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Full text of "A practical course in horology"

PRACTICAL COURSE 



HOROLOGY 



From the collection of the 



^ m 



Prelinger 
^ Jjibrary 

D t P 



San Francisco, California 
2008 



A PRACTICAL COURSE IN HOROLOGY 



A 



PRACTICAL COURSE 

IN 
HOROLOGY 



By HAROLD C KELLY 

Head, Department of Horology 

Southwestern Institute of Technology 

Weatherford, Oklahoma 




THE MANUAL ARTS PRESS 

PEORIA, ILLINOIS 



Copyright, 1944 

THE MANUAL ARTS PRESS 



No part of this book may be reproduced in any 
form without permission of the copyright owner 

34KS5 



PRINTED IN THE UNITED STATES OF AMERICA 



CONTENTS 



"TIME'' Poem, by Laurens L, Simpson . . 7 

Preface 9 

PART I: GENERAL PRINCIPLES 

Chapter 

ONE. Wheel Work 13 

TWO. Gearing 32 

THREE. The Lever Escapement 39 

FOUR. The Controlling Mechanism ... 52 

PART II: PRACTICAL REPAIRING 

ONE. Train Problems 62 

TWO. Jeweling 6^ 

THREE. Making a Balance Staff 72> 

FOUR. Pivoting 85 

FIVE. Fitting Balance Springs 88 

SIX. Escapement Adjusting 100 

SEVEN. Cleaning and Oiling 124 

5 



PART III: ADJUSTING 

ONE. Preliminary Notes on Adjusting . . 128 

TWO. Position Adjusting 140 

THREE. Adjustment to Isochronism . . . .150 

FOUR. Adjustment to Temperature. . . .156 

FIVE. Practical Work of Adjusting . . . 159 

Glossary of Terms 173 

Bibliography 182 

Index 185 



6 



TIME 

BY Laurens L. Simpson 
(written to accompany the gift of a watch) 

• 

/ am time. 

I come to give thee life 
Twenty-four hours of every day, 
All this to every man. 

I tick tick. 

I sound in peace, and strife, 
In sleep, in work and play. 
Forever, on and on. 

I never change 
To good and had alike. 
The rich, the brave, the free 
All use me as they may. 

I am gold 

To those who will; to others 
Lead, who do not see 
The benefit of industry. 

I am power. 

Weak to strong, coward to brave, 

Man grows as I move on, 

Or not, as will he may. 

(continued next page) 

7 



I am fame 

To those whose light is bright, 
Who shine with all their might, 
Pure, through day and night. 

I am happiness 
To those who serve and give, 
Who help the weak, mxike known 
The unknown, and live. 

Now or never 
Equal chance I give to all, 
My days to use or lose. 
Here once then gone forever. 



8 



PREFACE 

The art of horology unquestionably ranks among the 
most wonderful of the mechanical arts. One can only marvel 
at the diminutive size of the modern wrist watch and the 
accuracy of the machines by which the duplicate parts are 
made. 

Production and improved manufacturing methods have 
also changed the repairman's approach to horology. Dup- 
licate parts are available, so the horologist is seldom called 
upon to make a part. However, since the sizes of watches 
have been reduced, new tools and improved methods are 
essential to good workmanship. One must develop a greater 
skill in fitting staffs to small, uncut balance wheels, in adjust- 
ing small escapements, and in handling the new, alloyed 
balance springs. 

The purpose of this book is to present the fundamentals 
of horology, both in theory and practice. Part 1 deals with 
wheel work and gearing, which involve the work of calculat- 
ing the number of teeth of missing wheels and pinions and 
in determining their proper diameters. Principles of escape- 
ment design and an analysis of the balance and spring are 
given considerable space. Part 2 treats repair methods, in 
which the making of a balance staff and the adjustment of 
the escapement are given more than the usual space allotted 
to these subjects. Part 3 is concerned with the adjust- 
ments to position, isochronism, and temperature, factors that 



10 A PRACTICAL COURSE IN HOROLOGY 

may be called the finishing touches of the horological pro- 
fession. 

The author is indebted to T. J. Wilkinson and C. E. 
DeLong for the reading of parts of the manuscript and for 
helpful suggestions. The chapter on wheel work is based 
on a system by Jules Grossman, late director of the horolog- 
ical school of Locle. 

It is hoped that this work will contribute some small part 
toward the development of a generation of capable and well 
equipped horologists. 

HAROLD C. KELLY 



PART 1 



GENERAL PRINCIPLES 



Parti 

CHAPTER ONE 



Wheel Work 

Terminology 

Wheel work is the basis for the construction of all in- 
struments for the registering of time. Even the clepsydra, 
one of the earliest forms of a clock, which operated by the 
dripping of water, involved the use of wheels. The wheels of 
these early clocks as well as those of the first pendulum clocks 
were filed out by hand and although the workmanship on some 
of the later creations was quite skillfully executed, they were, 
of course, very crude as compared with the machine-made 
wheels of modern clocks and watches. Since wheels are 
fundamental to the construction of watches, we have decided 
that this opening chapter shall be given over to the considera- 
tion of wheels as they apply to the science of horology. Be- 
low are listed several definitions relative to the subject: 

Wheel: any circular piece of metal on the periphery of 
which teeth may be cut of various forms and numbers. 

Pinion: the smaller wheel with teeth called leaves, work- 
ing in connection with a larger wheel. 

Train: a combination of two or more wheels and pinions, 
geared together and transmitting power from one part of a 
mechanism to another. 

13 



14 A PRACTICAL COURSE IN HOROLOGY 

Barrel: a circular box of metal for the reception of the 
main spring. 

Balance: the vibratory wheel, which, in connection with 
the balance spring, controls the movement of the hands. 

Balance spring: a fine, coiled wire, one end of which is 
attached by a collet to the balance staff and the other end to 
some stationary part of the watch through the medium of a 
piece called a stud. 

Beat: one vibration of the balance and balance spring 
resulting from an impulse received by means of an escape- 
ment. 

Escapement: includes those parts of a watch which 
change the circular force of the escape wheel into the vibra- 
tory motion of the balance. 

Pallets: that part of an escapement which receives im- 
pulse from the escape wheel and by means of a lever delivers 
impulse to the balance. This term includes the pallet arms 
and jewels. 

Receiving pallet: that pallet stone over which a tooth 
of the escape wheel slides in order to enter between the 
pallet stones. 

Discharging pallet: that pallet stone over which a tooth of 
the escape wheel slides in order to leave from between the 
pallets. 

Lock: the overlapping contact of an escape wheel tooth 
on a pallet stone's locking face. 

Watch Trains 
Since the motive force stored In the main spring of a 
watch does not act directly on the balance, it is by necessity 



WHEEL WORK 15 

transmitted by a system of toothed wheels and pinions. This 
system of wheels and pinions, commonly called a train, is a 
scientific, mathematical assemblage of mobiles, and anyone 
who becomes familiar with the principles involved derives 
much satisfaction from such knowledge. 

In watches we have two trains, the main train and the 
dial train. The main train changes a slow motion into a 
fast one with the particular purpose of causing the wheel 
that carries the minute hand to make one turn in the same 
time that the escapement makes a required number of beats. 

The dial train, on the other hand, changes a fast motion 
Into a slow one for the purpose of governing the distance the 
hour hand travels to one turn of the minute hand. 

The Main Train 

Calculating the number of turns of a pinion. In order 

to obtain the number of turns of a pinion into which a wheel 

is geared, we divide the num- Q 

ber of teeth in the wheel by the 

number of leaves in the pinion. 

Suppose, for example, a wheel 

of 72 teeth gears into a pinion 

of 12 leaves. Designating the 

wheel as B and the pinion into 

which the wheel gears as c, 

Figure 1, the formula for the 

problem reads as follows : 

B 

— = number of turns of the pinion. Figure 1 




16 



A PRACTICAL COURSE IN HOROLOGY 



B 

Substituting — by their numerical values we have : 
c 

72 

— = 6 turns of the pinion to one of the wheel. 
12 



Calculating the number of turns of a complete train. 
Most watch trains contain five wheels, as shown in Figure 2. 
These include the main-spring barrel and the escape wheel, 
and all five mobiles are usually named as follows : 

B = barrel or first wheel 
C = center or second wheel 
T = third wheel 
F = fourth wheel 
E = escape wheel 

The pinions are as follows : 

c = center or second pinion 
t = third pinion 
f = fourth pinion 
e = escape pinion 




Figure 2. Main train. 



WHEEL WORK 17 

It will be noted that the second pinion is in reality the 
first pinion, but for convenience it is given the same name 
as the wheel of which it is a part and referred to as the 
center or second pinion. 

As an example of a modern train we shall select the num- 
ber of teeth of wheels and leaves of pinions as shown below. 
(Remember, the barrel, center, third, fourth and escape 
wheels are indicated by the capital letters B, C, T, F and E, 
and the center, third, fourth and escape pinions by the small 
letters c, t,f and e.) 

B 72 

C _80_ 
T 75 _ ^ 

1 lo"^ 

F 80 

Multiplying the numbers 6, 8, 7j^, and 10 together we 
get 3,600, which represents the number of turns of the escape 
wheel to one of the barrel. 

Dividing 3,600 by 6 (turns of center wheel to one of the 
barrel) we get 600. This number (600) represents the turns 
made by the escape wheel in one hour, since the center wheel 
carries the minute hand and, of course, makes one turn in an 
hour. Henceforth all calculations will be based on one turn 
of the center wheel, and on this basis we submit the follow- 
ing formula, in which, as above, the capital letters C, T, F 
indicate the wheels and the small letters t, f, e indicate the 
pinions. 



18 A PRACTICAL COURSE IN HOROLOGY 

CTF 80 X 75 X 80 

= = 600 turns of the escape wheel. 

tfe 10 X 10 X 8 
The fourth wheel in all watches designed to register 
seconds is so constructed that a second hand is fitted to the 
extremity of a long pivot extending through a hole in the 
dial. It follows, therefore, that according to the accepted 
plan for the division of time, the fourth wheel must make 
60 turns to one of the center wheel. Therefore : 

CT 80 X 75 

= = 60 turns of the fourth wheel. 

tf 10 X 10 

However, this is not necessary in watches where there is 
no second hand, and in many wrist watches the fourth wheel 
makes more than 60 turns to one of the center wheel, as we 
shall soon see. 

Calculating the number of beats. The escape wheel in 
most watches contains 15 teeth and delivers twice as many 
impulses to the balance, since each tooth delivers two im- 
pulses, first to the receiving pallet and later to the discharging 
pallet. Letting E indicate the escape wheel and e the escape 
pinion, the formula reads : 

CTF2E 

= number of beats per hour. 

tfe ^ 

Substituting the numerical values we have : 

80X75X80X2X15 

= 18,000 beats per hour. 

10 X 10 X 8 

Fast and slow trains. Not all watches make 18,000 beats 

per hour. Some of the older watches make 16,200 and 14,400 

beats per hour, whereas some newer American wrist watches 

make 19,800 and 21,600 beats per hour. There are other 

trains of varying beats per hour, particularly among those 



WHEEL WORK 19 

of Swiss manufacture. Below are shown two examples of 
slow trains : 

80 X 75 X 72 X 2 X 15 

== 16,200 beats per hour. 

10X10X8 

80 X 75 X 80 X 2 X 15 

= 14,400 beats per hour. 

10X10X10 

As already stated, watches without second hands may have 
any system of mobiles wherein the fourth wheel will not 
register seconds. Below are listed three trains of this type, 
all of which are fast trains used in small wrist watches. 

54X 50X48X2 X 15 



6X6X6 
64X66X60X2X15 



18,000 beats per hour. 



= 19,800 beats per hour. 



8X8X6 

42 X 42 X 35 X 35 X 2 X 12 

= 21,600 beats per hour. 

7X7X7X7 

The last train listed is unique in that the train has 6 wheels 
with an escape wheel containing 12 teeth. 

Comments on the fast trains. In the preceding para- 
graphs we discussed the slow and fast trains that have been 
in general use at various periods. We shall now consider 
further the modern fast trains used to some extent in very 
small wrist watches. 

The watch train making 18,000 beats per hour has been 
accepted as a sort of standard for many years. However, 
very small wrist watches making beats of various numbers 
per hour in excess of this figure are becoming more in evi- 
dence and the increased use of such trains would lead one 
to inquire into the reason for their popularity. 



20 A PRACTICAL COURSE IN HOROLOGY 

The reason lies in the fact that 18,000-beat trains, when 
applied to very small wrist watches, have a tendency to set 
on the locking. This is due to the fact that a light balance 
and a weak balance spring have not the necessary force to 
effect a satisfactory unlocking of the escapement. To over- 
come this fault of setting on the locking, it is necessary to 
reduce the drop lock to the very minimum. However, since 
it is difficult to expect the same precision of adjustment in 
small watches as is possible in larger watches, the fast trains 
offer a solution. The fast trains make the unlocking easier 
due to two factors: (1) the more rapid motion of the bal- 
ance and (2) the increased strength of the balance spring. 
In this way the new fast trains permit a greater tolerance 
with regard to the extent of the lock, resulting in a reduced 
tendency to set on the locking. Better timekeeping results. 

There is another point in favor of the new fast trains. 
Every horologist has observed how often the coils of the 
balance spring get caught in the regulator pins or get badly 
tangled due to a severe jolt. The stronger springs fitted to 
fast train watches do much to eliminate the difficulty or, at 
least, to lessen its frequent occurrence. 

Calculating the number of teeth and leaves of missing 

mobiles. We now wish to determine the number of teeth 

of wheels and leaves of pinions that are missing. Let F 

indicate the missing fourth wheel of the following train : 

80 X 75 X F X 2 X 15 

— —— ^ = 18,000 

10X10X8 

225F = 18,000 

F = 80 

According to the above solution the fourth wheel contains 
80 teeth. 



WHEEL WORK 21 

In the next problem, the third pinion is mission. Letting t 

indicate the mission pinion, the equation reads as follows : 

80 X 75 X 80 X 2 X 15 

— ——- — = 18,000 

t X 10 X 8 

180,000 

= 18,000 

t 

180,000= 18,000 1 

18,000 1 = 180,000 

t == 10 leaves of the third pinion 

Let us suppose that the complete fourth wheel and pinion 
of a wrist watch are missing in which F is the wheel and / 
is the pinion. The equation reads : 

54 X 50 X F X 2 X 15 



6xf X6 

2,250 F 

- = 18,000 



= 18,000 



f 
F 18,000 8 



f 2,250 1 

The result shows that the fourth wheel should have 8 
times as many teeth as the fourth pinion has leaves. Desig- 
nating / by 6, 7, 8, or 10 leaves, we may obtain any of the 
following solutions. 

48 56 64 80 

"6" '7 '¥ 'To 

Any of the solutions given above may be used; however, 
judging from the numbers of teeth and leaves of the train as 
a whole, the most suitable numbers would be : 

F 48 



22 A PRACTICAL COURSE IN HOROLOGY 

There are times when the ratios come out with a fractional 

numerator. For example we wish to determine the number 

of teeth and leaves of a missing third wheel and pinion in 

which T is the wheel and t is the pinion. 

54 X T X 48 X 2 X 15 

-— = 18,000 

tX6x6 

2,160T 

= 18,000 

t 

T 18,000 syi 

T^ 2,160 "T" 

The only numbers that may be tried without producing a 

fractional number of teeth are : 

75 50 

— and — 

9 6 

In this example the most suitable numbers would be : 
T 50 

T~6~ 

There are other times when we arrive at the answer im- 
mediately, as in the case of determining the number of the 
teeth of the escape wheel, E, and the leaves of the escape 
pinion, e. 

90 X 80 X 80 X 2E 



12 X 10 X e 

9,600E 

= 18,000 

e 

E 18,000 15 



= 18.000 



e 9,600 8 

The answer shows that the escape wheel contains 15 teeth 
and the escape pinion 8 leaves. 



WHEEL WORK 23 

Calculating a new train. We now wish to determine the 

number of teeth for the wheels and number of leaves for the 

pinions of a new train. Let us suppose the watch is to be a 

small baguette making 21,600 beats per hour. Using the same 

letters as before to indicate the wheels and pinions the 

formula reads as follows : 

CTF2E 

= 21,600 

tfe 

We may decide in advance the number of leaves for the 
pinions and the number of teeth for the escape wheel. For 
the pinions t, f, and e we shall use 6 leaves each. The escape 
wheel will have 1 5 teeth. The equation now reads : 

CTF2X 15 

21,600 

6X6X6 

21,000 X 6 X 6 X 6 

CTF = 

2X15 

CTF= 155,520 

The combined product of CTF is 155,520. In order to 
obtain the quantities desired, it is necessary to resolve this 
number into its prime factors and to form these factors into 
three groups which will represent the numbers for the teeth 
of the wheels C, T, and F. 

2)155520 2) 9720 3) 405 

2) 777Q() 2) 4860 

2) 38880 2) 2430 

2) 19440 3) 1215 

5 
Factoring, we find that CTF = 155,520 = 2^ X 3^ X 5. 



3) 


135 


3) 


45 


3) 


15 



24 A PRACTICAL COURSE IN HOROLOGY 

These factors may be formed into groups of various com- 
binations, but the most suitable arrangement for a watch 
train would be as follows : 

C = 5X3X22 = 60 

T = 33 X 2 = 54 

F = 3 X 2^ = 48 

Thus we show the complete train. 
60 X 54 X 48 X 2 X 15 



6X6X6 



= 21,600 beats per hour. 



The Barrel and Its Mainspring 

The barrel and its mainspring are important factors in the 
design of a watch. The ratio between the barrel and center 
pinion must show a definite relationship to the length and 
strength of the mainspring and must be determined with 
mathematical exactness if the watch is to perform satis- 
factorily and run a required number of hours. 

Calculating the number of hours a given watch will run. 
In order to determine the number of hours a watch will run 
we must first find the number of turns of the center wheel 
to one of the barrel. Letting B indicate the barrel and c the 
center pinion, the formula reads : 

B 

— = number of turns of center wheel to one of the barrel. 
c 

Using a numerical example, we have : 

84 ^ 

— = 7 turns of center wheel. 
12 

Knowing that the center wheel makes one turn in an hour, 
it follows that the barrel makes one turn in 7 hours. Next 



WHEEL WORK 25 

we must determine the number of turns necessary to com- 
pletely wind the spring. A trial has shown that it takes 5^ 
turns to wind the spring. The number of hours the watch 
will run is found by multiplying 7 by 5^, thus : 
7X5^== 3Sj4 hours the watch will run. 

The mainspring should run the watch not less than 32 
hours; 36 to 40 hours is better; in fact, some of the finest 
watches will run 45 hours and more. 

Calculating the correct thickness of the mainspring. 
We experience no difficulty in fitting mainsprings to standard 
makes of watches, for all we have to do is to select the spring 
as catalogued and graded by the particular manufacturer. 
There are times, however, when an old watch or one of 
unfamiliar make needs a new spring and, if we suspect that 
the old spring is not the correct one, we need to apply a bit 
of mathematical calculation to determine the correct thick- 
ness of the spring. In such cases the following method is 
suggested : 

1. Divide the teeth of the barrel by the leaves of the center 
pinion in order to determine the number of hours taken for 
one turn of the barrel. 

2. Determine the number of turns necessary to wind the 
spring by dividing 36 (hours of running) by the number of 
hours consumed in one turn of the barrel. 

3. Measure the inside diameter of the barrel and divide 
by 12.5. 

4. Divide the above quotient by the number of turns neces- 
sary to wind the spring. The result is the thickness of the 
spring. 

Suppose for example that the barrel, B, has 78 teeth and 



26 A PRACTICAL COURSE IN HOROLOGY 

the center pinion, c, has 12 leaves. The inside diameter of 
the barrel is 12 millimeters. 

1. — = — = 6.5 X 1 =6.5 hours, 
c 12 

36 

2. = 5.5 turns to wind sprmg. 

6.5 

12 

3. = .96 

12.5 

•96 ... 

4. = .17 mm., thickness of the spnng. 

5.5 

It should be understood that the answers are only ap- 
proximate. In some cases, as in a fine, 21- or 23- jewel watch, 
a weaker spring may be needed, whereas a 7- jewel watch may 
require a stronger spring. 

Calculating the correct length of the mainspring. The 
proper length of the spring need not be calculated in so many 
inches. Instead, we may state that the spring should occupy 
one half of the area between the inside wall of the barrel 
and the periphery of the arbor. If the spring does this, the 
length is correct. 

Observe that we say area and not space. The term space 
would lead one to infer that radial measurements are in- 
tended, which would be incorrect, inasmuch as a spring 
wound up would occupy more radial space than that of a 
spring run down. Thus, the statement often found in older 
books on horology to the effect that we allow one third of 
the space for the arbor, one third for the space, and one third 
for the spring is slightly in error and indicative of a spring 
a few coils too long. 

The correct rule should read : 



WHEEL WORK 



27 



One third of the space is occupied by the barrel arbor and 
one half of the remaining area is covered by the spring. 

This is clearly shown in Figure 3. It will be observed 
that the radial distance occupied by the spring is less than 




Figure 3. Barrel showing correct space for mainspring. 

that given to space. However the area of both spring and 
space are equal and it remains the same under all conditions, 
whether the spring is wound completely, partially let down, 
or completely let down. 

Now wind the spring in the barrel and if the spring oc- 
cupies more than one half of the area, break off the outer 
end and rewind in the barrel. When the correct area is 
determined the hook is affixed. A spring of the proper length 
contains from eleven to thirteen coils. More than the re- 



28 A PRACTICAL COURSE IN HOROLOGY 

quired number of coils only tends to increase friction and 
shorten the number of hours of running of the watch. 

The Dial Train 

The cannon pinion, minute wheel, minute pinion, and hour 
wheel make up the dial train. Referring to Figure 4, the 




Figure 4. Dial train. 

dial train is arranged as follows. The cannon pinion, c, gears 
into the minute wheel, M. The minute pinion, m, to which 
the minute wheel is attached, gears into the hour wheel, H. 
This latter wheel fits freely over the cannon pinion. The 
minute hand, of course, makes 12 turns to one of the hour 
hand. The formula for the dial train, therefore, reads as 
follows : 
HM 



= 12 



cm 

Let us suppose we wish to determine the number of teeth 
of wheels and the number of leaves of pinions of a new dial 
train. We shall decide on 12 leaves for the cannon pinion, c, 



WHEEL WORK 29 

and 10 leaves for the minute pinion, m. Letting H indicate 

the hour wheel and M the minute wheel, the equation reads : 

HM HM 

= 12 



cm 12 X 10 

HM=12X 12X 10; HM = 1,440 

Factoring in the manner as heretofore explained, we find 
that: 

HM = 25 X 32 X 5 
Combining these factors to form two groups representing 
the wheels H and M we have : 

H = 23 X 5 = 40; M = 22 X 32 = 36 

Thus the complete train reads as follows : 

HM 40 X 36 

= — -- — =12 

cm 12 X 10 

Various types of dial trains. Dial trains may be grouped 
into three types: (1) the regular, (2) the reverse, and 
(3) the irregular. In the regular the ratio of cannon pinion 
to minute wheel is 3 to 1 and the ratio of the minute pinion 
to the hour wheel is 4 to 1. 

M_36_ H_l^_4 

"c"~T2~ ' m"~10""" 

In the reverse the ratio of the cannon pinion to minute 
wheel is 4 to 1 and the ratio of the minute pinion to hour 
wheel is 3 to 1. 

M_32_ H_?l_^ 

T~'%~ ' m~"8"~ 

The irregular does not belong to either of the above types, 
as shown by the following example : 

HM 35X48 48X26 32X45 



cm 14 X 10 13 X 8 12 X 10 



12 



30 A PRACTICAL COURSE IN HOROLOGY 

Thus the dial train may be formed by working out various 
combinations, the only requirement being that the combined 
ratios equal 12. The most used, however, is the 3 to 1 — 
4 to 1 type referred to as the regular. 

Calculating the teeth and leaves of missing mobiles. 

Let us suppose that the cannon pinion is missing from the 
following train in which c represents the cannon pinion : 
54X32 



CX12 
i^ = 12 



= 12 



c 

144 = 12c 
12c = 144 
c = 12 leaves of the cannon pinion. 

We now wish to find the number of teeth of a missing 
hour wheel in which H represents the wheel. 
H X 25 _ ^^ 
10 X 10 

« = 12 
4 

H = 48 teeth of the hour wheel. 

Let us suppose that a complete minute wheel and pinion 
are missing in which M is the wheel and m is the pinion. 
48 XM 



14 X m 
24 M 



= 12 



= 12 



7m 
M 12X7 _ 7 _3^ 

m"~~24 2 ~~ 1 



WHEEL WORK 31 

The result shows that the minute wheel must have 3^^ 
times as many teeth as the minute pinion has leaves. Thus 
M_28_35_42_49 
m~" 8"~10~12~~l4 

Any of the above solutions may be used as the following 
equations will show. 

48X28 48X35 48x42 48x49 



14 X8 14 X 10 14 X 12 14 X 14 



= 12 



Problems 

1. What is meant by train ? 

2. How many trains has the ordinary watch ? Name them. 

3. Name the wheels of the average main train. 

4. How many turns does the escape wheel make to one of the 
center wheel in an 18,000-beats-per-hour train? How many turns 
in a 19,800-beats-per-hour-train? 

5. What are the arguments in favor of the fast trains for very- 
small wrist watches ? 

6. What portion of the space between the barrel and the arbor 
should the mainspring occupy ? 

7. What is the correct thickness of the mainspring if the barrel 
has 80 teeth with an inside diameter of 13 millimeters and the center 
pinion has 10 leaves? 

