Strange Oscillation in Balance

[Lawren5]

There is a strange oscillation in the balance wheel which causes it to slow down and then speed up. The oscillation appears to be constant in that it occurs in intervals of about five second as seen in the video.

The readings from my iphone "timegrapher" show amplitude and rate to be quite variable.
BPH: 18000
Beat Error: 12.5 ms
Amplitude: 190 to 290 deg
Rate: -180 to +180 s/d

The watch is a vintage Citizen alarm in which I ended up replacing both the exit and entry jewels manually. I don't have the tools for this process nor do I know the specs to which they should be set.
Is it possible that improper setting of the pallet jewels could cause this oscillation? Or could is be a combination of pallet jewels and excessive beat error? Or something else?

[clockboy]

I would check the escape wheel. Check it's pivots for damage and if they are straight, check all of the teeth for damage.  Also check its jewels. The beat is also a long way out which needs adjusting.,

[oldhippy]

Check these parts thoroughly balance complete this includes impulse pin, lose fitting of hairspring collet, pallets including pallet stones and the fork, escape wheel pivots and teeth and jewel holes. Make sure the hairspring is level and not rubbing on anything.

[nickelsilver]

Almost certainly your escapement is maladjusted. In an 18000bph watch the escape wheel makes one revolution per second, and is never perfectly concentric, thus the interval of amplitude drop.

[praezis]

1 hour ago, nickelsilver said:

Almost certainly your escapement is maladjusted. In an 18000bph watch the escape wheel makes one revolution per second, and is never perfectly concentric, thus the interval of amplitude drop.

Ooh, so fast? In my 18000 movements it takes 6 s for a revolution...

I would
1) test the security of rest and drop of each escape wheel tooth in one full revolution

2) not at all trust values presented by an iphone app...

Frank

[nickelsilver]

Ha of course you're right. Still corresponds to the 'about 5s' the op is seeing.

[JohnR725]

Did you actually replace the stones with new stones or just put the old stones back in for some unknown reason?

It's an easy thing to fix right now is the beat. To give you an idea of how bad 12.5 is most timing machines think 9.9 is very bad that's the maximum they'll go to. So if you put your stud the match the image I've attached you should be reasonably close then you can just manually move it one way or the other and get down closer.

Then for the escapement their entire books that cover how to adjust it in mean time a video. Remove the balance wheel move the fork back and forth for one complete revolution Of the escape wheel. Verify that the lock on both sides is the same and if it's not you're going to have to adjust that. Then just because the watch runs doesn't mean they're in the right place either.

https://www.youtube.com/watch?v=ejgyCZELQ64

[Lawren5]

Further examination revealed the escape wheel to have a bent pivot as shown in the photo.

From what I've read in another WRT post, attempts at bending pivots back into position presents a high risk of breakage.

[anilv]

what have you got to lose by trying to bend it straight?

Anyway if you want to try you can heat it up with a torch until it glows red and then quench it. It should now survive bending.

Next you have to harden it again.. this is done by heating it until it starts to turn black (or blue)  and letting it cool normally, it should not reach the point where it turns red/orange.

Before you rush out and try this I suggest you wait until others here have chipped in as there are many ways to temper steel and mine may not be the best. In fact I have a few failures where the supposedly un-tempered steel has broken!

Good luck

Anilv

Edited July 23, 2018 by anilv

[JohnR725]

3 hours ago, anilv said:

Anyway if you want to try you can heat it up with a torch until it glows red and then quench it. It should now survive bending.

Interesting process for annealing?  I was under the impression to soften steel you would slowly heat up to the proper temperature and allow it to cool very slowly. Then please remember to record a video I can't wait torch versus tiny escape wheel.

Then they do makes special tweezers for this.

 

http://boley.de/en/shop/1572.watchmaker-special/513303.pivot-straightening-tweezers

[nickelsilver]

That pivot is very straightenable. Ideally you'd want to chuck it in a lathe and use either the above tweezers or nickel/brass (my preference) which have been warmed to the point of just being uncomfortable to handle. Then turn the part slowly by hand while making small adjustments.

Basic heat treatment of steel review: To harden, heat to red and quench immediately. To temper, clean the piece, and heat slowly in brass shavings over an alcohol lamp and observe the color change. For a cutting tool stop at straw, for springs or arbors/pinions go to dark blue. To anneal, as John said bring to red, and allow to cool as slowly as possible. Best results if heated in something that will retain heat and slow the cooling.