Amplitude

[IJP]

Am getting horizontal amplitudes 275-285 and vertical 250s on recently overhauled gmt II from 2003 that ok?

[kilyung]

Full wind? Sounds normal.

[IJP]

Maybe a little less than a full wind.

[kilyung]

Still very acceptable, 270 being nominal.

[IJP]

Thanks very much!

[Rikki]

You'll always get a slight drop in amplitute in vertical positions because instead of the balance pivot riding on the point it's riding on the side of the pivot causing a bit more drag. It shoud still be slightly closer than 25 degrees away

[kilyung]

Rikki, I was told that an acceptable vertical drop could be as much as 45 degrees? Has it been your experience that the drop should be less than 10% for a vertical position?

OP: Just to clarify Rikki's point, in the horizontal position the balance rides on one of the balance's pivots. In the vertical position, the balance rides on the sides of both pivots thus increasing friction and slowing amplitude.

[Rikki]

I just finished a 18038 presidential and full wind dial down 280 full wind stem down 260 so actually less than 10% up to 45 is acceptable but usually means beginning of pivot problems and or dirty jewels. Rikki

[IJP]

When I look at the lines in my timing machine is it true it's best if the two lines are close together or better even, merged. If so, why? Thx!

[IJP]

Also, what would be the ideal amplitude for a 3185 movement from early 2000s? Thanks. When do I start worrying that watch isn't in great running shape? Is 270 dial-up acceptable but not "great" or is it more like a threshold - once the watch is in an acceptable range (270+?), it doesn't much matter what the exact amplitude is?

[kilyung]

Originally Posted by IJP

When I look at the lines in my timing machine is it true it's best if the two lines are close together or better even, merged. If so, why? Thx!

First, we need to define the asymmetrical oscillation of the balance wheel. The vibration of a balance wheel can be described by the rotating angle. If the watch has stopped, the zero position is defined by the position of the balance wheel. A “beat error” refers to the fact, that the vibration is not running in all test positions quite symmetrical around the zero position, i.e. the balance wheel is swinging in a direction further than the opposite. This asymmetry can be measured on a test device. The beat error is measured in ms. 

Normally, the beat sounds of a lever escapement come from three different pulses. The first sound occurs when the impulse pin of the roll strikes the fork of the pallets. This sound is very precise and is therefore used for the graph recording and for calculation of the rate deviation and the beat error. A second sound is created when a tooth of the escape wheel meets the pulse area of a pallet stone and the pallet fork touches the impulse pin. This sound is not used. The third and most powerful sound is created when a tooth of the escape wheel meets the locking plane of the pallet stone and the lever hits the banking-pin.

So on the timegrapher, the time between two successive watch beats (period) is measured and compared with the nominal value. If the measured time corresponds precisely to the nominal value, the new dot on the chart is set right by the previous. If the new beat is a bit too early or too late, the new dot, according to the time difference to the nominal value, is shifted up or down compared to the last dot. Make sense?

[kilyung]

Originally Posted by IJP

Also, what would be the ideal amplitude for a 3185 movement from early 2000s? Thanks. When do I start worrying that watch isn't in great running shape? Is 270 dial-up acceptable but not "great" or is it more like a threshold - once the watch is in an acceptable range (270+?), it doesn't much matter what the exact amplitude is?

270 is quite acceptable and I've seen some early 2000s clock in at 300. As Rikki pointed out, amplitude can degrade to 245 and still be serviceable but be symptomatic of issues at that point.

[IJP]

Thanks, this is outstanding information and help!

[IJP]

One more thing I can't figure out : when I first put my watch (2003 gmt) dial up on the timing machine, the amplitude starts out high (290s) then diminishes over the next few minutes until its "resting" sate (say 270+/-). I can't understand why it would take 3-5 minutes to settle in, as opposed to immediate or a few seconds. I have a cheap (hobby level) timing machine - maybe thats the problem/cause. Thanks again.

[kilyung]

Originally Posted by IJP

One more thing I can't figure out : when I first put my watch (2003 gmt) dial up on the timing machine, the amplitude starts out high (290s) then diminishes over the next few minutes until its "resting" sate (say 270+/-). I can't understand why it would take 3-5 minutes to settle in, as opposed to immediate or a few seconds. I have a cheap (hobby level) timing machine - maybe thats the problem/cause. Thanks again.

I don't think I've ever seen that. What does your graph look like? Does your timegrapher have scope display capabilities?

[IJP]

Yes. I will try to figure how to post a picture. But when I first put the watch on the amplitude is 290+, but as it continues to sample it (every 4 seconds) it slowly drops to 270+/- (same for my other watches). Is that normal?

[IJP]

Yes. I will try to figure how to post a picture. But when I first put the watch on the amplitude is 290+, but as it continues to sample it (every 4 seconds) it slowly drops to 270+/- (same for my other watches). Is that normal?

[IJP]

Yes. I will try to figure how to post a picture. But when I first put the watch on the amplitude is 290+, but as it continues to sample it (every 4 seconds) it slowly drops to 270+/- (same for my other watches). Is that normal?

[IJP]

Yes. I will try to figure how to post a picture. But when I first put the watch on the amplitude is 290+, but as it continues to sample it (every 4 seconds) it slowly drops to 270+/- (same for my other watches). Is that normal?

[IJP]

Yes. I will try to figure how to post a picture. But when I first put the watch on the amplitude is 290+, but as it continues to sample it (every 4 seconds) it slowly drops to 270+/- (same for my other watches). Is that normal?

[kilyung]

Samples every 4sec?

[IJP]

I think the chinese translated manual seems to say it measures amplitude every 4 seconds - is that weird?