S. Name the parts of the dial train. 

9. How many turns does the hour wheel make in 12 hours ? 
10. Name the various types of dial trains. Explain their difference. 



Part I 

CHAPTER TWO 



Gearing 

Terminology 

Gearing constitutes a system of wheels and pinions 
whose circumferences are covered with teeth so that the 
teeth of the wheel act upon the leaves of a pinion. The 
function is in reality as a system of levers in which a longer 
lever presses on a short one until one lever ceases to press and 
another lever comes into action. 

Gearing is a rather technical subject and it Is well first to 
study Figure 5. The terms given in the illustration are 
defined as follows: 

Pitch circle: a circle concentric with the circumference of 
a toothed wheel and cutting its teeth at such a distance from 
their points as to touch the corresponding circle of the pinion 
working with it, and having with that circle a common 
velocity, as in a rolling contact. 

Pitch diameter : the diameter of the pitch circle. 

Full diameter: the diameter from point to point of the 
teeth. 

Distance of centers: the distance measured on a straight 
line from center to center between the wheel and pinion. 

32 



GEARING 33 

Line of centers: a line drawn from center to center of 
any wheel and pinion. 

Circular pitch: the pitch circle divided into as many 
spaces as there are teeth on the wheel or pinion. 

Diametrical pitch: the diameter of the pitch circle 
divided into as many spaces as there are teeth on wheel or 
pinicn. 

ADDENDUM 
DEDENDUM 




Figure 5. 

Addendum: the portion of the tooth, either of wheel or 
pinion, outside of the pitch circle. 

Dedendum: the portion of the tooth of either wheel or 
pinion inside of the pitch circle. 

Driver : the mobile that forces the other along. 
Driven: the mobile that is being forced along by the 
driver. 

Principles of Gearing 
The addenda. In Figure 6 is shown a portion of a gircle, 
A, representing the pitch circle of a wheel. Rolling on this 
portion of a circle is another circle, B, the diameter of which 



34 



A PRACTICAL COURSE IN HOROLOGY 




Figure 6. Formation of the epicycloidal curve. 



equals half the pitch diameter of the pinion. If a pencil 
point were fixed at the lowest point of the circumference of 
the smaller circle (the generating circle) and then rolled on 
the larger circle without slipping, a curve would be traced 
along the path of the line C in the direction of the arrow. 
The curve thus formed is called the epicycloid and determines 
the shape of the addenda of the wheel teeth. 

The dedenda. The dedenda of the pinion leaves is formed 
by the same generating circle but not in the same manner. 
The smallef circle is rolled inside and along the pitch circle 
of the pinion. However, instead 
of a curved line a radial line is 
formed as shown by the line A 
in Figure 7. A circle rolling 
within a circle is called a hypo- 
cycloid and determines the shape 
of the dedenda of the pinion 
leaves. Thus when a wheel and 
pinion are made in conformance 
with the above principles of de- 




Figure 7. 



GEARING 35 

sign, a smooth and constant force is delivered to the pinion. 

Width of tooth. It has been observed that the generating 
circle forms one side of the tooth. The question now arises 
as to how to determine the width of the tooth. This is 
determined by dividing 360 (degrees in any circle) by the 
number of teeth in the wheel. This gives us in degrees the 
width of one tooth and one space, generally referred to as 
the circular pitch. 

360 
Thus = 4.5 degrees circular pitch. 

80 teeth 

The width of the tooth is equal to one half of the circular 

pitch ; the other half is, of course, equal to the space. 

4.5 degrees 

Therefore = 2.25 

2 

of which 2.25 degrees is the width of the tooth and 2.25 

degrees the width of the space. 

Now, by placing the generating circle, E, Figure 6, with 
the pencil point directly below and 2.25 degrees to the right 
of curve C, it will be in position to trace out the other side 
of the tooth by simply rolling the circle to the left as shown 
by the dotted line D. The intersection of the two curves, 
C and D, forms the point of the tooth. 

The pitch diameter. We now wish to determine the pitch 
diameter of a wheel and pinion, the center distance being 
known.* The first procedure is to determine the diametrical 



* The center distance is determined by means of a depthing tool, 
an instrument with adjustable male centers that can be adjusted to 
the holes in the plate and convenienth' measured with a micrometer 
or Boley gauge. 



36 A PRACTICAL COURSE IN HOROLOGY 

pitch, the formula for which reads as follows : 

center distance X 2 . , . , 

: — r-. — = diametrical pitch. 

teeth of wheel -j- leaves of pinion 

The diametrical pitch is now multiplied by the number of 
teeth in the wheel in order to determine the pitch diameter 
of the wheel, and in like manner the diametrical pitch is 
multiplied by the number of leaves in the pinion to determine 
the pitch diameter of the pinion. 

For example, the center distance is 8.5 millimeters ; the 
wheel has 80 teeth; the pinion has 10 leaves. Substituting 
the numerical values for the above formula, we have : 

= .1888 diametrical pitch. 

80+10 ^ 

Continuing the problem we find that : 

.1888 X 80 = 15.104 mm. pitch diameter of the wheel. 

.1888 X 10 = 1.888 mm. pitch diameter of the pinion. 

„ ^ 15.104+1.888 ^ ,^, , ,. 

Proof: = 8.496 mm., the distance between 

centers. 

The full diameter. The height of the addenda is a varying 
quantity depending on the ratio of the wheel to the pinion, 
but the production of theoretically correct gears or even 
knowing when they exist is not possible with the equipment 
available to the practising horologist. The usual practice is 
to add 2.5 diametrical pitches to the pitch diameter of the 
wheel and 1.25 to the pitch diameter of the pinion.* Experi- 



* There is one exception to the above statement For the dial 
train where the pinions drive the wheels and the wheels drive the 
pinions, as in the case of setting the watch to time, the addenda is 
figured as 2 for both wheels and pinions. 



GEARING 37 

ence has shown that the above figures are best for all practical 

purposes. 

We found that the wheel has for its pitch diameter 15.104 
millimeters and the pinion 1.888 millimeters. The diametrical 
pitch multiplied by 2.5 gives us the height of the addenda 
for the wheel : 

.1888 X 2.5 == .47 
Adding this to the pitch diameter of the wheel, we have : 

15.104 + .47 = 15.57 mm. full diameter of the wheel. 

Now, figuring the pinion we have : 
.1888 X 1.25 = .236 
1.888 + .236 = 2.12 mm. full diameter of the pinion. 

We may, however, figure the full diameters with a lot less 
work by adding 2.5 or 1.25 (addenda) to the number of the 
teeth or leaves. For example : 

(80 4- 2.5) .1888 == 15.57 mm. full diameter of the wheel. 

(10+1.25) .1888 = 2.12 mm. full diameter of the pinion. 

Circular pitch. It will be noted that the definition for 
circular pitch reads somewhat like the definition for diamet- 
rical pitch. The difference is : circular pitch is the division 
of the circumference of a circle (the pitch circle), whereas 
the diametrical pitch is the division of the diameter of a circle 
(the pitch diameter). In both cases the number of teeth or 
leaves is the divisor. 

We must know the actual width of tooth and space in order 
to select a cutter to make a wheel. Herein lies the importance 
of calculating the circular pitch. To attain this we make 
use of the following formula: 

pitch diameter X 3.1416 



teeth or leaves 



= one circular pitch 



38 A PRACTICAL COURSE IN HOROLOGY 

Substituting the numerical values : 
15.1 X 3.1416 



80 



= .592 mm. circular pitch 



The proportion of tooth or leaf to space is usually : 

for the wheels : one half of the circular pitch. 

for the pinions, 10 leaves or less : one third of the circular 

pitch, 
for the pinions, 12 leaves or more : two fifths of the 

circular pitch. 

Now, continuing with the above example to determine the 
width of the tooth of the wheel and the leaf of the pinion, 
we find that 
.592 



2 

.592 



= .296 mm., the width of the tooth, and 
= .197 mm., the width of the leaf. 



Problems 

1, What is the epicycloid? the hypocycloid? 

2. Define diametrical pitch. 

2. Calculate the diametrical pitch for the following: 
center distance — 7.5 millimeters, 
wheel — 75 teeth, 
pinion — 10 leaves. 

4. Calculate the pitch diameter for the above wheel and 
pinion. Calculate the full diameters. 

5. Define circular pitch. 

6. Calculate the circular pitch, using the specifications given 
in Problem J. 



Tl 



Part I 

CHAPTER THREE 



The Lever Escapement 

Time and experience have demonstrated the superiority 
of the lever escapement over all other types for portable 
timepieces. In fact, the several other types have now 
become obsolete. Since its introduction by Thomas Mudge 
in 1750 the lever escapement has been the object of much 
experimentation and study. It finally was developed into the 
state of perfection we see it today only after a number of 
unique and fantastic variations were tried and discarded. 

Terminology 
The several parts of the escapement are defined as follows : 

ESCAPE WHEEL 
The escape wheel is that part of an escapement that delivers 
impulse to the balance through the medium of a pallet fork. 

Ratchet-tooth wheel: the name given to the English 
type escape wheel, which has pointed teeth. 

Club-tooth wheel: that type of escape wheel which has 
a lifting face at the end of the teeth. Impulse face: the lifting 
plane of a club-tooth wheel. Locking face: the slanting face 
of the teeth on which the pallets lock. Toe: the intersection 
of the locking face and the impulse face of a club tooth. 



39 



40 A PRACTICAL COURSE IN HOROLOGY 

Heel: the intersection of the impulse face and the letting-off 
corner of a club tooth. 

PALLET FORK 

The pallet fork is that part of an escapement that, by 
means of pallet jewels, receives impulse from the escape 
wheel and delivers impulse to the balance. 

Pallets: the name given to the metal body to which the 
lever is attached. The term includes the pallet jewels. 

Lever: a metal piece attached to the pallets that carries 
impulse to the balance. The fork occupies the extreme end 
of the lever. 

Fork slot; a notch cut into the fork for the reception of 
the roller jewel. 

Horns: the circular sides of the fork that lead to the 
fork slot. 

• Receiving pallet : that pallet stone over which a tooth of 
the escape wheel slides in order to enter between the pallet 
stones. 

Discharging pallet : that pallet stone over which a tooth 
of the escape wheel slides in order to leave from between 
the pallets. Impulse face: the lifting plane of the pallet stone. 
Letting-off corner: the extreme end of the impulse face of a 
pallet stone where the tooth of the escape wheel lets ofiF. 
Locking face: the face of a pallet stone on which a tooth locks. 

ROLLER TABLE 

The roller table is the circular disk that carries the roller 
jewel. 



THE LEVER ESCAPEMENT 



41 



Crescent: a circular notch in the edge of the roller table 
for the reception of the guard pin or fingeV. 

Single roller: a roller action comprising a single metal 
disk. 

Double roller : a roller action comprising two metal disks, 
the larger disk carrying the roller jewel and a smaller disk 
in which a crescent is cut. 

Roller jewel or jewel pin: a flattened jewel that is 
inserted in the roller table. 

BANKING PINS 
Banking pins are pins that arrest or limit the angular 

motion of the lever. 



Equidistant, Circular and S emit an gent al Pallets 

There are three types of pallet arrangements used in the 
lever escapement: the equidistant, the circular and the 
semitangental. 

Equidistant pallets. In the equidistant the locking faces 
of the pallets are an equal distance from the pallet center, 




Figure 8. Equidistant pallets. 



42 



A PRACTICAL COURSE IN HOROLOGY 



as shown in Figure 8. As a result the lifting action on the 
discharging pallet takes place too far from the point of 
tangency, necessitating the need for a greater lifting angle 
on that stone. Although the unlocking is performed under 
favorable conditions, the lifting action is not, being unequal 
in its distribution and unequal also as to the pressure of the 
tooth on the pallets. This escapement calls for exceptional 
accuracy in its construction. 

c f 




Figure 9. Circular pallets. 

Circular pallets. Circular pallets have the central portion 
of the pallets' lifting faces an equal distance from the pallet 
center as shown by the lines CA and DA in Figure 9. One 
half of the width of the pallets is placed on each side of these 
lines, which requires that the locking faces stand at an un- 
equal distance from the pallet center, causing an unequal and 
increased unlocking resistance. However, the action of lift 
is more favorable. 

Semitangental pallets. Setting on the locking is a com- 
mon fault in small wrist watches; hence a light lock is 



THE LEVER ESCAPEMENT 



43 




Figure 10. Semitangental pallets. 

essential to good performance. With regard to this factor 
the semitangental escapement, a development of recent years, 
has found favor with many manufacturers because it lessens 
the resistance to unlocking, a natural fault with the circular, 
and at the same time minimizes the lifting error of the 
equidistant. Figure 10 shows the semitangental escapement. 
It will be observed that the unlocking on the receiving pallet 
takes place on the tangent EB at the intersection of CA. 
A slightly increased center distance results, since the line 
CA is placed 31 degrees to the left of the center line BA. 
The action of the discharging pallet is similar to that of an 
escapement with circular pallets. The designers claim that 
the unlocking and lifting actions are more nearly equally 
divided than any escapement that has yet been conceived. 



Number of Teeth in Escape Wheel 

Although nearly all watches have an escape wheel of 15 
teeth we may make them with 12, 14, 16, or practically any 



M A PRACTICAL COURSE IN HOROLOGY 

number in this range. The first lever escapement as made 
by Thomas Mudge had an escape wheel of 20 teeth. The 
larger numbers result in a rather clumsy action and are 
therefore not satisfactory. Escapements using a wheel of 
12 or 14 teeth are used today in some wrist watches and have 
certain advantages. For example, there is more clearance 
between the pallet arm and the escape wheel. The smaller 
number of teeth permit the use of wider pallet jewels and 
a wider lifting plane for the teeth. Also the actual measure- 
ment of 1^2 degrees of locking is greater because of the 
increased distance between the locking comers of the pallets 
and the pallet center. 

Wheel and Pallet Action 

The lever escapement has two distinct and separate func- 
tions: (1) the action of the wheel and pallets and (2) that 
of the fork and roller. These functions we shall now con- 
sider. The first, which has to do with the wheel and pallets, 
is divided into three actions. They are : 

1 the locking 

2 the draw 

3 impulse or lift 

The locking. The locking Is the overlapping of a tooth 
on a pallet when the lever rests against the bank. This locking 
is necessary for the reason that if one tooth lets of? a pallet 
and another tooth falls directly on the impulse face of the 
opposite pallet, there is a recoil of the lever toward the 
balance, causing a frictional contact between the guard pin 
and roller table. Contact in this manner would immediately 
stop the watch. To avoid this a certain amount of lock Is 



THE LEVER ESCAPEMENT 45 

necessary. However, it should be as little as possible con- 
sistent with the proper safety in action. 

The draw. In portable timepieces the lock in itself is not 
sufficient to insure safety in action. It is necessary to create 
an action whereby the pallets are drawn into the wheel. This 
is effected by inclining the locking faces of the pallets to the 
right of the lines CA and DA as shown in Figure 10. This 
slanting should be as little as possible, yet enough to overcome 
the friction of the tooth on the surface of the pallets, for 
it can readily be seen that the combined action of lock and 
draw makes a resistance to the motion of the balance and 
has an important relationship to the position and isochronal 
rating of a watch. 

It is generally conceded that 12 degrees draw on each 
pallet is satisfactory. However, because of the circular 
motion of the pallets the draw is changing continually, being 
strongest on the receiving pallet at the point of unlocking, 
whereas on the discharging pallet it is weakest at the point 
of unlocking. The nature of this action leads one to assume 
that a greater angle for draw should be given to the receiving 
pallet ; in fact, we find some authorities designing the escape- 
ment with 13 to 15 degrees draw on the receiving pallet. 
This would make the draw more nearly equal at the point 
of banking where it is most needed. 

The lift. In well-designed escapements of the club-tooth 
variety the actual lift is 8^ degrees, being divided between 
tooth and pallets in varying proportions. Adding 1^^ degrees 
for the lock, the total angular motion of the lever becomes 
10 degrees. 

Width of pallet and tooth. It will be observed that a 



46 A PRACTICAL COURSE IN HOROLOGY 

wide pallet requires a narrow tooth ; likewise a narrow pallet 
should be associated with a wide tooth if the drop* is to be 
kept to the minimum. In this connection several pallet and 
tooth combinations are listed below : 

CIRCULAR PALLETS 

PALLET TOOTH 

Lift Width Lift Width 

1 6 degrees 7 degrees 2J^ degrees 3^ degrees 

2 5J4 •' 654 " 354 " 4>^ " 
5 5" 6 " 3^ " Ay2 " 
^ 4 " 5 " 4H " 5^ " 

EQUIDISTANT PALLETS 

Lift Width Lift Width 

5 6 degrees 7 degrees 2y2 degrees 3 5^ degrees 

6 5H " 6 " 3 " 454 " 

7 5^ " 5M " 3 " 4^ " 

Attention should be given to this fact : in the equidistant 
pallets the lift on the tooth should be less than the Hft on the 
pallets. Circular and equidistant pallets are not always 
interchangeable. However, there are exceptions, as in the 
case of Number 1 and Number 5, which are alike and have 
been interchanged by Grossman. Number 4 is suitable only 
for circular pallets, especially so since the narrow pallets 
perform the act of locking nearer to the lines CA and DA, 
as shown in Figure 9. Numbers 5 and 6 would be suitable 
also for the semitangental escapement. 



* Drop is a term used to indicate the free motion of the escape 
wheel after one tooth lets off a pallet and another tooth locks on 
the opposite pallet. This factor is of more concern in practical 
benchwork and is treated fully in Part II, Chapter Six. 



THE LEVER ESCAPEMENT 47 

The Fork and Roller Action 

Unlocking and impulse actions. The relation between 
the fork and roller jewel as a mechanical action may be 
divided into two distinct and separate functions: (1) the 
unlocking of the pallets and (2) the impulse to the balance. 
One action is the reverse of the other. The unlocking action 
takes place as a result of power derived from the balance 
and spring, while the impulse to the balance receives its 
energy from the force delivered to the escape wheel by means 
of the main spring and the train. In the unlocking action, 
a short lever (roller- jewel radius) acts on a longer one (the 
lever fork). A short roller-jewel radius must be associated 
with a long lever which involves a large angle of contact as 
shown by the angle ABC in Figure 11. On the other hand, 
a long roller- jewel radius must be associated with a short 
lever which results in a small angle of contact as shown by 
the angle ABC in Figure 12. In other words, the shorter 
the roller- jewel radius the larger is the angle of contact, and 
the smaller the angle of contact the longer is the roller- jewel 
radius. 

A 4-to-l roller action. In Figure 11 the relation of the 
roller jewel to the fork slot is 4 to 1 ; that is, the lever moves 
10 degrees and the roller jewel remains in contact with the 
fork slot for a space of 40 degrees. The action of unlocking 
begins quite some distance from the line of centers because 
of the short roller-jewel radius. However, a short roller- 
jewel radius results in a much safer action and an easier 
unlocking of the pallets. 

A 3-to-l roller action. In Figure 12 the relation of the 
roller jewel to the fork slot is 3 to 1. Although the unlocking 



48 



A PRACTICAL COURSE IN HOROLOGY 



action is more difficult, the impulse to the balance is more 
energetic when it does occur. The 30-degree contact of the 
roller jewel with the fork slot is in accord with the theory 
that the lever should be as highly detached as possible for 
finer results in timing. 




Figure 11. Fork and roller ac- 
tion — single roller. 



Figure 12. Fork and roller ac- 
tion — double roller. 



The more delicate safety action of a long roller-jewel 
radius is not a problem in high-grade watches, for in such 
work we naturally expect a mechanical action that is more 
exact in its function. It follows, therefore, that a long roller- 
jewel radius which involves a small angle of contact is one 



THE LEVER ESCAPEMENT 49 

of the important factors to be considered in fine escapement 
design. Of course, in the cheaper work and in small wrist 
watches it is not always practical. 

A wide roller jewel. The wide roller jewel results in a 
particularly satisfactory action of unlocking by taking place 
near the line of centers. However, the impulse to the balance 
is not so favorable. A wide roller jewel is inseparable from 
a long roller- jewel radius, for such a principle of design 
results in a very delicate action. A wide roller jewel makes 
the safety action much less delicate. 

A narrow roller jewel. A wide roller jewel, if associated 
with a short roller- jewel radius, causes an unfavorable im- 
pulse to the balance too far from the line of centers, and the 
"uphill" circular path of the roller jewel along the side of 
the fork slot during the impulse to the balance results in 
considerable friction. Also, on account of the greater angle 
at which the roller jewel stands to the slot when the impulse 
takes place, the drop of the fork against the jewel will amount 
to more than its shake in the slot, if measured when standing 
on the line of centers. Thus a narrow roller jewel is better 
adapted for a short roller- jewel radius, and should always 
be associated with a single-roller escapement. 

Single-roller escapement. In the single-roller escapement, 
Figure 11, it is required that the roller table be as small as 
possible to preserve the safety action. Furthermore, friction 
between the guard pin and the circumference of the roller 
table would be considerably increased on a table roller that 
was larger than necessary. It is difficult to reduce the angular 
motion of the lever to less than 10 degrees, and any relation 
of fork to roller jewel less than a 3^ to 1 is not practical. 



so A PRACTICAL COURSE IN HOROLOGY 



V 



Double-roller escapement. ' We have learned,' that ii^ 
order to favor the impulse to the balance we require a long 
roller-jewel radius, and for the safety action a short radius. 
This is the reason for the passing of the single-roller escape- 
ment in favor of the double-roller type, Figure 12, for in the 
latter type we have two rollers, one for each action. 

The size of the safety roller is of no great importance. 
For the sake of soundness in action its radius should not be 
less than one half the radius of the roller jewel. The smaller 
the safety roller the sooner will the crescent approach the 
guard finger; and, likewise, the longer the roller-jewel 
radius the later will the roller jewel enter the fork slot. It 
follows, therefore, that the greater the difference between 
the respective radii of the roller jewel and the safety roller 
the longer must be the horns of the fork. The width of the 
roller jewel also plays a part in the length of the horns, for 
with any increase in the width of the jewel, the horns may 
be made proportionately shorter. 

The crescent. The circular notch in the roller is called 
the crescent and should be wide and deep enough so that it 
will be impossible for the guard finger to touch any part of 
it. If made too wide, longer horns on the fork would be 
required to preserve the safety action. 

The width of the crescent in the double-roller escapement 
is greater than in the single-roller type, for the reason that 
the guard finger, due to its increased length, has a larger 
space to cover for its safety action, or, stating the function 
in another way : it could be said that the velocity of the guard 
finger has increased, whereas the velocity of the safety roller 
has decreased. 



THE LEVER ESCAPEMENT 51 

Problems 

1. How do the equidistant pallets differ from the circular pallets? 

2. Compare the above with the semi-tangental escapement. 

3. What is meant by locking? 

4. Define draw. How does draw differ on the receiving pallet 
as compared with the draw on the discharging pallet ? 

5. How many degrees are generally intended for the lifting 
action ? 

6. Explain the difference between a 4 to 1 and 3 to 1 roller action. 

7. Which of the above actions is preferred? Why? 

8. Describe the single and double escapements. State the advan- 
tages and disadvantages of each type. 

9. What is the name of the small roller that makes up the double- 
roller escapement ? 

10. What is the purpose of the crescent? 



Part I 
CHAPTER FOUR 



The Controlling Mechanism 

The balance and balance spring are the most vital parts 
of a watch and may be properly called the controlling mechan- 
ism. Years ago the principal difficulty in maintaining accu- 
rate time was the temperature error, since the compensating 
balance was unknown prior to 1769. Often the error was as 
much as four or five minutes in twenty-four hours. The 
variation is due to three conditions : ( 1 ) the expansion and 
contraction of the metal in the balance, (2) changes in the 
length of the balance spring, and (3) variation of the elastic 
force of the spring. The variation of the elastic force of 
the spring is the most important factor; in fact, Ferdinand 
Berthoud has estimated that 82 per cent of the error is due 
to the variation of the elastic force. 

Experimental demonstration. A simple experiment to 
prove the correctness of the above statement may be tried 




Figure 13. 
52 



THE CONTROLLING MECHANISM S3 

if desired. The materials needed are a sheet of brass about 
4 or 5 inches long and 2 inches wide, a piece of brass wire, 
and an old mainspring. Drill two holes, A and B, Figure 13, 
about yi inch apart and insert two brass pins and rivet 
securely. Straighten the outer portion of the mainspring 
and place the end between the pins, the extreme end being 
placed under pin A and over pin B, while the coiled portion 
passes beyond the index C. The coil beyond the index will 
serve as a weight. Now, with the aid of an alcohol lamp and 
blowpipe heat the brass plate. It will be observed that 
the spring, after becoming heated slightly, has deflected 
noticeably, as may be seen by noting the position of the 
spring on the index. Upon cooling it will return to its orig- 
inal position. 

Temperature Error of the Balance and Balance 

Spring 

The compensating balance. The compensating balance, 
or bimetallic balance, as it is sometimes called. Figure 14, 
was designed to overcome the errors resulting from the use 
of the solid balance. This balance is constructed by brazing 
together brass and steel for the rim of the balance. The 
brass is on the outside and constitutes about three fifths of 
the total thickness. 

