HEALTH AND MANIPULATION.
PRESERVATION OF HEALTH.
=217.= Some of the following directions may perhaps be considered to
be over-minute and too restrictive; but they are not so. Good habits
contracted in youth are easily maintained, and, when the watchmaker
has tried them long enough to convince him of their influence on his
health, he will experience no difficulty in keeping them up.
THE SIGHT.
=218.= When working at any small mechanism, such as a watch, it is
necessary to use the glass, but this practice is apt to produce
inflammation of the conjunctiva or cornea and a weakening of the
eyesight; a too frequent and prolonged use of the glass will have the
same effect as using spectacles that are too strong.
In order to preserve his eyesight, the watchmaker should take the
following precautions:
He should not retain the glass at his eye by a contraction of the
muscles for more than a brief interval of time. The glass holder, which
can be at once set in any desired position, has therefore much to
recommend it.
Drill a few holes in the frame of the glass to avoid or at least
diminish the inconvenience that arises from the heating of the
enclosed air, as well as from the deposition of moisture on the surface
of the glass.
Do not use glasses of too great magnifying power; they needlessly
fatigue the eye.
Only use glasses that are truly achromatic. If compelled to use the
ordinary simple glass, place a ring of dead black paper inside the
frame and against the lens, which, by diminishing the field of view,
will reduce the inconvenience due to spherical aberration.
It is hardly necessary to advocate the use of a green cardboard shade
to the lamp, as they are so generally used by watchmakers. It should
be so arranged as to protect the head and eyes from radiation, and
cardboard is preferable to metal as it radiates less heat.
Working at night and by artificial light, more especially by the
dazzling light of gas, fatigues the eyes much more than with ordinary
daylight, and the workman will find it a relief, if obliged to work by
artificial light on very minute objects, to rest his eyes frequently
on large stationary bodies. If he can do so, it is a great comfort to
bathe the eyes in cold water.
It is good practice to habituate oneself to the use of either eye with
the glass.
By adopting these simple precautions, how many of our fellow-workers
who are now only able to see objects indistinctly and suffer from
incipient blindness would have preserved their sight uninjured. And
there is yet another precaution that has been pointed out by Dr.
Haltenhoff, of Geneva. He has shown that by avoiding an excessive
indulgence in alcoholic drinks or tobacco, many old watchmakers in that
town have succeeded in preserving their sight unimpaired, and it is
impossible to doubt the truth or over-estimate the importance of this
fact.
The same authority draws attention to the necessity of taking care
that, before adopting watchmaking as a trade, youths should ascertain
that they do not suffer from progressive nearsightedness, which is
often hereditary, as in such a case they would most certainly be
compelled to abandon it in after life. Boys should not be set to work
on such small objects as the details of a watch too early in life,
before the membranes of the eye have assumed a certain degree of
rigidity.
Mr. Brudenell Carter, a well-known ophthalmist, is of opinion that the
habitual use of the glass by watchmakers has the effect of actually
developing and preserving the power of the eye.
THE BODY IN GENERAL.
=219.= It is often found that an old, or even middle-aged watchmaker is
irritable, often tired and soured. This arises, not so often from an
over-excited uneasiness in regard to his trade, an explanation that is
usually urged, as from a derangement of his digestive organs brought
about by the habit of life he is compelled to adopt. Prolonged working
at minute horological mechanism is perhaps more wearying to the mind
and body than any other trade or occupation.
To avoid its ill effects the watchmaker should adopt the following
precautions as far as possible:
Do not use a stool with a stuffed seat, but prefer one of cane or wood.
Take care that the relative heights of the board and stool are such
that an excessive compression of the muscles of the chest, etc., is
avoided during any long operation that renders it necessary to maintain
the body in a constrained position.
A stool with adjusting screw similar to a music stool is convenient
from this point of view.
Change the position as much and as often as possible, especially when
working with the file or graver. With this object in view many workmen
have a second board of such a height that they can work standing.
When using the lamp let it always be provided with a cardboard shade as
already recommended.
A screen to protect the head from the direct heat of the flame is often
found advantageous; in fact, the watchmaker should adopt the advice of
Boerhaave: “Keep the head cool and the feet warm.”
