Re: isochronism

I wouldn't dare argue with your vast practical experience, but I will argue
with the physics of this. It seems to me that amplitude is directly
correlated with impulse power. In basic physics energy is based on mass x
velocity. In a watch, the mass of the escape system, never changes, so
speeding it up (faster impulse) increases the amount of total power.
Spreading the power over a short or long interval doesn't change the fact
that a slower moving system has less power to begin with - of course the
faster system is in contact for a shorter period of time.

Think of hitting a ball with a baseball/ cricket bat - how far the ball
goes is directly proportional to the speed of your swing. Since the bat
always weighs the same the only way to get more power into the bat is to
swing it faster. A slow swing, even if it remains in contact with the ball
longer, will not have the same effect as a fast one.


"Frank Adam" <fajp@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:avgqj19lqnnh7uuobkk78qaoek0qmg06e0@xxxxxxxxxx
> On 29 Sep 2005 09:36:31 -0700, "djohnson" <djohnson64@xxxxxxxxx>
> wrote:
>
>>
>>Frank Adam wrote:
>>
>>> That could well be due to an old mainspring.
>>> While it is true that loss of power can cause a gain, that theory only
>>> works until the power is still sufficent to drive through the train
>>> and give the balance a resonable push.
>>
>>
>>All your causes would boil down to "not enough power to overcome
>>friction", and should show reduced amplitude, right? My limited
>>experience is that amplitude over 180 degrees will probably work OK.
>>If it's less than 180, I clean and lube it. If it's less than about 90,
>>it's probably gaining a bunch, and is about to stop. Is there an
>>amplitude where the watch will lose, but continue to run?
>>
> Well amplitude is a funny thing. To get a reasonable amplitude you
> don't need full power, not even perfectly constant power. IOW, the
> amplitude is the last thing we should look at when we're talking about
> getting a watch isochronic.
>
> I thought about it and have an idea of why it happens, but it's mere
> theory and while theories are good, i tend to go first and foremost
> with what practice and experience taught me. That is, to make sure
> that the train and spring/barrel and pallets are in 100% nick, before
> i'll start playing with anything to do with precision timing.
>
> Anyway, my theory is that the amount of power available at the escape
> wheel will determine the amount of time the escape wheel tooth will
> spend in contact with the pallet stone(or pin). A faster moving pallet
> will deliver a more abrupt and shorter duration impulse, a swift kick
> to the balance. The slower one will deliver a less powerful kick, but
> it will spend more time doing it. The end result is negligable as far
> as amplitude is concerned, as long as we're not talking about big
> differences in power, but the time spent to do each tick will
> increase, so the watch should lose time.
> of course, when power drops off to the stage where it will struggle to
> keep up to the balance, the watch will become very sick and amplitude
> will drop sharply.
>
> But that's just my theory, let's see if anyone has a better one...
>
> --
>
> Regards, Frank


.

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