Heat causes the metals in the balance assembly to expand ; 
the arms become longer and, as the brass expands more than 
the steel, the loose ends of the rim curve inward toward the 
center. Cold causes the loose ends to move outward away 
from the center, while the arms become shorter. This is 
clearly shown in Figure 15. It will be further observed that 
the loose ends remain reasonably circular during temperature 



54 



A PRACTICAL COURSE IN HOROLOGY 




Figure 14. Compensating balance, 

changes, but the radii of the curves change, their centers 
being at the balance center O for the normal temperature and 
shifting along the arms AA for the high and low tempera- 
tures. However, the points BB, about 60 degrees from the 
arms, remain at a fixed distance from the balance center, and 
it is at these points that alterations for the purpose of timing 
should be made. 

Middle-temperature error. It is evident from the above 
analysis that we can adjust the balance screws in such a 
manner as to compensate for the expansion and contraction 
of the balance alone and maintain a constant mean diameter. 
This, however, would not take care of the lengthening and 
shortening of the balance spring nor for the changes in the 



THE CONTROLLING MECHANISM 



55 




Figure 15. 



elastic force. To compensate for the effects of temperature 
on the spring, it is necessary to add extra weight to the loose 
ends of the rim. This results in a temperature error, between 
the extremes of heat and cold, known as the middle-tempera- 
ture error due to the fact that the balance does not com- 
pensate equally for changes in the elastic force and for 
changes in the length of the spring. This is shown by in- 
sufficient compensation (weights not moving in near enough 
toward the center of the balance) in the higher temperatures ; 
and too great a compensation (weights moving too far away 
from the center) in the lower temperatures. The result is 
a higher rate in the normal temperature, usually from two 
to six seconds in twenty-four hours, depending on the grade 
of the watch. 



56 



A PRACTICAL COURSE IN HOROLOGY 




Figure 16. 



This factor is clearly shown in Figure 16. The line AB 
indicates the uniform loss in the rate due to a rising tempera- 
ture on the balance spring only. To exactly offset this rate 
by some means of compensating the error, we must produce 
the opposite effect indicated by the line CD. The theoretical 
results would be a constant mean rate along the line EF. 



2ec 


onJs 




4 
3 
2 
1 

















y^ 




\ 




/ 


/ 




\ 


\ 


/ 










/ 










'0° S0° 60° 70° 80° &i 


/ 



Figure 17. Middle-temperature error. 



THE CONTROLLING MECHANISM 



S7 



However, since the actual compensating effect of the balance 
alone lies along the dotted line GH, the actual rate is similar 
to that shown in Figure 17. 

There is no way of rectifying this condition except to use 
a nickle-steel alloy called Invar, the perfection of which has 
been realized only in recent years. This remarkable metal 
expands and contracts only a very little for changes in 
temperature, and in using it instead of the ordinary steel 
the middle-temperature error is considerably reduced. 

Still more recently another type of alloy made of iron, 
nickle-chromium, and tungsten and known as Elinvar has 




Figure 18. Solid balance. 



58 A PRACTICAL COURSE IN HOROLOGY 

been developed for the use of balance springs. Elinvar main- 
tains a constant elasticity and is, therefore, used in connec- 
tion with a solid, single-metal balance as shown in Figure 18. 
The metal has the further advantages of being nonrusting 
and only slightly subject to magnetism. Also there can be 
no middle-temperature error. 

The Balance Spring 

There are two forms of balance springs in general use. 
These are the flat spring, Figure 19, and the Breguet, Figure 
20. The former has the stud fixed to the same plane as the 
body of the spring, with the result that the vibrations take 
place in an eccentric manner. The latter, referred to as 
Breguet, has a portion of the outer coil raised above and 
over the body of the spring. The original Breguet spring 
was created by Abraham Louis Breguet (1747-1823), famous 
French horologist, but the spring by him bore no resemblance 




Figure 19. Flat balance spring. 



\ 



THE CONTROLLING MECHANISM 



59 




-YA 



Figure 20. Overcoil balance spring. 

to the theoretical terminals as applied to modern watches. 
The terminals as we now find them are based on the founda- 
tion laid down by M. Phillips, French mining engineer, and 
have placed the art of adjusting on a scientific basis. 

Theoretical terminals. The value of the theoretically 
corrected terminals lies in their capacity to correct position 
and isochronal errors by eliminating the eccentric wanderings 
of the center of gravity that are everpresent in the flat spring. 
The outer and inner terminals designed by L. Lossier perform 
this function very satisfactorily. These are shown in Figures 
20 and 21. 

In the outer terminal, Figure 20, note that the overcoil is 
composed of portions of two circles. The outer coil tends 



60 



A PRACTICAL COURSE IN HOROLOGY 




inward at A and forms an arc 
of 180 degrees to B, which is 
planted at a point equal to .67 
of the radius R. The overcoil 
continues for another 83 de- 
grees, the radius of which is 
CO. To this must be added 
the amount necessary to reach 
through the stud. 

Figure 21 shows the Lossier 
inner terminal. The elements 
of the curve are the same as 
Figure 21. Theoretical inner terminal, the outer terminal and are 
clearly shown in the illustration. Although the overcoil is 
applied to practically all watches today, the theoretically 
corrected inner terminal is not, its use being confined only 
to the very finest watches. The reason no doubt lies in the 
fact that the Lossier inner terminal is difficult to make and 
harder to adjust and, unless the curve is 100 per cent perfect, 
it is no better than a true terminal of the ordinary type. 
Careful poising of the collet is also necessary. 

Problems 

1. Describe the compensating balance. 

2. What is the middle-temperature error? 

3. What type of balance springs are used with solid, single-metal 
balance wheels ? 

4. How does the Breguet spring differ from the flat spring? 

5. What are the advantages of the theoretical terminals? 

6. Draw a sketch showing the proportions of the theoretical 
curves, both outside and inside. 



\ 



PART II 
PRACTICAL REPAIRING 



Part II 

CHAPTER ONE 



Train Problems 

General observations in gearing. Attention should 
always be paid to the action of the outgoing tooth, noting 
that its point is not used and that the incoming tooth takes 
up its load without drop. The incoming tooth should begin 
pressing on the pinion leaf as near as possible to the line of 
centers, allowing for the fact that this is a varying quantity 
depending on the number of leaves in the pinion. The best 
possible actions for pinions of ten, eight, and six leaves are 
shown in Figures 1, 2, and 3. Note that in Figure 1 the action 

begins on the line of centers, in 
Figure 2 slightly before the line 
of centers, and in Figure 3 quite 
some distance from the line of 
centers. 

Gearing may be found defec- 
tive with regard to several fac- 
tors. Below are listed the most 
common. 

Pinion too large 
Pinion too small 
Depthing too deep 
Figure 1. Ten-leaf pinion. Depthing too shallow 




62 



TRAIN PROBLEMS 



63 




Figure 2. Eight-leaf pinion. Figure 3. Six-leaf pinion. 

Let us now examine the errors in the order listed above. 

Pinion too large. Referring to Figure 4 it will be ob- 
served that the incoming tooth butts into the end of the pinion 




Figure 4. Pinion too large. Figure 5. Pinion too small. 



64 



A PRACTICAL COURSE IN HOROLOGY 



leaf, thereby stopping the watch. If the error is slight the 
action can be improved by enlarging the wheel, in which case 
the outgoing tooth will propel its leaf farther, resulting in a 
sufficient clearance between the incoming leaf and the in- 
coming tooth. 

Pinion too small. A pinion too small, Figure 5, results 
in a waste of power and much noise, since the outgoing tooth 
propels the leaf even to the point of slipping off before the 
incoming tooth has started to press on a leaf. Hence, if much 
too small, the incoming tooth will fall with a click on the 
leaf. Wear is considerable and an error of this kind should 
never be allowed to pass without correction. The fitting of a 
larger pinion is the only satisfactory solution. 




Figure 6. Depthing too deep. Figure 7. Depthing too shallow. 



Depthing too deep. In a depthing too deep, Figure 6, 
the outgoing tooth continues its action too long, most likely 
with the point affected by excessive wear and a loss of power. 



TRAIN PROBLEMS 65 

Depthing too shallow. A shallow depth, Figure 7, is 
always unsatisfactory. Note that the outgoing tooth cannot 
propel its leaf far enough and the incoming tooth presses on 
a leaf before the line of centers. In a very shallow depth a 
butting action usually results. Enlarging the wheel some- 
times puts the depth in a passable condition. 

Worn pinions. If a watch stops in the train and starts 
with the slightest movement it is well to look at the pinions 
and see if they are worn. Modern wrist watches frequently 
use a six-leaf escape pinion, which when well designed gives 
good service, but has the disadvantage of about 18 degrees 
engaging in friction. Wear is as a result quite pronounced 
and in time will cause trouble. Often the fourth wheel can 
be raised or lowered so that the wheel drives the pinion on 
the previously unused portion. 

Repairing a Train 

Stretching a train wheel. The enlarging of train wheels 
is a job that comes occasionally to the horologist, for it 
happens that some watches are not right when they leave the 
factory. It is, of course, better to fit a new wheel, but there 
are times, particularly if the watch is not an expensive one, 
that enlarging the old wheel is permissible. The fact remains 
that if the wheel was imperfect to begin with and wx make it 
serve its purpose and the watch runs better, we feel justified 
in the act. 

The staking tool may be used to stretch the wheel. It is 
preferred that we work on the lower side of the wheel, so 
that the markings made by the flat punch will not be visible 
when the watch is assembled. We first select a hole in the 



66 A PRACTICAL COURSE IN HOROLOGY 

die to loosely fit either the staff of the pinion or the entire 
pinion as the case may require. The die is so adjusted that 
the rim of the wheel comes under the punch. It frequently 
happens that the part of the rim we wish to work on comes 
over, or partly over, another hole in the die. When this 
happens we may select a larger hole and plug it with pith. 
This will hold a staff in position while stretching the rim 
over a smooth and solid part of the die. 

To stretch a wheel we use a flat- face punch of such width 
as to completely cover the rim including the teeth. Tap the 
punch gently a succession of blows and at the same time turn 
the wheel slowly. This stretches the rim satisfactorily and 
with scarcely any visible punch marks, except where the arms 
are crossed. 

To keep the wheel as nearly round as possible, it is neces- 
sary to stretch the arms, as we should not rely on the cutter 
of the rounding-up tool to bring the wheel circular. Stretch- 
ing of the arms is done separately — ^that is, after the enlarging 
of the rim and teeth — and great care should be exercised 
so as not to overdo the stretching. 

The rounding-up tool. Having finished the stretching 
we are ready to use the rounding-up tool. First, select one 
of the brass beds the diameter of which is sufficient to sup- 
port the wheel and at the same time be perfectly free of the 
cutter. Next, select a cutter that exactly fits the space be- 
tween the teeth. Occasionally, we find wheels the teeth of 
which are too wide. In such cases a wider cutter is required 
in order to reduce the teeth to a width that will satisfactorily 
gear into the pinion. Having selected the cutter and placed 
it in the tool, we center it in line with the guide, a knifelike 



TRAIN PROBLEMS 67 

piece provided for the purpose of making certain that the 
teeth will be cut perfectly upright. Tha wheel to be rounded- 
up is now placed between centers and so adjusted that the 
wheel turns freely and the rim barely touches the brass bed. 
Carefully advance the cutter so as to engage it with the 
wheel. See also that the guide on the cutter is properly 
centered within the space preceding the one that the cutter 
occupies. Cut the wheel but proceed carefully. It is well to 
try the wheel frequently in the watch so as to not overdo the 
correction. 

Problems 

i. How many leaves are required of a pinion so that the action 
begins on the line of centers ? 

2. Name four defects that are sometimes found in gearing. 

3. If a train is noisy what may be the reason? 

4. Why is a shallow depth always unsatisfactory? 

5. If a watch stops frequently in the train, what may be the 
reason ? 



Part II 

CHAPTER TWO 



Jeweling 

The use of jewels as bearings for watches is, without 
question, one of the most important achievements to the 
attainment of precision timekeeping. Nicholas Facio, an 
Italian residing in London, successfully applied jewels to 
watches about the year 1704. The system used by Facio was 
not the same as employed in making the jeweled bearing of 
today. Instead of a hole piercing a jewel, a V-shaped depres- 
sion was ground into the jewel. The pivot was pointed and 
worked into the depressed jewel in much the same way as in 
the present-day alarm clock. The Swiss were quick to 
realize the advantages of jeweling and began experiments 
which finally resulted in the making of jewels as we find 
them today. 

Bezel-Type Jeweling 

Jeweling of the bezel type is a rather difficult task when 
attempted by the usual hand methods. Yet the lathe attach- 
ment intended for such work is practical only when a con- 
siderable number of jewels are to be set. We shall, therefore, 
describe only the hand method — a method which, after the 
necessary experience, will satisfy the needs for all practical 
purposes. Few tools are needed. These are a supply of drills, 
the usual gravers, a jewel graver, Figure 8, and a burnisher, 

Figure 9. 

68 



JEWELING 



69 




Side 
Figure 8, Jewel graver. 



Bottom 




Figure 9. Jewel burnisher. 

The procedure is as follows. Secure in the lathe a piece 
of four-millimeter brass wire. Face off the end of the wire 
and turn a small center. Select a drill slightly smaller than 
the jewel to be used and bore a hole about five millimeters 
deep. With the jewel graver enlarge the hole slightly to true 
it up. Next turn a seat to fit the jewel. The depth should be 
sufficient so that the jewel will lie slightly below the surface 
of the wire. Next, cut a groove close to the opening for the 
jewel with a long, pointed graver. The jewel is now to be 
inserted but should first be moistened with a little oil to 
keep it from falling out. Now rest the burnisher on the 
T-rest; thrust the point of the burnisher in the groove, 



70 



A PRACTICAL COURSE IN HOROLOGY 





Figure 10. 



Figure 11. Bezel type jewels. 



forcing the brass against the jewel, thereby holding the jewel 
in place. A jewel thus set is perfectly secure and the brass 
may be faced off level to the jewel if desired. Figure 10 
clearly shows the work as described above. The dotted lines in 
the figure show the manner in which the setting is turned to 
fit the watch plate. End shake is tried before the wire is cut 
off. This being satisfactory the wire is cut off, turned to 
the proper thickness, and stripped out with a sapphire jewel 
stripper or a highly polished graver. The face is polished 
by sliding the setting on an agate polishing stone or burnish 
file previously prepared with a Number- 1 buff. 

Three styles of bezel-type jewels are used in watches and 
are shown in Figure 11. The method for setting all styles 
is the same. 

Friction Jeweling 
Friction jeweling of watches is a simple and quick method 
of inserting a jewel in a plate, bridge, or setting by means of 
friction. Swiss manufacturers started using this system in 
1920, and since then more and more manufacturers, both 
Swiss and American, have adopted this method. 



JEWELING 



71 



In fitting a friction jewel, the first procedure is to deter- 
mine the depth the jewel is to be set to give the proper end 
shake. This is accomplished by using a machine especially 
made for the purpose, of which there are many varieties on 
the market. First, rest the pusher on the broken jewel and 
adjust the metric screw near the top of the machine so that 
the new jewel may be forced in to the same depth as the 
broken one had been. Second, push out the broken jewel 
and ream out the hole with the smallest reamer that will cut 
away enough metal to give to the plate a clean, straight hole. 
Third, select the proper jewel, the outside diameter of which 
is 1/100 of a millimeter larger than the hole in the plate. 
Remove the burr left by the reamer with the wheel counter- 
sinks and push the jewel in place. 

Replacing a friction jewel. To replace a jewel in a 
watch that had a friction jewel in it before, it is necessary 
only to measure the size of the hole in the plate. This may 
be done by inserting the reamers or using a special gauge 
that is available for the purpose. Having determined the 
hole size, select the jewel required and push it in to the proper 
depth. 







Figure 12. Friction Jewels. 



n A PRACTICAL COURSE IN HOROLOGY 

Fitting jewel in removable setting. If we wish to fit a 
jewel in a setting that may be removed from a plate, as in 
the case of a balance or cap jewel, we need special tools to 
hold the setting securely while reaming out the hole. There 
are various types of tools on the market all of which are 
used in connection with the friction- jeweling machine. 

Several types of friction jewels are shown in Figure 12. 

Problems 

1. What are the tools needed in fitting bezel-type jewels? 

2. Name the styles of bezel-type jewels used in watches. 

3. How do friction-type jewels differ from bezel-type jewels? 

4. How do you determine the depth a friction-type jewel is to be 
set? 



Part II 

CHAPTER THREE 



Making a Balance Staff 

Many horologists consider the making of a balance staff 
a difficult task. We find workmen doing almost anything to 
a watch to avoid the necessity of making a staff. Balance 
bridges are bent up or down. Unsightly graver marks are 
found on plates and bridges. The balance arms are sometimes 
bent out of line in an attempt to permit the balance to clear 
the various parts, and pivots are often ground too short. 
However, the making of a staff is not difficult if the repair- 
man would go about learning the art the same as with any 
other performance requiring skill. No one ever learned to 
play a musical instrument in a few lessons or ever became 
an expert engraver in a few months. 

Preliminary Notes on Staff Making 

Gravers for turning staffs. Three gravers of the styles 
shown in Figure 13 are needed for staff work. A is for 
general use, suitable also for square shoulders and the 
cylindrical portion of cone pivots. B has a rounded point 
for turning the cone portion of the cone pivot. C has the 
point flattened and is used for turning the lower end of the 
staff prior to cutting it off. 

73 



74 



A PRACTICAL COURSE IN HOROLOGY 





ABC 

Figure 13. Gravers for turning balance staff. 
Sharpening the gravers. Sharpening the gravers does not 
seem to be given the attention by the average horologist that 
it should. We have seen v^orkmen trying to cut a square 
shoulder pivot with a graver having a point like a wire nail. 
Naturally their work was unsuccessful, yet these workmen 
did not reflect on the fact that possibly the graver was at 
fault. The graver must have a sharp point. Even the best 
gravers cannot retain a keen edge very long while cutting 
tempered steel. Therefore keep a sharpening stone handy and 
make frequent use of it. Some workmen use an emory or 
carborundum wheel to grind gravers. This should never be 
done, as the point of the graver is frequently softened and 
this point is the most important part. Instead we use two 
stones, a soft Arkansas stone and a hard Arkansas stone. 
The soft stone is for rapid cutting and the hard stone is for 
the final finishing. After grinding the face, sHde the sides on 
the stone so as to produce a flat and smooth cutting surface. 

Making pivots for practice. The beginner should prac- 
tice making square shoulder and cone pivots before attempt- 



MAKING A BALANCE STAFF 



75 



ing the making of a staff. It will be found that the larger 
pieces of pivot wire are excellent for the purpose, as the 
wire is hardened and tempered, ready for use. The length of 
the cylindrical portion of a cone pivot is twice the diameter. 
The length of a square shoulder pivot is three times the 
diameter. 

Measuring for the staff. Now, returning to our problem 
of making a staff, the first act is to take the necessary meas- 
urements, preferably from the watch, for the reason that the 
old staff may not be correct. The well-known Boley gauge 
serves the purpose very well, since it reads both ways, 
between the calipers and from the end of the foot. See that 
the balance bridge lies flat with the lower plate. Now remove 
the cap jewels. Make certain that the hole jewels are 
securely pushed in place. For the full length of the staff A, 
Figure 14, measure from the side of the lower hole jewel to 




Figure 14. 



76 A PRACTICAL COURSE IN HOROLOGY 

the side of the upper hole jewel. The height of the seat for 
the roller table B is found by measuring the distance from th^ 
side of the lower hole jewel to the top of the lever, adding 
enough for clearance and the thickness of the roller table. 
In like manner the distance for the balance seat C is measured 
from the side of the lower hole jewel to the top of the pallet 
bridge, adding for the necessary clearance. The length of 
the upper end of the staft D is found by subtracting the 
length of the lower end to balance seat C from the full 
length A. 

Preparing the steel. Preparing the steel wire for the staff 
is next in order. Select a piece of steel, the diameter of which 
will be a little larger than the largest part of the staff when 
finished. Heat over a gas flame to a cherry red and plunge 
quickly into water. This should be done in a rather dark 
place so as to see better the degree of heat, for if the light 
is too bright, one is apt to overheat the steel and thereby 
ruin it. 

The wire is now too hard to turn and we must therefore 
draw the temper. The wire must be made white in order to 
blue it. This is done in the lathe by holding a piece of fine 
emory paper against the wire. 

The tempering is done by drawing the wire through the 
flame of an alcohol lamp; or, better still, lay the wire on a 
curved sheet of copper, keeping the wire rolling while being 
held above the lamp. A full blue color is satisfactory for 
staffs. 

Turning the staff. Tighten the wire securely in the lathe, 
having extended the wire from the chuck sufHciently to 
include the full length of the staff and about two millimeters 



MAKING A BALANCE STAFF 



77 




Figure 15. Pivot polisher. 



additional. With the hand graver turn the upper end — first 
turning the balance seat to length from the end and almost 
to size, say .05 of a millimeter of the finished diameter. Next 
turn the collet axis, followed by turning the remaining end 
nearly to the size of the hole in the roller table. 

Turning a conical pivot. Turn the cylindrical portion of 
the pivot almost to size. Next, using the graver with the 
point slightly rounded, turn the cone, bringing it down to 
meet the cylindrical portion of the pivot. This is followed 
by cutting the slope between the collet axis and the cone of 
the pivot. The turning of the upper end of the staff is now 
completed and we are ready for the pivot polisher and the 
preparation of the grinding mediums. 

The pivot polisher. The pivot polisher, Figure 15, is a 
very neat little instrument for grinding and polishing. The 
superiority of the instrument over any hand method is un- 
questionable ; it does the work in a factory-like manner and 
polishes the pivot most beautifully. It is to be regretted that 
the pivot polisher is not more generally used. 



78 



A PRACTICAL COURSE IN HOROLOGY 



However, the successful use of the pivot polisher depends 
on the proper preparation of the laps and we shall digress 
for a moment to consider the method by which they are 
made — how to keep them in good condition, and their vari- 
ous uses. We need laps of cast iron, bell metal, and box- 
wood, and the material may be purchased from hardware 
stores and material houses. 

Cast-iron and bell-metal laps. Laps made of cast iron 
and bell metal are used principally for grinding. The mate- 
rial may be purchased in rods of various diameters. For most 
needs of the horologists, rods of about ^ inch in diameter 
will suffice. Having selected the materail, saw off a piece 
about ^2 inch long and bore a hole in it of such size that a 
reamer of the required taper may be used to enlarge the hole. 
The hole is reamed out with a reamer of the same taper as 
the taper chuck shown in Figure 16. The blank is placed in 
the taper chuck for turning with the slide rest. Laps of 
various shapes are needed. Those most used are shown in 
Figure 17. 




Figure 16. Taper chuck. 






Figure 17. Laps for pivot polisher. 



MAKING A BALANCE STAFF 79 

Having turned the laps, the face and side must be filed to 
enable the lap to hold the grinding or polishing medium. 
Filing, it is admitted, has a tendency to destroy its truth, yet 
this is necessary in order to do good work. Experience has 
shown that it is possible to file a lap many times and still 
run practically true. File the lap by laying it face down on a 
Number 4 or 5 file. Holding the lap between the thumb and 
fingers, slide the lap along the cutting teeth of the file about 
an inch or so. The lap should then be turned partly around 
and another stroke made. This crosses the lines, providing 
a suitable surface for the embedding of the abrasive medium. 
Next, prepare the side of the lap. This is done by drawing 
the lap on the file in a direction parallel to the hole in the 
lap. Continue in this manner until the entire circumference 
is filed. 

Boxwood laps. Boxwood laps are used for putting a high 
polish on steel. We may use the slide rest in turning the 
boxwood in the same manner as we did in preparing the 
cast-iron and bell-metal laps. It is important that the grain 
of the wood run parallel with the hole in the lap so that the 
end of the grain touches the work. The lap is filed on the 
face only with a Number file. 

Preparing the grinding material. Now that the laps are 
ready, the preparation of the grinding medium is next in 
order. We proceed as follows : 

Apply a small quantity of oilstone powder to the first com- 
partment of the three-compartment polishing block. Add a 
little watch oil and mix with a small knife or spatula until a 
thin paste is produced. Place the pivot polisher on the lathe 
and adjust the lap spindle so that it stands at the same height 
from the bed as the lathe spindle. Adjust the index at the 



80 



A PRACTICAL COURSE IN HOROLOGY 



base of the polisher to }i degree, so as to give the staff a 
slight taper toward the end when the grinding takes place. 
With the belting so fitted that the grinding surface of the lap 
and the surface of the staff rotate in opposite directions to 
each other, feed the lap up to the work by means of the hard- 
rubber knob at the rear. Apply thinly but evenly the oilstone 
paste to the lap and grind the balance seat. Continue the 
grinding until the balance just fits the seat. Be sure the 
undercutting is deep enough so that the corner of the lap 
does not touch the staff. If this is the case the balance can 
be riveted true and flat when the staff is finished. Next, 
grind the collet axis to size ; after which, grind that portion 
of the staff between the cone of the pivot and the collet seat. 

Grinding and polishing a cone pivot. Clean the work of 
the grinding material with a piece of pith previously dipped 
in benzole and hold it against the staff. Finish cleaning with 
a dry piece of pith. For the cone pivot, the polisher is set 
with the spindle at right angles to the pivot with the index 
set at degree. It is further adjusted so that the center of 

the lap stands above the pivot 
as shown in Figure 18. This 
reduces the straight portion of 
the pivot perfectly cylindrical 
and forms the cone at the same 
time. The shape of the cone 
can be varied by raising or 
lowering the spindle of the 
polisher. 

