After checking that, remove de hairspring from the balance wheel, correct any obvious bends (and out of flat issues), and mount it on the balance cock so you can check if the hairspring stays properly centered while going through the terminal curve and adjust if needed.

[nevenbekriev]

See, the truth is that it is easy to shape the terminal curve as needed, bu it will not help to make watch go faster. You best option now is to use the roller table from the new balance and put it on the old one.

There is small possibility that I am wrong, so you better try first to shape the curve.

The end 'Z' that ends with the stud mus be opened as shown with green. The sprint will get out of center. Then the angle pointed with red mus be opened a little as to the spring to get centered again

Edited January 31 by nevenbekriev

[Daimon]

As I lost trust to this new balance, decided to take a different route.

Removed roller jewel from new roller, made liquid shellac, installed new jewel into old roller with liquid shellac, heated by touching soldering iron to other side of roller.

Works just fine, no rate or regulation problems.