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How A Chronometer Works Part II |
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Articles -
Watchmasters Corner
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Written by Ziggy Zumba
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Page 4 of 4
Reset to Zero
Resetting any sub-dial to the “0”
zero position requires a heart piece and reset hammer.
Here is the heart piece (so named
because it resembles a heart). When the hammer presses against it, it forces the dial to
return to the neutral or zero position. A better view of the heart piece will come later when
we do the seconds gear.
Here’s the hammer in action:
I want to point out a few area’s here, note how the cam
activation post is just sitting barely in the arm assembly:
And here is a view of the shaft without the arm, note the
small pivot is off center and that’s how it moves the arm as it rotates:
The other thing I want you to see, is this spring assembly.
See how everything is just hanging on and sitting there, and then you are expected to keep all
these pieces in place, and install this stupid little spring and expect the pieces to not move
when they are barely holding on to start with…. I hate installing this spring……….but wait it
gets better…….after your done this, a big honking bridge has to go over the whole thing, and if
you slip one millimeter, “SPRONG” the whole thing flies apart…..that’s in part 3, unless I
loose my mind by then……
Potential problems:
1. if your 12 hour sub-dial does
not stay stopped, then the most likely problem is the plastic lever has come out of this
notch.
2. if you can’t reset the 12 hour sub-dial, then most
likely these tabs are not lining up when the chronograph is OFF
Important points to remember about this
sub-dial
1 it is connected directly to the mainspring and runs all the time
2
with the chronograph OFF or Stopped, the clutch is slipping all the time and possibly
wearing out
3 with the chronograph ON, the clutch is released, therefore the drag on
the movement is reduced (the brake is off, so less resistance now) and the 12 hour wheel is
free to rotate.
Now my favorite part, and no
cheating…..
Questions
What position(s) of the chronograph are the most
likely to cause the most wear to the 12 hour wheel and clutch, and what position has
the most drag or friction on the basic movement:
Your choices are:
1. the OFF
position
2. the ON or Running position
3. the Stopped position
If you
answered 2, then you have failed and must send me all your reps (My address is Mr. PM, 24
Sussex Drive, Ottawa, Ontario, Canada).
If you answered 1 and 2, then you passed this
part and can move on to the next one, and you get to keep your reps (for now, more quizzes to
come, your not off the hook yet).
I will post Part 2A later this week, this is very time
consuming to do up, and is getting too long, so probably best to break it up and not bore
everyone to death with pictures and stuff.
Till next time….
RG
Articles 
ETA 
ETA 7750 
Watchmasters Corner 
Ziggyzumba 
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Ziggy Zumba |
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Last Updated ( Tuesday, 14 August 2007 )
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