Instead of the cast-iron lap 




Figure 18. Method of polishing 
conical pivot. 



we now use a bell-metal lap 
and a grinding medium of cro- 



MAKING A BALANCE STAFF 81 

cus. Reduce the pivot, frequently trying the jewel until it 
fits rather closely. Now remove the bell-metal lap and fit in 
its place a boxwood lap and polish the pivot, using a paste of 
diamantine and oil previously prepared on the top section of 
the polishing block. Continue the polishing until the pivot 
fits the jewel freely. 

The slope between the collet axis and the cone of the pivot 
may now be smoothed further by holding a jasper slip in 
the hand. It is then polished with a boxwood slip and 
diamantine. 

Turning hub and roughing out lower end of staff. Now 
that the upper end of the staff is finished we next turn with 
the hand graver a long slope from the balance seat to the 
lower end of the stafif. With the pivot polisher set at the 
necessary angle, grind the slope for most of its length, using 
oilstone powder and oil. Smooth further with jasper slip 
and polish with boxwood lap, diamantine, and oil. 

Next, cut out roughly the lower part with a graver slightly 
flattened at the point. Leave the hub a little longer than 
the finished staff is to be and the roller axis a little larger. 

Cut off the staff and measure the overall length. The staff 
is, of course, a little too long. Place the collet axis in a split 
chuck and stone off the lower end until the staff is worked 
down to the correct length. Remove the staff and remeasure 
the overall length between the calipers of the Boley gauge 
as many times as is required, taking only a little oflf the end 
at a time so that the staff will not be made too short. This is 
positively the most exact method of bringing a staff to the 
correct length. Any other method, such as measuring back 
from a predetermined amount of extra length and cutting 
off after the work is cemented, is likely to result in errors. 



82 



A PRACTICAL COURSE IN HOROLOGY 




Figure 19, Cement chuck. 



The cement chuck. The staff having been brought to the 
correct length we are now ready for the cement chuck. A 
screw brass tightly screwed in a chuck must have a center 
turned in it, deep enough to take the staff up to and in- 
cluding the hub. Figure 19 shows the center with the staff 
in place and properly secured in the cement. 

Setting the staff in the cement chuck. Place a small 
alcohol lamp under the cement brass. Heat sufficiently so 
that the brass will melt the cement and fill the center, at the 
same time running the lathe slowly. While the cement is 
still soft, insert the staff with the thumb and first finger. 
Again keeping the lathe in motion, reheat the brass until 
the cement adheres to the staff. Holding the staff in place 
with a hollowed-out piece of pegwood resting on the T rest, 
continue running the lathe until the cement is slightly cooled. 
Now, true up the staff while the cement is still soft by 
resting the pointed end of the pegwood on the T rest and 
bringing the pointed end against the roller axis. The T rest 
must be placed at an angle so that we may first hold the 
staff in place while allowing the cement to cool. The truing 



MAKING A BALANCE STAFF 83 

follows immediately by holding the pegwood in front of 
and at a right angle to the staff. 

Turning the lower end of the staff. Turn the lower end 
of the staff, measuring from the end up to the roller seat, and 
bring the hub to the correct length. Reduce the roller axis 
to 0.1 of a millimeter of the correct diameter. Set the pivot 
polisher in position with the index adjusted to ^ degree 
taper and grind the roller axis until the roller table slides 
on and wedges tight at a distance about two thirds the way 
up to the hub. The pivot is next turned and polished as per 
instructions already given. 

The staff is now removed from the cement chuck. Fill the 
boiling pan or test tube with alcohol and boil off cement. 

Finishing the ends of the pivots. The ends of the pivots 
have not yet been finished but it is well first to try the staff 
in the watch and test for end shake, so we may know better 
in what manner to proceed. Since the measurement for the 
length was made without allowance for end shake, it usually 
follows that a slight touching up of the ends of the pivots is 
needed. To accomplish this, place the staff in a split chuck 
and flatten each end slightly, using a hard Arkansas slip. 
Polish further with a jasper slip and finally finish with a 
hardened steel burnisher and round the corners slightly. 

COMMON ERRORS IN STAFF MAKING 

Beginners are very apt to overlook certain important 
details in the turning of a staff. One of the most common 
is the absence of a square shoulder for the roller seat, so 
that the roller table will not lie flat to the full diameter 
of the hub. Undercutting for this purpose is not objection- 



84 A PRACTICAL COURSE IN HOROLOGY 

able, for many watch factory staffs are made in this manner. 
In like manner the balance wheel should fit the staff, that is, 
flat to the full diameter of the hub. 

The collet axis, the balance axis, and the roller axis should 
show a definite taper so that the parts in question will fit 
properly. This is easily attained with the pivot polisher, for 
the instrument may be set to the desired taper. In using 
the hand graver, the eye must be trained to recognize a 
suitable taper. 

The straight portion of the pivots should be cylindrical 
and not tapering as we sometimes find them, and the cones 
should be shaped alike. Again these conditions are made 
possible with the pivot polisher and likewise more difficult 
to attain without it. Satisfactory undercutting at the top of 
the balance seat is also important. 

Success will be realized if the beginner will pay strict 
attention to detail, and it will be found that staff making is 
not as difficult as some workmen would have you believe. 

Problems 

1. What gravers are needed in turning a staff? 

2. How do you measure for a staff? 

3. Explain in detail the hardening and tempering of the steel for 
staff making, 

4. Name the steps in turning the upper end of a staff in their 
proper order. 

5. How do you go about bringing the staff to the proper length ? 

6. Must the staff run absolutely true in the cement chuck? 

7. Name the points of particular importance in staff making. 



Part II 

CHAPTER FOUR 



Pivoting 

Success in pivoting depends largely on the quality of the 
drills and in keeping the drills sharp. It is better to drill the 
pinions without tempering, yet there are times when temper- 
ing must be resorted to, and in such cases a small copper 
wire shaped as shown in Figure 20 may be used. The leaves 
of the pinion are held in a pin vise or parallel pliers to prevent 
the heat from spreading to that part while the copper is 
heated over an alcohol lamp. The end of the pinion is 
tempered to a blue color. 

The pinion may be centered in the split chuck if it runs 
true; otherwise, the cement chuck must be used. Face off 
the pivot to the square shoulder and turn a small center. 
Place the pivot drill in a pin vise and drill a hole, which 
should be a little deeper than the length of the average pivot. 
Should the drill cease to cut, sharpen it immediately. A dull 
drill is apt to burnish the bottom of the hole, presenting a 
serious problem. Should this happen, flatten the end of the 
drill, which usually results in the drill cutting again. The 
hole having been drilled to a satisfactory depth, secure a 
piece of pivot wire in a pin vise, and file sufficiently to just 
start and hang in the hole in the pinion. Caution should be 
exercised in filing the wire to show as little taper as possible. 



85 



86 



A PRACTICAL COURSE IN HOROLOGY 



Roll the wire as the filing takes place so as to leave the wire 
round. Finish with the Arkansas slip. Next, force the wire 
in the hole, cut off the wire with the cutting pliers, and tap 
the plug with a small hammer, thereby forcing the plug 
securely in the hole. The pivot is turned nearly to size with 
the hand graver and finished to the proper size as already 




III I I I I I I-T1 




I I I I II umi 



Figure 20. Copper wire in position for tempering pinion. 



PIVOTING 



87 



explained. It is advisable to undercut the square shoulder 
slightly before polishing in order to keep the corner sharp as 
shown in Figure 21. 




Figure 21. 

Problems 

1. What are the important points to remember in drilling a pinion 
for repi voting ? 

2. If a drill ceases to cut what may be done so that the drill will 
cut again ? 

3. What would be the most Hkely reason for a pivot working 
loose when turning with the graver ? 



Part II 

CHAPTER FIVE 



Fitting Balance Springs 

In fitting balance springs the first procedure is to deter- 
mine the number of vibrations of the balance per minute. 
This may be found in any watch fitted with a second hand 
by first dividing the number of teeth in the fourth wheel by 
the number of leaves in the escape pinion ; then, by multiply- 
ing the quotient by twice the number of teeth in the escape 
wheel, we have ascertained the number of vibrations of the 
balance per minute. 

For example, the fourth wheel has 80 teeth; the escape 
pinion has 8 leaves ; the escape wheel has 1 5 teeth. 

80X30 



8 



= 300 vibrations of the balance per minute 



Other examples are as follows : 
72X30 



8 

64X30 

8 



= 270 vibrations per minute 



= 240 vibrations per minute 



In watches where the fourth wheel does not register 
seconds we have to go back to the center wheel, as shown in 
the following examples : 

54 X 50 X 48 X 30 



6X6X6 



= 18,000 vibrations per hour 



88 



FITTING BALANCE SPRINGS 



89 



64 X 66 X 60 X 30 
8X8X6 



= 19,800 vibrations per hour 



Fitting a Flat Spring 

In fitting a flat spring to a watch, it is necessary to know 
the proper size. This is determined by centering the spring 
to the balance jewel as shown in Figure 22. The correct 
radius is located on the first coil that stands inside the 
inner regulator pin. Next, we desire to determine the ap- 
proximate strength, which may be found by suspending the 
balance and spring an inch or two above the bench. If the 
distance between the point where the spring is held by the 
tweezers and the rim of the balance is J^ inch, the spring 
is approximately of the strength 
desired. It does not matter if the 
balance is large or small ; the 
distance remains practically the 
same. Of course, this does not 
necessarily decide that a particu- 
lar spring is to be used, but it does 
eliminate all unnecessary attempts 
at vibrating a spring that is posi- 
tively unsuited for a balance. 

After trying several springs, 
finally selecting one that conforms 
to the above test, the next pro- 
cedure is to vibrate the spring. 
This can be done by counting the 
vibrations or by using an instru- 
ment commonly known as a vi- 
brator. Since nearly all watches Figure 22. Method for deter- 

r . J '.1 mining correct size of flat 

of recent years are made with a ^^^^^^ ^^^-^^^ 




90 A PRACTICAL COURSE IN HOROLOGY 

300-beats-per-minute train, it is convenient to use the vibrator, 
about which more will be written in the next paragraph. For 
the other trains it will be necessary to count the vibrations, 
using a watch of known accuracy. The counting is done with 
every vibration that takes place in a clockwise direction ; that 
is, the return vibration is not counted. The usual practice is 
to suspend the balance and spring by means of tweezers sup- 
ported in the lathe bed. The lower pivot of the balance staff 
rests on the watch crystal. Thus, counting for one minute 
there would be 150 counts for a 300-beat train, 135 counts 
for a 270-beat train, etc. 

The vibrator. Vibrators may be purchased from material 
houses or may be made from an old balance and spring 
properly timed. Material catalogs may be consulted if the 
horologist desires to make his own instrument. 

The method of using the vibrator is that of comparison — 
that is, watching the balance spring to be vibrated and the 
vibrator balance and noting whether or not both vibrate in 
unison. We may slide the tweezers as much as a half a coil 
in toward the center of the spring or out a quarter of a coil 
toward the outside without altering the radius too much for 
a satisfactory fitting of the spring. 

Having found a spring that vibrates properly, break it off 
one quarter of a coil beyond the vibrating point. Next the 
spring is pinned in at the stud and the balance bridge with 
balance and spring attached is placed in the watch for the 
final timing. 

Fitting the Breguet Spring 
The fitting of the Breguet spring to a watch involves all 
of the work of fitting a flat spring, plus the forming of the 



FITTING BALANCE SPRINGS 



91 




Figure 23. 



overcoil. The diameter need not be so exacting; however, 
it should not be larger than one half of the diameter of the 
balance, including half of the screws. 

We shall assume that the watch in need of a new spring is 
ideally suited to the Lossier terminal shown in Figure 23. 
The procedure is as follows: Vibrate the spring in the flat 
and break off the spring about two millimeters beyond the 
vibrating point. The length of the active portion of the 
overcoil must be determined and for this we must resort 
to a bit of calculation. We desire to find the length of the 
portion BC and AB (Figure 23). The following formula 
gives us the length of BC. 

Number 1 : 

2 CO X 3.14 X S3 



BC = 



360 



92 A PRACTICAL COURSE IN HOROLOGY 

The radius CO multiplied by 2 gives us the diameter of 
that part of the overcoil concentric to O. Hence the diameter 
2 CO multiplied by 3.14 gives us the circumference, which in 
turn is divided by 360 to determine the length of I degree. 
Multiplying the length of 1 degree by 83 degrees gives us 
the length of 5C. 

We now desire to know the length of AB, which, when 
added to BC, gives us the total length of the curve. 

Number 2: 

(AO + OB) 3.14 



AB = 



2 

Since AO + OB equals the diameter and since one half of 
the circumference is required, it is only necessary to multiply 
AO + OB by 3.14 to give the circumference and divide by 2. 

Now, taking a practical example, let us suppose that the 
diameter of the spring is 8 millimeters. The radius would be 
4 millimeters. According to the elements of the curve, CO 
is .67 of the radius. Thus : 

CO = 4 X .67 = 2.68 mm. 
Substituting this value for CO in equation Number 1 we 
may determine the angular distance for BC. 

5.36 X 3.14 X 83 

BC = = 3.88 mm. 

360 

Substituting again for equation Number 2 we learn the 

length of AB. 

^ (2.68 + 4)3.14 ^^^^ 

AB = -^ -^— ^ = 10.48 mm. 

2 

For the full length we add 3.88 and 10.48, giving us 14.36 
millimeters. 



FITTING BALANCE SPRINGS 93 

We now grasp the spring at the point intended for the 
regulator pins and slide the spring along a scale in order 
to determine the actual length of the curve, allowing for 
sufficient extra length for the spring to reach the stud. It 
is permissible to make a slight mark at this point to indicate 
the starting point of the curve. 

Raising the overcoil. We are now ready to raise the 
overcoil. This is accomplished with rather heavy tweezers. 
Grasp the spring with the tweezers about 25 degrees from 
that point where the inward bend starts. Hold the spring 
tightly and press into a piece of softwood until the outer coil 
takes on the shape shown in Figure 24. Turn the spring 
over and, measuring 22 degrees from the first bend, bend 
again until the outer coil lies level wnth the body of the spring, 
Figure 25. Bring in the raised portion so that the overcoil 
takes the form shown in Figure 23. To form the overcoil, 
tweezers of many shapes are desirable. These are shown in 
Figure 26. Alterations should be made gradually, being 
careful not to bend the spring too much, for in so doing, the 




Figure 24. First bend in forming overcoil. 



Figure 25. First and second bends in forming overcoil. 



94 



A PRACTICAL COURSE IN HOROLOGY 




Figure 26. Balance spring tweezers. 

spring is liable to be considerably weakened and possibly 
broken. 

The Lossier curve is not adaptable to most small watches 
for the reason that the curve is brought in nearer to the 
central portion of the total mass than these watches will 
permit. However, the above analysis may be used as a basis 
for calculating other forms, since the length of the curve 
does not vary very much. The forms more adaptable to 
present-day small watches are shown in Figures 27 and 28. 
In Figure 27 note that the radius of the overcoil along the 
path of the regulator pins is three fourths of the radius of 
the spring. The length of the curve is 180 degrees plus 20 
degrees. Again in Figure 28 the portion of the overcoil at 
the regulator pins is placed in a position nearly in line with 
the full radius of the spring. In this type, the curve usually 
takes the form shown in the illustration and the bend for 
the overcoil starts at a point opposite the regulator pins. 

Converting a Flat Spring into a Breguet 
In order to obtain a closer position and isochronal rate in 
a watch originally fitted w4th a flat spring, it is sometimes 
desirable to make the spring over into a Breguet. In many 



FITTING BALANCE SPRINGS 



95 




Figure 27. 




Figure 28. 



96 A PRACTICAL COURSE IN HOROLOGY 

watches where there is room enough under the balance 
bridge this can be done without much difficulty. The curve 
suitable for a case of this kind is composed of quadrants 
of two circles connected by a straight line as shown in 
Figure 29. The radii of the circles A and B are equal to 
about one half of the radius of the spring. Owing to the 
spiral nature of the spring the radius of the circle 5 is a 
little longer than that of circle A. The dotted line CC shows 
the outer coil of the flat spring and the solid line DD shows 
the same coil after it was formed into a Breguet. Figure 30 
shows the same spring with the circles and dotted lines 
removed. A clearer picture of its relative form is thus 
realized. The only change to be made to the watch is to 
shorten the regulator pins and raise the stud. The curve is 




c \ 



Figure 29. 



FITTING BALANCE SPRINGS 97 




Figure 30. 

theoretically correct and if properly executed it will be found 
to be equal to any type of overcoil. 

Eccentric Motion of the Spring 
After a spring has been fitted to a watch an eccentric 
vibration may be observed due to a faulty form of the over- 
coil. The rules for correcting the eccentric motion are as 
follows : 

1. If the eccentric motion takes place opposite the regula- 
tor pins (as in a flat spring), bring in part of the overcoil 
toward the center of the spring. 

2. If the eccentric motion takes place on the same side as 
the regulator pins, move part of the overcoil hack into the 
main body of the spring. 

Truing Balance Springs 

The attainment of successful balance-spring truing comes 
only with continued practice and patience. It is one of those 



98 



A PRACTICAL COURSE IN HOROLOGY 



accomplishments that are difficult to teach through the 
printed page. For this reason we shall make only a few 
general statements as to the manipulative operations. 

In truing the round it is never necessary to manipulate the 
spring beyond the first quarter of the inner coil, assuming 
that the spring is true except for that portion which is likely 
to be out as a result of pinning in at the collet. Figure 31 
shows a spring divided into quarters. The sections are 
referred to as first quarter, half, third quarter, and pinning 
point. The spring may be wide at or near any of these points 
and the procedure in truing consists of pushing or twisting 
the spring in the desired directon. The dotted lines in Figure 
32 show the manipulating required to bring the spring true 
in the round. 



2 




Figure 31. 



FITTING BALANCE SPRINGS 



99 





Figure 32. Dotted lines indicate manner in which the balance spring is 

twisted to true in the round. 



In truing the flat the spring is pushed down or raised up 
at those points that are high or low. 

Problems 

1. Give the formula for determining the number of beats per 
minute of a watch. 

2. How do you determine the correct size of a flat spring for a 
given watch ? 

3. How do you determine the correct size of a Breguet spring? 

4. What is the correct length of a Lossier outer curve if the 
diameter of the balance spring is 6.5 millimeters ? 

5. How do you go about forming the overcoil ? 

6. How do you correct an eccentric motion of the spring that 
takes place opposite the regulator pins ? 

7. How do you correct an eccentric motion that takes place on 
the same side as the pins ? 



Part II 

CHAPTER SIX 



Escapement Adjusting 

In this study of the lever escapement we are particularly 
concerned with practical benchwork ; that is, the placing in 
good order the escapement of a given watch. It is important, 
however, that we have some understanding of the theoretical 
principles involved and w^e shall indulge, therefore, in as 
much theory and escapement design as is necessary to aid 
in the execution of practical repair problems. 

The importance of understanding the escapement cannot 
be overestimated. Large pocket watches often function 
quite satisfactorily with faulty escapements but with small 
wrist watches it is very different. The escapement in small 
ladies' watches must be practically perfect. Since the larger 
per cent of the watches that are brought in for repair today 
are wrist watches there is need for greater skill in escapement 
work. Inadequate knowledge results only in an endless 
amount of trouble with watches that stop persistently, though 
perhaps only occasionally. Erratic rates, too, can be traced 
to defective escapements, 

Wheel and Pallet Action 
The best way to obtain a practical understanding of the 
escapement is to proceed step by step, studying the separate 

100 



ESCAPEMENT ADJUSTING 101 

functions, after which the escapement action as a whole will 
be analyzed. Our attention will first be directed to the prob- 
lem of banking the escapement to the drop. 

Banking to the drop. The term "banked to the drop" 
means that the banking pins are turned in such a position 
that a tooth of the escape wheel will slide past the letting-off 
corner of a pallet, thereby permitting the lever to reach the 
opposite banking pin. 

In order to effect a banked-to-the-drop condition, it is 
first necessary to turn in both banking pins. The impulse 
face of one pallet will now show contact with the impulse 
face of a tooth of the escape wheel, but owing to the fact 
that the banking pins have been turned in, the tooth is unable 
to pass the letting-off corner of the pallet. Let us assume that 
the impulse faces of the receiving pallet and a tooth show 
contact. Turn the banking pin, against which the lever now 
rests, away from the line of centers slowly until a tooth 
passes the letting-off corner of the receiving pallet. At this 
instant another tooth will lock on the locking face of the dis- 
charging pallet. Next, move the lever to the opposite banking 
pin, resulting in a contact being shown between the impulse 
faces of the discharging pallet and a tooth. Turn the banking 
pin, against which the lever rests, away from the line of 
centers until the tooth drops as already explained, and the 
job of banking to the drop is completed. 

DROP LOCK 
The extent of the lock on the pallets after an escapement 
has been banked to the drop is called drop lock. This lock 
takes place the instant a tooth drops on the locking face 
of a pallet. 



102 A PRACTICAL COURSE IN HOROLOGY 

In Swiss watches and some American wrist watches it is 
not practical to bank the escapement to the drop because of 
the fact that the banking pins are not supplied with eccentric 
screws. In this case the usual practice is to slowly move the 
lever until the escape tooth drops and at the same instant 
cease moving the lever and take note of the extent of the 
lock on the pallets. A slight additional motion of the lever 
should be required before the lever will reach its bank, which 
is, of course, beyond that of drop lock. The additional motion 
is called slide and will be considered further in the later 
portion of this chapter. 

Correct drop lock. Drop lock is a varying quantity, de- 
pending on the position of the pallet stones in the pallet 
arm, but it should be as light as possible consistent with 
proper safety in action. A drop lock of 1^^ or 2 degrees is 
the amount usually adopted for pocket watches, whereas 2 or 
3 degrees is allowed for wrist watches. 

Altering the drop locks. If the drop locks are too light 
or unsafe, a deeper lock can be had by moving out one or 
both pallets. Likewise if the drop locks are too deep a lighter 
lock can be had by moving in one or both pallets. It will 
be observed that when one pallet is moved the lock is changed 
on both pallets and any alteration of the pallets should always 
be followed by rebanking to the drop. 

Out of angle. The lever should move an equal distance 
on either side of the line of centers. If the lever does not 
move an equal distance the lever is said to be "out of angle." 
If the drop locks are deep, out of angle can be corrected by 
moving in the pallet on the side where the lever's angular 
motion is shorter from the line of centers. If the drop locks 



ESCAPEMENT ADJUSTING 103 

are light, out of angle can be corrected by moving out the 
pallet on the side where the lever's angular motion is longer 
from the line of centers. If the drop locks are satisfactory, 
out of angle (if slight) can be corrected by carefully bending 
the lever as close as possible to the pallet staff. This can be 
done by holding the lever with a small pair of pliers and 
bending it with the thumb and first finger. And remember — 
rebank the escapement to the drop after each alteration. 

THE DRAW 
The force that keeps the lever against its bank is called 
"draw." It exists because of the inclination or slant of the 
pallet's locking face and the shape of the tooth. It will be 
observed in Figure 36 that the receiving pallet inclines in the 
direction toward the pallet center and the discharging pallet 
inclines in the same direction but away from the pallet 
center, thus forming the angle for draw. A draw of 12 
degrees is considered sufficient by most horologists. 

Examining the draw. Take a watch oiler or similar small 
tool and lift the lever away from its bank, but not far enough 
to cause the escapement to unlock. Now release the lever, 
and in so doing the lever will, if the escapement is correct, 
return immediately to its bank. Try this again with the lever 
against the opposite banking. The lever should at once return 
to its bank. 

The purpose of draw is to avoid unnecessary friction be- 
tween the guard pin and the roller table. When the watch 
receives a jolt the lever is thrown away from its bank and 
the guard pin comes in contact with the roller table, but the 
action of draw causes the lever to return at once to its bank. 
Draw should be sufficient to effect the return of the lever 
to its bank for all ordinary conditions. If the draw is exces- 



104 A PRACTICAL COURSE IN HOROLOGY 

sive, there will be an unnecessary recoil of the escape wheel, 
causing a condition whereby too much of the force of the 
balance and spring is used in unlocking the escapement. The 
result is a waste of power and a shorter arc of motion of 
the balance. 

Altering the draw. As a rule want of draw is due to in- 
sufficient angle of a pallet stone. In most cases the jewel may 
be tilted in the pallet arm. If the jewel fits tightly, a thinner 
jewel may be substituted or the slot may be widened to give 
the jewel more angle. 

THE DROP 

Drop is defined as the free motion of the escape wheel at 
the time when one tooth passes the letting-off corner of 
a pallet and another tooth comes in contact with the locking 
face of the opposite pallet. Drop may be also defined as the 
distance a tooth of the escape wheel travels without doing 
any work. 

Examining the drop. With a tooth locked on the re- 
ceiving pallet observe the space that separates the letting-off 
corner of the discharging pallet from the heel of the tooth. 
Now move the lever to the opposite banking pin, thereby 
causing a tooth to lock on the discharging pallet. Next ob- 
serve the space that separates the letting-off corner of the 
receiving pallet from the heel of the tooth. 

Of course, the drop should be equal, but we do not always 
find it so. A small drop on the receiving pallet is called 
"close outside," and a small drop on the discharging pallet 
is called "close inside." These errors call for correction. If 
close inside, tip one or both pallets away from the pallet 
stafif. If close outside, tip one or both pallets toward the 
pallet staff. 



