Unexpected irregular Time Gains

[nlapietr]

Hello all,

I have been playing with some old cheap watches.  A 1970s Sheffield Jump Hour watch has caught my fancy.  It is a BFG 582 digital movement.  I took it down, cleaned it, etc. and have it running.  However, it will run very well for hours (within 30 - 60 seconds a day based on position, which I think is good for a one jewel 50ish year old movement) but then will suddenly gain 5 - 10  minutes in a short span of time, then seems to go back to running ok (within 30 seconds a day on the timegrapher).   Any ideas?  I have attached a video of it running but am not sure that will help.

 

Edited August 24, 2021 by nlapietr
couldn't seem to get video working, uploaded image

[oldhippy]

Have you demagnetized the hairspring? You need to do that first. Make sure the hairspring is clean. I always advice when working on a watch movement to make sure the tools you are going to use are demagnetized and to do the same with the watch movement before working on it. It can save a lot of trouble. Also make sure the hairspring is free and not rubbing it must also be free between the regulator no matter where the regulator is on the hairspring. Looking at the photo the hairspring looks one sided to the left. An easy test to see if it's magnetized remove the balance from the cock and with your tweezers or a clean oiler touch the hairspring and see if any part of the hairspring when touching stick together if so it could be magnetized, dirt or oil.   

[nlapietr]

Thank you.  I have tried demagnetizing it but will try again.  I will also see if it is free between the regulator...  Hopefully I can find the issue.  I had it on the timegrapher for the day.  When I left it showed a consistent loss of about 30 seconds a day, when I cam home it was showing a loss of between 15 and 30 seconds, yet it gained about 5 minutes during my work day.   Probably a dumb question but are the timegrapher's accurate with pin-lever movements? I don't see why it wouldn't be yet it shows a loss of time on the timegrapher but a gain on the watch.  I will continue to try and figure it out.  Thanks again.

[oldhippy]

I'm not sure about these modern timegrapher's and pinlevers. Are the pallet pivots jeweled? have you oiled the pallet pivots if so what oil did you use and what about the escape wheel.  

[jdm]

On 8/24/2021 at 2:02 AM, nlapietr said:

I have attached a video of it running but am not sure that will help.

That won't work, please see:

 

[nlapietr]

17 hours ago, oldhippy said:

I'm not sure about these modern timegrapher's and pinlevers. Are the pallet pivots jeweled? have you oiled the pallet pivots if so what oil did you use and what about the escape wheel.  

There is only one jewel in this movement, on the balance pivot....  I did oil the pivots, pins on the lever and escape wheel with 9010.  I wonder if I used too much (probably the case).  I was trying to track the time gain today.  From about 0700 - 1100 it ran very well.  Between 11 and 12 it picked up 7 minutes.  Between 12 and 6 or 7 it ran well then picked up another four minutes between 6 - 8 sometime.  I am wondering if somehow the escape lever gets stuck in a position that allows free movement of the escape wheel and gear train, then gets nudged back into operation again.  that is about the only thing I can think of due to the irregularity of the issue.  If I had a bent pin or wheel, or was missing teeth the issue would show up every hour (as it is a jump hour watch, the hour wheel is not driven by the gear train but moves due to a "pin" on the  minute wheel).  I will probably tear it down again, clean it, try not to over oil it, and see if that helps.

[nlapietr]

18 minutes ago, nlapietr said:

 (as it is a jump hour watch, the hour wheel is not driven by the gear train but moves due to a "pin" on the  minute wheel). 

Rereading the quoted portion I see it really doesn't have any bearing or make much sense.... Sorry.

[oldhippy]

With pin pallets it is best to oil the escape wheel teeth (every other) then to oil the pallet pins, the action will distribute the oil.  

[nlapietr]

18 hours ago, oldhippy said:

With pin pallets it is best to oil the escape wheel teeth (every other) then to oil the pallet pins, the action will distribute the oil.  

