Jump to content

Weird timegrapher results


Recommended Posts

Hello. Sorry if this question already has been answered, but I didn't know what to look for. 

I recently cleaned a certina 28-10 and it was keeping excellent time. The next morning I noticed it had lost a lot of time (about 40 seconds) and I put it on a timegrapher. The accuracy went from +4 to - 40.. I then re-regulated it and a few hours went. I then checked again and thw same problem had occurred. Only this time it had only gone from +5 to - 20. 

 

I also noticed that sometimes the amplitude drops to about 170 and the beat error goes up to 10ms for a few seconds and then returning to normal again. You can see that in the picture. This has happened several times. What could be the cause of all this?

IMG_20200526_155951.jpg

Edited by Bopmd
New headline
Link to comment
Share on other sites

Is this in a particular position? I think (and I'm still pretty new at this) it looks like the balance or hair spring are hitting/rubbing on something. For it to register as beat error, I imagine the timegrapher would have to have seen a fairly sharp noise, so I'd suspect hitting rather than rubbing. However, I think hitting would be more likely to make it run fast than slow, whereas rubbing would be more likely to slow it down. This is where it'd be nice if the timegrapher gave you the actual audio/trace rather than a beep/click. Check end play, and remove the balance cock/bridge to see if there are any tattle tale marks where it's hitting/rubbing.

Link to comment
Share on other sites

I had an experience recently where a watch was experiencing similar problems. After MUCH looking I finally found the lower hole where barrel arbor rests was oval and barrel had lots of play. I happen to have a old movement so I switched the parts to the old movement plate and problem was resolved. So, I guess my reply is to see if barrel arbor upper/lower holes are worn and causing excess play and wobble.

Regards

Link to comment
Share on other sites

On 5/26/2020 at 7:06 AM, Bopmd said:

I recently cleaned a certina 28-10 and it was keeping excellent time

We need a clear clarification of what cleaned means? In other words did you fully disassemble it did you change the Mainspring?

At 170° everything gets magnified so don't worry about the beat error it's only because the amplitude crashed and burned.

I assume the watch is currently cased up?

 

 

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&Certina_28_10

 

Link to comment
Share on other sites

On 5/26/2020 at 7:22 PM, spectre6000 said:

 

Everything seems to be fine now. The accuracy is not receding anymore and the rest seems to have stopped. Sorry for the late replies and thank you for yours :)

Link to comment
Share on other sites



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • Hello again, I meant to say the movement above was in a Chronosport Atlantis 20 ATM on eBay and wondered if you had the same movement in your watch, all the other Chronosport watches had auto-matic movements....
    • Also been looking at the same ones as Tom 0.1.- 1mm around 55 quid inc shipping. The pivot straightner i have runs from 0.07  -  0.15 in increments of 25 microns.  I guess you could use a balance staff of sizes under 0.1 to make up the remainder of the lower sizes.
    • I have always had it in my mind that hairsprings can fatigue in just the same way as mainsprings can. If a hairspring has gone through a rough process of repair then its structure will have changed ( bending any metal backwards and forwards will cause micro fractures and eventually breakage ) in those areas of heavy manipulation. Its strength and elasticity is no longer linear over its full length so no longer isochronical.  
    • This seems to be complicated case... We have many variables here and we need to exclude some of them to make some progress. We have plots that show amplitude variations, but we don't know if this variations are significant, as they can be 'amplified' or 'smoothed' by the software. So, some observation of the amplitude by eye will be of help. Then, if we really have not isochronical work, then the main reason for this would be the hairspring being not 'linear'. And not linear may be sometimes not only because 'touching', but because bad hairsping material structure. Some of the advanced watchmakers claim that repairing badly bent hairspring is useless, because this springs will never be isochronic again.  Well, my own observations are that such thing happens, but not in all the cases and it depends on the case if the result is acceptable or not. I will not suppose here that this spring has been repaired, but it has some strange behavior watching at it's work. It will be good if it is possible to test the movement with another balance or thest the balance on another movement...
    • The more common Jewel hole diameters are from about 0.07mm to 0.50mm. Those are the sizes in the Seitz jewel gauge tool.
×
×
  • Create New...