ESCAPEMENT ADJUSTING 105 

Usually, moving one pallet is all that is necessary. The 
question may arise as to which pallet to move. This would 
depend largely on the condition of the draw, the drop locks, 
and the angular motion of the lever from the line of centers, 
for we shall soon learn that whenever a pallet is shifted for 
any reason all of the above conditions are altered. 

SHAKE 
Shake is defined as that space separating the letting-ofif 
corner of the pallet from the heel of a tooth when the 
opposite pallet is locked at the lowest locking corner. Shake 
is similar to drop except that the examination for shake 
occurs at the time when the tooth is locked at the lowest 
locking corner of the pallet. When moving the lever away 
from its bank but not enough to unlock the escapement, it 
will be observed that a slight recoil of the escape wheel has 
taken place. This action lessens the space between the letting- 
off corner of the pallet and the heel of the tooth, showing 
that shake is always less than drop. If an escapement has no 
shake the watch will stop. 

THE LIFT 
Modern escapements have a total lift of 83^ degrees. The 
amount of lift separately on tooth and pallet is designed in 
varying proportions in different makes of watches. The lift 
in a club-tooth escapement is a very complicated action and 
requires considerable study to understand it. It will be 
noticed that the lift does not function exactly the same on 
both pallets. On the receiving pallet the wheel moves up as 
also does the pallet and the pallet's locking corner moves with 
greater velocity than the letting-off comer. On the discharg- 
ing pallet the condition is reversed and the wheel moves 



106 



A PRACTICAL COURSE IN HOROLOGY 






Figure 33. Lift on receiving pallet 





Figure 34. Lift on discharging pallet. 



down while the pallet moves up. Also, the letting-off comer 
of the discharging pallet moves with greater velocity than 
the locking corner. 

A good action between the wheel and pallets is shown in 
Figures 33 and 34. Note that as the tooth leaves the locking 
faces of the pallets, the toe of the tooth shows contact only 
with the pallet's impulse faces. Contact in this manner con- 
tinues completely across the pallets until finally the two 
impulse faces meet nearly parallel, and after that the heel 



ESCAPEMENT ADJUSTING 107 





Figure 35. Curved pallet stones by A. Lange & Son. 

of the tooth passes the letting-off corner of the pallets. The 
heel of the tooth comes into action quicker on the discharging 
pallet ; also there is a tendency for the tooth to move faster 
along that portion of the lifting plane near the letting-off 
corner. The opposite takes place on the receiving pallet; 
that is, the action is faster at the start of the lift. 

To obviate this difficulty, A. Lange and Sons some years 
ago made watches with escapements so designed that the 
receiving pallet had a convex lifting face, the discharging 
pallet a concave lifting face, and the lifting faces on the teeth 
were also curved (Figure 35). This system, it will be ob- 
served, would cause the lifting action of the tooth to func- 
tion at a more nearly constant velocity. 

Loss in the lift. There is a definite amount of loss of 
lift on the discharging pallet of the club-tooth escapement. 
This is shown in Figure 36. 5C is a straight line but the 
escape wheel describes the circle DD ; hence these lines must 
deviate from each other. In order that 5^^ degrees of lifting 
take place, a lifting angle of 6% degrees is required of the 
discharging pallet. However, this loss of lift is a problem to 
be reckoned with principally in the equidistant pallets. In 
the circular pallets the loss of lift is very little for the reason 



108 



A PRACTICAL COURSE IN HOROLOGY 




p< 

c 
a 

CO 

•3 






ESCAPEMENT ADJUSTING 



109 




CO 

u 



CO 



no A PRACTICAL COURSE IN HOROLOGY 

that the tangents are planted mid-way between the locking 
and letting-oif corners of the pallets (Figure 37). The loss 
of lift in the semitangental escapement is also small, usually 
amounting to about one-half degree (Figure 40). 

The Fork and Roller Action 
In this study of the lever escapement we have up till now 
concerned ourselves with such factors as banking to the drop ; 
drop lock, draw, drop, shake, and the lifting action. These, 
it is observed, constitute the escape wheel and pallet action. 
We are now ready to investigate the fork and roller action 
which is quite a study in itself. There is, however, a definite 
relationship between the two actions and the last mentioned 
cannot be successfully studied without taking particular 
account of the former. Hence the wheel and pallet action 
in its entirety was outlined first and it is assumed that our 
escapement is in satisfactory adjustment up to this point. 

The lever's angular motion. We have stated that the 
combined lift on the tooth and pallets is S}^ degrees. Adding 
this to a drop lock of 1^ degrees, the total angular motion 
of the lever becomes 10 degrees. The lever's angular motion 
of 10 degrees should be all that is necessary for the roller 
jewel to pass in and out of the fork satisfactorily without 
catching. Now, placing the balance in the watch, we are 
ready to try the tests for the safety locks. These are the 
guard safety test and the corner safety test. Using a strong 
eyeglass in making the tests, we proceed as follows. 

SAFETY LOCK TESTS 
Guard safety test. Rotate the balance so that the roller 
jewel stands outside of the fork and with the first finger 



ESCAPEMENT ADJUSTING 



111 




Figure 3S. Guard safety test 

hold the balance in this position. Now, with a watch oiler or 
similar small tool, lift the lever away from its bank, thereby 
causing the guard finger to come in contact with the edge 
of the safety roller as shown in Figure 38. With the lever 
held in this position examine the remaining lock on the pallet. 
This remaining lock is called a safety lock and it should 



112 A PRACTICAL COURSE IN HOROLOGY 

represent one half of drop lock or }i 
degree of lock. The test should next 
be tried on the opposite pallet and a 
similar lock should be found. 

Corner safety test. Starting with 
the roller jewel in the fork slot, rotate 
the balance slowly until such time that 
one tooth passes the letting-off corner 
of a pallet and another tooth comes in 
contact with the locking face of the 
opposite pallet. A slight additional 
motion applied to the balance will bring 
the roller jewel in a position opposite 
to the slot corner. With the balance 
held in this position, lift the lever away 
Figure 39. from its bank, thereby causing the slot 

Corner safety test. corner to come in contact with the 
roller jewel as shown in Figure 39. With the lever held thus, 
examine the remaining or safety lock. Try this test on the 
opposite pallet and if the safety lock is the same on both 
pallets the lever's angular motion from the line of centers is 
practically equal. 

The safety lock shown by the comer test should be the 
same as the safety lock shown by the guard test ; that is, the 
safety locks from both sources should show }i degree of 
lock. Note — Although this is correct in theory it does not 
always work out in practice. If the safety lock shown by the 
corner test is less than the safety lock shown by the guard 
test — that is, if the corner freedom is greater than the guard 
freedom — no harm results, provided that the locking of both 
pallets is safe on all of the teeth of the escape wheel. How- 




ESCAPEMENT ADJUSTING 113 

ever, if the corner freedom is less than the guard freedom, 
the roller jewel is apt to catch on the tips of the horns of the 
fork, causing the watch to stop. 

The curve test. To test an escapement for the error stated 
above, we use what is called the curve test. To apply this 
test it is necessary to rotate the balance so that the roller 
jewel stands completely past the horns of the fork. Next, lift 
the lever away from its bank, thereby causing the guard 
finger to come in contact with the safety roller and, while 
the lever is held thus, turn the balance so that the roller jewel 
will move toward the fork slot. If the roller jewel passes the 
horns of the fork and enters the slot, the escapement is satis- 
factory as far as this test is concerned. If the roller jewel 
catches on the tips of the horns, a number of faulty condi- 
tions could be present. The most common are: guard finger 
too short, roller jewel advanced too far, or lever too long. 

The drop locks being correct, it is now apparent that the 
guard, corner, and curve tests aid in determining the correct 
length of the lever. It is common practice in escapement 
work to lengthen the lever by stretching it or to shorten it 
by grinding the horns as the case may require. So bear in 
mind that the condition of the drop locks is first taken ac- 
count of and the fork and roller action afterward. 

Slide 
Up to this point in our discussion, the escapement has 
been banked to the drop. The subject of slide is next in 
order. The opening of the banking pins beyond that of drop 
lock is called slide. Slide should be large enough to permit 
freedom for escaping; usually }^ degree is considered suffi- 
cient. Any amount more than this only increases the angular 



114 A PRACTICAL COURSE IN HOROLOGY 

motion of the lever and its connection with the balance, 
resulting in an increased unlocking resistance, a shorter arc 
of motion of the balance, and poor timekeeping. The banking 
pins should be placed as far as possible away from the pallet 
center so as to lessen the strain on the lever pivots should 
the escapement overbank. 

Slide is the last adjustment, the finishing touches, so to 
speak, in escapement adjusting. 

The Theoretically Correct Escapement 

As sort of summary of our discussion of the escapement, 
let us consider the specifications of a correctly designed 
escapement. 

When banked to the drop, the specifications should read 
as follows : 



Drop lock 


V/2° 








Safety lock 


Va° 








Corner freedom 


Ya" 


(1/°- 


-Ya'- 


= Ya") 


Guard freedom 


Ya' 


(1/°- 


-Ya"' 


= Ya°) 



With slide added, the specifications now read : 
Total lock 2 ° (lJ^° + ^°=2°) 

Safety lock ^° 



Comer freedom \y^° (2° - 


-^°-iM°) 


Guard freedom 1^4° (2° - 


-^°-iK°) 


Slide lock ^° (2°- 


-ly-y^) 


Droplock 1>^° (2°- 


-y^-iyn 



Drawing the Lever Escapement 

This chapter would not be complete without adding a few 
lines about drawing the lever escapement. We have selected 



ESCAPEMENT ADJUSTING 



115 




1 

a 

s 

«> 

c 
bo 



it 



4> 



116 A PRACTICAL COURSE IN HOROLOGY 

for this purpose the semitangental escapement shown in 
Figure 40, as it comprises the best and latest design in 
escapement construction. 

The materials needed for drawing are : a drawing board, 
drawing instruments, pencil, large and small protractors, 
drawing paper, and India ink. A T square, two triangles, 
and a French curve would be desirable although not absolutely- 
necessary. 

Study the drawing thoroughly before starting. Note at 
what points the various angles originate. It is important, 
also, to make the drawing on a large scale so as to minimize 
the errors arising from imperfections in our drawing instru- 
ments. Students who have no knowledge of mechanical 
drawing would do well to read several chapters in any good 
textbook on mechanical drawing. 

Recommended texts: 

Roberts, William E., Beginning Mechanical Drawing. The 

Manual Arts Press, Peoria, Illinois, 1943. 
Bennett, Charles A., Beginning Problems in Mechanical 

Drawing. The Manual Arts Press, Peoria, Illinois, 1934. 

Practical Application of Escapement Tests 

Knowledge of the several escapement tests will be of little 
value unless they reveal the necessary corrections to be made 
in defective escapements. The purpose of this section is, 
therefore, to show the application of the several tests as a 
guide to escapement alterations. All of the examples listed 
in the following pages are based on actual problems experi- 
enced and corrected by the writer in the course of practical 
work at the bench. 



ESCAPEMENT ADJUSTING 117 

In all cases it is first assumed that the escapement was 
banked to the drop. 

Adjustment 1. 

Drop locks — correct 
Guard freedom — excessive 
Corner freedom — correct 

In this escapement the guard freedom was greater than the 
corner freedom. When the curve test was tried the roller 
jewel would catch on the horns of the fork. The correction 
consisted of flattening the end of the guard finger. For this 
purpose a punch should be ground so that the end will fit 
in the fork slot. A very light tap with a small hammer will 
do the work. In some cases the guard pin may be lengthened 
by forcing it further through the piece in which the pin is 
placed. In this case, however, the pin could not be length- 
ened, and, besides, the crescent in the safety roller was 
rather wide. After flattening the guard finger the sides were- 
stoned to provide the necessary guard freedom. The guard 
safety test, the comer safety test, and the curve test were 
tried and all tests were found satisfactory. The banking 
pins were opened for slide. 

Adjustment 2. 

Drop lock — correct 
Guard freedom — excessive 
Corner freedmn — excessive 

When the guard test and the comer test were tried the 
pallets would recede from the tooth to such an extent that 
the impulse faces of both tooth and pallets would show 



118 A PRACTICAL COURSE IN HOROLOGY 

contact; that is, the safety locks did not function on some 
of the teeth. Since the drop locks were correct the excessive 
guard and corner freedom suggested that the error was that 
of a short fork. The lever was therefore stretched and the 
guard test and corner test were again tried. It will be well 
to state at this time that the stretching should be done a very- 
little at a time, frequently making use of the tests. To 
stretch a lever, place a small, flat- faced stump in the staking 
tool and lay the lever thereon. Using a punch with sides 
flattened, lightly tap the lever. If the lever becomes bent 
during the act of stretching, turn it over on the stump and 
give it another very light tap, using the same punch. Having 
found the guard and corner tests satisfactory after stretching 
the lever, the banking pins are opened for slide. 

Adjustment 3. 

Drop locks — deep 

Guard freedom — satisfactory 

Corner freedom — satisfactory 

Since the drop locks were deep, the first act was to move 
in both pallet stones and rebank to the drop. It was found 
after rebanking to the drop that the roller jewel would not 
pass in and out of the fork. The roller jewel was reset in a 
position a little nearer to the balance staflf. Replacing the 
balance, the corner test was tried and the comer freedom 
was found to be correct, but when trying the guard test no 
guard freedom was found. This example being an escape- 
ment of the single roller type, the guard pin was bent away 
from the roller table. The guard test, the comer test, and 
the curve test were tried and all were found satisfactory, after 
which the banking pins were opened for slide. 



ESCAPEMENT ADJUSTING 119 

Adjustment 4. 

Drop locks — light 
Guard freedom — none 
Corner freedom — faulty 

Since the drop locks were light the first act was to increase 
the drop lock. This made it necessary to spread the banking 
pins to a new banked-to-the-drop position. A proper guard 
freedom and safety lock were found when trying the guard 
test but when the corner test was tried the freedom was 
found to be excessive and the locking was not safe on all 
of the teeth. Examination showed that the roller jewel 
tipped slightly toward the staff. The roller jewel was reset 
in a position parallel with the staff and the corner test was 
again tried, this time showing the correct comer freedom and 
safety lock. As a final check-up, the guard, comer, and curve 
tests were tried and all were found satisfactory, after which 
slide was added. 

Adjustment 5. 

Drop locks — deep 
Out of angle 

When banked to the drop the escapement showed too much 
guard freedom on the side of the receiving pallet and prac- 
tically correct freedom on the side of the discharging pallet. 
To correct the deep lock and to equalize the angular motion 
of the lever from the line of centers, the discharging pallet 
was moved in. The escapement was again banked to the drop 
and the guard and corner tests were tried, showing too much 
guard and corner freedom, also a complete absence of safety 
lock. The drop locks were considered passable, so the error 
was assumed to be that of a short fork. The lever w^as 



120 A PRACTICAL COURSE IN HOROLOGY 

stretched and the guard and corner tests were tried, showing 
satisfactory guard and corner freedom and safety lock. The 
banking pins were opened for slide. 

Adjustment 6. 

Drop locks — satisfactory 

Out of angle 

Drop and shake — close outside 

The drop locks being practically correct, the first act was 
to correct the condition of out of angle. As the out of angle 
was slight with the access of freedom on the side of the 
discharging pallet, the lever was bent in the direction toward 
the receiving pallet. After banking to the drop and repeating 
the several tests, the lever was found equal with regard to 
the corner freedom, but the drop was still inequal, the 
condition being that of close outside. It will be noted that 
by bending the lever, the draw was increased, and for this 
reason it was decided that the receiving pallet should be 
tipped toward the pallet staff to equalize the drop. This was 
accordingly done and a test for draw followed, showing a 
satisfactory condition. All tests were tried and found 
satisfactory. The banking pins were opened for slide. 

Adjustment 7. 

Drop locks — correct 
Guard freedom — none 
Corner freedom — none 

After banking to the drop, this escapement did not show 
any guard and corner freedom. Since the drop locks were 
correct it was reasoned that the lever was too long. The 
correction consists of grinding back the horns of the fork. 



ESCAPEMENT ADJUSTING 121 

This is done by fitting to the lathe an iron wire, part of 
which is turned to fit the curve of the horns of the fork. 
Using oilstone powder and oil, the horns are ground by- 
holding the lever with a pair of cutting pliers against the 
iron wire. Frequent applications of the corner test while 
grinding prevented any possibility of overdoing the correction. 
After grinding and polishing, the several tests showed a 
very satisfactory escapement action. The banking pins were 
opened for slide. 

Adjustment 8. 

Condition of escapement — satisfactory 
Error — guard pin jams against roller table 

In this example we haye single roller type of escapement. 
After banking to the drop, the corner test was tried and 
found satisfactory. When the guard test was tried, the guard 
pin would jam or stick on the edge of the roller table. This 
error, responsible for frequent stopping, occurs occasionally 
in single roller escapements, but in double roller escapements 
only when the guard finger is loose or bent. The correction 
in the above example consisted of turning down and repolish- 
ing the edge of the roller table and advancing the guard pin. 
All tests showing satisfactory conditions, slide was added 
and the watch proved to be an excellent timekeeper. 

Adjustment 9. 

Drop locks — deep 

Out of angle 

Draw — wanting on both pallets 

This escapement was out of angle, with the excessive 
guard freedom on the side of the receiving pallet, and since 



122 A PRACTICAL COURSE IN HOROLOGY 

the drop locks were deep and the draw was deficient it was 
reasoned that all faulty conditions could be corrected by 
moving in the discharging pallet. The discharging pallet 
was accordingly moved in and after rebanking to the drop 
a thorough examination showed that the drop locks were 
correct; the lever's angular motion from the line of centers 
was equal and the draw was satisfactory. This example 
should be remembered. Errors of this kind occur quite 
frequently and the correction is easy and the results are 
certain. 

Problems 

i. What is meant by "banked to the drop" ? 

2. Define drop lock. 

3. State in degrees the correct amount of drop lock. 

4. What is meant by "out of angle"? 

5. How do you correct out of angle? 

6. Define draw. 

7. How do you examine draw? 

8. Define drop. 

9. How do you examine drop? 

10. Define shake. 

11. What is the lift? 

12. What are the characteristics of a good action of lift? 

13. What is meant by the expression "loss in the lift" ? 

14. On what type of escapement is the loss in the lift greatest? 

15. State in degrees the total angular motion of the lever when the 
escapement is banked to the drop. 

16. Should a watch run when banked to the drop ? 

IT. In what manner do you go about making the guard safety test ? 
corner safety test? curve test? 

18. What is the purpose of the guard safety test? corner safety 
test? curve test? 



ESCAPEMENT ADJUSTING 123 

19. What do the above tests aid in determining, if the drop locks 
are correct ? 

20. Define slide. 

21. When is slide added? 

22. Give the specifications for a correctly designed escapement, first 
without slide, secondly with slide. 

23. Does altering the banking pins change the drop lock ? 

24. Define total lock. 

25. Does altering the banking pins change the total lock ? 

26. How do you correct an escapement in which the drop locks are 
correct but there is an excessive guard and corner freedom ? 

27. What is the error in an escapement that has a deep lock yet 
the guard and corner freedom are satisfactory? 

28. If the drop locks are light and the guard and corner tests show 
no freedom, what is the correct procedure to put the escapement in 
order ? 

29. The drop locks are deep and the escapement is out of angle 
with no guard and corner freedom on the side of the discharging 
pallet. There is, however, too much guard and corner freedom on 
the side of the receiving pallet. How would you go about correcting 
this escapement ? 



Part II 
CHAPTER SEVEN 



Cleaning and Oiling 

Two METHODS are used in cleaning watches. The first 
that we shall consider is the older method generally referred 
to as the hand method. The second involves the use of the 
cleaning machine. 

The Hand Method 

In using the hand method we proceed as follows : After 
taking the movement apart string the larger pieces on a wire 
loop, place the pieces in benzine, benzole, or any other good 
cleaning preparation for several minutes. Remove and wash 
pieces in hot water, using castile soap and a soft brush. 
Rinse in clean water, dip in cyanide of potassium, rinse again 
in clean water, immerse in alcohol, and dry in warm sawdust. 
The same treatment is given to the wheels and other small 
pieces that can be strung on the wire loop, but separately, 
after the plates have been cleaned. The other small pieces 
such as the pallet fork and the jewels, may be held against 
a piece of hard pith or cork with a pair of tweezers especially 
prepared for the purpose and brushed thoroughly with a 
fine toothbrush previously dipped in benzole. After being 
brushed, the pieces are dipped in alcohol and allowed to dry 
on a sheet of watch paper. The balance must be cleaned 
separately. The usual method is to dip the balance first in 



124 



CLEANING AND OILING 125 

benzole, then in water followed by cyanide, again in water 
and finally in alcohol, after which it is dried in sawdust. 
The parts are now dry and the jewels should be rubbed with 
two pieces of pegwood, one which has been pointed so as 
to go through the holes and another that has been shaped 
to fit the cups of the jewels. 

The watch having been cleaned, the assembling and oiling 
are next in order. Certain parts are oiled as the watch is 
put together. For example, the main spring is oiled in the 
barrel with clock oil. The winding mechanism, the escape 
wheel, the pallet jewels, and the hole jewels where cap jewels 
are used in connection are also oiled in the process of 
assembling. The train is oiled after the watch is assembled, 
also the center post that carries the cannon pinion. The 
roller jewel is not oiled. 

The W atch-cleaning Machine 
The newer method of cleaning watches with the cleaning 
machine has some advantages. It eliminates the use of 
cyanide. Instead, an especially prepared cleaning solution 
is used, together with water and a drying solution. The 
machine is particularly satisfactory for the cleaning of small 
pieces like the pallet fork, the jewels, and screws and has the 
further advantage of eliminating the use of sawdust. 

Briefly, the procedure is as follows : Place the parts in the 
basket. There are provided several small spaces for the 
small pieces and one large space for the plates. Lower the 
basket into the jar containing the cleaning solution and allow 
the motor to run for several minutes at a moderate speed. 
Throw off the cleaning solution by raising the basket sufifi- 
ciently to clear the solution. Lower the basket in a jar 



126 A PRACTICAL COURSE IN HOROLOGY 

containing water and rinse off the cleaning solution. Next, 
lower the basket in the drying solution and run the motor as 
before. Finally, allow the basket to spin in a receptacle 
containing a lighted electric light bulb for a quick drying of 
the watch parts. Thus the cleaning job is completed. 

Problems 

1. Is it important that the jewels should be cleaned with peg- 
wood? 

2. What parts of a watch do you oil? 

3. What parts should not be oiled ? 

4. Name some advantages in using the cleaning machine. 



PART III 
ADJUSTING 



Part III 
CHAPTER ONE 



Preliminary Notes on Adjusting 

There is a greater demand for watches of accurate time- 
keeping qualities today than there was years ago. The rail- 
roads require that their employees' watches run within certain 
close limits and the complexity of modern life has shown a 
need for greater accuracy also. To repair watches so that 
close timing can be assured, a working knowledge of adjust- 
ing is necessary. 

The horologist who has never been concerned about the 
theory and practice of adjusting has missed the real fascina- 
tion and satisfaction of watch work. Aside from gaining 
pleasure for himself, the repairman who applies the principles 
of adjusting to his work will win the respect of his employer 
and the sincere appreciation of his customers. 

Adjusting consists in the execution of such manipulative 
operations of the balance spring and other parts as to cause 
a watch to function uniformly, the rate being within well- 
defined limits under various conditions. Adjusting is nat- 
urally divided into three branches: (1) position adjusting, 
(2) isochronal adjusting, and (3) temperature adjusting. 
These require independent methods of correction but in the 
final analysis all three are inseparable when the work of 
adjusting is completed. 

128 



PRELIMINARY NOTES ON ADJUSTING 129 

General Observations 

Before considering the more complex problems it will be 
well to outline briefly those conditions which must be as 
nearly perfect as possible before work can be attempted. 

THE MAIN TRAIN 

Close position and isochronal rating cannot be expected 
unless the main train is in first-class condition. Extreme 
variation is often caused by defects in any of the train wheels 
and especially in the center wheel and mainspring barrel. 
A correct amount of end shake and side shake is important. 
It is well, therefore, to examine a number of high-grade 
movements with regard to train freedom and note, also, the 
recoil of the escape wheel after the train runs down when 
winding the mainspring even to the slightest degree. 

All train-wheel and balance pivots should be round and 
well polished. A pivot that is not perfectly round will 
function fairly well in a jewel hole that is round, but jewels 
frequently do not have perfectly round holes. To show the 
effect plainly, insert a three-cornered piece of steel in a 
jewel that has a perfectly round hole. The triangular piece, 
if it fits the jewel properly, will turn in the hole as perfectly 
as a well-rounded pivot, but if we change the jewel for 
one that is not round and repeat the experiment, the result 
will be different. The triangular piece will become wedged 
and will not turn. The effect exists in a lesser degree when 
an imperfect jewel and an out-of -round pivot are used 
together, yet the combined action of the two affects the time- 
keeping qualities of a watch. 

Furthermore, it is impossible to poise the balance if the 
pivots of the staff are not round, and in this connection we 



130 A PRACTICAL COURSE IN HOROLOGY 

recommend the pivot polisher on all occasions where a 
balance pivot needs reducing or polishing. This lathe attach- 
ment forms the pivots perfectly round and cylindrical 
(assuming the machine is properly adjusted), and it does 
the work quickly and with a factorylike polish. 