Did you mean to oil the escape wheel teeth instead of the pallet pins, or along with the pallet pins.  Would you also oil the pallet pivots?

Thanks for the advice.

N

[HectorLooi]

Did you notice any pattern to the irregular time keeping? Like whether it occurs at a certain time of the day, or a certain minute of the hour, or when the watch is in a particular position?

Also, was the movement cased up or out on the bench when it acts up?

I have a jump hour watch that runs fine on the bench but when it is cased up, it starts it nonsense. I tracked the fault down to a warped hour disc and crystal. (If you can call the front plastic plate a crystal.)

[oldhippy]

6 hours ago, nlapietr said:

Did you mean to oil the escape wheel teeth instead of the pallet pins, or along with the pallet pins.  Would you also oil the pallet pivots?

Thanks for the advice.

N

Just the escape wheel teeth. Not the pallet pivots. 

[nlapietr]

On 8/26/2021 at 9:30 PM, HectorLooi said:

Did you notice any pattern to the irregular time keeping? Like whether it occurs at a certain time of the day, or a certain minute of the hour, or when the watch is in a particular position?

Also, was the movement cased up or out on the bench when it acts up?

I have a jump hour watch that runs fine on the bench but when it is cased up, it starts it nonsense. I tracked the fault down to a warped hour disc and crystal. (If you can call the front plastic plate a crystal.)

I have not discovered a pattern yet but have  not been able to just look at it every hour.  It is cased and seems to happen in multiple positions, as it has happened when I was wearing it, and when it was lying face up on a flat surface)  I will check the date wheel.  thanks.

[Nucejoe]

What does it take to restart? 

 Just shaking the watch or advancing the hands or winding....

The answer is yes to your question, a bent pin pallet can get stuck in lock position. 

[JohnC]

Depending on your amplitude it may be knocking the bankings, which will cause an alarming gain. I had this recently. Did you replace the mainspring? Try running it horizontal vs. vertical for several hours at a stretch. Does it gain more in one position? If it is knocking it is most likely to do this while horizontal.

Edited September 20, 2021 by JohnC

[nlapietr]

On 9/20/2021 at 8:25 AM, JohnC said:

Depending on your amplitude it may be knocking the bankings, which will cause an alarming gain. I had this recently. Did you replace the mainspring? Try running it horizontal vs. vertical for several hours at a stretch. Does it gain more in one position? If it is knocking it is most likely to do this while horizontal.

Good day.  I have not yet replaced the main spring but did purchase a new one from Cousins which I hope to install soon.  

[nlapietr]

On 8/28/2021 at 6:59 AM, Nucejoe said:

What does it take to restart? 

 Just shaking the watch or advancing the hands or winding....

The answer is yes to your question, a bent pin pallet can get stuck in lock position. 

The watch starts easily enough.  I believe it just requires a wind but I put it down a couple of weeks ago awaiting a new main spring and haven't played with it since.  

[nlapietr]

On 8/28/2021 at 5:22 AM, nlapietr said:

I have not discovered a pattern yet but have  not been able to just look at it every hour.  It is cased and seems to happen in multiple positions, as it has happened when I was wearing it, and when it was lying face up on a flat surface)  I will check the date wheel.  thanks.

After I posted this response I did do an hourly check for about 12 hours.  It seemed to gain time during the 10:00 hour then again in the 7:00 hour (I think, it was several weeks ago).  All other times it kept great time....   I am going to replace the  main spring and see if that helps (If I don't screw it up that is....)

[Nucejoe]

 Can you eliminate the jump mech on this caliber?    To see if the base movement runs steady.   I am sure that was your own first instinct, but you think a strong mainspring would make it over power any extra load that jump mech adds. 

 

[nlapietr]

All,

Thanks for the help.  I apologize for taking so long to close the loop.  It turns out that there were several areas on the barrel with broken teeth.  I replaced the barrel and mainspring and the watch is running quite well, or as well as can be expected for a 1970's one jewel movement....  

 

v/r