Let him always remember that nothing does more harm than sitting to the
bench immediately after a meal. He should allow an interval of half an
hour to elapse and with some temperaments, even this is not enough;
during this period he should only do work at which it is possible to
stand. A little exercise, such as a walk that is not hurried, will
be still better; it will stimulate the circulation and stretch the
muscles that have been maintained in a constrained position for a long
time through the prolonged attention and slight motion that his labors
involve.
USE OF THE FILE AND GRAVER.
=220.= The first operations that a watchmaker ought to learn are to
file flat and square, to turn round, to forge, to hammer-harden a piece
of metal without deteriorating it. These accomplishments are but too
much neglected in the modern training of an apprentice, an omission
that is partly owing to the want of good instructors and partly to the
shortness of the time he can afford to devote to learning his trade.
TO FILE FLAT AND SQUARE WITH BOTH HANDS AT ONCE.
=221.= It is a very common practice to place an old file in the hands
of an apprentice, to fix in the jaws of a vise a piece of metal, either
brass, iron or steel, and to set him to work rubbing and filing the
surfaces with great labor, the only result being that they are utterly
mis-shapen and covered with brilliant spots.
This method is bad. The action of the file is mechanical and the
problem that has to be solved is the following: To produce good work in
the shortest possible time, and with the least expenditure of force.
It is therefore only by very slow degrees that an apprentice can hope
to acquire the requisite ability, if he is set to work trying to shape
an object in some hard metal before he knows how to maintain lines
straight and surfaces flat. Not knowing how to proportion his effort
to the resistance to be overcome, and allowing the file to travel
irregularly over the surface, he gets confirmed in the tendency to give
a rocking motion to the file, whereby the surface is left round, and he
will find it all the more difficult to throw this habit aside.
It is far better to let him commence on round pieces of common wood,
filing with a rasp or coarse-cut file, without removing too much at
once. By this means he may rely on learning to file flat and square by
the eye alone without the aid of a straight-edge.
When he works well in common wood, he can be set to file harder woods,
box for an example, roughing with a rasp and finishing with a new
bastard file. He should not be allowed to have hard wood until able to
file a surface so well that, on placing a metal rule across it in any
direction, it is found to be flat.
=222.= Let him then advance to brass, which, if cast, should be
previously dipped in acid to remove the hard surface, as this should
not be filed off. The resistance it offers would cause a jerky motion
of the file that would be apt to disturb the slight amount of decision
the hand has already acquired.
As brass opposes a considerable resistance, the pupil should be
carefully watched with a view to preventing too rapid movement and an
excessive pressure, involving waste of power, while he fancies the work
is being proportionately advanced; the manner in which the file is
applied to the surface should also be observed, taking care that little
or no pressure is applied during the backward stroke. The teacher
should both explain and demonstrate that the main secret of success
consists in a perfect equilibrium between the actions of the two hands;
one should increase as the other decreases with the horizontal motion
of the file, since the two levers in use, namely the portions on either
side of the point of contact, are continually the one increasing and
the other decreasing.
By filing steadily and attentively, the hands will gradually acquire
the requisite sensitiveness, or tact, that enables each to adjust the
pressure in proportion to the other, as well as the knack that enables
them to maintain the surface flat. It is important to avoid short and
jerky movements.
Practical instruction from a competent teacher must be relied on to
complete the directions here given; no written instructions can replace
it.
It is advisable to use new, or nearly new files in the above lessons;
the wear will have brought them into good condition for working iron or
steel.
Proceed with these metals as already explained in regard to brass, and
special attention must still be given in order to prevent hurry on the
part of the pupil. The files remove less metal at a time and a greater
pressure is necessary, so that he does not make such rapid progress
as with brass, and this gives rise to a tendency either to use new
files, which are soon spoilt, or to give the stroke too suddenly, while
applying considerable pressure, especially during the return stroke. He
thus heats his file, breaks off the crests of the teeth, which become
embedded in the metal and do much to further damage the file. Moreover,
he will lose some of the sensitiveness of touch that his hand has
already acquired.