INFLUENCE OF THE LEVER ESCAPEMENT ON THE 

ADJUSTMENTS 

The impulse communicated to the balance through the 
escapement should take place at the moment when the balance 
spring is at its state of rest, that is, at that moment when 
the spring is under no tension whatsoever. This ideal 
condition would permit the balance and spring to perform 
its arcs of vibration in the same time that a free balance 
and spring would perform these arcs. However, the 
mechanical means at one's disposal to keep the balance 
vibrating does not meet the above requirements and one is 
obliged to take account of the following laws. 

1. An impulse delivered to a balance or pendulum before 
the point of rest -will accelerate the vibrations. 

2. An impulse delivered to a balance or pendulum after 
its point of rest will retard the vibrations. 

This principle can be easily demonstrated with a simple 
pendulum. Impulse given to a pendulum before it reaches 
its point of rest causes it to arrive at the point of rest more 
quickly than if it were acted upon by gravity alone. Given 
impulse after reaching the point of rest results in driving 
the pendulum farther, resisting the force of gravity and at 
no particularly accelerated rate, if any. Hence a retardation 
takes place and the greater the distance the impulse takes 
place after the point of rest, the greater is the retardation. 



PRELIMINARY NOTES ON ADJUSTING 131 

Now consider this factor in relation to the lever escape- 
ment. The total angular motion of the lever is 10.5 degrees, 
allowing for 2 degrees of lock. The relationship between 
the acting length of the lever and the roller jewel radius is 
3.5 to 1. The total lifting angle or contact with the balance 
would be 3.5 X 10.5 or 36.75 degrees. Placing one half of 
this figure on either side of the line of centers we would 
have 18.375 degrees. However, the locking must be removed 
from that portion of contact before the line of centers 
(point of rest). Thus the impulse communicated before 
the line of centers would be 18.375 —(3.5 X 2) = 11.375 
degrees. The impulse after the line of centers would be the 
full amount or 18.375 degrees. 

According to the above analysis a retardation would result 
for the short arcs. Further retardation occurs because of 
the unlocking action, which is a serious resistance to the 
free motion of the balance. Hence it is clearly seen that a 
carefully adjusted escapement is of the utmost importance 
in the fine position and isochronal rating of a watch. 

WEIGHT OF THE ESCAPE WHEEL AND PALLET FORK 
The escape wheel should be as light as possible consistent 
with proper firmness. The sluggishness of a heavy escape 
wheel directly increases the inequality of the impulse between 
the receiving and discharging pallets owing to the inequality 
of the draw and the lift on the pallets. 

The lever, too, should be made as light as possible. It 
was formerly the practice of manufacturers to add a counter- 
poise to the lever, supposing that it was necessary to secure 
close position rating. Research into the problem has demon- 
strated that this is not necessary; in fact, it can be shown 
that lightness of the lever is of much more importance. The 



132 A PRACTICAL COURSE IN HOROLOGY 

counterpoise only gives the force at the circumference of 
the escape wheel more work to do and thus tends to make 
the actions of the escapement and balance more sluggish. 

MAINSPRINGS AND BALANCE MOTION 
A mainspring unwinding in a barrel generally does not 
take place in a concentric manner. Were it possible that 
this ideal condition could be attained, there would be Httle 
or no friction between the coils and a more smooth and 
even motive power would result. This eccentricity in the 
act of unwinding varies with the type of brace or hook used 
on the outer end of the spring. Experience has shown that 
any type of hook that maintains a quarter turn of the external 
coil flat against the wall of the barrel gives good results and 
it is gratifying to note that more and more manufacturers 
are adopting some form of hook with this end in view. 

It is important that the horologist use the very best main- 
springs that money can buy. The superior performance of 
a good spring is so apparent in the position rating of a watch 
that no argument is necessary to convince the most skeptical. 
Springs that are set, even to a comparatively slight degree, 
should be replaced with new ones and the mainspring winder 
should always be used. 

The proper arc of motion of the balance is 540 degrees 
when the watch is fully wound and lying in a horizontal 
position. Horologists experience a feeling of real satisfaction 
when a full balance arc is attained with the fitting of the 
weakest possible mainspring. It is an indication that the 
most even motive power will be maintained for the full 24 
hours of running and that there will be only a slight falling- 
off of the balance arc at the end of a 24 hours run. 



PRELIMINARY NOTES ON ADJUSTING 133 

How to ascertain the arc of motion. The question may 
arise as to how we are able to ascertain this arc of motion. 
This the eye can be trained to recognize easily and at a 
glance by using the following method : Suppose the balance 
is at rest with the roller jewel in the fork slot midway 
between the banking pins. Now move the balance one half 
of a circle or 180 degrees and stop. Release the balance 
and the force of the spring will cause it to return to its point 
of rest and 180 degrees farther on the opposite side. The 
arc of motion would be 360 degrees. Again move the balance, 
three fourths of a circle or 270 degrees, and allow it to 
return on its own power to its point of rest and as far on 
the opposite side. The arc of motion is now 540 degrees 
and the balance will continue to vibrate between these points 
as long as the proper motive power is maintained. 

The arms of the balance become visible at the moment the 
balance completes the arc of motion and starts in the opposite 
direction on its return vibration. It is, therefore, at that 
time when the balance stops that 
the arc of motion can be deter- - o 

mined. 

With the assistance of Figure /3S^ | j^s 

1, the problem can be more 
clearly explained in this manner : 

When the balance vibrates 180 /^{fm^m^imt^ ^a^^^Mi ^ ** 

degrees and returns to degrees 
and continues as far on the 
opposite side — that is, when the 
arms are visible at 180 degrees | 

and degrees — the arc of mo- 270" 

tion is 360 degrees. When the Figure 1 






134 A PRACTICAL COURSE IN HOROLOGY 

balance vibrates 225 degrees and returns to degrees and 
continues as far on the opposite side — that is, when the arms 
are visible first at 225 degrees and 45 degrees and on its 
return vibration at 135 degrees and 315 degrees (forming a 
cross at right angles) — the arc of motion is 450 degrees. 
When the balance vibrates 270 degrees and returns to 
degrees and continues as far on the opposite side — that 
is, when the arms are visible at 270 degrees and 90 degrees — 
the arc of motion is 540 degrees. 

The horologist should examine the balance arc in all 
positions and if the motion is faulty in certain positions the 
necessary corrections should be made before any adjustment 
to position or isochronism is attempted. Note carefully if 
there is any difference between the arcs of dial up and dial 
down. These positions should be equal. Note also the arcs 
of pendant up, pendant right, pendant left, and pendant 
down. The arcs for the vertical positions should be the 
same although somewhat shorter than those for the two 
horizontal positions, owing to the increased friction on the 
balance pivots. 

The arc of motion should never be longer than 540 
degrees. Experience has shown that an arc longer than the 
above figure produces a very fast rate for the first few hours 
of running, after which time (the arcs becoming shorter) 
the watch functions at its normal rate. 

THE POISE OF THE BALANCE 
One of the most common causes of variation between 
positions is want of poise of the balance. The horizontal 
positions are not affected but the error in the vertical positions 
is considerable. The extent of the variation in the rate is 
in proportion to the extent of the error in poise. 



PRELIMINARY NOTES ON ADJUSTING 135 

// the excess of weight is on the lower side of the balance 
when at rest, the watch will lose when the arc of motion is 
greater than 450 degrees, and will gain when the arc is less. 

If the weight is on the top side when the balance is at 
rest, the result will be reversed and the watch will gain when 
the arc of motion is greater tlmn 450 degrees and will lose 
when the arc is less. 

Nature of error due to want of poise. Let us assume 
that the excess of weight is on the lower side of the balance 
when at rest. Suppose the balance vibrates at an arc of 
almost 360 degrees, and in doing so the weight will stop near 
the top of the balance. The force of the spring in returning 
the balance to its point of rest will receive an added energy 
in that of gravity acting on the weight. This means that 
the spring will return to its point of rest a little more quickly 
than when acted upon by the force of the spring alone. Now 
assume that the weight, after having reached the bottom, 
continues the arc on the opposite side. The force of gravity 
acting on the weight is an added resistance to that of the 
spring; in other words, the result of an added weight is, 
in effect, the same as if a stronger spring were used and the 
arc will be performed more quickly. 

Now suppose that the motion is increased to 540 degrees 
and in vibrating to this extent the weight starts from its 
point of rest at the bottom and turns three quarters of a circle 
and stops at right angles to a vertical line drawn through 
the center of the balance. The force of the spring will 
encounter a resistance due to gravity acting on the weight 
as it starts upward toward the top, and after reaching the 
top and starting downward, the force of gravity is an added 
force downward. The effect would be a retardation during 



136 A PRACTICAL COURSE IN HOROLOGY 

the first portion of the path and an acceleration during the 
latter portion to the extent that, for arcs above approximately 
450 degrees the watch will lose. It would seem, therefore, 
that at some point near to 450 degrees these forces would 
counteract each other. Some authorities place this figure 
at 444 degrees. 

Poising the balance. Place the balance on a poising tool 
and start the balance in motion. During the time it is rotating 
hold a small compass as near as possible to the circumference 
of the balance so as to ascertain whether or not it is mag- 
netized. It is useless to attempt to poise a magnetized 
balance; hence the first act is to demagnetize it if it shows 
even the slightest bit of magnetism. 

The balance having been demagnetized and found satis- 
factory, proceed with the poising. Having located the posi- 
tion of the heavy point it is good practice to take note of the 
position of the regulator. This is our guide in deciding 
whether we should reduce the weight at the heavy point or 
add weight opposite to the heavy point, thus saving a certain 
amount of timing after the watch is again running. 

Should we find, when altering the weights, that the heavy 
point has shifted a short distance we may feel certain that 
good progress is being made. However, if it is found that 
the heavy point has been shifted to the opposite side it is 
evident that the correction has been overdone. It follows, 
therefore, that in altering the weights we should proceed 
with caution and thereby save much time, besides realizing 
a much better piece of work. 

Parallel pliers with cardboard glued to the jaws are very 
effective for holding the balance while removing and replacing 
the screws. 



PRELIMINARY NOTES ON ADJUSTING 137 

MAGNETISM 

Magnetism is an ever-constant and insidious enemy to 
horologists. The means by which a watch may be magnetized 
are so numerous today that it is important that the repairman 
form the habit of testing every watch for magnetism that 
comes in for regulation, examination or repair. 

In testing for magnetism place a small compass not only 
over the balance but also over the winding wheels. The 
mainspring being subject to magnetization as well as other 
steel parts, has definite poles at the time the magnetic lines 
of force passes through the watch. These poles are split 
up into countless numbers as the mainspring unwinds. This 
constant alteration of the relative position of the poles 
between the mainspring, winding wheels, and the balance 
helps to explain the erratic performance of magnetized 
watches. 

Theory of demagnetization. An alternating current is 
that type of electrical current that changes its direction 
constantly and when such current flows through a coil of 
wire the poles also change. Figure 2 shows a conception of 
an alternating current wave as it moves through time, and 
the complete wave is called a cycle. An alternating current 
of 60 such waves per second is said to have a frequency of 
60 cycles. 

When a steel rod is inserted in a demagnetizer and the 
flow of alternating current is suddenly cut off, the steel rod 
will be found to be magnetized, its poles being that of the 
last half cycle that was sent through the wire. However, 
if the current is left on and the rod gradually withdrawn, 
the result will be different. It will be repolarized for every 
cycle and each successive polarization will be weaker than 



138 A PRACTICAL COURSE IN HOROLOGY 




Figure 2. Wave form of alternating current 

the preceding one. When withdrawn entirely from the field, 
the magnetism has disappeared. 

Demagnetizing a watch. The procedure in demagnetizing 
a watch is much the same as explained above. Withdraw 
the watch, keeping it central with the opening and giving it 
a slight twist after leaving the opening. Continue the with- 
drawal until the watch is about three feet or more from the 
demagnetizer. If the first attempt fails to remove all mag- 
netism repeat the operation. 

Magnetized tools. The horologists' tools are subject to 
being magnetized. Screw drivers and tweezers should be 
closely watched. Avoid placing such tools in a north-south 
position in or on the bench. 

Problems 

1. Why should balance pivots be made perfectly round ? 

2. What is the effect of giving impulse to the balance or pendu- 
lum before the point of rest? after the point of rest? 



PRELIMINARY NOTES ON ADJUSTING 139 

3. What is the effect of the lever escapement on the position 
rating of a watch? 

4. Is the counterpoise on the pallet fork of very great importance? 

5. Does the type of fastening on the outer end of the mainspring 
have anything to do with the friction between the coils? 

6. What is the proper arc of motion of the balance ? 

7. How do you ascertain the correct arc of motion? 

8. What is the most common cause of position error ? 

9. If the excess of weight is on the lower side of the balance 
when at rest, will the watch gain or lose when running at an arc of 
540 degrees ? when running at an arc of 350 degrees ? 

10. What balance arc is considered the neutral arc? 

11. How do you go about poising the balance? 

12. How do you demagnetize a watch ? 



Part III 

CHAPTER TWO 



Position Adjusting 

The first portion of this chapter treats on position error 
as related solely to the balance spring and of the effect of 
gravity which is an ever-present force acting upon the inner- 
most coils. The nature of this action is such that a positive 
position error is produced. 

A watch may be mechanically perfect — that is, its con- 
struction from barrel to balance may be as exact as human 
skill knows how to make it — and yet, in spite of such per- 
fection, there will be a variation of from 15 to 30 seconds 
in 24 hours between some two vertical positions due to the 
condition of the balance spring alone. In watches that are 
less perfect the error is frequently as high as 40 seconds or 
more. 

The Balance Spring and Its Poise Error 

The oscillation of the inner portion of the spring cor- 
responds very nearly to that of the collet ; that is, when the 
collet travels three fourths of a circle, the first coil in the 
center travels nearly an equal distance. It is further evident 
that each of the several coils, as they tend to become more 
distant from the center, will travel a shorter path until the 
movement ceases altogether at the regulator pins. If the 
coils are marked in a straight line from collet to regulator 



140 



POSITION ADJUSTING 141 

pins, one would readily observe the distance traveled by the 
several coils and the extent of their path under different arcs 
of motion. 

It is impossible to poise a spiral spring. Therefore it is 
at once evident that it is the oscillation of the unpoised inner 
portion of the spring, when acted upon by the pull of gravity, 
that causes position error in the vertical positions. A state- 
ment as to how this works need not be repeated here, for 
the analysis given in the preceding chapter relative to the 
poise error of the balance, applies to this condition also. 
However, slightly varied effects under different arcs of 
motion result, due to the fact that the greater mass of the 
unpoised inner portion of the spring vibrates in a shorter arc 
than does the balance proper. 

Experimental demonstration. A demonstration at the 
command of every horologist is to take several watches and 
run them, first with the figure 1 up, and following with the 
figures 2, 3, 4, etc., continuing the experiment around the 
dial with all figures up, running the watches in each of the 
12 positions for 24 hours and taking note of the rate in each 
position. If an electric timing machine is available the 
experiment can be made most conveniently and in a very 
short time. 

Table 1 shows the result of an experiment as stated above, 
using four popular makes of American watches. All watches 
were in excellent condition with balances perfectly poised, 
fitted with theoretically corrected overcoils, and the grades 
ranged from 17 jewels to 21 jewels. The arc of motion of 
the balance of all watches was about 540 degrees when fully 
wound and more than 450 degrees after 24 hours of running. 

In watch Number 1 the rate was fastest at the time when 



142 A PRACTICAL COURSE IN HOROLOGY 

the figure 1 1 was up ; in watch Number 2 the rate was fastest 
at the time when the figure 3 was up. The watches Number 
3 and Number 4 had definite fast positions also, and in all 
watches the slow position was opposite or nearly opposite that 
of the fast position. 

TABLE 1 





NO. 1 


NO. 2 


NO. 


3 


NO. 4 




Sees. 


Sees 


Sees. 


Sees. 


1 





+ 4 


+ 


1 


+ 3 


2 


4 


+ 5 


+ 


1 





3 


6 


+ 8 




3 


2 


4 


8 


+ 3 


— 


3 


5 


5 


—11 







7 


— 7 


6 


10 


2 


— 


5 


— 8 


7 


5 


6 


+ 


1 





8 


1 


10 


+ 


2 


+ 1 


9 


2 


12 


+ 


2 


+ 5 


10 





— 3 


+ 


3 


+ 5 


11 


+ 4 





+ 


5 


.+ 6 


12 





+ 3 


+ 


4 


+ 8 



THE NATURAL ERROR AND METHODS OF CORRECTION 

An examination of the balance spring showed that the 
fastest rate always occurred at the time when the middle of 
the first half of the innermost coil happened to be up. This 
error, due to the oscillation of the center of gravity of the 
inner portion of the spring, is called the natural error and 
is unavoidable. We can, however, make such alterations so 
as to limit the fullest manifestation of the error in three 
ways. These are as follows : 

1. Pin the spring at the collet in such a position that the 
natural error imll he the least detrimental to the uniform 
rate of the watch. 



POSITION ADJUSTING 



143 




Figure 3. Proper pinning at the collet. Figure 4. Proper pinning at the collet 



2. Reduce the natural error by the application o, correct 
terminal curves both outside and inside. 

3. Neutralise the effect of the natural error by counter- 
poising the balance. 

These corrections will now be considered In the order 
stated above. 

The proper pinning at the collet. When fitting new 
balance springs to pocket watches, certain pinning points 
should be observed if the best position rates are to be 
expected. The proper pinning at the collet is shown in 
Figures 3 and 4. The first half of the innermost coil tends 
upward as it leaves the collet in the direction of pendant up. 



144 A PRACTICAL COURSE IN HOROLOGY 

producing a fast pendant-up rate. It does not matter if the 
spring tends to the left as shown in Figure 3 or tends to the 
right as shown in Figure 4, for it can be readily seen that, 
in either case, the middle of the first half of the innermost 
coil stands in the direction of pendant up. When the spring 
is pinned as stated above, the pendant-right and pendant- 
left positions will have a slower but a nearly equal rate, 
provided the balance spring is properly centered and vibrates 
concentrically. The greater part of the natural error will 
show up only in the pendant-down position, and since a pocket 
watch in practical usage is seldom if ever subjected to this 
position, it follows naturally that the pendant-down error is 
of little importance. 

Reducing the natural error. It was stated in the first 
portion of this chapter that finely constructed watches vary 
from 15 to 30 seconds in 24 hours between some two vertical 
positions and watches that are less perfect would vary as 
much as 40 seconds and more. If the natural error is shown 
to be more than 30 seconds in 24 hours, the excessive 
variation is due to want of perfection of the inner terminal 
of the spring. A slight eccentric motion at the inner terminal 
will cause a greater variation than would be the case if the 
spring were perfectly true. Thus it is clear that the balance 
spring should always be faultlessly trued at the collet and 
equal attention should be given to both the flat and the round. 

The Breguet type balance spring on position error. It 
would now be natural for one to inquire as to the effect of 
the Breguet spring with correct terminal as compared with 
the ordinary flat spring on position error. Experiments 
have demonstrated that the Breguet spring does reduce the 



POSITION ADJUSTING 145 

variation in the vertical positions, but only to a small degree, 
proving that the position error is due primarily to the 
oscillation of the center of gravity of the inner portion of the 
spring. 

Table 2 shows the results of an experiment using both 
the flat and Breguet springs. The watch selected for this 
example was an 18 size, 15- jewel grade, fitted with a flat 
spring. The first column of the table shows the rate with 
the flat spring, and the second column shows the rate with 
the same spring after it was made over into a Breguet with 
correct terminal. The watch was run in each position for 
24 hours. 





TABLE 2 






FLAT 


BREGUET 




SPRING 


SPRING 




Sees. 


Sees. 


Pendant up 


+ 7 


+ 7 


Pendant right 


+ 5 


+ 3 


Pendant left 


— 6 


2 


Pendant down 


8 


—10 



Counterpoising the balance. If the most perfect terminal 
curves do not produce the desired results, counterpoising 
may be tried. A general rule for the alteration is as follows : 
Reduce the weight on the lower side of the balance in the 
position that is slow. It is assumed that the balance has a 
good motion and that at no time does the arc of motion fall 
below 450 degrees during the 24 hours that the watch is 
under observation. This is important if success in counter- 
poising is to be expected. It should further be understood 
that any alteration of the poise should be practiced only to 
a limited extent ; otherwise, a most unsatisfactory and erratic 



146 A PRACTICAL COURSE IN HOROLOGY 

rate will result. Usually just a slight touch of the poising 
saw will reduce the natural error as much as 5 to 10 seconds 
in 24 hours. 

Use of the Regulator Pins in Adjusting 

The condition of the regulator pins play an important 
part in the position rating of a watch. In fact, by slightly 
opening or closing the pins as the case may require, it is 
possible to bring the horizontal and vertical positions in 
close agreement. 

Let us suppose, for example, that the regulator pins are 
opened slightly and the first coil of the spring vibrates equally 
between the pins. We have literally made the active length 
of the spring longer and the watch will go slower. It also 
changes the rate between the long and short arcs. The effect 
can be explained in this way : 

Suppose that the balance is vibrating at an arc of 180 
degrees and the first coil of the spring barely touches the 
pins. For arcs below 180 degrees, the active length of the 
spring will commence very nearly from the stud. Now, if 
the arc of motion is increased to 540 degrees, the active 
length of the spring will be shortened, commencing more 
nearly from the pins. This will make the long arcs go faster 
and the effect will vary in proportion to the changes taking 
place in the arc of motion. 

Suppose now that the pins are open, but instead of the 
first coil of the spring vibrating equally between them, the 
first coil leans against one of the pins. Assume that it 
requires an arc of 360 degrees to lift the coil away from the 
pin against which it leans. It is plain that for arcs below 
360 degrees the active length of the spring will commence 



POSITION ADJUSTING 147 

from the pins, and for arcs above 360 degrees the active 
length will commence more nearly from the stud. This 
condition will make the long arcs go slower, or, in other 
words, opposite to that in the former instance. Thus it can 
be seen that the condition of the regulator pins may be the 
cause of many of the disorders in the performance of watches. 
It is also true that an intelligent manipulation of the pins is 
the quickest and simplest means of correcting the variation 
in the rate between the horizontal and vertical positions 
because of the fact that the arc of motion is always shorter 
in the vertical positions. The practical use of the regulator 
pins is stated in the following rules : 

1. If the regulator pins are closed and the watch gains 
in the pendant-up position, a slower pendant-up rate is 
obtained by opening the pins. 

2. If the regulator pins are open and the watch loses in 
the pendant-up position, a faster pendant-up rate is obtained 
by closing the pins. 

The spring should be so adjusted that the vibration of the 
coil between the pins is equal ; otherwise, the coil will strike 
one pin with more force than the other, and the result will 
be very different from that stated in the above rules. Also 
in spreading the pins, the vibration of the coil between them 
should be very slight and discernible only with a powerful 
glass. The pins should never be spread more than enough 
to slow the mean rate 3 seconds an hour. If spread beyond 
that amount the watch is apt to become a very unreliable 
timepiece ; in other words, position adjusting by the manipu- 
lation of the regulator pins can be practiced only to a limited 
extent. 



148 A PRACTICAL COURSE IN HOROLOGY 

Adjustment to the Horizontal Positions 

Effect of manipulating the regulator pins on the hori- 
zontal positions. We have seen that the rates between dial 
up and pendant up can be equalized by the manipulation of 
the regulator pins. Should we alter the pins to secure the 
desired results between dial up and pendant up, we could 
expect a change in the rate between the horizontal positions 
also. Often the horizontal rates are improved; sometimes 
they are reversed. This would suggest that the adjustment 
to the horizontal positions should be made last — that is, after 
the corrections for dial up and pendant up are satisfactory. 

After a little reflection it is evident that the difference 
in the rate is due to the anisochronism of the balance spring. 
The manipulation of the pins not only corrects the rate be- 
tween dial up and pendant up, but more often than other- 
wise it improves the isochronal rate also. This can be shown 
by running a given watch in the position of dial up for 8 
hours at an arc of 540 degrees and taking note of the rate 
and then running it again for another 8 hours at an arc of 
360 degrees. If the rate is slower when running at 360 
degrees the pendant-up rate will usually be slower. Occasion- 
ally there are exceptions. 

Correction of errors in the horizontal positions. Errors 
between the horizontal positions come generally under the 
head of frictional errors and have to do with changes in 
the arc of motion of the balance. A variation of 2, 3, or 
even 4 seconds Is unimportant. Extreme variation can be 
laid to rough pivots, dirt or thick oil, hole jewels that are 
too small or too large, pitted cap jewels, balance pivots not 
the same size, or a balance spring out of flat. As a rule the 



POSITION ADJUSTING 149 

fast position takes the shorter arc, which would suggest that 
the position producing the fast rate is the one that calls for 
correction. Assuming that the staff and jewels are as nearly 
perfect as an inspection with a strong glass can determine, a 
general rule for the correction of the rate in the horizontal 
positions reads as follows : Round slightly the lower pivot in 
the position that is fast. 

Problems 

1. Is it possible to poise perfectly a balance spring? 

2. What is the natural error ? In what manner does it affect the 
position rating of a watch ? 

2. What is the proper pinning at the collet ? 

4. Does the outer terminal of the balance spring have a greater 
or smaller effect on the position rating of a watch as compared with 
the inner terminal ? 

5. Can the regulator pins be of use in adjusting a watch to posi- 
tion? Explain. 

6. What are the usual causes of position error in the horizontal 
positions ? 



Part III 

CHAPTER THREE 



Adjustment to Isochronism 

The adjustment to isochronism is that adjustment which 
has to do with the maintaining of a constant rate over a 
definite period of time. Absolute isochronism is impossible 
to attain because of several factors which are inherent in the 
balance spring and for which there are no practical remedies. 

