Murray-hermle.pdf

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The Hermle Floating Balance – Adjusting the Beat & Increasing the Speed
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The balance wheel is contained within the bracket. This bracket is
sometimes referred to as the floating balance unit. There are no balance
staff pivots. Instead, the balance staff is a hollow tube. A taut steel wire
runs through the tube. The hairspring is a double helical or cylindrical
spring. One end is attached to a stud at the top of the bracket. The other
end is colleted and attached normally at a point above the balance staff.
The length of the spring is adjusted to make the balance wheel float
suspended above the bottom of the bracket. This suspension of the wheel
eliminates a great deal of friction as well as providing for shock-proofing. To
run properly, the balance wheel must be kept close to a horizontal position.
This self-contained balance unit needs no lubricating. It can be
cleaned by rinsing in a good quality solvent (99% isopropryl alcohol or one
dip hairspring cleaner) and blown dry. The thin wire is fragile, always handle
the unit with care.
Adjustments
Normally all adjustments are made at the factory. Do not make any
alterations unless malfunctioning clearly indicates a speclfic problem.
1.
Banking pins are formed from the bottom of the steel bracket. These
are to be open only enough to allow proper drop at entrance and exit pins.
2.
These pins should “rest” about ¾ of the way down the locking surface
of the escape wheel. For practally sake anywhere from �½ the way down to
almost the bottom of the locking surface will suffice.
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3.
The roller jewel consists of two polished pins. These must not rub the
side of the fork excessively. Nor can they have too much shake in the fork
slot.
4.
The head of the fork has been tipped at right angles to the fork stem.
The right side or horn of the fork is elongated to form a guard pin. This pin
works in conjunction with the "C" shaped safety roller. Interaction of the
vertical guard pin and the C roller prevents the escapement from rebanking.
When the balance wheel is in a counterclockwise swing, the pin rides just
clear of the outside of the C safety roller. A clockwise swing brings the
guard pin inside the C where it rides just clear again. If sluggish balance
wheel action is present, check to see that the guard pin is not dragging
inside or outside the C roller. During this check, the fork is against the
banking pin. Diagram (3).
5.
Regulating for fast and slow consists of sliding the two-small weights
attached to the center of the balance wheel. Inwards for fast and outwards
for slow. Hold the wheel and push the small adjustment "finger" (any one of
the three will work, see Diagram 2). Moving the finger toward your right will
be faster and visa versa. Moving the finger one dot represents a change of
10 seconds per day. Occasionally a balance unit will continue to run slow
at maximum fast adjustment. Diagram (2) shows to adjust the balance to
run faster if you have maxed out the adjustment finger. Small dots on the
wheel are easily punched out and be sure to properly secure the balance on
a hole stake or "holed" anvil for support before you remove any of these
dots.
Punch out dots only in pairs, one on each side of the balance wheel,
exactly opposite each other. Dots (weights) are always removed equally
from each side of the balance wheel.
It is critical that all other adjustments and set-ups must be correct
before you start removing or adding weight to adjust the speed and this
includes making sure that the movement has been properly serviced.
6.
The cylindrical hairspring used in this escapement serves a practical
purpose. Note that the spring reverses spiral direction at its halfway point.
A single spiral spring would cause the balance wheel to move up and down
as the spring coiled and uncoiled. The opposing spirals keep the wheel
moving in the same plane.
As with the flat hairspring, the balance is put into beat by turning the
hairspring collet, in this case the finger. Diagram (1) shows the small finger
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attached to the upper collet at the top of the bracket. This finger is moved
clockwise of counterclockwise as required to bring the roller jewel into
alignment with the pallet arbor.
Repairing a broken balance wheel wire is fairly simple. Do not distort
or otherwise danmage the hairspring when handling. Select a wire about .
25mm in diameter. Crimp it in the wire slot at the bottom of the bracket.
Thread it through the balance tube, pull taut and crimp at the bracket top.
Adjust the tension by gently bending up the top of the bracket overhang.
Check to see that the whole unit truly floats on the spring. Neither the top
nor the bottom of the balance tube should touch the bracket.
You should have 180 degrees rotation each direction.
One of the "tricks" I perform is to place a beat amplifier near the
balance and then spin it very wide and fast.
This way you will hear if anything is rubbing. Usually the fork’s position
has been incorrectly adjusted after it leaves the factory. By spinning the
balance wide you should only hear the ticking of the pallet pins as they
contact the escape wheel. Any other noise will indicate that something is
amiss and that most always is the fork position.
As stated earlier, make sure that the balance tube is truly “floating”
and not rubbing on the bottom of the bracket. The length of the spring is
adjusted to make the balance wheel float suspended above the bottom of
the bracket.
Copyright 2005 - 2013 Mike’s Clock Clinic and Michael P. Murray
1600 Maryland Avenue
Myrtle Point, OR 97458-1508
Phone: 541-559-1090
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