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Transcriber's notes:
Some minor typographical errors have been corrected.
The author's spelling has been retained.
A TREATISE
ON
STAFF MAKING
AND
PIVOTING
CONTAINING COMPLETE DIRECTIONS FOR MAKING
AND FITTING NEW STAFFS FROM
THE RAW MATERIAL
EUGENE E. HALL
WITH NUMEROUS ILLUSTRATIONS
CHICAGO:
HAZLITT & WALKER, PUBLISHERS
1910
CONTENTS.
CHAPTER I.
The raw material. The gravers. The roughing out. The hardening
and tempering 5
CHAPTER II.
Kinds of pivots. Their shape. Capillarity. The requirements of
a good pivot 13
CHAPTER III.
The proper measurements and how obtained 19
CHAPTER IV.
The gauging of holes. The side shake. The position of the graver 23
CHAPTER V.
The grinding and polishing. The reversal of the work. The wax
chuck 29
CHAPTER VI.
Another wax chuck. The centering of the work 35
CHAPTER VII.
The finishing of the staff. Pivoting. Making pivot drills. Hardening
drills. The drilling and fitting of new pivots 39
STAFF MAKING AND PIVOTING.
CHAPTER I.
To produce a good balance staff requires more skill than to produce any
other turned portion of a watch, and your success will depend not alone
on your knowledge of its proper shape and measurements, nor the tools at
your command, but rather upon your skill with the graver and your success
in hardening and tempering. There are many points worthy of consideration
in the making of a balance staff that are too often neglected. I have
seen staffs that were models as regards execution and finish, that were
nearly worthless from a practical standpoint, simply because the maker
had devoted all his time and energy to the execution of a beautiful piece
of lathe work, and had given no thought or study to the form and size of
the pivots. On the other hand, one often sees staffs whose pivots are
faultless in shape, but the execution and finish so bungling as to offset
all the good qualities as regards shape. To have good tools and the right
ideas is one thing, and to use these tools properly and make a practical
demonstration of your theory is another.
I shall endeavor to take up every point in connection with the balance
staff, from the steel to the jewels, and their relation to the pivots,
and I believe this will then convey to the reader all the necessary
points, not only as regards staffs, but pivots also, whether applied to a
balance or a pinion staff.
It may be argued, and we often do hear material dealers advance the
theory, that to-day, with our interchangeable parts and the cheapness of
all material, it is a waste of time to make a balance staff. To the
reader who takes this view of the situation I simply want to say, kindly
follow me to the end of this paragraph, and if you are still of the same
opinion, then you are wasting your time in following me farther. For a
material dealer to advance this theory I can find some excuse; he is an
interested party, and the selling of material is his bread and butter;
but the other fellow, well I never could understand him and possibly
never shall. When we seriously consider the various styles and series in
"old model" and "new model," of only one of the leading manufacturers of
watches in this country, to say nothing of the legion of small and large
concerns who are manufacturing or have manufactured in the past, and then
think of carrying these staffs in stock, all ready for use, we then begin
to realize how utterly absurd the idea is, to say nothing of how
expensive! On the other hand, if you reside in a large city and propose
to rely on the stock of your material dealer, you will find yourself in
an embarrasing situation very often, for as likely as not the movement
requiring a new staff was made by a company that went out of business
back in the '80s, or it is a new movement, the material for which has
not yet been placed on the market. This state of affairs leads to
makeshifts, and they in turn lead to botch work. The watchmaker who does
not possess the experience or necessary qualifications to make a new
balance staff and make it in a neat and workmanlike manner, is never
certain of having exactly what is needed, and cannot hope to long retain
the confidence of his customers. In fact, he is not a watchmaker at all,
but simply an apprentice or student, even though he be working for a
salary or be his own master. There are undoubtedly many worthy members of
the trade, who are not familiar with the making of a balance staff, who
will take exceptions to this statement; but it is nevertheless true. They
may be good workmen as far as they go; they may be painstaking; but they
cannot be classed as watchmakers.
This article is intended for the benefit of that large class whose
opportunities for obtaining instruction are limited, and who are ready
and willing to learn, and for that still larger class of practical
workmen who can make a new staff in a creditable manner, but who are
always glad to read others people's ideas on any subject connected with
the trade and who are not yet too old to learn new tricks should they
find any such.
[Illustration: _Fig. 1._]
Good tools, in good condition, are the most essential requisites in
making a new staff. I would not advise any particular make of lathe, as
the most expensive lathe in the world will not produce a true staff if
the workman cannot center his work accurately and does not know how to
handle his graver, while on the other hand fine work can be done on the
simplest and cheapest lathe by a workman possessing the requisite skill.