A pendulum will make the long and short vibrations in 
equal time. Start a pendulum in motion, traveling over a 
given space in a given time. As the motion falls off, it will 
be observed that the time consumed in each vibration does 
not change. A slower or faster rate can be produced only 
by lengthening or shortening the pendulum. The pendulum 
is in reality a falling body and the laws which apply to 
falling bodies apply to the pendulum also. Therefore adding 
or reducing the weight of the pendulum does not affect the 
time of vibration, for any change made in the mass carries 
with it a proportional force in that of gravity. 

Adding to or reducing the mass of the balance varies the 
rate of vibration, for the strength of the balance spring does 
not change. There are three factors upon which the time 
of the vibration of the balance depends. They are : 

1. The weight of the balance. 

2. The diameter of the balance. 



150 



ADJUSTMENT TO ISOCHRONISM 151 

3. The strength of the balance spring. 

As already stated, the balance spring is the cause of the 
more important disturbing factors in the isochronal rating 
of watches. Of these disturbing factors, our attention will 
first be directed to the problem of isochronism as affected by 
varying the total length of the spring. 

The Length of the Balance Spring on Isochronism 

In every balance spring there is a certain length in which 
the long and short vibrations are practically isochronal. Now 
if this length is ascertained and we 'tnake the spring shorter 
by whole coils, the short arcs will go faster; and if we make 
the spring longer by whole coils, the short arcs will go slower. 

It will be observed that the shortening or lengthening is 
done only by whole coils. The reason for this is explained 
in the following statement. If the spring is shortened by 
some portion of a coil and not by whole coils, another effect 
would take place which would alter the isochronism. For 
example, the shortening of the spring by one half of a coil 
may cause the short arcs to produce a losing rate instead of 
a gaining rate. This problem is one that is distinctly separate 
from the one now under discussion and it will be treated 
more in detail in the next section. 

A spring that is practically isochronal as far as the length 
is concerned usually consists of about 13 coils. Springs 
supplied by the manufacturer are correct for length. The 
thought to remember from that which has been stated above 
is that in fitting a new spring, the spring should not be 
shortened excessively in timing, for in so doing the isochronal 
rate is affected. 



152 A PRACTICAL COURSE IN HOROLOGY 

The Flat and Breguet Balance Spring 
on Isochronism 

The flat spring. If one will examine a flat spring in a 
watch during the time the balance is in motion, it will be 
observed that the vibration is wholly on one side and on the 
side opposite the regulator pins. This is not all the eccentric 
motion present in the spring, however, for a similar motion 
takes place opposite the inner terminal, although it is less 
visible to the eye. These eccentric motions affect the iso- 
chronism because of several conditions. The principal ones 
are: (1) a constant oscillation of the center of gravity, 
(2) a persistent pushing and pulling at the balance pivots, 
and (3) the effect of torsion, with which this section is 
particularly concerned. 

Action of the flat balance spring. Torsion is a circular 
impulse which takes place at the innermost coils of the 
spring. The result is a retardation or an acceleration, de- 
pending on the relative positions of the two eccentric motions 
as the balance vibrates. The anisochronism thus produced 
can be varied by altering the length of the spring. Such 
alterations, of course, change the angular distance between 
the inner terminal and the regulator pins, and it is this change 
of angular distance that decides the rate between the long and 
the short arcs. The laws governing the isochronism as con- 
cerned with the above statement are as follows : 

1. When the angular distance between the inner terminal 
and the regulator pins stands at even coils, that is, whole 
coils, the short arcs gain. 

2. When the angular distance between the inner terminal 
and the regidator pins stands at even coils, plus half a coil, 
the short arcs lose. 



ADJUSTMENT TO ISOCHRONISM 153 





Figure 5. Figure 6. 

3. When the angular distance between the inner terminal 
and the regulator pins stands at even coils plus one fourth or 
three fourths of a coil, the long and short arcs are more 
nearly isochronal. 

Let us assume that the arc of motion of a given balance is 
360 degrees, as an example of a short arc. If the spring is 
pinned at even coils, the eccentric motions will stand in 
opposite directions. According to rule 1, this produces a 
gaining rate as compared with the long arcs. This can be 
explained by reason of the fact that the eccentric motion of 
the outermost coils exerts a force (when wound up) in the 
direction of the arrow A, Figure 5, while the eccentric 
motion of the innermost coil exerts a force in the direction of 
the arrow B, and since these forces are in opposite directions, 
there is a tendency toward acceleration as the arcs become 
shorter than 540 degrees and the maximum is reached at 360 
degrees. In unwinding, the forces are reversed but their 
relation to each other is the same. 

If the spring is pinned at even coils plus half a coil, the 
eccentric motions will stand in the same direction, namely: 
opposite the regulator pins. According to rule 2, this pro- 
duces a losing rate as compared with the long arcs. Since the 
forces of the eccentric motions are in the same direction, 



154 A PRACTICAL COURSE IN HOROLOGY 

Figure 6, there is less resistance or divergence of forces and 
the balance may vibrate a little farther; hence a retardation 
takes place. 

If the spring is pinned at even coils plus one fourth or 
three fourths of a coil, the eccentric motions will stand at 
right angles to each other, the effects stated in rules 1 and 2 
will be neutralized, and the watch will function at a more 
nearly isochronal rate. Of course, when the watch is put to 
practical usage, the motion of the balance is constantly 
changing and this fact considerably complicates results. 

The effect of torsion should not be confused with that of 
the oscillation of the center of gravity, for the latter is a 
function that is distinctly different and plays only a small 
part in producing an anisochronism. The effect of torsion is 
by far the most disturbing element and the only way its 
effect may be reduced, aside from varying the terminal 
pinnings, is the application of the most perfect terminal 
curves, both outside and inside. 

Reducing the isochronal error. The superior perform- 
ance of the Breguet spring in the attainment of isochronism 
is the reason for the passing of the flat spring. The above 
analysis of the flat spring would at once suggest that it is 
possible to vary the isochronism by manipulating the over- 
coil of the Breguet spring so as to throw the eccentric motion 
in some desired direction. That is correct reasoning; how- 
ever, a spring that produces concentric vibrations will attain 
close enough isochronism in most watches while at the 
same time realizing the best position rating in the vertical 
positions. 

Modem watches are built with a better design and pro- 
portion of parts than the older models and the correction of 



ADJUSTMENT TO ISOCHRONISM 155 

isochronism by means of altering a correct terminal is 
seldom necessary. However, if the most perfect terminal 
curves do not produce the desired results, the following rules 
for altering the overcoil may be used. 

1. If the short arcs are slow, bring in part of the body of 
the spring and add it to the overcoil. 

2. If the short arcs are fast, take part of the overcoil 
and move it back into the body of the spring. 

Problems 

1. What is the effect of shortening a balance spring by whole 
coils on the isochronal rating of a watch? 

2. What is torsion ? What are the effects on a flat balance spring? 

3. In what manner do you alter the overcoil to accelerate the 
short arcs? 

4. In what manner do you alter the overcoil to retard the short 
arcs? 



Part III 

CHAPTER FOUR 



The Adjustment to Temperature 

In order to attain a practical system for the temperature 
adjustment, the general practice has been to solder together 
brass and steel for the rim of the balance. The brass occupies 
the outer portion of the rim, consuming about three fifths 
of the total thickness. The rim is cut near the arms to permit 
the turning in and out of the loose ends, thus changing the 
active diameter of the wheel. This movement compensates 
for the changing elasticity of the balance spring during 
temperature changes. This type of balance is known as the 
compensating balance. A compensating balance made of 
brass and Invar (a nickle-and-steel alloy) when used in 
connection with a hardened steel balance spring has been and 
is today the most satisfactory arrangement for combating 
the temperature error. 

However, there is a definite trend toward the use of a 
plain uncut balance of a single metal and a balance spring 
of a nonrusting, nonmagnetizing alloy, made principally of 
iron, nickle, chromium, and tungsten, called Elinvar. A 
slight temperature error exists, but there are certain advan- 
tages that make it desirable to continue research for further 
improvement. This is apparently the opinion of watch fac- 
tories, for new models have appeared lately with definite 

156 



ADJUSTMENT TO TEMPERATURE 157 

changes in the design of the movement as well as the balance 
and spring, showing a persistent effort on the part of manu- 
facturers to improve this new type of balance assembly. 

Correcting the temperature error. Watches with com- 
pensating balances are usually adjusted to temperature be- 
tween 40 degrees Fahrenheit and 95 degrees Fahrenheit. 
The rules for the adjustment are as follows : 

1, If the watch runs slow in heat, move any even number 
of screws that are opposite each other an equal distance 
toward the loose ends of the rims. 

2. If the watch runs fast in heat, move any even number 
of screws that are opposite each other an equal distance 
toward the balance arms. 

Experience in effecting temperature adjustment is neces- 
sary before the horologist is able to decide on the extent of 
the alterations. More often than otherwise, several trials 
are required. If the screws are moved considerable distance 
the poise should be examined. Temperature adjustment is 
practically permanent. The balance may be trued and poised 
many times without interfering with the temperature adjust- 
ment. However, in changing a balance spring, readjustment 
would be necessary. 

Equipment used for temperature adjusting. The equip- 
ment used for temperature adjusting is an oven and a refrig- 
erator. An oven suitable for the purpose need be nothing 
more than a box fitted with an electric light bulb, a rheostat, 
and a thermometer. The thermometer is placed inside and 
in such a manner that it can be conveniently read through 
an opening in the box. An ordinary electric refrigerator will 
serve the purpose for the lower temperature. 



158 A PRACTICAL COURSE IN HOROLOGY 

Problems 

1. Does the fitting of a new balance spring alter the temperature 
adjustment of a watch? 

2. A watch that is equipped with a compensating balance runs 
slow in heat. How do you correct the error ? 

3. Name the advantages of a solid, single-metal balance and 
Elinvar balance spring. 



Part III 

CHAPTER FIVE 



The Practical Work of Adjusting 

The practical use of the instruction that has been written 
in these pages will presently be demonstrated by several 
examples taken from actual practice when the writer was 
engaged in practical work at the bench. The data for the 
watches to be adjusted are kept in a small notebook. The 
date, customer's name, the make, size and grade of the watch 
are recorded, followed by the several rates and an account 
of the changes made to effect a satisfactory rating. 

Practical Problems in the Adjustment to Positions 

Preliminary notes. It will be necessary to briefly discuss 
several factors before considering the concrete problems. 
The method of computing the variation of the rate in the 
different positions will be next in order and to assist in the 
explanation, the reader is referred to Adjustment 4 on page 
163. The first column, reading down, shows the progressive 
rate — that is, the rate without setting the watch except at the 
beginning of the test. The first figure shows a loss of 2 
seconds, the rate for 24 hours, written — 2, the rate for dial 
up. Without setting the watch, the figure below shows the 
variation after running the watch in the position of dial 
down, which is -\-2. The next figure below shows the varia- 

159 



160 A PRACTICAL COURSE IN HOROLOGY 

tion after running in the position of pendant up, the rate 
being — 19. For pendant right the progressive rate is — 30 
and for pendant left the progressive rate is — 43. 

The rate for each period of 24 hours is computed by sub- 
tracting the lesser figure from the greater, provided the rates 
are all plus or all minus. However, if the rates are plus and 
minus, the figures are added and the sign before the last 
rate added is prefixed to the 24-hour rate and entered in the 
second column. To make this clear, we shall continue with 
the example, explaining it in this way : The rate for dial up, 
recorded as — 2, is carried to the second column. The rate 
for dial down is computed by adding together — 2 and -j-2 
and the rate is entered in the second column as -j-4, showing 
the amount of the gain in excess of correct time. The rate 
for pendant up is computed by adding together -\-2 and — 19, 
and the result is entered in the second column as — 21, 
showing the amount of loss deducted from correct time. The 
rate for pendant right is the difference between — 19 and 
— 30 and the rate for pendant left is the difference between 
— 30 and — 43, both of which are shown in the second 
column. Thus we may compute the 24-hour rate without 
the necessity of setting the watch for every trial. Of course, 
this is not necessary when the electric timing machine is used. 

Maximum allowance in positions. Before testing in 
positions the watch should be regulated to run within 15 
seconds in 24 hours. The extent of variation between 5 
positions in high-grade, 16-size watches should not exceed 
6 seconds in 24 hours. For watches of a cheaper grade 
and for most of the average grades in the 12 size, a variation 
of not more than 10 seconds is considered passable. The 
rate between the positions of dial up and pendant up are the 



PRACTICAL WORK OF ADJUSTING 161 

most important and should receive special consideration. The 
rate between these two positions should not exceed 3 or 4 
seconds ; in fact, it is not difficult to produce close agreement 
and in most cases the manipulation of the regulator is all 
that is necessary. 

In the following pages are shown several examples of 3 
and 5 position adjusting. These examples should be studied 
carefully. 

Adjustment 1. 

Watch — 16 size, 23 jewels 

Repairs — cleaned, staff fitted, balance poised. 

After cleaning and repairing, the watch was tested in 3 
positions and it was found to have a variation of 15 seconds 
with a gain in the pendant-up position. 

Dial up — 6 — 6 

Dial down — 12 — 6 

Pendant up — 3 +9 (15) 

An examination showed that the spring was level and 
properly centered and that the regulator pins were tightly 
closed. Accordingly the pins were spread slightly and after 
timing by turning in a pair of timing screws, the test was 
again tried, this time with the following results. 

Dial up — 2 — 2 

Dial down — 5 — 3 

Pendant up —9 — 4 (2) 

Adjustment 2. 

Watch — 16 size, 7 jewels 

Repairs — Cleaned, main spring fitted 

The first test showed a variation of 28 seconds as shown 
below. 



162 A PRACTICAL COURSE IN HOROLOGY 

Dial up +8+8 

Dial down +15 +7 
Pendant up +48 +33 (28) 

The error being considerable in the pendant-up position, it 
was reasoned that the balance was out of poise. The spring 
was removed and the balance was tested for poise. A slight 
poise error was found, but the want of poise could not be 
responsible for the whole variation of 28 seconds. There- 
fore in addition to poising the balance, the regulator pins 
were spread slightly and after timing the watch, the next 
test showed a much improved rate. 

Dial up +3 +3 

Dial down +6 +3 

Pendant up +5 — 1 (4) 

Adjustment 3. 

Watch — 16 size, 17 jewels 
Repairs — cleaned, balance poised 

This example showed a loss in the pendant-up position 
instead of a gain as found in the previous examples. 
Dial up — 2 — 2 

Dial down — 4 — 2 
Pendant up —18 —14 (12) 

As the watch was in excellent condition throughout, the 
error was most likely to be found in the regulator pins. An 
examination showed that the pins were open and the correc- 
tion consisted of closing the pins. A much improved rate is 
shown on the second test. 

Dial up —1 —1 

Dial down — 2 — 1 

Pendant up — 5 — 3 (2) 



PRACTICAL WORK OF ADJUSTING 163 

The adjustment to five positions consists in running the 
watch in the positions of pendant right and pendant left in 
addition to dial up, dial down, and pendant up. Because you 
find a close rate between the three positions is no proof that 
the watch will be an excellent timepiece. Errors could be 
present that would show up only in the pendant-right and 
pendant-left positions. Fine watches should be adjusted to 
five positions, for often an unsuspected error in the general 
construction of the watch is discovered. 

Adjustment 4. 

Watch — 18 size, 15 jewels 
Repairs — cleaned 

The first test showed the following rate. 

— 2 
+ 4 
—21 
—11 
—13 (25) 

The balance spring was pinned so that the fast position 
stood in the direction of pendant up, yet the pendant-up rate 
was slow. The dial-up and dial-down rates were also too 
great to be allowed to pass. 

The balance was placed in the truing calipers and the bal- 
ance spring was examined and found to have an eccentric 
motion at the collet. (Incidentally, the spring was removed 
and the balance vv^as tested for poise, showing a slight poise 
error with the excess of weight on the lower side of the 
balance when in the pendant-up position.) The balance was 
poised and the balance spring replaced and trued. Further 
examination showed a slight vibration of the sprin.sr between 



Dial up 


2 


Dial down 


+ 2 


Pendant up 


19 


Pendant right 


30 


Pendant left 


—43 



164 A PRACTICAL COURSE IN HOROLOGY 

the regulator pins. Since the rates in the vertical positions 
were all slow the pins were closed. The watch was regulated 
to mean time and the results of the second test are shown as 
follows : 

—2 

—1 

—4 



Dial up 


2 


Dial down 


3 


Pendant up 


7 


Pendant right 


12 


Pendant left 


20 



—5 
-8 (7) 

Adjustment 5. 

Watch — 16 size, 21 jewels 

Repairs — cleaned, staff fitted, balance poised 

The horologist should be cautioned that there will be fre- 
quently found watches that do not function satisfactorily in 
position even though the balance and spring and the general 
construction seem perfect in every detail. As already stated, 
the watch must be mechanically in good order and it is 
possible that some mechanical detail has been overlooked. 
The example below was selected to show that the general 
condition of the watch was responsible for the error in 
position. 

— 2 

+ 8 

+ 1 
+ 10 

—27 (37) 

The first test, as shown above, was far from satisfactory. 
This condition could not be due to want of adjustment of 
the balance and spring as the balance was poised and the 
spring was properly fitted, with the regulator pins closed. 



Dial up 


2 


Dial down 


+ 6 


Pendant up 


+ 7 


Pendant right 


+ 17 


Pendant left 


10 



PRACTICAL WORK OF ADJUSTING 165 

The arc of motion of the balance was examined and 
found to be somewhat shorter than it should be. Since the 
escapement was in excellent condition, it was assumed that 
the main spring was set, and an examination showed that 
such was the case. A new spring was fitted and the motion 
was considerably improved. The train was examined and 
a cracked jewel in the pallet bridge was discovered, al- 
though the crack was so slight that it was discernible only 
with a strong glass. A new jewel was fitted and without 
doing anything else the next test showed a much improved 
rate. 

Dial up +2 +2 

Dial down +3 +1 

Pendant up — 1 — 4 

Pendant right —1 

Pendant left —7 —6 (8) 

Adjustment 6. 

Watch — 12 size, 17 jewels 

Repairs — cleaned, balance poised, balance spring trued 

This example shows that it is possible to have a close rate 
between the horizontal positions and pendant up, yet the 
pendant-right and pendant-left positions may be far from 
satisfactory. 

Dial up — 5 — 5 

Dial down — 4 -|- 1 

Pendant up — 3+1 

Pendant right —23 —20 

Pendant left —98 —75 (76) 

The watch showed an abnormally slow rate in the pendant- 
left position. It was observed that the arc of motion of the 



166 A PRACTICAL COURSE IN HOROLOGY 

balance was shorter than it should be. Further examination 
showed that the drop locks were too deep, and, accordingly, 
the drop locks were made lighter. The escapement was re- 
banked to the drop and the necessary corrections made, yet 
after the balance was replaced the arc of motion was still too 
short. The mainspring was removed and found to be some- 
what set and a little weaker than should be used in this grade 
of watch. After replacing the mainspring with one of the 
proper strength, the next test in position showed the follow- 



ing results : 






Dial up 


4 


—4 


Dial down 





1 


Pendant up 


5 





Pendant right 


11 


—6 


Pendant left 


18 


7 



(7) 

Adjustment 7. 

Watch — 16 size, 23 jewels 

Repairs — cleaned, staff fitted, balance poised. 

The first test in positions showed the following rate : 
Dial up 

Dial down — 1 — 1 

Pendant up + 4 -|- 5 

Pendant right +17 +13 
Pendant left +13 —4 (17) 

The watch having a fairly satisfactory rate except for the 
pendant-right position, it was reasoned that a slight counter- 
poise would correct the error. Accordingly, the screw on the 
lower side of the balance in the position that was slow, namely 
pendant left, was reduced very slightly. The next test showed 
the following results : 



Dial up 





Dial down 


2 


Pendant up 





Pendant right 


+3 


Pendant left 


+5 



PRACTICAL WORK OF ADJUSTING 167 



—2 
+2 
+3 
+2 (5) 

It will be observed that the counterpoise retarded the fast 
position more than it accelerated the slow position. This is 
always the case. The excess of weight, when placed below 
the center of gravity, will retard the rate more than the same 
weight, when placed above, will accelerate the rate. This is 
a point to remember when attempting the correction of a 
position error by counterpoising. 

Adjustment 8. 

Watch — 12 size, 17 jewels 

Repairs — cleaned, balance poised, new balance spring 
fitted 

In this example the balance spring was selected from a 
stock of uncolleted springs. The spring was vibrated, coUeted 
and trued at the collet, overcoil formed, and corrected to pro- 
duce concentric vibrations. The first test showed the follow- 
ing rate. 

+ 5 
—10 
+17 
+ 10 
+ 12 
—15 (32) 

The natural error being considerable. It was decided that 
a new inner terminal should be made. About three inner 
coils were broken out and the Lossier inner terminal was 



Dial up 


+ 5 


Dial down 


5 


Pendant up 


+ 12 


Pendant right 


+22 


Pendant left 


+34 


Pendant down 


+ 19 



168 A PRACTICAL COURSE IN HOROLOGY 

formed. Noting also that the dial-up position was fast the 
lower pivot was rounded slightly. After timing the watch, 
the second test showed the following rate. 

Dial up Pendant right — 5 — 5 

Dial down Pendant left — 8 — 3 
Pendant up Pendant down —18 —10 (10) 

This example with the Lossier inner curve is given to show 
how the natural error can be reduced. The very best rates 
can be attained only with poised collets and theoretical inner 
terminals. The above watch when carried by the owner pef- 
formed at a rate within ten seconds a month. 

Practical Problem in Isochronal Adjusting 

In the chronometer it is possible to attain isochronism by 
altering the form of the terminal curves or by selecting a 
certain relation of the pinnings between collet and stud. How- 
ever, any attempt made to effect isochronism by these meth- 
ods in watches may seriously interfere with the position 
adjustment. As the position adjustment is more important, 
it is desirable to sacrifice the isochronal rating when both 
cannot be satisfied. If the spring is pinned correctly for 
position adjustment, the best pinning for isochronism may 
or may not exist, depending on the length of the spring and 
the design of the watch. As stated in Chapter Three, 
Isochronal Adjusting, the best we can do to attain practical 
isochronism in watches lies in the correct formation of the 
terminal curves. 

Balance springs supplied by the manufacturer. When 
fitting a spring supplied by the manufacturer for a certain 
model of watch the proper length need not be considered. 



PRACTICAL WORK OF ADJUSTING 169 

for that factor has already been taken care of by the maker. 
There are occasions, however, when the spring in the watch 
has been considerably shortened by some workman who was 
not acquainted with the laws of isochronism as governed by 
the length of the spring. In such cases the spring must be 
replaced with a new one of the proper length, if practical 
isochronism is to be expected. 

Method used in testing isochronism. After being wound 
and set, the watch is run for 6 hours, after which time the 
rate is recorded. The watch is then run for 24 hours from 
the time it was wound and set, when rate is again recorded. 
The watch is run 6 hours longer without winding and the 
rate is recorded for the third time. The rate for the first 
and last period of 6 hours is separately computed for a 
period of 24 hours. In this manner the variation of the rate is 
shown for the long and short arcs. 

A practical problem. In showing an example of isochronal 
adjusting it is possible only to prove that which has already 
been stated. The following example, therefore, shows how 
the correction of the eccentric motion of the balance spring 
improves the isochronism. The spring had an eccentric motion 
in the direction opposite the regulator pins and the first test 
showed the following results : 

[2 :00 P.M. set 

8:00 P.M. —1 

Rate in 24 hours — 4 
'2 :00 P.M. next day —3 
8 :00 P.M. —7 

Rate in 24 hours —16 (12) 

The first test showed a loss of 12 seconds in the short arcs. 



Long arcs 



Short arcs 



170 A PRACTICAL COURSE IN HOROLOGY 

After correcting the overcoil so that the vibrations of the 
spring were concentric to the center of the balance, the next 
test showed a much improved rate : 

'9 :(X) A.M. set 

3:00 P.M. 

Rate in 24 hours 

'9 :00 A.M. next day +1 
3 :00 P.M. +1^ 

Rate in 24 hours —2 (2) 



Long arcs 



Short arcs 



Practical Problem in Temperature Adjusting 

Of all the adjustments of watches temperature adjustment 
is the best understood, no doubt because of the fact that it 
has been the principal error to be eradicated in the chronom- 
eter and therefore studied more than the other. 

One example of temperature adjusting will suffice, as the 
correction in all cases consists merely of moving opposite 
pairs of balance screws from one position to another. 

The example shown below had a rate of 20 seconds fast in 
heat: 

Cold— 5 Heat +15 

To show the location of the screws and the position to 
which they are moved, it is customary to number the screw 
holes. The holes nearest the arms are numbered 1, the next 2, 
the next 3, etc., the highest number indicating the last holes 
near the loose ends of the rims. 

Since this example showed a gain in heat, the correction 
consisted of moving the screws at the free ends of the rims 
toward the balance arm. Accordingly, the screws in holes 
number 9 were moved to holes number 5, and the screws in 



PRACTICAL WORK OF ADJUSTING 171 

holes number 11 were moved to holes number 9. The next 
test showed a variation of 10 seconds slow in heat. 