=223.= It would perhaps be well to subdivide the day into three parts
for as long as appears necessary; the first to be devoted to filing,
the second to turning, and the third to forging and cold hammering.
By this means he will be quicker in acquiring the requisite skill of
hand and eye, and, when he has attained to this ability, it will be
time to practice himself in the management of various tools. Feeling
certain of himself he will soon become quick in his work.
It is prejudicial to the true instruction of a pupil and a false
economy of both time and money, to let him commence either a clock or
watch before arriving at this point. He will experience difficulty
in making even the simplest pieces, which, besides being very badly
made, will take up a long time; he will keep forgetting as he goes on,
because, owing to the slowness with which he works, the construction of
a machine occupies months, or even years, whereas it would only have
occupied a few weeks, or months, if he had possessed sufficient manual
skill to enable him to handle properly the file and graver.
We insist specially on the need of this preliminary training of the
young horologist, because, with very rare exceptions, if a pupil is set
to delicate details before he is master of his tools, he works with a
want of decision, and, therefore, with difficulty. He will, as a rule,
make a workman of but moderate ability, and will soon become disgusted
with his trade, from the mere fact that he cannot work with ease and
rapidity.
Time is an element of success; hence gratuitous apprenticeships for
short terms, that become a tax on the master if he does not soon make
use of his pupil’s services, will very seldom produce good watchmakers.
TO FILE FLAT WITH ONE HAND.
=224.= When an object is to be held on a cork or wood block fixed in
the vise, with one hand, and filed with the other hand, special care
must be taken to lay the file flat without any hesitation after each
return stroke, and the hand should be able to feel if the file is
wrong in this respect, and to at once bring it flat. After the pupil
has learned this, he will very soon be able to adjust the pressure and
the force exerted in moving the file horizontally, so that it shall
remove an equal amount from the entire surface operated upon. It often
happens that the object can conveniently be rested upon a finger of the
left-hand while the right-hand holds the file. The maintenance of the
file flat is in that case much easier.
=225.= _Mechanical device for filing flat._ This (the _pradel_)
consists in placing behind the workman a horizontal bar, on which rests
one end of the file handle, prolonged for the purpose to about a yard
in length; thus the file has two points of support: the bar, adjusted
at a convenient height, behind the workman, and the object to be filed
flat fixed in the vise in front.
This method, while convenient for amateurs, may be utilized in teaching
an apprentice, letting the supports be hinged at one and press at the
other end on a rather strong spring index, which must be prolonged so
as to be brought under the eye of the pupil.
The displacement of the index will show him every false movement of his
hands, and will guide him in adjusting them. It would be best if the
prolongation of the handle were as light as possible, but rigid and
arranged so that the file can be held naturally.
TO TURN CYLINDRICAL PIVOTS, ETC., AND SQUARE SHOULDERS.
=226.= Just as in working with the file, advice and demonstration by a
good master are here indispensable.
The materials should be worked in the same order as is explained in
parts =221-4=; that is: wood, brass, iron, steel, hardened and tempered
steel; no one sample being set aside until the student can turn it
perfectly round, flat on shoulders, etc., and smooth throughout.
He should turn for a long time, whether it be by the lathe or bow,
exclusively with the point of a square, or lozenge-shaped graver, the
end of which is ground off on a slope; this is the only possible method
of learning to turn true, and it enables the workman to acquire great
delicacy of touch.
Owing to carelessness, or to the fact that, when first beginning, they
were set to work on metal that was too hard or rough, most learners
turn with gravers that are ground to very blunt points; as the graver
bites less, they are obliged to apply a proportionately increased
pressure, and only succeed in tearing the metal away, subjecting it to
a kind of rolling action, and rendering the hand heavy. If a pupil will
not practice turning with the graver point, so as to preserve it intact
for some time, dependent on the nature of the metal, he will never be
able to turn perfectly true.
The bow should be used through its entire length, and with a motion
that is progressive, not jerky. The knack of the turner with the
bow consists mainly in keeping the simultaneous actions of the two
hands quite distinct; one drawing the bow downwards, while the other
depresses the point of the graver supported on the =T=-rest, and these
two movements of the hands must be performed at the same time, but
quite independently.
