Improved Centering Tool.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improved Centering Tool.
JONATHAN JACKS Blacksmith 65 Upper Orwell Street Ipswich Suffolk do
hereby declare the nature of this invention to be as follows :—
When parts of machines are to be joined together by bolts and some of the parts
have holes and the other parts, to be joined thereto have not, the usual practice is
to lay the parts together and scribe round the holes of the one part so as to make
circles for the holes on the other parts. The centre of these circles have then to
be found by the aid of compasses or other means. Now my improved centering
tool very much facilitates this operation. It is constructed as follows:-It will be
readily supposed that these centering tools will serve for holes of various ranges
of size but for explanation I will describe one which would serve for holes from "
todiameter. A tube diameter outside and about 4 inches long, has legs.fitted
to the interior, these legs are about one inch long their upper ends being shaped
like a pin are inserted into holes through the thickness of the tube. The lower
ends of the legs (which may be called feet) play in notches in the lower end of the
tube, the legs thus swing on the upper ends, so that the outer edge of the feet may
be either flush with the outside of the tube or project of an inch beyond the tube
and so fit a inch circle.
A second tube fits inside the one just described and has grooves on its outer
surface, corresponding with and fitting over the backs of the legs which are so
inclined that when the inner tube is pushed downward the feet of the legs are
forced outward until they meet the sides of the hole into which the tool is placed.
The inner tube is bored to receive a turned centre-punch which will give the true
centre of the circle. In cases where holes are to be punched, I remove the centre
punch and substitute a brush to make the usual print mark, or the centre punch
may be retained to operate at the same time as the brush, that is passing through
the centre of the brush.
Deted this 2nd day of April 1805
Improved Centering Tool.
I, JONATHAN JACKS of 65 Upper Orwell Street Ipswich in the County of
Suffolk, Blacksmith 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:-
My invention relates to a improved centering tool or appliance by which when
parts of machines are to be joined together by bolts or rivets and some of the parts
have the holes and the other to be joined thereto have not.
My improved centreing tool very much facilitates this operation.
constructed as follows.
It is
A tube having legs fitted to the interior, these legs are made with a boss on the
outer side so as to fit through the thickness of the tube the lower end of legs play

page_text: in notches in the lower end of the tube, the legs thus swing on the boss so that the
outer edge of legs may be either flush with the outside of the tube or project beyond
the tube.
A second tube fits inside the one just described and has grooves on its outer
surface corresponding with and fitting over the backs of the legs which are so
inclined that, when the inner tube is pushed downward the feet of the legs are
forced outward untill they meet the sides of the hole into which the tools are
placed.
The inner tube is bored to receive a turned centre punch. To use the above
described tool, a tap being given to the head of the centre punch aforesaid a slight
indention will be made by the pointed end of the punch in the object to be operated
upon which will give the true centre of the circle.
The proceeding particulars have reference to centreiug various objects to be
jointed together.
In the accompanying drawings illustrative of my invention in the drawing A
is a plan view of the centre punch, B is the inner tube, C the outer tube
hereinfore referred to, D is set screw for keeping B and C in position.
E is the slot in which D works, F is the groove on inner tube H hole for the
boss of the legs to work in, I is the notches of the outer tube, G legs.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed,
I claim all tools constructed in the manner and principle heretofore described.
Dated this 28th day of December 1895.
JONATHAN JACKS,
65 Upper Orwell Street, Ipswich, Suffolk.