Cold +10 Heat 

This shows that the correction was overdone. Therefore 
the screws in holes number 9 were moved to holes number 11. 
The next test as recorded below shows a very satisfactory 
rate. 

Cold +6 Heat +5 

Final Timing and Regulating 

Timing screws and washers. After a watch has been 
cleaned and repaired, the variation in time should not be 
corrected by moving the regulator, but rather by turning in 
or out the timing screws as the watch may require. Some 
watches do not have timing screws and the correction must 
necessarily consist in undercutting the balance screws or 
adding timing washers. H the watch runs within 30 seconds 
in 24 hours the regulator may be used. 

The middle temperature error. It was stated in Chapter 
Four of Part I that the middle temperature error causes a 
variation of from 2 to 6 seconds, being faster than the rates 
between the extremes of heat and cold. It is better, therefore, 
to regulate the watches on the rack to run a few seconds fast 
rather than just on time, for the watches on the rack are 
running in the normal temperature and the middle tempera- 
ture errort is in effect. When carried in the pocket the 
higher temperature would cause the watch to run slow. 

Delivering the watch. When delivering a watch to the 
customer tell him that it is preferable to wind the watch in 



172 A PRACTICAL COURSE IN HOROLOGY 

the morning. There is a good reason for so doing. The best 
part of the mainspring is used during the day when the 
watch is carried. Since the balance has a sHghtly shorter arc 
of motion when running in a vertical position, it is better 
to take advantage of the extra power that would be avalable 
by winding in the morning. Because a watch is usually laid 
flat on a table or dresser at night it is at once evident that a 
more nearly uniform balance arc takes place if the above 
practice of winding the watch is adhered to. 

The horologist should take time to explain to the customer 
that there will probably be a variation of several seconds 
during the first few weeks of carrying the watch and ask the 
party to come in, in a week or two, for comparison with the 
correct time and for further regulation if necessary. Tell 
the customer that it takes several weeks to properly regulate 
a watch and that he may come in as often as he finds it con- 
venient. In this manner much of the dissatisfaction of the 
repair department is eliminated besides making many friends 
for the store. 



GLOSSARY OF TERMS 



Addendum. The portion of a tooth of a wheel or pinion 
beyond the pitch circle. 

Arbor. Axis of the balance wheel or mainspring barrel. 

Balance. The vibrating wheel of a watch, which, in con- 
junction with the balance spring, regulates the progress of 
the hands. 

Balance arc. A part of the vibration of a balance. 

Balance cock. The support for the upper pivot of the bal- 
ance staff. 

Balance spring. A long fine spring that regulates the vibra- 
tion of the balance. 

Balance staff. The axis of the balance. 

Banking pins. Two pins that limit the angular motion of 
the lever. 

Banking to the drop. An adjustment of the banking pins 
permitting the escape wheel teeth to drop off the pallets. 

Barrel. A circular box for the reception of the mainspring. 

Barrel arbor. The axis of the barrel, round which the main- 
spring coils. 
Beat. One vibration of the balance and spriiig. 

Beryllium alloy. An alloy of iron, nickel, and a small 
percentage of beryllium, used for balance and balance 
spring. 

173 



174 A PRACTICAL COURSE IN HOROLOGY 

Breguet spring. A balance spring in which the outer coil is 
raised above and carried over the body of the spring. 

Bridge. Upper plates in a watch for the support of the 
wheels. 

Butting. Two wheels touching on the points of the teeth 
when entering into action with each other. 

Cannon pinion. The pinion with a long pipe to which the 
minute hand is fixed. 

Center of gravity. That point in a body around which the 
mass is evenly balanced. 

Center wheel. The wheel in a watch the axis of which 
usually carries the minute hand. 

Chronograph. A watch that has a center-seconds hand 
driven from the fourth wheel which can be started, stopped, 
and caused to fly back to zero by pressing on a knob or 
lever. 

Chronometer. A boxed timepiece for use on ships at sea. 

Chronometer escapement. A spring detent escapement used 
in chronometers. Invented by Pierre LeRoy about 1765. 

Circular escapement. An escapement so constructed that 
the central portion of each pallet stone's impulse face 
stands at an equal distance from the pallet center. 

Circular pitch. The pitch circle divided into as many spaces 
as there are teeth on the wheel or pinion. 

Club-tooth wheel. That type of wheel which has a lifting 
face off the end of the teeth. 

Clutch pinion. The pinion surrounding the square of the 
stem. Serves alternately to wind and set the watch. 



GLOSSARY OF TERMS 175 

Collet. A small, circular piece fitting friction-tight to the 
balance staff and which is pierced to receive the inner coil 
of the balance spring. 

Compensating balance. A balance the rim of which is made 
of brass and steel. The diameter is caused to increase or 
decrease in different temperatures, so as to compensate for 
changes in temperature on both balance and spring. 

Corner safety test. A test to show the presence or absence 
of safety lock when the slot corner is brought in contact 
with the roller jewel. 

Crescent. A circular notch in the edge of the roller table 

for the reception of the guard pin or finger. 
Crown. A grooved circular piece fastened to the stem for 

winding the watch. 

Crown wheel. A wheel that drives the ratchet wheel. 

Curb pins. Regulator pins. 

Curve test. A test used to discover if the curves of the 
lever horns are correctly related to the roller jewel. 

Cylinder escapement. A frictional escapement patented by 
Thomas Tompion 1695. 

Dedendum. The portion of the tooth of either wheel or 
pinion inside of the pitch circle. 

Dial train. A train of two wheels and two pinions that con- 
trol the progress of the minute hand and the hour hand. 

Diametrical pitch. The diameter of the pitch circle divided 
into as many spaces as there are teeth on a wheel or pinion. 

Discharging pallet. The pallet stone which an escape- 
wheel tooth slides over in order to emerge from between 
the pallet stones. 



176 A PRACTICAL COURSE IN HOROLOGY 

Distance of centers. The distance on a straight line from 
center to center, as between balance center and pallet center. 

Double-roller escapement. A form of lever escapement in 
which a separate roller is used for the safety action. 

Draw. A force that keeps the lever against the banking pins, 
created by the slant of the pallet stones. 

Driven. The mobile that is being forced along by the driver. 

Driver. The mobile that forces the other along. 

Drop. The free motion of the escape wheel after impulse to 
the pallets has been given. 

Drop lock. The extent of the lock on the pallets after an 
escapement has been banked to the drop. 

Duplex escapement. A watch escapement in which the 
escape wheel has two sets of teeth. One set locks the wheel 
by pressing on the balance staff. The other set gives im- 
pulse to the balance. The balance receives impulse at every 
other vibration. Accredited to Pierre LeRoy about 1750. 

Epicycloid. A curve generated by a point in the circum- 
ference of a circle as it rolls upon another circle. It forms 
the kind of tooth used in watch wheels. 

Equidistant escapement. An escapement so constructed 
that the locking faces of the pallet stones stand at an equal 
distance from the pallet center. 

Elinvar. A nonrusting, nonmagnetizing alloy containing 
iron, nickel, chromium, tungsten, silicon and carbon. Used 
for balance and balance spring. 

Fork. The horns and slot of the lever. 



GLOSSARY OF TERMS 177 

Fourth wheel. The wheel of a watch that drives the escape 
pinion. 

Guard pin or finger. A pin or finger working in and out of 
the crescent to preserve the safety action. 

Guard safety test. A test to show the presence or absence 
of safety lock when the guard pin or finger is brought in 
contact with the edge of roller. 

Heel of tooth. Letting-oif corner of a tooth of the escape 
wheel. 

Horns. The circular sides of the fork leading into the slot. 

Hour wheel. The wheel that carries the hour hand. 

H3rpocycloid. A curve generated by a point in the circum- 
ference of a circle when it is rolled within another circle. 

Impulse pin. Roller jewel. 

Invar. A steel alloy containing about 36 per cent nickel. 
Used in the making of balance wheels. 

Isochronism. The property of a balance spring that allows 
it to perform the long and short arcs in equal time. 

Letting-off comer. Corner of a pallet stone from which a 
tooth lets off. 

Lever. A metal piece attached to the pallets that carries 
impulse to the balance. 

Lever escapement. A watch escapement that delivers im- 
pulse to the balance by means of two pallet stones and a 
lever. The extremity of the lever has a forked slot that 
acts directly on a roller jewel which is attached to the 
balance. Invented about 1750 by Thomas Mudge. 

Lift. The pitch or slant of a tooth or pallet stone. 



178 A PRACTICAL COURSE IN HOROLOGY 

Line of centers. A line drawn from center to center, as of 
any wheel or pinion. 

Locking. The overlapping of a tooth on a pallet stone. 

Lossier curves. The theoretical outer and inner terminals 
as designed by L, Lossier. 

Main train. The toothed wheels in a watch that connect the 
barrel with the escapement. 

Middle-temperature error. The temperature error between 
the extremes of heat and cold characteristic of a com- 
pensating balance and steel balance spring. 

Minute v^^heel. The wheel driven by the cannon pinion. 

Out of angle. Unequal angular motion of the lever from the 
line of centers when an escapement is banked to the drop. 

Overbanked. A term used to indicate that the lever escape- 
ment is out of action. 

Overcoil. The last coil of the Breguet spring that is bent 
up and over the body of the spring. 

Pallet arms. The metal body which contains the pallet stones. 

Pallets. The metal body attached to or a part of the lever. 
The term includes the pallet arms and pallet stones. 

Pallet staff. The axis of the pallets. 

Pallet stones. Jewels or stones inserted in the pallet arms. 

Phillips* spring. A balance spring with terminal curves 
formed on lines laid down by M. Phillips. The term 
"Phillips' curve" is rarely used. 

Pinion. The smaller wheel with teeth called leaves, working 
in connection with a larger wheel. 



GLOSSARY OF TERMS 179 

Pitch circle. A circle concentric with the circumference of 
a toothed wheel and cutting its teeth at such a distance 
from their points as to touch the corresponding circle of 
a pinion working with it and having with that circle a 
common velocity, as in a rolling contact. 

Pitch diameter. The diameter of the pitch circle. 

Pivot. The end of a rotating arbor. 

Plate. Discs of brass or nickel which form the foundation 
of a movement. The lower plate lies next to the dial. The 
upper pieces supporting one, two, or three wheels are 
generally referred to as bridges. In the full-plate watch 
the upper piece is called the top plate. 

Potence. A hang-down bracket used for supporting the 
lower pivot of the balance staff in full-plate watches. 

Quarter screws. Four screws used in timing. 

Ratchet wheel. A wheel that is fastened to the barrel arbor. 

Ratchet tooth wheel. The name given to the English type 
escape wheel which has pointed teeth. 

Receiving pallet. The pallet stone over which a tooth of 
the escape wheel slides in order to enter between the pallet 
stones. 

Remaining lock. The lock remaining when the guard and 
corner tests are tried. More often called "safety lock." 

Repeater. A watch that strikes, having two hammers and 
two gongs. A lever Is provided to set the striking mech- 
anism into action. A quarter repeater strikes the hour and 
the last quarter hour. A minute repeater, in addition, 
strikes the number of minutes since the last quarter. 



180 A PRACTICAL COURSE IN HOROLOGY 

Right-angled escapement. An escapement in which the Hne 
of centers of the escape wheel and pallets are at right angles 
to pallets and balance. 

Roller jewel. A long, thin jewel inserted in the roller table ; 
sometimes called impulse pin. 

Roller table. A circular disc attached to the balance staff 
in which is fitted the roller jewel. 

Run of lever. The motion of the lever toward the banking 
pins when slide is present. Run always equals slide. 

Safety lock. The lock remaining when the guard and corner 
tests are tried. 

Semitangental escapement. An escapement where the lock- 
ing face of the receiving pallet is planted 31 degrees from 
the line of centers and the discharging pallet 29 degrees 
from the line of centers. The receiving pallet locks only on 
the tangent. 

Shake. The space separating the letting-off comer of the 
pallet from the heel of a tooth when the opposite pallet is 
locked at the lowest locking corner. Shake is always less 
than drop. 

Single roller escapement. A form of lever escapement in 
which one roller performs the functions of both impulse 
and safety actions. 

Slide. The opening of the banking pins beyond that of drop 
lock. 

Steady pins. Pins used to secure the perfect alignment of 
two pieces of metal. 

Stem. The winding arbor of a watch. 



GLOSSARY OF TERMS 181 

Stop work. A mechanical device for preventing the over- 
winding of a mainspring. 

Straight line escapement. An escapement in which the 
centers of the escape wheel, pallets, and balance are planted 
in a straight line. 

Stud. A small piece of metal pierced to receive the outer coil 
of the balance spring. 

Third wheel. The wheel of a watch that drives the fourth 
pinion. 

Timing screws. Screws used to bring a watch to time, 
sometimes called the mean-time screws. 

Toe of tooth. Locking corner of a tooth of the escape wheel. 

Total lock. Drop lock with slide added. 

Train. A combination of two or more wheels and pinions, 
geared together and transmitting power from one part of 
a mechanism to another. 

Tripping. A tooth of the escape wheel running past the 
locking face of a pallet stone at a time when safety lock 
should be present. 

Wheel. Any circular piece of metal on the periphery of 
which teeth may be cut of various forms and numbers. 

Winding pinions. A pinion surrounding the stem that 
drives the crown wheel. 



WATCHES 

Borer and Bowman, 

Modern Watch Repairing and Adjusting 

DeCarle, Donald, 

With the Watchmaker at the Bench 

Garrard, F. J., 

Watch Repairing, Cleaning and Ad j testing 

Gribi, Theo., 
Practical Course in Adjusting 

Grossman, Jules and Herman, 
Lessons in Horology 

Hood, Grant, 

Modern Methods in Horology 

Kleinlein, Walter J., 

Rules and Practice in Adjusting Watches 
Practical Balance and Hairspring Work 

Thisell, A. G., 

Watch Repairing Simplified 

Wilkinson, T. J., 

The Escapement a7id Train of American Watches 

182 



BIBLIOGRAPHY 183 

WATCHES AND CLOCKS 
Britten, F. J., 

Watch and Clock Makers* Handbook 

Haswell, Eric, 
Horology 

Saunier, Claudius, 

Treatise on Modem Horology 

CLOCKS 
Garrard, F. J., 

Clock Making and Repairing 

Gordon, G. F. C., 

Clock Making, Past and Present 

Langman and Ball, 
Electrical Horology 

Philpott, Stuart F., 
Modern Electric Clocks 

Robinson, T. R., 

Modern Clocks, Their Repair and Adjustment 

HISTORY 
Britten, F. J., 

Old Watches and Clocks and Their Makers 

Chamberlin, Paul M., 
If s About Time 

Gould, Rupert T., 

The Marine Chronometer, Its History and Developinent 



184 A PRACTICAL COURSE IN HOROLOGY 

Hering, D. W., 

The Lure of the Clock 

Nutting, Wallace, 
The Clock Book 

ALLIED SUBJECTS 

Bennett, Charles A., 

Beginning Problems in Mechanical Drawing 

Eaton and Free, 

Machine Shop Science and Mathematics 

Feirer and Williams, 
Basic Electricity 

McMackin and Shaver, 
Mathematics of the Shop 

Roberts, William E., 

Beginning Mechanical Drawing 



INDEX 



A 

Action PAGE 

fork and roller 47, 110 

four-to-one roller 47 

of flat spring 152 

three-to-one roller 47 

safety in 45, 110 

unlocking and impulse. 47 

pallet on wheel 44, 100 

wheel and pallet_44, 100, 106 

Addenda 33 

Adjusting 128-172 

escapement 100-113 

isochronism 

128, 150-155, 168, 169 

position 128, 140-149 

practical work of 159 

regulator pins 146, 147 

temperature 

128, 156-158, 170 

Altering drop locks 102 

Angle, escapement, out of 

102,119,120,121 
Angular motion of lever_ liO 
Arc of motion of balance. 133 

185 



B 

PAGE 

Balance 14, 52-53 

axis 84 

counterpoising 145 

motion 132 

pivots 129 

poise of 134, 136 

Balance spring 14, 53, 58 

action of flat 152 

and its poise error 140 

Breguet type 144 

eccentric motion of 97 

fitting of 88, 89 

flat 58 

isochronal condition of _ 150 
length of, on ischronism 151 

on position error 144 

truing of 97 

Balance staff 73-84 

Banking pins 41-101 

Banking to drop 101 

Barrel 14,24 

Beat 14 

Bell-metal laps 7S 



186 



A PRACTICAL COURSE IN HOROLOGY 



PAGE 

Bezel-type jeweling 68, 70 

Boxwood laps 79 

Breguet balance spring 

58,90,144,152 

Burnisher 69 

Butting 63 

Butting error, example of 121 

c 

Calculating 

a new train 23 

beats 18,88 

length of mainspring 26 

length of overcoil 91 

number of hours watch 

will run 24 

teeth and leaves of miss- 
ing mobiles 20-22, 30 

thickness of mainspring 25 

turns of pinion 15 

turns of train 16-18 

Cannon pinion 28 

Cast-iron laps 78 

Cement chucks 82, 85 

Center of gravity 59-141 

Center wheel and pinion. 16 
Centers 

distance of 32 

line of 33 

Circular pallets 42 



PAGE 

Circular pitch 33, 37 

Cleaning watches 124-126 

Close inside 104 

Close outside 104, 120 

Club-tooth escapement 

45, 107, 108 
Qub-tooth escape wheeL 39 

Collet 77, 80, 84, 143 

Comments on fast trains- 19, 20 

Compensating balance 53 

Cone pivot 80 

Controlling mechanism _52-60 
Converting flat spring into 

Breguet 94,95 

Corner freedom 117, 120 

Comer safety test 110, 112 

Counterpoising 145 

Crescent 41, 50 

Curve test 113 

Dedenda, dedendum 

33, 34, 175 

D 

Degrees of angular motion 1 10 
Degrees of lift 110 

Delivering the watch 171 

Demagnetizing a watch__ 138 

Depthing too deep 62, 64 

Depthing tool 35 

Depthing too shallow 62, 64 



INDEX 



187 



PAGE 

Dial train 15, 28-31 

Diameter, full 32, 36 

pitch 32 

Diametrical pitch 33 

Dimensioning, three and 

five position 161-164 

Discharging pallet 14,40 

Distance of centers 32 

Double roller 41, 50 

Draw 45, 103, 104 

Drawing lever escapement 1 14 

Driven 33 

Driver 33 

Drop 46, 104 

banking to the 101 

close outside 120 

Drop lock 101, 102 

deep 118,119,121 

light 119 

E 

Eccentric motion of bal- 
ance spring 97 

Effect of manipulating 

regulator pins 146 

Elinvar 57, 156 

Epicycloid 33 

Equidistant pallets 41 

Equipment for tempera- 
ture ad j usting 157 



PAGE 

Errors common in staff 

making 83 

Escapement 14, 39-51, 100-123 

adjusting 100-123 

double-roller 50 

drawing 114 

lever 44 

semitangental 43 

single-roller 49 

tests 116 

theoretically correct 114 

Escape wheel 16, 39 

number of teeth of 43 

weight of 131 

F 

Fast pendant-up 161 

Fast trains 19 

Final timing and regulat- 
ing 171 

Finishing end of balance 

pivots 83 

Fitting balance springs 88-99 

Five positions, adjustment 

to 163 

Flat spring 

on isochronism 152 

on position error 144 

Flat springs, fitting 89 

Fork and roller action 47-1 10 



188 



A PRACTICAL COURSE IN HOROLOGY 



PAGE 

Fork slot 40, 47 

Four-to-one roller action. 47 
Fourth wheel and pinion_ 16 
Friction jeweling 70, 71 

G 

Gearing 32-38, 62 

Gravers 

for setting jewels 68, 69 

for turning staff 73, 74 

Grinding and polishing 

cone pivot 80 

Grinding materials 79 

Guard freedom 

excessive 117 

none 119 

Guard pin jams 121 

Guard safety test 110 

Guard tripping error 117-119 

H 

Hand method of cleaning 

watches 124 

Heel of tooth 40 

Horizontal positions, ad- 
justment to 148 

Horns of fork 40 

Hours of running 24 

Hour wheel 28 



PAGE 

Hub, turning and rough- 
ing 81 

Hypocycloid 34 

I 

Impulse 130 

Impulse and unlocking ac- 
tion 47 

Impulse face 40 

Influence of the escape- 
ment on the adjust- 
ments 130 

Invar 57, 156 

Isochronal adjustment, 

example of 168 

Isochronal error 154 

Isochronism 

adjustment to 150-155 

length of balance spring 

on 151 

testing to 169 

J 

Jeweling : 68-72 

Jewel pin or roller jeweL40, 41 

L 

Laps 78,79 

Length of balance spring- 151 
Letting-of¥ corner 40 



INDEX 



189 



PAGE 

Lever 40 

angular motion of 110 

escapement 

39-51,114,116,130 

Lift 45,105,107,110 

Line of centers 33 

Lock 

drop safety, tests 

14,101,110-113 

total 114 

Locking 44 

Locking face 40 

Lossier inner and outer 

terminals 59, 60, 91, 95 

M 

Machine method of clean- 
ing watches 125 

Magnetized tools 138 

Magnetism 137 

Main train 15, 129 

Mainspring 

length of 26 

space in barrel 26, 27 

thickness of 25 

Mainsprings 24, 132 

Maximum allowance in 

positions 160 

Measuring for balance 

staff 75 



PAGE 

Middle-temperature error 

54, 171 

Minute pinion 28 

Minute wheel 28 

Motion of balance 133 

Motion of balance spring. 97 

N 

Natural error 142, 144 

Narrow roller jewel 49 

Number of teeth of escape 

wheel 43 

o 

Oiling watches 124 

Outside drop, close 120 

Out of angle 102-120 

Overcoil 58,93,94 

P 

Pallet and tooth, width of 45 

Pallet and wheel action 44 

Pallet fork 40,41, 131 

Pallet impulse face 40 

Pallet letting-off corner 40 

Pallet locking face 40 

Pallets 14,40, 131 

adjusting of 100 

circular 42, 46 

discharging 40 



190 



A PRACTICAL COURSE IN HOROLOGY 



PAGE 

equidistant 41, 46 

lift on 105 

receiving 40 

safety action 45, 110 

semitangental 42 

Pallet stone 40 

Pinion 

depthing too deep 62, 64 

depthing too shallow 62, 64 

minute 28 

too large 62, 63 

too small 62, 64 

Pinions 13,32,62,65,85 

Pinning of balance spring 

at the collet 143 

Pitch 

circle 32 

circular 33, 37 

diameter 32, 35 

diametrical 33 

Pivot, conical, turning a 77 

Pivoting 85-87 

Pivot polisher 77, 79 

Pivots, making and turn- 
ing 74,77 

Poise error, analysis of 135 

Poise of the balance 134-136 

Polishing cone pivot 80 

Position adjusting 

140-150, 159 



PAGE 

Practical work of adjust- 
ing 159 

Principles of gearing 33 

Problems in adjusting 

escapement 117 

isochronism 168 

position 161 

temperature 170 

R 

Ratchet tooth escape 

wheel 39 

Receiving pallet 40 

Regulating and timing 171 

Regulator pins, adjust- 
ment of 146 

Remaining lock 111 

Resistance to unlocking 

19, 42, 103 
Roller, single and double 

41,49,50 
Roller and fork action_47, 100 

Roller axis 82,83 

Roller jewel 40,41,49 

Roller table 40 

Rounding-up tool 66 

s 

Safety lock tests 110 

Screws, timing 171 



INDEX 



191 



PAGE 

Setting jewels (^ 

Setting staff in cement 

chuck 82 

Semitangental pallets 42, 110 

Shake 105, 120 

Short fork 117 

Slide 102,113 

Slot, fork 40 

Springs 

balance 52, 88-99 

Breguet, fitting 90 

flat, fitting 89 

Staff, balance 7?> 

Staff, in cement chuck 82 

Staff making, common er- 
rors in 83 

Staff, measuring for 75 

Staff, turning 76, 83 

Staking tool 65 

Steel, preparation of 76 

T 

Teeth in escape wheel 43 

Temperature, adjustment 

to 156-158,170 

Temperature error _ 52-54, 157 

Terminals, theoretical 59 

Testing escapement 

draw 104 

drop 104 



PAGE 

droplock 101 

lift 105 

safety locks 110 

shake 105 

Theoretically correct es- 
capement 114 

Theoretical terminals 59 

Theory of demagnetiza- 
tion 137 

Third wheel and pinion 16 

Three positions, adjust- 
ment to 161 

Three-to-one roller action 47 

Timing and regulating 171 

Timing screws 171 

Timing washers 171 

Toe of tooth 39 

Tooth, width of 35-46 

Torsion 152, 154 

Train 13 

dial 15, 28-31 

fast 19 

main 15, 129 

problems 62-67 

repairing 65 

slow 18 

wheel 129 

wheel, stretching 6 

Tripping error 117-119 



192 



A PRACTICAL COURSE IN HOROLOGY 



^ PAGE 

Unlocking and impulse ac- 
tions 47 

Unlocking resistance, an- 
alysis of 42 

Use of regulator pins in 

adjusting 146 



Vibrating a balance spring 89 

Vibrations 88 

Vibrator 89,90 



w 

Washers, timing 



171 



PAGE 

Watch-cleaning machine _ 125 

Wheel and pallet action 

44,100 
Wheel and pinion prob- 
lems 62 

Wheel 

reducing 66 

stretching 65 

Wheels and pinions 13 

Wheel work 13-31 

Width of crescent 50 

Width of pallet 45 

Width of tooth 35,46