Improvements in the Manufacture of Billiard-balls.
Year: 1893

page_text: Date of Application, 24th Aug., 1893-Accepted, 7th Oct., 1893
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Billiard-balls.
1, PETTER ADOLF ÖSTBERG, of 10 Bryggaregatan, Stockholm, in the Kingdom
of Sweden, Engineer, 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 well known, that it becomes more and more difficult to procure good billiard-
balls, as ivory becomes more and more scarce and attempts to make billiard-balls
from other materials, such as hard wood, rubber, celluloid, and the like have not
proved successful.
I have succeeded in making billiard-balls from iron and steel quite equal to
those made from ivory, both as regards their elasticity and their correct evenness
or uniform heaviness.
As far as my experience goes, my billiard-balls are moreover more durable than
those made from ivory. Further, I can make them at same time equal in size
and weight to those of ivory. The billiard-ball is made hollow and as nearly as
possible of even thickness all round. As raw material I use either steel, which is
afterwards hardened or mild iron, which is afterwards case hardened.
I have made billiard-balls from two pressed segments of spheres, screwed or
soldered together; but such balls have not proved to be durable, as the joints will
readily break up and the edges at the joints get broken almost at once. I prefer
either to make the balls from two pressed segments of spheres and unite these by
means of electric welding or to cast the balls. In the latter case both the mould
and the core must be made with the utmost care so that the cast shell will be free
from blowholes, smooth and of as regular a thickness as possible; for the purpose
of supporting the core during the operation of casting as well as for the purpose of
removing the core afterwards, the shell is provided with a small hole.
The core is carefully removed from the casting and the hole is carefully filled up
with a plug from the same raw material and of about the same thickness as the
shell and the plug being carefully united preferably by means of electric welding.
The ball is then turned perfectly round and pretty well polished, so that the surface
is smooth.
Out of several hundred balls already made I have not as yet found a single one,
which after being thus turned is of a truly uniform heaviness, without special
adjustment I have always found that the centre of gravity does not coincide with
the centre of the sphere. The ball is therefore examined on a horizontal polished
metallic plan, whereby the heavier half of the ball turns down and the lighter half
turns up. The ball is then adjusted.
If the irregularity is only extremely small, the adjustment may be effected
simply by drilling in the centre of the heavier half a very small perforation, which
if sufficiently small does not injure the ball; or several small holes may be drilled
regularly around the centre of the heavier half. If the irregularity is greater, as
is usual, the adjustment may be effected by drilling a hole in the centre of the
lighter half of the ball and filling the hole with a plug of just sufficient weight
to shift the centre of gravity so much that it coincides with the centre of the
sphere.
The adjustment however may be effected by again turning the ball, for which
purpose it is so placed in the lathe that, by taking away the least amount of
material from the centre of the lightest half and the most from the centre of the
heaviest half, the centre of gravity is made to coincide with the centre of the
sphere. The two last mentioned methods of adjusting the ball, although they may

page_text: appear difficult and unreliable are in fact quite easy for a skilful workman after
some practice.
After turning the adjusted ball into its proper size and polishing it perfectly, it
is hardened, if made from steel, and case hardened, if made from soft iron.
The characteristic properties of a billiard-ball, are: (1) It must be perfectly
spherical, so as to roll easily and smoothly. (2) It must be perfectly elastic, so as
not to change its form permanently on striking against another ball or other hard
body. (3) It must be perfectly correct or uniform as regards its heaviness,
depending upon the centre of gravity coinciding with the centre of the sphere, so
as to make the ball roll in a perfectly straight line, when rolling either quickly or
slowly. The word "perfectly" indicating such a high degree of the respective
qualities, as is practically possible to obtain, or as is possessed by an ivory ball.
I am well aware that spherical balls of metal have previously been made and
used for different purposes, such as shots, bullets cartridges, balls for seats in
pumps, balls for bearings and the like. But none of these metallic balls, whether
solid or hollow, has possessed such qualities as are hereinabove mentioned as
essential for a billiard-ball, viz. perfect elasticity and perfect uniformity as regards
heaviness. I do not therefore claim as my invention any kind of hollow metallic
ball, but only such a hollow metallic ball, which is both perfectly spherical and
through its hardness perfectly elastic and perfectly adjusted so that the centre of
gravity and the centre of the ball coincide, all which qualities combined make the
ball a billiard-ball.
Billiard-balls as hitherto existing have been made from ivory, hard wood, rubber
or celluloid and have been solid; the billiard-balls which are the subject of my
invention, are made from hardened iron or steel and are hollow.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:~
The herein described billiard-balls, made hollow, from hardened steel or case-
hardened iron.
Dated this 24th day of August 1803
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.