Wheels for Watches and Chronometers.
Year: 1886

page_text: Wheels for Watches and Chronometers.
I, PHILIP ARTHUR NEWTON of the Office for Patents, 6 Bream's Buildings,
Chancery Lane, in the County of Middlesex, Patent Agent, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
It is a known fact that watches with ordinary compensation balances, composed
of brass and steel, are unfortunately subject to important causes of disturbance, the
principal of which are rust and electric and magnetic influences.
Under the influence of electricity or magnetism, the ordinary steel and brass
balance becomes magnetized, and practically a compass, in consequence of which
the regularity of the watch is destroyed. The result is also the same if any part of
the works, a case-spring for instance, becomes magnetized, even when the balance
is not so affected.
It has been sought to remove these difficulties by manufacturing the balance
from metals which are neither oxidizable nor magnetic. As the result of these
experiments, a compensation balance has been constructed composed of two
different metals, the inner rim being of palladium alloy, and the outer rim of silver
or brass.
The description of said alloy is given fully in the specification accompanying an
application for a patent N° 6367, dated May 11th 1886..
The following is the process for manufacturing the balances :-
After melting the alloy, the molten metal is poured into a mould to form a plate.
This plate, when cold, is forged or bammered, being frequently heated to red heat,
if becoming too hard, until the desired thickness is obtained. There is then
stamped out, by means of a die, a disc, in the centre of which a hole is pierced,
and the disc is turned true, so as to attain the shape indicated in Fig. 1. The hole
and the one side of the disc is then filled up and covered with a fire-proof clay, or
any such suitable material (plumbago for instance), see Fig. 2, which is allowed to
dry on the disc, so that the latter, in all its parts so covered, will not be touched

page_text: by the second metal in the subsequent operation. The so prepared disc is now
inserted in a crucible, in which pieces of brass or silver and borax are placed and
melted, the crucible being introduced into a muffle furnace. The molten metal
will form a rim around the disc, in the manner indicated in Fig. 2. If preferred,
the silver rim may be produced by depositing this metal by a galvanic process.
The melting of the metal around the alloy disc will require some skill or
experience, inasmuch as care must be taken that the metal is not heated more than
required for melting the same, so as to avoid melting of the alloy disc, or even to
avoid the molten metal attacking the alloy disc. If the rim or ring is made of
brass, the melting of the latter may be facilitated by an ample addition of zinc,
which may form 40 to 50 per cent of the brass. In using silver, about 20%
of zinc may be added. The ample addition of zinc offers this advantage, that the
metal becomes more expansible, and thereby increases the function of the bimetallic
balance. If silver is deposited by the galvanic process, this will require the
employment of screws or heavy masses, for the compensation to be a sufficient one.
The rest of the work for making the balance is an entire mechanical one, and
does not differ materially from the method heretofore in use.
First, the excess of metal is removed by means of a file or a hand-tool-lathe, and
then the centre part of the disc, either from one side, or from both sides, is
hollowed out, so that in this centre part there remains a thickness only, corre-
sponding to the thickness of the middle arm, which is to be cut out, care being
taken to preserve a bimetallic rim of such width, that it is composed by ½ of
palladium alloy and by of brass or silver. By partially removing the remaining
central part of the disc (by filing or otherwise), the central arm or arms for the
central pin are formed, so as to complete a balance, as represented in cross section
and plan, Fig. 3.
The boring of the screw holes and the cutting of the thread in them, is made by
means of a dividing engine.
The arm or arms of the balance, as well as the interior of the bimetallic rim are
generally tempered, whereas the exterior, and the faces of said rim, may be
polished.
It is desirable, in order to give hardness, to heat the balance in the same way
as for tempering hair springs. The bimetallic rim of the balance is then cut
toward the arms, and provided with its screws or set weights. It is then ready
for use.
It will at once be seen that balance wheels manufactured according to this
invention are practically indestructible, and electric or magnetic action, no matter
how strong, will have no effect on them; they will also resist rust, or the action of
acid vapours, or the salt air of the ocean.
! Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
Manufacturing compensation balance wheels for watches and chronometers in
the manner above described and shown in the accompanying drawings, for the
purpose set forth.