IMPROVEMENTS IN THE CONSTRUCTION OF PENTAGRAPH MACHINES
Year: 1881

page_text: LETTERS PATENT to John Hope, of Providence, Rhode Island, in the United
States of America, but at present residing at Manchester, in the County of
Lancaster, for an Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF
PENTAGRAPH MACHINES."
(Void by reason of the Patentee having neglected to file a Specification in
pursuance of the conditions of the Letters Patent.)
PROVISIONAL SPECIFICATION left by the said John Hope at the Office of
the Commissioners of Patents on the 6th September 1881.
"
JOHN HOPE, of Providence, Rhode Island, in the United States of America, but
at present residing at Manchester, in the County of Lancaster. IMPROVEMENTS
IN THE CONSTRUCTION OF PENTAGRAPH MACHINES."
The Invention relates to the construction of the well known machines used for
engraving copper printing rollers called "pentagraph machines," the object of the
Invention being to produce certain effects not hitherto obtainable by means of such
machines.
The first part of the Invention relates to the "stylus" or tracing point, which
instead of being permanently fixed in the tracer-carrier as usual, is so attached
thereto that it can be caused either to revolve merely upon its own axis so as to
mark a point, or to make a small circle, the diameter of which can be graduated or
regulated as required.
In the socket of the tracer carrier where the the stylus or tracer is usually fixed I
place a conical pin capable of revolving, and having a small winch handle fixed at
its upper end. At its lower end is attached a small fixing or bracket carrying a
worm wheel and a worm or screw in gear therewith.
The stylus or tracer (which I prefer to make with a diamond point) is fixed in a
socket in the lower face of the worm wheel at a point which (which when the
worm wheel is in a certain position) is coincident with the centre of the conical
D
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page_text: pin above named, so that when in this position it acts as an ordinary stylus or
tracer, excepting that it can be made to revolve by the winch handle. When the
screw or worm however is caused to revolve (being provided with a flattened bead
for that purpose) it brings the stylus or tracer into a position more or less excentric
with regard to the conical pin, and on revolving the latter by the winch handle the
tool is caused to make a circle upon the face of the copper roller, the diameter of
the said circle depending upon the amount of excentricity given to the stylus or
tracer. The worm is provided with a notched disc, and the bracket with a spring
catch, so that it can be set and held to the exact amount of excentricity required,
according to the size of circle wanted, and the winch handle is provided with a
small set screw, by means of which it can be set and held in a concentric position
when the tool is not required to make circles.
The object of the second part of the Invention is to make zig-zag lines, and this
part of the Invention is attached to the main carriage of the machine. It consists
principally of a hinged nut attached to the carriage working on a long screw. The
end of the screw is attached to the end of a short shaft carried in bearings, but a
variable amount of excentricity with regard to the axis of the shaft can be given
to the screw, so that as the short shaft revolves in its bearings the screw has a
compound movement given to it, and at the same time that it draws the carriage
along by the screw working in the nut the excentric movement of the screw gives
a rapid transverse to and fro motion to the nut, and the latter being connected by
a rod to the diminishing gear gives a corresponding motion to the tool carriage, and
the result is that the tool makes a zig-zag line on the copper, the breadth of the
zig-zag corresponding with the amount of excentricity given to the screw with
regard to the axis of the short shaft, to the end of which it is.connected.