Improvement in Lathe for Turning Printing Plates.
Year: 1892

page_text: Date of Application, 17th Sept., 1892
Complete Specification Left. 17th June, 1893—Accepted, 2nd Sept., 1893
PROVISIONAL SPECIFICATION.
Improvement in Lathe for Turning Printing Plates.
I, ALEXANDER GRAY of The Mansion, Frognal, N.W., Consulting Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention consists in the use of one or more rollers which are pressed by
springs or weights against the plate close to the tool whilst the plate is being
turned, so that the printing surface may be brought hard up against the face plate
of the lathe in spite of any small degree of buckling which may exist in the printing
plate, and the thickness of the plate thus turned be thereby rendered more uniform
than as hitherto done.
tomboy 1000
COMPLETE SPECIFICATION.
Improvement in Lathe for Turning Printing Plates.
I, ALEXANDER GRAY of The Mansion, Frognal, London, N.W. 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:—
This invention consists in the use of one or more rollers by which the plate to be
turned or faced up is held down in contact with the face plate of the lathe, close
to the tool.
"
Plates for printing from, known as " stercos or ❝ electros have hitherto been
faced up in a lathe of the ordinary form in which the face plate revolves in a
vertical plane, and the plates are held in the lathe by means of a jaw chuck, the
jaws of which are worked by screws. If too much pressure is applied by the
screws, the plates get sprung, and when taken off the chuck spring back again, so
that the truth of the surface is destroyed. It is also a matter of considerable
difficulty to fix the plates in the chuck so that they bed fairly on it, and if the
printing surface of the plate is not true, the plate often projects at one corner or
edge, and this corner or edge in such case becomes thinner than other parts of the
plate, involving extra care and trouble in preparing the plate for printing from.
To avoid these disadvantages of the usual method of facing up printing plates,
I use a lathe by preference in which the face plate or chuck revolves in a horizontal
plane as shown in Fig. 1 of the annexed drawing.
In the drawing, Fig. I is an elevation of the lathe and Fig. II a section on an
enlarged scale showing the roller used for keeping the plate firmly down on the
face plate.
A is a circular pedestal, B is the face plate, driven by a belt over a pulley A¹
through mitre wheels A' and the shaft A*.*
C is a plate to be faced up, laid on the face plate and held in place laterally by
means of dogs, (not shown in the drawing). D is one of a pair of brackets-sup-
porting the slide E which extends across the top of the pedestal from one side to
the other. Sliding on this slide is a saddle E' carrying a vertical slide F, worked
by the hand wheel F', and having on it a tool box F in which the tool holder G is
held. G is the tool. The saddle E' is worked across the slide automatically or
by hand in the usual way by a screw.
H is a lever rocking on a bar I, which extends from one bracket to the other.
On this rod I the lever H slides, so that it can travel along with the tool G³, when
TD 07

page_text: pushed by the bracket O, to which it is attached by a bolt sliding up and down in a
slotted hole in the bracket O. This bracket O is bolted firmly on to the saddle E¹.
The lever H carries a roller K shown in detail in Fig. II. This lever is caused to
press down the roller K on to the plate with any desired degree of force by means
of a weight L on the lever H. This weight pulls the lever H down until its
movement is stopped by the roller M meeting the bar N. This bar N extends
across the front of the pedestal horizontally as far as the roller M on the lever H
travels, so as to support the weight L constantly at the same level.
P is a right and left handed nut whereby to adjust the pressure of the roller K
on the plate C.
I
The roller attached to the lever H is thus caused to travel along with the tool
and remains always close to it, holding the plate down firmly against the cut.
sometimes use two rollers or even three, and then place them on each side of and
in front of the tool. For small plates two rollers are desirable to ensure the
corners and edges of the plates being held down firmly, as a single roller would
sometimes not be in contact with the plate at the beginning or end of the cut.
In Fig. II, H is the lever with a boss on one side; this boss is bored and lined
with a bush K. K is a roller the periphery of which may be of metal, leather,
hard rubber or soft rubber as preferred, or of other suitable material. If of leather
or metal it is provided with a ring of rubber K' inside, but if made in rubber, the
peripheral part and K¹ may be made in one piece. The roller is mounted on a
revolving spindle K³.
When I use only one roller, I make the outer ring of leather, but when I use
two rollers, I make the outer part of that one nearest the centre of the face plate
of steel, and the outer part of the other roller of leather or of hard rubber. The
roller or rollers may be pressed against the plates as they revolve by means of
springs, levers, weights, or by a combination of these means.
To use the lathe one or more plates are laid on the face plate B, and are fixed
laterally by means of dogs or stops; the lever H is now so adjusted that the
rollers K press the plates down with sufficient force to resist any upward force
applied by the action of the tool, and at the same time to take any slight buckling
out of the plate which may tend to raise it in places from the surface of the face
plate B.
The tool G¹ is now adjusted to cut the plate down to within 32" of the thickness
required; the lathe is started, the tool is fed across the plates and back again.
The tool is now adjusted to the thickness of plate required to be produced, and a
fine cut taken, which leaves the plates true and of uniform thickness all over
within 001", if the lathe is carefully worked.
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 ;
1. A lathe, either of the vertical or horizontal type, in which printing plates are
kept against the face plate close to the tool by means of one or more rollers, pressed
against the plates as they revolve by means of springs levers or weights or com-
binations of these means.
2. The special arrangement of rocking and sliding lever H carrying a roller,
with the weight L attached limited in its movement by the stop roller M running
on a horizontal bar N.
3. The construction of roller shown in the detail drawing Fig. II consisting of a
.metal or leather peripheral part with a lining of rubber K³.
Deted this 19th dow of June 1802
ALEXR. GRAY.