Irregular and sudden depressing of the graver point, or engaging it
too deeply, causes its frequent rupture. This also sometimes arises
from the fact that the point is not removed with sufficient rapidity,
so that on raising the bow the metal catches it while traveling in the
reverse direction; the graver is thus drawn slightly towards the work,
and its point will be found too close in when the bow again descends.
As has been already observed, the bow, which must not be too short,
should be used to its full length with a regular, but not rapid motion.
Afterwards, when the hand has learnt how to manage the graver, the
speed can be gradually augmented. There is always a danger of losing
time, teaching, and, therefore, money, if pupils are too much hurried
in their lessons. Before trying to work quickly, they should, at any
rate, know how to work fairly well.
Short and sudden movements of the bow will make the object turned jerk;
it will be heated, and the sharp angles of the graver will jamb in the
metal; thus there is less work done, although there is more noise, and
this is done badly.
=227.= When sufficient experience has been gained in turning with
the graver point, and a trial is made with the cutting edge, do not
attempt to remove much at a time by pressing heavily, but take the
metal sideways so as to remove a continuous thread, using all the
points of the edge in succession and the entire length of the bow. The
metal will thus be removed as a thin ribbon or shaving. When the hand
has had some experience, it will be found easy to remove long strips,
and the work can be done quickly, although there be no hurrying in the
movement of the bow. These remarks are equally applicable to turning
with a lathe.
=228.= Hardened steel that has been let down to a blue temper requires
certain precautions. If the graver is found not to cut cleanly, it must
at once be sharpened, and no attempt should be made to remove more
metal by increasing the pressure of the hand, because the steel will
burnish and become hard under a point or edge that is blunt, and the
portions thus burnished are sometimes so hard as to resist the best
gravers. The only way of attacking them is to begin at one side with a
fine graver point which must be sharpened for each stroke; at times it
becomes necessary to temper the metal afresh before it will yield. It
is asserted that by moistening the point of the graver with petroleum
it becomes more able to attack hard substances, and that a mixture of
two parts petroleum and one part turpentine enables it to turn very
hard steel with comparative ease. Indeed, for all turning it is a
common practice to moisten the graver with oil, water, turpentine, or
simply by introduction into the mouth.
We have frequently seen apprentices, and even watchmakers, themselves,
careless as to the proper sharpening of their gravers and thinking
that they could hasten their work by the application of considerable
pressure; they thus produced bright spots that required several hours
of work before they could be removed.
There is one essential condition for ensuring good work with the lathe,
and this consists in the perfect roundness of the points or holes of
the runners or centers, and of the holes or points that are supported
in them; this perfect truth is nevertheless very rarely met with, for
it is noticeable that barely one watchmaker in ten knows at the present
day how to roll such a point. We shall subsequently indicate the
precautions to be observed in order to secure this accuracy.
The diameter of ferrule is also to be considered; if it is too small,
the bow will slip and the object will only rotate by jerks; if too
large, it loads the object unnecessarily and the velocity of rotation
is reduced, since for the same stroke of the bow the ferrule must make
a less number of turns. Moreover, if it is of large diameter, only a
light bow must be used, because otherwise the force applied would be
excessive.
Swiss workmen—at least the great majority of them—turn with the right
or left-hand indifferently. This is a very useful accomplishment easily
acquired when young.
The working of various tools, such as the English or Geneva mandrel,
and any lathe driven by a treadle, will be a great help in developing
the sense of touch and in making it more certain.
But it must not be forgotten that, in order to turn well, the lathe
must be well made and planned; without this, no accurate work can be
done. The lathe is the first and most important of tools, and a great
number of very serviceable accessories can be added to it, which,
unfortunately, but few watchmakers know how to make properly. As a rule
they content themselves with a simple pair of finishing turns on which
but a comparatively small amount of work can be done.
Without committing the mistake of having a too great multiplicity of
tools, let the pupil rest certain that a well-planned set of tools in
good condition both facilitates and abridges his work and renders it
more perfect.