Re: Question about timing machine and Stowa Chronometer



On Mon, 10 Mar 2008 23:51:12 GMT, "Bruce Markowitz"
<scosgt@xxxxxxxxxxxxxxxx> wrote:

Hi Group
I have an MTG-3000 timing machine, which generally works very well (bought
it on the auction site for around $800 or so).
It is a GREAT tool for doing minor regulation to my own watches - all my ETA
and Valjoux autos run +/- one or two seconds a day! And as the lube and wear
changes I can re-regulate.
Also, whenever I get a new addition, I can check it out on the timing
machine and tell right away if it needs service (and if it has been dropped
and has a bent balance staff!)
Now the question:
I recently obtained a Stowa Pilot with chronometer movement (with the
certificate) and it is probably around one year old.
It has the onion crown.
When I put it on the machine, crown at the pickup, it reads +12 seconds or
so,
When I put the sensor opposite the crown (some watches need to be seated
this way to get a proper reading, depends on the crown and case) it
reads -17 seconds a day. Beat error is 0.2, which is OK, although the
amplitude readings seem low.
HOWEVER, the watch actually keeps +1 second a day consistantly!
So why can't I get an accurate reading? Does this have something to do with
the case?
I find that if I give it around 10 turns of the crown, SOMETIMES crown to
the pickup it reads properly, that is almost dead zero. But most of the
time, it will read +12 or so, even just a few moments later.
The timing machine does work accurately with just about all my other
watches, this one is strange.
Any ideas from the experts?
And of course, the other question is how will I regulate it when the time
comes, if I can not get an accurate reading?


Whether the crown touches the microphone or not, usually should not
make a difference, since the mic is picking up the pallet drops.
However, some watches have a shield of sort covering the movement
under the back. Those things can reverberate the sound and mislead the
timing machine. Normally that sounds like clatter and results in snow
on the output, not a proper graph, but i suppose it may happen that it
will just give the wrong result.

Btw, i'm not familiar with that machine, but i guess it is this one :
http://www.jwwatch.com/showphoto.asp?photo=product%2F440%2F1%5F1%2Ejpg&cat=440&id=1
Link may wrap, because i'm bad and lazy. :)

When you say you hold the pickup to the watch, do you mean you don't
actually mount the watch on the microphone ?
Because the proper way to do this is to set the watch up as you see it
on the picture above, then rotate the mic head to the positions you
need. Also sometimes you need to increase or decrease the sensitivity,
otherwise the mic can pick up some unwanted sounds. Best way is to
turn it down until it picks up nothing, then increase it until you get
a solid reading.

--

Regards, Frank
.