I will take it for granted that you use an American-made lathe of some
kind, or a foreign-made lathe manufactured on American lines. It is
advisable, though not absolutely necessary, to have three gravers similar
to those illustrated in Fig. 1, A being used for turning the staff down
in the rough; B for the conical pivots and square shoulders and C for the
under-cutting. The other tools and attachments needed will be described
as I come to them in use.
The balance staff should be made of the best steel, tempered to such a
degree as to give the longest service and yet not so hard as to endanger
the breakage of the pivots. Select a piece of Stubb's steel wire, say No.
46, or a little larger than the largest part of the finished staff is to
be, and center it in a split chuck of your lathe. Be careful in selecting
your chuck that you pick one that fits the wire fairly close. The chuck
holds the work truest that comes the nearest to fitting it. If you try to
use a chuck that is too large or too small for the work, you will only
ruin the chuck for truth. Turn the wire to the form of a rough staff, as
shown in Fig. 2, leaving on a small part of the original wire, as shown
at A. After the wire is roughed out to this general form, remove from the
chuck and get ready to harden and temper it. The hardening and tempering
may be effected in various ways, and I am scarcely prepared to say which
method is the best, as there are several which give about the same
general results. One method of hardening is to smear the blank with
common yellow soap, heat it to a cherry red, and drop endwise into
linseed oil. Petroleum is preferred by some to linseed oil, but, to tell
the truth, I can see no difference in the action of linseed, petroleum or
olive oil. Be sure and have enough oil to thoroughly cool the blank, and
a deep vessel, such as a large-mouthed vial, is preferable to a saucer.
The blank will now be found too hard to work easily with the graver, and
we must therefore draw the temper down to that of fine spring steel.
Before doing this the blank should be brightened, in order that we may
see to just what color we are drawing it. The main object in using the
soap in hardening is that it may form a scale upon the blank, and if the
heating is effected gradually the soap will melt and form a practically
air-tight case around the blank. This scale, if the hardening is
carefully and properly done, will generally chip and fall off when the
blank is plunged in the oil, particularly if the oil is cool, and if it
does not fall off of its own accord, it can easily be removed by rolling
the blank upon the bench. If it does not come out clean, or if soap is
not used, it may be brightened by again inserting in the lathe and
bringing it in contact with a piece of fine emery paper or cloth.
[Illustration: _Fig. 2._]
I draw the temper in the following manner: Place some fine brass filings
in a boiling-out cup or bluing pan and lay the blank upon these filings,
holding the pan over the flame of an alcohol lamp until the blank assumes
a dark purple color, which it will reach when the heat gets to about 500 deg.
F. This I consider the right hardness for a balance staff, as it is not
too hard to work well under the graver nor too soft for the pivots. At
this degree of hardness steel will assume an exquisite polish if properly
treated. Another method of tempering is to place the staff on a piece of
sheet iron or copper (say 1 inch wide by 4 long), having previously bent
it into a small angle, for the reception of the staff, as shown in Fig.
3. This piece of metal, when nicely fitted into a file handle, will
answer all the purposes of the bluing pan and presents quite a neat
appearance. Having placed the blank in the angle, lay on it a piece of
yellow wax about the size of a bean, and heat it over your lamp until the
wax takes fire and burns. Blow out the flame and allow the staff to cool,
and it will be found to be of about the right hardness.
[Illustration: _Fig. 3._]
We have now arrived at an important station in staff making, a junction,
we may term it, where many lines branch off from the main road. At this
particular spot is where authorities differ. I have no hesitation in
saying that at this particular point the split chuck should be removed
from the lathe head and carefully placed in the chuck box and the cement
chuck put in its place. I believe that all of the remaining work upon a
staff should be executed while it is held in a cement chuck. On the other
hand I have seen good workmen who turned and finished all the lower part
of a staff while in a split chuck, cut it off and turned and finished the
upper part in a cement chuck. All I have got to say is that they had more
confidence in the truth of their chucks than I have in mine. I have even
read of watchmakers who made the entire staff in a split chuck, but I
must confess I am somewhat curious to examine a staff made in that way,
and must have the privilege of examining it before I will admit that a
true staff can be so made.
We will suppose that the workman has a moderately true chuck, and that he
prefers to turn and finish all the lower portions in this way. Of course
the directions for using a cement chuck on the upper part of a staff are
equally applicable to the lower. Before going further I think it
advisable to consider the requirements of a pivot, but will reserve this
for another chapter.