Good Sunday evening, everyone

[ITProDad]

I just finished servicing an 1894 Illinois 18s pocket watch. It was filthy. Came out great except for two things. It’s running 300+ seconds fast at the slowest setting. No problem, I can add timing washers. However my timegrapher is showing an amplitude of 152 degrees. My slow-mo video shows a healthy 300+ degrees rotation. Any ideas why the timegrapher would show such a large difference from the visual check?

 

The performance is very similar in dial up & down and crown up positions. I’m stumped. The timegrapher is new and has appeared accurate on other watches.

 

Regards and thank you!!

 

 

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[JohnR725]

It would help if we could see a picture of the timing machine results. Then preferably two positions would be nice at a minimum. One of the dial positions and crown up because it's a pocket watch.  

Then a picture of the balance wheel would be nice preferably when it's not running so we can see what it looks like.

[WatchMaker]

This is quite an informative document in general if you have a timegrapher: https://www.witschi.com/assets/files/sheets/Witschi Training Course.pdf

Given that the amplitude is calculated by the machine as "the time between the first pulse and the third pulse of the beat noise" could there be something that is causing an unexpected noise in between that is causing the timegrapher to throw up its wrong calculation? It's perhaps notable that the machine's calculation and your observation are a factor of two out (152 vs 300+).

[jdrichard]

Download another computer timer like Tickoprint or WildSpectra and try those. Use the mic from a earbud set and it works fine.


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[ITProDad]

I’ll try your suggestions when I get back to the homestead. Away on business for a few days.

Thanks team!


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[Marc]

Just a suggestion to make sure that you are comparing apples with apples....

The amplitude reported by the Timgrapher is the rotation angle between the resting position of the balance when there is no power on the mainspring (with the impulse jewel sitting between the horns of the pallet fork) and either one of the extremes of rotation (the point at which it reverses direction). The total angle of rotation (extreme clockwise point, through the pallet fork, and then out to extreme anticlockwise point) is double the amplitude.

I mention this just in case you are looking at the slow mo video and comparing the total angle of rotation with the Timegrapher results, which would result in discrepancy by a factor of 2.

[Hamish]

Hi there...

Just a couple of thoughts for you. Check you have not accidently placed any oil on the balance spring, check its not magnetised and check (you said it was filthy) there is not some residue or gunk after cleaning that is causing the spring coils to stick...any of these things will cause that massive +300/day issue. If you can look at the action under magnification, you should be able to pick up such an abnormality.

Cheers

[ITProDad]

Just a suggestion to make sure that you are comparing apples with apples....
The amplitude reported by the Timgrapher is the rotation angle between the resting position of the balance when there is no power on the mainspring (with the impulse jewel sitting between the horns of the pallet fork) and either one of the extremes of rotation (the point at which it reverses direction). The total angle of rotation (extreme clockwise point, through the pallet fork, and then out to extreme anticlockwise point) is double the amplitude.
I mention this just in case you are looking at the slow mo video and comparing the total angle of rotation with the Timegrapher results, which would result in discrepancy by a factor of 2.

I did not know that. However, if that is the case, why do my other watches, and those I’ve seen in videos here and on marks you tube, show a good amplitude of around 240-260 degrees?


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[jdm]

2 hours ago, ITProDad said:

I did not know that. However, if that is the case, why do my other watches, and those I’ve seen in videos here and on marks you tube, show a good amplitude of around 240-260 degrees?

 

Because they are OK in balance pivot, escapement, and mainspring, while your P/W it is not. We no way to know why ,you can read many threads about "reduced amplitude", hope you can find out.

[Marc]

4 hours ago, ITProDad said:

I did not know that. However, if that is the case, why do my other watches, and those I’ve seen in videos here and on marks you tube, show a good amplitude of around 240-260 degrees?

As JDM alludes to in his response, a movement in good order from the mainspring through to the escapement should reasonably be expected to have an amplitude of between about 270 and 300 degrees unless designed otherwise, the highest that I've seen has been about 320 but this is not common (talking here about Swiss lever type escapements, not sure how this might vary with English lever or cylinder escapements). This means that the total angle of rotation between the two extremes of swing will be in the order of 540 to 600 degrees. Theoretically it is possible for the amplitude to be as high as perhaps 355 degrees before the impulse pin crashes into the outside of the pallet fork, however this is undesirable as amplitude can be affected by  movement of the watch during use; a watch with an amplitude of 355 on the timing machine could well find that a quick twist of the wrist has the balance crashing against the wrong side of the pallet fork with potential for damage.

If your Timegrapher is showing an amplitude of 152 degrees (assuming that you have the correct lift angle set for the movement under test) then that would indicate a problem with the movement. It might also explain why the rate is so high as at very low amplitudes the rate can increase considerably.

To improve things you are going to have to go back in and do some trouble shooting.

[ITProDad]

Thank you Marc. I had not considered the relationship between a low (and fast) amplitude increasing the beat rate. Makes perfect sense! I’ve simply not run into that occurrence. I will take a look at the amplitude more closely before I add timing weights or washers. The hairspring looks to have been re-pinned as it has near a centimeter of “extra” length beyond the stud. Perhaps I’ll consider re-pinning the stud and lengthening the hairspring. Of course I’ll need to adjust the collet for beat error, but it might be the most appropriate fix.

I genuinely appreciate everyone’s input! Thank you.


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[ITProDad]

@Marc and JDM!
I was misinterpreting what the amplitude means. I was looking at the rotation of the balance wheel with the tic and too extremes. Not per beat.

Thank you for the welcome lesson in understanding one more facet of my love of mechanical watches. Sincere thanks!!


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[JohnR725]

On 9/22/2019 at 4:46 PM, ITProDad said:

I just finished servicing an 1894 Illinois 18s pocket watch. It was filthy. Came out great except for two things. It’s running 300+ seconds fast at the slowest setting. No problem, I can add timing washers. However my timegrapher is showing an amplitude of 152 degrees. My slow-mo video shows a healthy 300+ degrees rotation. Any ideas why the timegrapher would show such a large difference from the visual check?

I notice quoting your original question that you have a timegrapher which one? Then can we have pictures really helpful for making diagnostics?

Then in comparison with a "1894 Illinois 18s pocket watch " Versus a modern wristwatch you're going to notice differences. Like for instance the lift angle it's probably not 52° that's going to change or amplitude on the Timing machine a little bit. Plus your Watch is 125 years old a lot of people of touched it between when it left the factory and now a lot of very creative people lots of strange things have occurred. It also be nice to have a picture of the balance wheel looking straight down there's things we need to look at their in addition to the timing machine results.